ARRT MRI Exam — Questions and Answers

Question 1: Which MRI phenomenon occurs when protons at the boundary of fat and water tissues experience a frequency offset, causing a dark or bright band?

Magnetic susceptibility artifact
Gibbs ringing
Wraparound (aliasing) artifact
Chemical shift artifact (Correct answer)

Correct answer: Chemical shift artifact

Chemical shift artifact results from the ~3.5 ppm frequency difference between fat and water protons, causing spatial misregistration along the frequency-encode direction.

Question 2: A method of expressing the gradient performance in terms of T/m/s, which is the gradient magnetic field's acceleration to its maximum amplitude.

Slew rate (Correct answer)
Coil configuration
Rise time

Correct answer: Slew rate

Slew rate is a critical performance metric for MRI gradient coils, measuring how quickly a gradient can reach its maximum strength. It is expressed in Tesla per meter per second (T/m/s), representing the acceleration of the gradient magnetic field. A higher slew rate allows for faster switching of gradients, which translates to quicker image acquisition and shorter echo times, improving overall scan efficiency.

Question 3: What is the Specific Absorption Rate (SAR) a measure of in MRI?

Speed of gradient switching in Tesla per meter per second
Rate of image data acquisition in k-space
Contrast agent uptake rate in tissue
Rate at which radiofrequency energy is absorbed by the patient's tissue per unit mass (Correct answer)

Correct answer: Rate at which radiofrequency energy is absorbed by the patient's tissue per unit mass

SAR (W/kg) quantifies RF energy deposition in tissue and is a primary safety limit to prevent excessive tissue heating during MRI.

Question 4: IV line tubing and monitoring cables used inside the MRI suite must be:

Made of stainless steel only
MR-conditional equipment specifically rated for use in the magnetic field (Correct answer)
Removed prior to scanning and replaced after
Standard clinical-grade equipment from any hospital supply

Correct answer: MR-conditional equipment specifically rated for use in the magnetic field

All equipment used within the MRI environment must be labeled MR-conditional or MR Safe to prevent projectile events, burns, or device malfunction.

Question 5: Which MRI-specific safety topic is explicitly listed under the ARRT exam content specifications within Patient Care and Education?

Screening for implants and metallic foreign bodies (Correct answer)
Radiofrequency power amplifier maintenance
Gradient coil winding techniques
Cryogen manufacturing standards

Correct answer: Screening for implants and metallic foreign bodies

Screening patients for implants and metallic foreign bodies is a core patient safety responsibility explicitly included in the content specifications.

Question 6: What determines the slice thickness in a standard 2D MRI acquisition?

The number of phase-encoding steps
The repetition time and echo time
The bandwidth of the RF pulse and the slope of the slice-select gradient (Correct answer)
The field of view and matrix size

Correct answer: The bandwidth of the RF pulse and the slope of the slice-select gradient

Slice thickness = RF bandwidth / (gyromagnetic ratio × gradient strength); a wider RF bandwidth or shallower gradient yields a thicker slice.

Question 7: What is the preferred patient position and coil for imaging the rotator cuff of the shoulder?

Sitting upright, surface coil
Supine, arm at side in neutral rotation, dedicated shoulder coil (Correct answer)
Supine, arm abducted 90°, flex coil
Prone, body coil

Correct answer: Supine, arm at side in neutral rotation, dedicated shoulder coil

Supine positioning with the arm at the side in neutral rotation and a dedicated shoulder coil provides optimal SNR and comfort for rotator cuff imaging.

Question 8: MR spectroscopy (MRS) of the brain measures metabolite concentrations. Which metabolite, reduced in neuronal loss and gliosis, is considered a marker of neuronal integrity?

Choline (Cho)
Creatine (Cr)
Lactate (Lac)
N-acetylaspartate (NAA) (Correct answer)

Correct answer: N-acetylaspartate (NAA)

NAA (N-acetylaspartate) is located predominantly in neurons; its reduction indicates neuronal loss or dysfunction, making it a key spectroscopic marker of neuronal integrity.

Question 9: Phase contrast MRI (PC-MRI) is primarily used to measure:

Tissue T1 values
Chemical metabolite concentrations
Velocity and flow of fluids such as blood and CSF (Correct answer)
Myelin content

Correct answer: Velocity and flow of fluids such as blood and CSF

PC-MRI encodes velocity as phase shifts of moving spins, allowing quantitative measurement of blood flow velocity and volume, and CSF pulsation.

Question 10: Which classification of GBCAs carries the LOWEST risk for NSF based on ACR guidance?

Group II (linear non-ionic)
Group III (macrocyclic) (Correct answer)
Group I (linear ionic)
All GBCAs carry equal NSF risk

Correct answer: Group III (macrocyclic)

Macrocyclic GBCAs (Group III) have a more stable cage-like structure that resists transmetallation and are associated with the lowest NSF risk.

Question 11: Which of the following is a mandatory competency category that must be documented before a student can sit for the ARRT MRI registry?

MRI-guided biopsy procedures
Head MRI without contrast (Correct answer)
Cardiac MRI stress testing
MRI-compatible pacemaker implantation

Correct answer: Head MRI without contrast

Head MRI without contrast is among the required clinical competencies students must document as part of ARRT's clinical requirements.

Question 12: Which k-space trajectory fills the center of k-space first, providing low-spatial-frequency (contrast) information early in the acquisition and reducing motion sensitivity?

Reverse linear ordering
EPI single-shot trajectory
Linear (sequential) k-space filling
Centric (elliptic centric) k-space ordering (Correct answer)

Correct answer: Centric (elliptic centric) k-space ordering

Centric k-space ordering acquires the low-frequency center of k-space at the beginning of the scan, capturing image contrast during peak enhancement and minimizing motion effects on image quality.

Question 13: The landmark for centering an MRI brain exam using a head coil is located at:

Occiput
Top of the skull
Nasion or bridge of the nose (Correct answer)
External auditory meatus

Correct answer: Nasion or bridge of the nose

The nasion (bridge of the nose) is the standard external landmark used to center the isocenter of the MRI system for brain imaging.

Question 14: A candidate applying for the ARRT MRI registry via the post-primary pathway must hold a primary ARRT certification in which of the following disciplines?

Dental radiology
Medical dosimetry
Medical assisting
Radiography, nuclear medicine, radiation therapy, or sonography (Correct answer)

Correct answer: Radiography, nuclear medicine, radiation therapy, or sonography

The post-primary pathway requires a current, active ARRT primary credential in an approved imaging or therapy discipline.

Question 15: A technologist who holds an RT(MR)(ARRT) credential and allows it to lapse must complete which process to reinstate it?

Complete only a practical competency evaluation
Retake the full MRI registry examination
Apply for reinstatement and fulfill CE requirements (Correct answer)
Resubmit all original application materials and retake the exam

Correct answer: Apply for reinstatement and fulfill CE requirements

ARRT allows lapsed credential holders to reinstate by applying for reinstatement and meeting outstanding CE obligations.

Question 16: Iron oxide nanoparticles (e.g., USPIO) used as MRI contrast agents primarily shorten which relaxation time?

T2 only with no T2* effect
T1 only
T2 and T2* (susceptibility effect) (Correct answer)
Neither T1 nor T2

Correct answer: T2 and T2* (susceptibility effect)

Iron oxide particles create local magnetic field inhomogeneities that predominantly shorten T2 and T2*, causing signal loss (darkening) on T2-weighted and gradient echo images.

Question 17: On a T1-weighted MRI, which substance normally appears hyperintense (bright)?

Subacute blood (methemoglobin) (Correct answer)
Cerebrospinal fluid
Edema
Cortical bone

Correct answer: Subacute blood (methemoglobin)

Methemoglobin in subacute hemorrhage shortens T1 relaxation time, producing a bright signal on T1-weighted images.

Question 18: Which property of hydrogen makes it the most commonly used nucleus in clinical MRI?

High natural abundance and large magnetic moment (Correct answer)
Absence of electron cloud interference
High atomic number and radioactivity
Low atomic mass and zero spin

Correct answer: High natural abundance and large magnetic moment

Hydrogen (¹H) is abundant in the body and has a large gyromagnetic ratio, producing strong MRI signals.

Question 19: Which MRI sequence is most sensitive for detecting early bone marrow edema in stress fractures?

Proton density without fat saturation
GRE in-phase
STIR or fat-saturated T2 (Correct answer)
T1-weighted SE

Correct answer: STIR or fat-saturated T2

STIR and fat-saturated T2 sequences suppress the bright fat signal of normal marrow, making the high-signal edema of stress fractures conspicuous.

Question 20: Which MRI finding is characteristic of a benign rotator cuff tear involving a full-thickness supraspinatus tendon rupture?

Fluid signal gap (T2 bright) extending through the full thickness of the tendon (Correct answer)
Low signal on all sequences through the tendon
T1 bright signal in the tendon
Low T2 signal with thickening of the tendon

Correct answer: Fluid signal gap (T2 bright) extending through the full thickness of the tendon

A full-thickness tear shows fluid (T2 hyperintense) extending completely through the tendon from bursal to articular surface.

Question 21: Which MRI registry credential is awarded by the American Registry of Radiologic Technologists (ARRT) for MRI technologists?

RMT(ARRT)
RT(MR)(ARRT) (Correct answer)
MRI(ARRT)
MR(ARRT)

Correct answer: RT(MR)(ARRT)

The ARRT awards the RT(MR)(ARRT) credential to registered technologists who pass the MRI examination.

Question 22: In the ACR zone system, who is responsible for controlling access to Zone III?

Radiology technologists only
MR-trained non-MR personnel
Level 2 MR personnel (Correct answer)
Any hospital staff with ID badge

Correct answer: Level 2 MR personnel

Zone III access must be controlled by Level 2 MR personnel (those with full MR safety training) to prevent non-screened individuals from entering.

Question 23: A T1 hyperintense (bright) lesion in the brain is most consistent with which finding?

Pure fluid-filled cyst
Acute infarct
Vasogenic edema
Subacute blood or fat-containing lesion (Correct answer)

Correct answer: Subacute blood or fat-containing lesion

T1 hyperintensity in the brain is classically associated with subacute hemorrhage (methemoglobin), fat, protein-rich fluid, or melanin.

Question 24: Gadolinium contrast extravasation at the IV injection site is classified as which type of adverse event?

Non-allergic physiologic reaction
Local injection site reaction (extravasation) (Correct answer)
Vascular reaction
Allergic-like reaction

Correct answer: Local injection site reaction (extravasation)

Extravasation occurs when contrast leaks from the vein into surrounding tissue; it is a local injection site reaction, not a systemic allergic event.

Question 25: This magnet has a strength of up to 0.3 T, can be switched off, and can be used in both horizontal and vertical field systems.

Resistive magnet (Correct answer)
Selenoid magnet
Superconducting
Permanent magnet

Correct answer: Resistive magnet

Resistive magnets consist of coils of wire through which a large electric current is continuously passed to generate a magnetic field. They can be switched off, offer field strengths typically up to 0.3 Tesla, and can be designed for both horizontal and vertical field orientations. However, they require significant continuous power and generate substantial heat, limiting their use in high-field MRI.

Question 26: What is a 'quench' in MRI terminology?

A patient motion artifact
A sudden loss of superconductivity causing helium boil-off (Correct answer)
A gradient coil failure
A rapid increase in field strength

Correct answer: A sudden loss of superconductivity causing helium boil-off

A quench occurs when the superconducting magnet loses its superconducting state, causing liquid helium to vaporize rapidly and potentially displacing oxygen in the room.

Question 27: What term describes an object becoming a high-speed projectile when brought near a strong MRI magnetic field?

Missile effect (Correct answer)
Quenching effect
Gradient artifact
Susceptibility effect

Correct answer: Missile effect

The missile effect (or projectile effect) occurs when ferromagnetic objects are rapidly accelerated toward the bore by the strong static magnetic field.

Question 28: MR Conditional implants are safe to scan only when:

The scan time is under 30 minutes
Specific conditions of field strength, SAR, and gradient limits are met (Correct answer)
The patient gives verbal consent
The radiologist approves verbally

Correct answer: Specific conditions of field strength, SAR, and gradient limits are met

MR Conditional devices are safe only when the defined conditions of use (field strength, SAR, gradient dB/dt, scan duration) are strictly followed.

Question 29: Magnets formed of ferrous material found naturally or from blocks or slabs.

Permanent (Correct answer)
Selenoid
Reistive
Superconducting

Correct answer: Permanent

Permanent magnets are created from naturally occurring ferromagnetic materials or specially treated blocks of ferrous material. These magnets retain their magnetism without requiring an external power source. They produce a constant magnetic field and are typically utilized in low-field MRI systems, offering a simpler and less costly design.

Question 30: A 'corduroy' or 'herringbone' artifact covering the entire image is most often caused by:

A spike (impulse noise) in k-space (Correct answer)
Gradient eddy currents
Patient motion
RF transmitter miscalibration

Correct answer: A spike (impulse noise) in k-space

A single corrupted point (spike) in k-space Fourier-transforms into a sinusoidal wave overlaid across the entire image, producing a corduroy or herringbone pattern.

Question 31: What does the term 'repetition time' (TR) refer to in MRI pulse sequences?

The time between the RF pulse and the echo
The total scan duration
The time between successive RF excitation pulses applied to the same slice (Correct answer)
The time for magnetization to return to equilibrium after T2 decay

Correct answer: The time between successive RF excitation pulses applied to the same slice

TR is the interval between the beginning of one RF excitation pulse and the beginning of the next for the same slice, controlling T1 contrast.

Question 32: When a constant magnetic field is present, hydrogen protons

Stay basically orientated randomly while rotating around the field axis. (Correct answer)
do not experience any magnetic field effects
Align yourself along the field and revolve around its center.
Ascend the field and rotate around its center.

Correct answer: Stay basically orientated randomly while rotating around the field axis.

When hydrogen protons are placed in a strong constant magnetic field (B0), they align either parallel or anti-parallel to the field, creating a slight net magnetization. However, individual protons do not simply align; they also precess (rotate) around the axis of the main magnetic field at their characteristic Larmor frequency. While there's a net alignment, their individual spin orientations remain somewhat random relative to each other as they precess.

Question 33: In diffusion-weighted imaging (DWI), a high b-value results in:

Increased signal from rapidly diffusing molecules
Greater diffusion weighting and lower overall signal (Correct answer)
Less diffusion weighting and higher signal
Reduced T2 contribution to signal

Correct answer: Greater diffusion weighting and lower overall signal

Higher b-values apply stronger diffusion-sensitizing gradients, so freely diffusing water loses more signal, increasing lesion conspicuity for restricted diffusion.

Question 34: Which coil type generally provides the highest SNR for imaging a small superficial structure?

Surface coil (Correct answer)
Body coil
Volume coil
Quadrature head coil

Correct answer: Surface coil

Surface coils placed close to the target anatomy have superior SNR for small or superficial structures because they detect signal from a limited volume with less noise.

Question 35: In a spin echo (SE) sequence, increasing the repetition time (TR) while keeping TE short primarily results in:

Decreased T1 weighting (more proton density/T2-like contrast) (Correct answer)
Increased SNR only with no contrast change
Increased T1 weighting
Increased T2 weighting

Correct answer: Decreased T1 weighting (more proton density/T2-like contrast)

A long TR allows full T1 recovery of all tissues, reducing T1 contrast differences; combined with short TE, this produces proton density weighting.

Question 36: What is the purpose of crusher (spoiler) gradients in a spin echo sequence?

To select the imaging slice thickness
To dephase residual transverse magnetization before the next RF pulse (Correct answer)
To encode spatial position in the frequency direction
To refocus magnetization after the 180° pulse

Correct answer: To dephase residual transverse magnetization before the next RF pulse

Crusher gradients surround the 180° refocusing pulse to eliminate stimulated echoes from imperfect flip angles that could contaminate image quality.

Question 37: What is the primary consequence of using a high acceleration factor in parallel imaging?

Reduced SNR due to the g-factor penalty (Correct answer)
Reduced scan time with no image quality loss
Increased spatial resolution
Improved T1 contrast

Correct answer: Reduced SNR due to the g-factor penalty

High acceleration factors in parallel imaging introduce a geometry (g-factor) penalty that reduces SNR, especially in the center of the image where coil sensitivity overlap is less distinct.

Question 38: Which ARRT ethics requirement must be fulfilled as part of the MRI registry application process?

CPR certification
Pre-application ethics review if applicable (Correct answer)
Magnetic field safety officer training
Advanced cardiac life support (ACLS)

Correct answer: Pre-application ethics review if applicable

Applicants with certain violations must complete a pre-application review, and all applicants must attest to meeting ARRT's Standards of Ethics.

Question 39: Fast spin echo (FSE/TSE) sequences reduce scan time compared to conventional spin echo by:

Reducing the number of slices acquired
Acquiring multiple phase-encoding lines after each 90° excitation (echo train) (Correct answer)
Using a shorter repetition time
Increasing the voxel size to reduce k-space lines needed

Correct answer: Acquiring multiple phase-encoding lines after each 90° excitation (echo train)

FSE uses a train of 180° pulses after each excitation to fill multiple k-space lines per TR, reducing total scan time by a factor equal to the echo train length.

Question 40: Continuing education (CE) requirements for ARRT MRI credential renewal are completed over what cycle length?

2 years (Correct answer)
3 years
1 year
5 years

Correct answer: 2 years

ARRT requires 24 CE credits completed within a 2-year renewal cycle to maintain the MRI credential.

Question 41: What is the primary reason gadolinium-based contrast agents should not be used in patients undergoing hemodialysis without a specific clinical indication?

Risk of NSF remains even after hemodialysis removes gadolinium (Correct answer)
Gadolinium is not effectively removed by standard hemodialysis
Risk of anaphylaxis is higher in dialysis patients
Dialysis filters destroy the contrast agent before it reaches the target tissue

Correct answer: Risk of NSF remains even after hemodialysis removes gadolinium

While hemodialysis can remove most gadolinium, some residual free gadolinium remains after each session, and repeated exposure can still cause NSF in high-risk patients.

Question 42: Fast spin echo sequences, in contrast to spin echo, have

T2 weighting increased but susceptibility decreased (Correct answer)
Diminished susceptibility and T2 weighting
T2 weighting decreased but susceptibility rose
elevated susceptibility and elevated T2 weighting

Correct answer: T2 weighting increased but susceptibility decreased

Fast Spin Echo (FSE) sequences utilize multiple 180-degree refocusing pulses, which effectively reduce the impact of magnetic susceptibility artifacts by repeatedly rephasing spins. This leads to decreased susceptibility artifacts compared to conventional spin echo. Additionally, FSE sequences can achieve stronger T2 weighting due to the extended echo train and multiple echoes contributing to the signal, often resulting in increased T2 weighting.

Question 43: Which GBCA is approved by the FDA as a liver-specific agent taken up by hepatocytes?

Gadobenate dimeglumine (MultiHance)
Gadoxetate disodium (Eovist/Primovist) (Correct answer)
Gadopentetate dimeglumine (Magnevist)
Gadobutrol (Gadavist)

Correct answer: Gadoxetate disodium (Eovist/Primovist)

Gadoxetate disodium (Eovist in the US, Primovist in Europe) is taken up by functioning hepatocytes via OATP transporters, providing hepatobiliary phase imaging for liver lesion characterization.

Question 44: The normal intervertebral disc nucleus pulposus appears as which signal on T2-weighted MRI in a healthy young adult?

High signal (bright) (Correct answer)
Signal void
Intermediate signal
Low signal

Correct answer: High signal (bright)

The healthy nucleus pulposus is rich in water-containing proteoglycans and appears bright (high signal) on T2-weighted sequences.

Question 45: Which safety zone in an MRI facility is defined as the area that requires screening and controlled access due to the fringe magnetic field?

Zone II
Zone IV
Zone I
Zone III (Correct answer)

Correct answer: Zone III

Zone III is the area where the fringe field poses risk and requires restricted access; only screened individuals may enter.

Question 46: Provide more coverage area without sacrificing signal-to-noise ratio by using numerous coils and receivers.

Helmholtz pair
Vertical
Quadrature
Phased array (Correct answer)

Correct answer: Phased array

Phased array coils consist of multiple small, independent receiver coils, each with its own receiver channel. This innovative design allows for a larger field of view (coverage area) without sacrificing the high signal-to-noise ratio (SNR) typically associated with smaller coils. The signals from individual coils are then combined to form a comprehensive and high-quality image.

Question 47: What is the primary advantage of parallel imaging techniques (e.g., GRAPPA, SENSE) in MRI?

They improve T1 contrast
They eliminate the need for gradient coils
They increase SNR at the same scan time
They reduce scan time or allow higher spatial resolution by using multiple coil elements to under-sample k-space (Correct answer)

Correct answer: They reduce scan time or allow higher spatial resolution by using multiple coil elements to under-sample k-space

Parallel imaging exploits spatial sensitivity differences among phased-array coil elements to reconstruct fully sampled images from under-sampled k-space, reducing scan time by the acceleration factor (R).

Question 48: In a spin-echo sequence, what is the role of the 180° refocusing pulse?

It excites protons from equilibrium into the transverse plane
It suppresses fat signal by inverting its magnetization
It encodes spatial information along the frequency direction
It reverses phase dispersion caused by static field inhomogeneities to form an echo (Correct answer)

Correct answer: It reverses phase dispersion caused by static field inhomogeneities to form an echo

The 180° pulse flips the transverse magnetization so that faster and slower precessing spins rephase, forming a spin echo and eliminating fixed inhomogeneity effects.

Question 49: The corpus callosum is best evaluated on which MRI plane for assessing callosal agenesis?

Oblique
Sagittal (Correct answer)
Coronal
Axial

Correct answer: Sagittal

The sagittal midline plane provides the best single view of the entire corpus callosum from genu to splenium for assessing agenesis or dysgenesis.

Question 50: The term 'T1 mapping' in cardiac MRI using gadolinium is used to quantify which clinically important tissue property?

Extracellular volume fraction (ECV) as a marker of fibrosis (Correct answer)
Ejection fraction
Myocardial perfusion rate
Coronary artery stenosis grade

Correct answer: Extracellular volume fraction (ECV) as a marker of fibrosis

Pre- and post-contrast T1 mapping allows calculation of the extracellular volume (ECV), which is an established quantitative biomarker of diffuse myocardial fibrosis.

Question 51: Which positioning aid is used to maintain the ankle in a 90° neutral position during MRI to optimally visualize the Achilles tendon?

Vacuum immobilization device
Ankle positioning block or foam wedge (Correct answer)
Sand bag
Compression bandage

Correct answer: Ankle positioning block or foam wedge

A foam wedge or ankle block holds the foot perpendicular to the leg, minimizing magic angle artifact and providing consistent Achilles tendon orientation.

Question 52: In MRI safety, what is the specific absorption rate (SAR)?

The static field strength absorbed by implants
The rate of acoustic energy deposited in tissue
The rate of gradient switching measured in T/m/s
The rate of RF energy absorbed per unit mass of tissue, measured in W/kg (Correct answer)

Correct answer: The rate of RF energy absorbed per unit mass of tissue, measured in W/kg

SAR measures RF power deposition in tissue; regulatory limits exist to prevent tissue heating, especially important at higher field strengths and with certain sequences.

Question 53: In which direction does the chemical shift type 2 (India ink) artifact appear at fat-water interfaces, and on which sequence type is it seen?

Frequency direction on spin-echo sequences
Both directions on EPI
Phase direction on gradient-echo sequences (Correct answer)
In-phase direction on STIR sequences

Correct answer: Phase direction on gradient-echo sequences

Chemical shift type 2 (India ink or black boundary artifact) occurs in gradient-echo sequences at fat-water voxel boundaries and appears as a dark rim at these interfaces.

Question 54: What score does ARRT use to determine passing on the MRI registry examination?

A raw score of 75%
A criterion-referenced passing standard set by content experts (Correct answer)
A norm-referenced score based on the current testing cohort
A scaled score of 75 out of 99

Correct answer: A criterion-referenced passing standard set by content experts

ARRT uses a criterion-referenced passing standard established by a panel of content experts, not a simple percentage or norm-based cut score.

Question 55: A candidate who fails the ARRT MRI registry exam may retest after what mandatory waiting period?

90 days (Correct answer)
6 months
60 days
30 days

Correct answer: 90 days

ARRT requires a 90-day waiting period between examination attempts for registry candidates.

Question 56: Which type of aneurysm clip is considered MR Unsafe regardless of age or appearance?

Ferromagnetic stainless steel clips (Correct answer)
Cobalt-chromium clips
Platinum clips
Titanium clips

Correct answer: Ferromagnetic stainless steel clips

Ferromagnetic stainless steel aneurysm clips are MR Unsafe because the static field can exert significant torque on the clip, risking rupture of the aneurysm.

Question 57: What is the purpose of the radiofrequency (RF) pulse in an MRI sequence?

To suppress gradient coil noise
To increase static magnetic field strength
To tip net magnetization away from B0 (Correct answer)
To align hydrogen nuclei with each other

Correct answer: To tip net magnetization away from B0

The RF pulse at the Larmor frequency tips the net magnetization vector away from the longitudinal axis to induce signal.

Question 58: In contrast to SE, GRE sequences employ

longer TE and shorter TR
reduced TR and TE lengths (Correct answer)
shorter TE and longer TR
greater TE and TR lengths

Correct answer: reduced TR and TE lengths

Gradient Echo (GRE) sequences typically employ significantly shorter repetition times (TR) and echo times (TE) compared to Spin Echo (SE) sequences. This is feasible because GRE sequences use smaller flip angles for excitation and do not require the longer timing associated with the 180-degree refocusing pulses. These reduced TR and TE values enable much faster image acquisition, which is advantageous for dynamic imaging or when scan speed is crucial.

Question 59: A technologist increases slice thickness from 3 mm to 6 mm. What is the expected change in image quality?

Both SNR and spatial resolution improve
No change occurs because FOV is unchanged
SNR decreases and spatial resolution improves
SNR improves but through-plane resolution decreases (Correct answer)

Correct answer: SNR improves but through-plane resolution decreases

Thicker slices contain more protons and generate more signal, improving SNR, but fine anatomical detail in the through-plane direction is reduced.

Question 60: Which MRI-compatible monitoring device is used to detect heart rate and trigger cardiac-gated sequences?

Standard hospital ECG with adhesive electrodes
MR-conditional ECG with carbon or fiber-optic leads free of conductive loops (Correct answer)
Finger-clip optical pulse oximeter (used for cardiac gating)
Blood pressure cuff inflation timing

Correct answer: MR-conditional ECG with carbon or fiber-optic leads free of conductive loops

MR-conditional ECG systems with non-conductive or carbon fiber leads detect the R-wave for cardiac gating without creating conductive loops that could cause burns.

Question 61: Which of the following best describes the 'magic angle' artifact and at what angle it occurs?

Artifactual T1/PD signal increase in ordered collagen structures at ~55° to B0 (Correct answer)
Chemical shift banding in fat at 55°
Susceptibility dropout at 45° to B0
T2 darkening of tendons at 45° to B0

Correct answer: Artifactual T1/PD signal increase in ordered collagen structures at ~55° to B0

When ordered collagen fibers (tendons, ligaments) are oriented at ~55° to B0, dipole-dipole interactions average to zero, artifactually increasing signal on short TE sequences.

Question 62: What is the effect of increasing receiver bandwidth on MRI image quality?

SNR decreases but chemical shift artifact is reduced (Correct answer)
SNR increases and scan time decreases
Spatial resolution decreases
Image contrast improves significantly

Correct answer: SNR decreases but chemical shift artifact is reduced

Increasing bandwidth reduces chemical shift artifact and allows shorter TE/TR, but more noise is accepted per unit time, lowering SNR.

Question 63: Nephrogenic Systemic Fibrosis (NSF) is a serious complication associated with GBCA administration in patients with:

Liver failure
Allergy to iodine
Active infection
Severe renal impairment (GFR <30 mL/min/1.73m²) (Correct answer)

Correct answer: Severe renal impairment (GFR <30 mL/min/1.73m²)

NSF occurs almost exclusively in patients with severe kidney disease (GFR <30) because impaired renal clearance prolongs gadolinium exposure, allowing transmetallation and tissue deposition.

Question 64: In cardiac MRI, which sequence is used to assess myocardial viability and detect scar tissue?

Late gadolinium enhancement (LGE) with inversion recovery (Correct answer)
Black-blood T2 STIR
True FISP cine imaging
First-pass perfusion with adenosine stress

Correct answer: Late gadolinium enhancement (LGE) with inversion recovery

Late gadolinium enhancement (LGE) uses an inversion recovery sequence 10–15 minutes after GBCA injection; scarred myocardium retains gadolinium and appears bright against nulled normal myocardium.

Question 65: When performing MRI on a patient with an insulin pump, which step is essential before beginning the exam?

Leave the pump in place since insulin is not ferromagnetic
Remove the pump (if removable) or verify the pump is MR-conditional with the manufacturer before scanning (Correct answer)
Tape the pump to the patient's leg during the scan
Increase the insulin dose before scanning

Correct answer: Remove the pump (if removable) or verify the pump is MR-conditional with the manufacturer before scanning

Insulin pumps may malfunction, heat, or be damaged in the MRI environment; removal or manufacturer verification of MR-conditional status is mandatory.

Question 66: Which artifact appears as parallel bright and dark bands in the phase-encoding direction when the FOV is too small and the patient extends beyond it?

Aliasing (wraparound) (Correct answer)
Susceptibility artifact
Gibbs ringing
Chemical shift type 2

Correct answer: Aliasing (wraparound)

When anatomy outside the FOV is phase-encoded, it aliases (wraps around) and appears as a superimposed copy on the opposite edge of the image, sometimes appearing as bands.

Question 67: One forms a spin echo through

Turning B0 in the opposite direction
Using a gradient of a negative magnetic field
changing the path of a proton using a radiofrequency pulse (Correct answer)

Correct answer: changing the path of a proton using a radiofrequency pulse

A spin echo is formed by applying a 180-degree radiofrequency (RF) pulse after an initial 90-degree RF excitation pulse. This 180-degree pulse effectively 'flips' the spins, causing them to rephase and produce a detectable echo signal. By reversing the effects of static magnetic field inhomogeneities, the 180-degree pulse allows for the recovery of signal that would otherwise be lost due to T2* dephasing.

Question 68: In the context of the ARRT MRI registry, 'structured education' refers to which requirement?

Online CE modules totaling 50 hours
Attending MRI vendor training only
Hospital orientation programs
Completion of an accredited primary radiologic technology program (Correct answer)

Correct answer: Completion of an accredited primary radiologic technology program

Structured education means graduating from a formal, ARRT-recognized educational program as the foundation for registry eligibility.

Question 69: Which MRI technique measures cerebral blood flow and volume without contrast injection, using arterial water protons as an endogenous tracer?

Phase contrast MRI
BOLD fMRI
Dynamic susceptibility contrast (DSC) MRI
Arterial spin labeling (ASL) (Correct answer)

Correct answer: Arterial spin labeling (ASL)

ASL uses RF pulses to magnetically label (invert) arterial blood water protons proximal to the imaging slab; labeled images are subtracted from control images to quantify cerebral perfusion.

Question 70: What minimum distance from the MRI magnet bore is generally recommended to keep unsecured ferromagnetic oxygen cylinders?

3 meters
Distance depends on field strength and cylinder size (Correct answer)
1 meter
5 meters

Correct answer: Distance depends on field strength and cylinder size

The safe exclusion zone for ferromagnetic oxygen cylinders depends on both the scanner's field strength and the cylinder size, so no single fixed distance applies universally.

Question 71: Most superconducting magnets have a (horizontal or vertical) magnetiic field and are of the design type __.

Selenoid magnet (Correct answer)
Permanent magnet
Superconducting
Resistive magnet

Correct answer: Selenoid magnet

Most high-field superconducting MRI magnets are designed as solenoid magnets. In this configuration, the superconducting wire coils are arranged to create a strong, uniform magnetic field that runs horizontally through the bore of the scanner. This solenoid design is highly efficient for generating the powerful and homogeneous fields required for advanced MRI imaging.

Question 72: Which gradient is responsible for determining slice position in a 2D MRI acquisition?

Slice-selection gradient (Correct answer)
Frequency-encoding gradient
Spoiler gradient
Phase-encoding gradient

Correct answer: Slice-selection gradient

The slice-selection gradient is applied simultaneously with the RF pulse to excite only protons in the desired anatomical plane.

Question 73: Which anatomical landmark is used to prescribe the standard axial plane for brain MRI?

Hard palate line
Orbitomeatal baseline
Frankfurt plane
Anterior commissure–posterior commissure (AC-PC) line (Correct answer)

Correct answer: Anterior commissure–posterior commissure (AC-PC) line

Axial brain MRI slices are typically aligned parallel to the AC-PC line for standardized anatomical coverage and comparison.

Question 74: On diffusion-weighted MRI (DWI), an acute ischemic infarct typically shows:

High signal on DWI and low ADC values (Correct answer)
Low signal on DWI and high ADC values
High signal on DWI and high ADC values
Low signal on both DWI and ADC maps

Correct answer: High signal on DWI and low ADC values

Cytotoxic edema in acute infarction restricts water diffusion, producing high signal on DWI and low apparent diffusion coefficient (ADC) values.

Question 75: What sound pressure level (dB) can MRI gradient noise reach, necessitating hearing protection for patients?

130–140 dB
60–70 dB
99–115 dB (Correct answer)
75–85 dB

Correct answer: 99–115 dB

MRI gradient switching can generate noise levels of 99–115 dB SPL, exceeding safe hearing thresholds and requiring earplugs or headphones for patients.

Question 76: Which ARRT resource provides the official list of examination content categories, subcategories, and approximate percentage weighting for the MRI registry exam?

ASRT curriculum guide
ARRT Content Specifications document (Correct answer)
ACR MRI practice parameters
JRCERT program outcomes report

Correct answer: ARRT Content Specifications document

The ARRT Content Specifications document is the authoritative blueprint that outlines all tested domains and their weightings for the MRI registry exam.

Question 77: Gibbs (truncation) artifact is caused by:

Undersampling of k-space — insufficient high-frequency data to represent sharp tissue interfaces (Correct answer)
Aliasing from a FOV smaller than the patient
Field inhomogeneity near air-tissue interfaces
Patient motion during scanning

Correct answer: Undersampling of k-space — insufficient high-frequency data to represent sharp tissue interfaces

Gibbs artifact arises from the Fourier series representation of sharp edges when high spatial-frequency k-space data is truncated, producing ringing lines parallel to the interface.

Question 78: Gibbs ringing artifact is caused by:

Chemical shift between fat and water
Truncation of k-space data at high spatial frequencies (Correct answer)
Motion during phase encoding
RF pulse imperfections

Correct answer: Truncation of k-space data at high spatial frequencies

Gibbs ringing (truncation artifact) occurs when k-space is sampled with insufficient high-frequency data, causing oscillating bands near sharp tissue interfaces.

Question 79: By adding more loops and circuitry, these coils increase the efficiency with which the MR signal is induced in the coil and raise SNR by about 40% when compared to coils of the same size.

Helmholtz pair
Phased array
Vertical
Quadrature (Correct answer)

Correct answer: Quadrature

Quadrature coils (or circularly polarized coils) utilize two receiver coils oriented 90 degrees to each other. By combining the signals from both coils, they can detect the rotating component of the MR signal more efficiently. This design leads to a theoretical 41% increase in signal-to-noise ratio (SNR) compared to a single linear coil of the same size, improving image quality.

Question 80: In a spin-echo sequence, which combination of TR and TE produces a T2-weighted image?

Long TR, short TE
Long TR, long TE (Correct answer)
Short TR, long TE
Short TR, short TE

Correct answer: Long TR, long TE

T2-weighting requires long TR (to minimize T1 contrast by allowing full recovery) and long TE (to allow T2 differences between tissues to accumulate).

Question 81: What is the primary trade-off when reducing the field of view (FOV) in MRI?

Improved SNR with no change in resolution
Decreased scan time and improved SNR
Improved spatial resolution but increased risk of aliasing artifacts (Correct answer)
Increased slice coverage with same resolution

Correct answer: Improved spatial resolution but increased risk of aliasing artifacts

Reducing FOV increases spatial resolution by making voxels smaller, but if anatomy extends beyond the reduced FOV, aliasing (wrap-around) artifacts occur.

Question 82: In contrast to the spin echo sequence (SE), the gradient echo sequence (GRE)

has a T2 dephasing pattern and no 180-degree pulse.
has T2* dephasing and lacks a 180-degree pulse. (Correct answer)
possesses a 180-degree pulse and T2* dephasing.
possesses a 180-degree pulse and T2 dephasing

Correct answer: has T2* dephasing and lacks a 180-degree pulse.

Gradient Echo (GRE) sequences fundamentally differ from Spin Echo (SE) sequences because they do not use a 180-degree radiofrequency refocusing pulse. Instead, GRE sequences employ a gradient reversal to rephase the spins and create an echo. Since there is no 180-degree pulse to correct for static magnetic field inhomogeneities, GRE sequences are sensitive to T2* dephasing, making them more prone to susceptibility artifacts than SE sequences.

Question 83: How many scored questions appear on the ARRT MRI registry examination?

175 (Correct answer)
200
100
220

Correct answer: 175

The ARRT MRI exam contains 175 scored questions plus a small number of unscored pilot questions.

Question 84: Substances in the presence of an applied magnetic field that show a modest rise in magnetic field. They exhibit both positive and low susceptibility.

Ferromagnetic
Paramagnetic (Correct answer)
Diamagnetic
Superpapmagnetic

Correct answer: Paramagnetic

Paramagnetic materials exhibit a weak, positive susceptibility to an external magnetic field. Their unpaired electrons align with the field, causing a modest increase in the local magnetic field, but this effect is lost once the external field is removed. Gadolinium, a common MRI contrast agent, is a well-known paramagnetic substance.

Question 85: Which MRI technique encodes functional brain activity by detecting changes in blood oxygenation level?

Blood oxygen level-dependent (BOLD) fMRI (Correct answer)
MR spectroscopy (MRS)
Diffusion tensor imaging (DTI)
Arterial spin labeling (ASL)

Correct answer: Blood oxygen level-dependent (BOLD) fMRI

BOLD fMRI detects regional neural activity via the magnetic susceptibility difference between oxyhemoglobin and deoxyhemoglobin, providing maps of brain activation.

Question 86: What does k-space represent in MRI?

The gradient amplitude map
The physical space inside the magnet bore
The raw data space containing spatial frequency information from which the MR image is reconstructed by Fourier transform (Correct answer)
The frequency range of the RF pulse

Correct answer: The raw data space containing spatial frequency information from which the MR image is reconstructed by Fourier transform

K-space is the mathematical data domain where raw MRI signal is stored as spatial frequencies; a Fourier transform converts k-space data into the final diagnostic image.

Question 87: In MRI, what does the term 'k-space' represent?

A map of gradient field inhomogeneities
The raw frequency-domain data before Fourier transformation into an image (Correct answer)
The final reconstructed image space
The physical space inside the MRI bore

Correct answer: The raw frequency-domain data before Fourier transformation into an image

K-space is the mathematical frequency domain where raw MRI data is stored; a Fourier transform converts k-space data into the final spatial image.

Question 88: What is the effect of increasing the number of signal averages (NSA/NEX) on MRI image quality?

Spatial resolution increases
Scan time decreases
SNR decreases proportionally
SNR improves proportionally to the square root of NSA (Correct answer)

Correct answer: SNR improves proportionally to the square root of NSA

Averaging multiple acquisitions improves SNR by a factor of √NSA, though it linearly increases scan time.

Question 89: Which breast MRI positioning protocol is standard for screening and diagnostic evaluation?

Upright in a dedicated open MRI
Lateral decubitus with the ipsilateral breast dependent
Supine with arms overhead
Prone with the breasts in a dedicated bilateral breast coil (Correct answer)

Correct answer: Prone with the breasts in a dedicated bilateral breast coil

Prone positioning with bilateral dedicated breast coils provides optimal tissue separation, bilateral coverage, and reproducible enhancement kinetics.

Question 90: Which of the following is a documented risk of MRI during the first trimester of pregnancy?

Gadolinium retention in fetal tissue
Acoustic noise damage to fetal hearing
All of the above except ionizing radiation (Correct answer)
Ionizing radiation exposure

Correct answer: All of the above except ionizing radiation

MRI does not use ionizing radiation, but first-trimester risks include acoustic noise and potential gadolinium retention; non-contrast scanning is preferred.

Question 91: Which MRI sequence is most commonly used for evaluating liver lesions using T2 contrast with heavy T2 weighting for the bile ducts?

T1 in-phase/opposed-phase
DWI b1000
MRCP (heavily T2-weighted 3D or thick-slab) (Correct answer)
STIR of the abdomen

Correct answer: MRCP (heavily T2-weighted 3D or thick-slab)

MRCP uses heavily T2-weighted sequences to make bile and pancreatic fluid appear bright, providing a non-invasive map of the biliary and pancreatic ductal system.

Question 92: A 'DC offset' or 'center dot' artifact seen as a bright spot in the center of the image is related to:

Excessive TR causing saturation effects
Patient positioning off-isocenter
B1 field inhomogeneity
A small DC current offset in the receiver causing a spike in the center of k-space (Correct answer)

Correct answer: A small DC current offset in the receiver causing a spike in the center of k-space

A DC offset artifact occurs when a constant voltage offset in the MR receiver chain introduces a spike at the origin of k-space (DC component), appearing as a bright dot at image center.

Question 93: What is contrast-to-noise ratio (CNR) in MRI and why is it important?

The number of phase encodes used to improve tissue differentiation
The difference in SNR between two adjacent tissues; it determines the ability to distinguish lesions from normal tissue (Correct answer)
The ratio of gadolinium dose to body weight
The ratio of TR to TE for optimal contrast

Correct answer: The difference in SNR between two adjacent tissues; it determines the ability to distinguish lesions from normal tissue

CNR is the SNR difference between adjacent tissues; high CNR is essential for detecting lesions because it reflects how well two tissues can be discriminated from each other.

Question 94: A patient with a cochlear implant is scheduled for MRI. What is the primary concern?

Acoustic noise damage
Heating of the cochlear fluid
Claustrophobia from the device signal
Device displacement or demagnetization by the static field and RF heating (Correct answer)

Correct answer: Device displacement or demagnetization by the static field and RF heating

Cochlear implants contain magnets that can torque, displace, or demagnetize in the MRI field, posing significant safety risks.

Question 95: Which gradient is primarily responsible for frequency encoding in MRI?

Slice-select gradient
Readout gradient (Correct answer)
Spoiler gradient
Phase-encoding gradient

Correct answer: Readout gradient

The readout (frequency-encoding) gradient is applied during signal acquisition, causing spins at different positions to precess at different frequencies.

Question 96: Which MRI sequence is best suited for evaluating articular cartilage because it provides excellent contrast between cartilage, fluid, and bone?

Inversion recovery (STIR)
T1-weighted SE
FLAIR
Proton density fat-saturated (PD FS) (Correct answer)

Correct answer: Proton density fat-saturated (PD FS)

PD fat-saturated sequences highlight cartilage defects as intermediate-signal cartilage contrasts sharply against bright joint fluid and suppressed fat.

Question 97: Which MRI sequence is most sensitive to hemorrhage detection because of its sensitivity to blood products?

Gradient echo (GRE) (Correct answer)
Inversion recovery (IR)
Fast spin echo (FSE)
Diffusion-weighted imaging (DWI)

Correct answer: Gradient echo (GRE)

Gradient echo sequences are sensitive to magnetic susceptibility differences caused by hemosiderin and deoxyhemoglobin, making them ideal for detecting hemorrhage.

Question 98: The b-value in diffusion-weighted imaging controls the degree of diffusion weighting. Increasing the b-value:

Increases diffusion contrast but decreases SNR (Correct answer)
Has no effect on image quality
Decreases T2 contribution
Increases overall image SNR

Correct answer: Increases diffusion contrast but decreases SNR

Higher b-values provide greater diffusion contrast by increasing the dephasing of mobile water protons, but at the cost of reduced SNR due to greater signal attenuation from all spins.

Question 99: On an axial MRI of the abdomen at the level of L1, which structure is seen as a round low-signal structure anterior to the aorta?

Inferior vena cava
Celiac axis
Superior mesenteric artery (Correct answer)
Portal vein

Correct answer: Superior mesenteric artery

The superior mesenteric artery (SMA) arises from the anterior aorta at approximately L1 and appears as a round flow-void structure surrounded by fat on axial images.

Question 100: These materials are employed as T2 contrast agents because they show positive susceptibility, are stronger than paramagnetic materials but weaker than ferromagnetic materials.

Superpapmagnetic (Correct answer)
Ferromagnetic
Diamagnetic
Paramagnetic

Correct answer: Superpapmagnetic

Superparamagnetic materials possess magnetic properties stronger than paramagnetic substances but, unlike ferromagnetic materials, they do not retain magnetism once the external field is removed. They are often used as T2 contrast agents in MRI because their large magnetic moments create significant local field inhomogeneities, leading to rapid T2 decay and signal loss, which enhances contrast in certain tissues.

Question 101: In MRI of the breast, a finding described as a 'rim-enhancing mass' on dynamic contrast imaging is most suspicious for:

Simple cyst
Fat necrosis
Malignant lesion (Correct answer)
Fibroadenoma

Correct answer: Malignant lesion

Rim enhancement of a breast mass, indicating peripheral enhancement with central necrosis, is a suspicious finding associated with malignancy.

Question 102: The magnetic field's intensity is changed by this gradient coil from right to left.

Y
Z
X (Correct answer)

Correct answer: X

In a standard MRI coordinate system, the X-axis typically corresponds to the right-to-left (or left-to-right) direction across the patient. The X-gradient coil is engineered to produce a linear change in the magnetic field strength along this X-axis. This gradient is primarily used for spatial encoding, particularly for frequency encoding, in the right-to-left dimension.

Question 103: Which of the following changes will increase spatial resolution without changing the FOV?

Increasing slice thickness
Increasing NEX
Increasing the matrix size (Correct answer)
Decreasing the matrix size

Correct answer: Increasing the matrix size

Increasing matrix size means more phase and frequency encoding steps, reducing voxel size and improving spatial resolution within the same FOV.

Question 104: Which ARRT exam content domain addresses gradient performance, field homogeneity, and RF coil function?

Patient Care and Education
Physics and Instrumentation (Correct answer)
Image Production
Procedures

Correct answer: Physics and Instrumentation

Physics and Instrumentation covers hardware components including gradients, RF coils, and magnet systems.

Question 105: Which of the following precautions is required before administering a GBCA to a breastfeeding mother, according to ACR recommendations?

Breastfeeding should be interrupted for 24–48 hours after GBCA administration
The infant must receive a blood test before the mother can resume breastfeeding
No precautions are required as only trace amounts enter breast milk (Correct answer)
Breastfeeding must be permanently stopped

Correct answer: No precautions are required as only trace amounts enter breast milk

The ACR states that GBCAs enter breast milk in very small amounts (<0.04%) and oral bioavailability is negligible; no interruption is required, though the mother may choose to withhold for 12–24 hours if concerned.

Question 106: For a brain MRI, which standard plane best demonstrates the corpus callosum in its entirety?

Oblique
Axial
Sagittal (Correct answer)
Coronal

Correct answer: Sagittal

The midsagittal plane shows the entire corpus callosum from the genu to the splenium as a continuous C-shaped structure.

Question 107: Which organization accredits MRI education programs whose graduates may be eligible to sit for the ARRT MRI registry?

American Society of Radiologic Technologists (ASRT)
The Joint Commission (TJC)
Joint Review Committee on Education in Radiologic Technology (JRCERT) (Correct answer)
American College of Radiology (ACR)

Correct answer: Joint Review Committee on Education in Radiologic Technology (JRCERT)

JRCERT accredits radiologic technology education programs, and graduation from an accredited program satisfies ARRT educational requirements.

Question 108: Which of the following is the most effective method to reduce motion artifact from bowel peristalsis in abdominal MRI?

Increase TR
Use a larger FOV
Administer an antiperistaltic agent such as glucagon (Correct answer)
Apply saturation bands inferior to the FOV

Correct answer: Administer an antiperistaltic agent such as glucagon

IV or IM glucagon inhibits smooth muscle contraction (antiperistaltic effect), reducing bowel motion artifact during abdominal MRI acquisitions.

Question 109: The 'ABER' position used in shoulder MRI arthrography stands for:

Abduction and Endorotation
Abduction and Elbow Rest
Adduction and External Rotation
Abduction and External Rotation (Correct answer)

Correct answer: Abduction and External Rotation

ABER (Abduction and External Rotation) positions the arm to tension the inferior glenohumeral ligament and improve detection of partial-thickness undersurface rotator cuff tears.

Question 110: The anterior and posterior horns of the lateral ventricles are best evaluated for periventricular leukomalacia (PVL) on which MRI plane?

Coronal only
Sagittal only
Axial and coronal (Correct answer)
Oblique

Correct answer: Axial and coronal

Axial and coronal planes together best demonstrate periventricular T2 signal changes and volume loss around the lateral ventricular horns in PVL.

Question 111: For pituitary gland MRI, which plane is considered the primary imaging plane?

Axial
Coronal (Correct answer)
Sagittal
Oblique axial

Correct answer: Coronal

Coronal thin-slice images are the primary plane for pituitary imaging because they best demonstrate lateral extension, cavernous sinus invasion, and microadenomas.

Question 112: In dynamic contrast-enhanced (DCE) MRI of the breast, which kinetic enhancement curve pattern is most concerning for malignancy?

No enhancement
Persistent (type I)
Plateau (type II)
Washout (type III) (Correct answer)

Correct answer: Washout (type III)

A washout (type III) kinetic curve — rapid initial enhancement followed by signal decrease — is most suspicious for malignancy due to arteriovenous shunting in tumor neovasculature.

Question 113: Which MRI technique uses the difference in signal between in-phase and opposed-phase images to detect intravoxel fat within a lesion?

MR spectroscopy
Chemical shift imaging (Dixon technique) (Correct answer)
STIR fat suppression
Diffusion-weighted imaging

Correct answer: Chemical shift imaging (Dixon technique)

Chemical shift imaging exploits the precession frequency difference between fat and water; signal drop on opposed-phase images indicates intravoxel fat content.

Question 114: Wraparound (aliasing) artifact in MRI is caused by:

Phase errors from pulsatile flow
Structures outside the FOV contributing signal that is folded back into the image (Correct answer)
Gradient non-linearity at the edges of the bore
T2* dephasing from metallic objects

Correct answer: Structures outside the FOV contributing signal that is folded back into the image

When anatomy extends beyond the selected FOV in the phase-encode direction, it is aliased and appears superimposed on the opposite side of the image.

Question 115: Following an RF burst, protons will

As per T2*, dephase in accordance with T1 and then recover along B0.
Dephase in accordance with T2*, then recover in accordance with T1 along B0. (Correct answer)
As per T2*, recover along B0, and thereafter dephase in accordance with T1.
As instructed by T1, recover along B0, and then dephase as instructed by T2*.

Correct answer: Dephase in accordance with T2*, then recover in accordance with T1 along B0.

Immediately following an RF burst, the excited protons begin to lose their phase coherence, causing the transverse magnetization to decay. This dephasing is governed by T2* relaxation, which includes both intrinsic molecular interactions and static magnetic field inhomogeneities. Simultaneously, the longitudinal magnetization, which was tipped away from B0, begins to recover along the B0 field, a process governed by T1 relaxation.

Question 116: Which portion of k-space primarily determines image contrast?

The periphery (high spatial frequencies)
The corners of k-space only
The center (low spatial frequencies) (Correct answer)
The edges equally with the center

Correct answer: The center (low spatial frequencies)

The center of k-space contains low spatial frequency data, which encodes the bulk signal intensity and contrast of the image.

Question 117: A patient with a GFR of 45 mL/min/1.73m² requires a contrast-enhanced MRI. According to ACR guidelines, which GBCA group is preferred?

Contrast should be completely avoided
Group III macrocyclic agents (Correct answer)
Group II linear non-ionic agents
Group I linear ionic agents

Correct answer: Group III macrocyclic agents

The ACR recommends macrocyclic GBCAs (Group III) for patients with reduced renal function (GFR 30–60) due to their superior thermodynamic and kinetic stability.

Question 118: Which coil configuration is used to image the entire spine in a single acquisition with uniform SNR?

Phased-array spine coil spanning cervical, thoracic, and lumbar regions (Correct answer)
Head and neck coil alone
Body transmit/receive coil only
Single surface coil placed at the lumbar spine

Correct answer: Phased-array spine coil spanning cervical, thoracic, and lumbar regions

A multi-element phased-array spine coil allows large FOV imaging with high SNR throughout the cervical, thoracic, and lumbar spine in a single or stitched acquisition.

Question 119: Which MRI technique is used to assess brain perfusion by tracking the first pass of a gadolinium bolus?

Arterial Spin Labeling (ASL)
Magnetic Resonance Spectroscopy (MRS)
Diffusion Tensor Imaging (DTI)
Dynamic Susceptibility Contrast (DSC) perfusion (Correct answer)

Correct answer: Dynamic Susceptibility Contrast (DSC) perfusion

DSC perfusion MRI uses rapid T2*-weighted sequences to measure signal drop as gadolinium transits through the brain capillaries.

Question 120: During an MRI exam, a patient begins experiencing intense burning sensations on their skin near monitoring cables. What is the most likely cause?

SAR limit exceeded
Gradient-induced peripheral nerve stimulation
RF-induced heating from looped or coiled cables (Correct answer)
Quench event beginning

Correct answer: RF-induced heating from looped or coiled cables

Looped or coiled cables act as antennas and can develop high RF-induced currents causing thermal burns on the skin.

Question 121: Chemical shift artifact of the first kind occurs at interfaces between fat and water and manifests as:

Image wrap-around from the opposite side
A bright band and a dark band at the fat-water interface in the frequency-encoding direction (Correct answer)
Zebra-stripe banding artifact
Signal voids around metallic implants

Correct answer: A bright band and a dark band at the fat-water interface in the frequency-encoding direction

First-kind chemical shift artifact creates a bright rim on one side and a dark void on the other side at fat-water interfaces in the frequency-encoding direction due to the 3.5 ppm resonance frequency difference.

Question 122: Which of the following best describes the concept of signal-to-noise ratio (SNR) in MRI?

The number of signal averages divided by scan time
The ratio of mean signal intensity in a region of interest to the standard deviation of background noise (Correct answer)
The ratio of TE to TR
The difference in signal between two adjacent tissues

Correct answer: The ratio of mean signal intensity in a region of interest to the standard deviation of background noise

SNR is quantitatively defined as the mean signal from a region of interest divided by the standard deviation of noise measured in a background air region.

Question 123: Which of the following is the correct management for a patient who experiences an acute severe allergic-like reaction (anaphylaxis) following GBCA injection?

Administer IV saline bolus only
Administer 50 mg IV diphenhydramine and continue scan
Stop contrast injection, call code team, administer epinephrine 0.3 mg IM (1:1000) (Correct answer)
Administer oral Benadryl and observe for 15 minutes

Correct answer: Stop contrast injection, call code team, administer epinephrine 0.3 mg IM (1:1000)

Anaphylaxis requires immediate cessation of injection, emergency team activation, and epinephrine 0.3 mg IM (1:1000 concentration) in the lateral thigh as first-line treatment.

Question 124: Magnetization transfer (MT) contrast in MRI works by selectively saturating which proton pool?

Intracellular sodium protons
Free water protons in tissue
Bound protons in macromolecules (semisolid pool), which transfers saturation to free water (Correct answer)
Fat protons at 3.5 ppm

Correct answer: Bound protons in macromolecules (semisolid pool), which transfers saturation to free water

An off-resonance RF pulse saturates the restricted macromolecular proton pool; saturation is transferred to free water through magnetization exchange, reducing the water signal proportional to MT ratio.

Question 125: Which MRI artifact is caused by periodic patient motion such as cardiac or respiratory movement?

Gibbs ringing artifact
Magnetic susceptibility artifact
Chemical shift artifact
Ghosting (motion) artifact (Correct answer)

Correct answer: Ghosting (motion) artifact

Ghosting artifacts appear as repeated copies of moving structures along the phase-encoding direction due to periodic physiologic motion.

Question 126: What document must candidates agree to when submitting an ARRT MRI registry application?

JRCERT Accreditation Standards
ASRT Scope of Practice
ARRT Standards of Ethics (Correct answer)
ACR Practice Parameter for MRI

Correct answer: ARRT Standards of Ethics

All ARRT applicants must attest to adhering to the ARRT Standards of Ethics as a condition of application.

Question 127: A pregnant MRI technologist should follow which guideline regarding working in the MRI suite?

Limit time in the scanner room primarily during the first trimester due to acoustic and gradient exposure (Correct answer)
Avoid all scanner rooms during pregnancy
Wear a lead apron to reduce MRI exposure
Take a leave of absence immediately upon learning of pregnancy

Correct answer: Limit time in the scanner room primarily during the first trimester due to acoustic and gradient exposure

Current guidelines suggest limiting time within the bore and active scanner room primarily in the first trimester; there is no requirement to cease work entirely.

Question 128: T2* relaxation differs from T2 relaxation primarily because T2* includes:

Only spin-lattice interactions
Magnetic field inhomogeneities in addition to spin-spin interactions (Correct answer)
Gradient-induced dephasing only
Chemical shift effects only

Correct answer: Magnetic field inhomogeneities in addition to spin-spin interactions

T2* accounts for both intrinsic spin-spin relaxation (T2) and additional dephasing caused by local magnetic field inhomogeneities.

Question 129: For MRI of the internal auditory canals (IACs), which imaging plane is most commonly used as the primary plane?

Coronal
Sagittal oblique
Oblique coronal
Axial (Correct answer)

Correct answer: Axial

Axial high-resolution images are the primary plane for IAC MRI because they show the full length of CN VII and CN VIII within the canal.

Question 130: Cardiac MRI uses which technique to synchronize data acquisition with the cardiac cycle and minimize cardiac motion artifact?

ECG gating or cardiac triggering (Correct answer)
Breath-hold sequences only
Real-time imaging without synchronization
Respiratory gating only

Correct answer: ECG gating or cardiac triggering

ECG gating (prospective triggering or retrospective gating) synchronizes k-space acquisition to specific phases of the cardiac cycle, minimizing motion artifact from myocardial contraction.

Question 131: What differentiates T2 from T2* is

T2* is the product of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity, which is represented by T2.
The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity, or T2*, is represented by T2.
The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity is represented by T2*, which equals T2. (Correct answer)
The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity is represented by T2*, or T2*.

Correct answer: The combination of changing molecular magnetic field inhomogeneity and static magnetic field inhomogeneity is represented by T2*, which equals T2.

T2 relaxation describes the decay of transverse magnetization due to intrinsic molecular interactions and microscopic magnetic field inhomogeneities. T2* relaxation, however, encompasses both these intrinsic T2 effects and additional macroscopic static magnetic field inhomogeneities inherent to the scanner and patient. Therefore, T2* is always shorter than or equal to T2, as it accounts for more dephasing factors.

Question 132: Which MRI protocol modification is used to evaluate the acetabular labrum of the hip with maximum sensitivity for tears?

T1 fat-saturated without contrast
MR arthrography with intra-articular gadolinium dilution (Correct answer)
Diffusion-weighted imaging of the hip
Standard T2 FSE without contrast

Correct answer: MR arthrography with intra-articular gadolinium dilution

MR arthrography with intra-articular dilute gadolinium distends the joint capsule, separating the labrum from the femoral head and maximizing sensitivity for labral tears.

Question 133: What is the effect of reducing the number of phase-encoding steps while keeping FOV and frequency steps constant?

Through-plane resolution is affected
SNR improves and scan time increases
Scan time decreases and phase-direction spatial resolution decreases (Correct answer)
Frequency-direction resolution decreases

Correct answer: Scan time decreases and phase-direction spatial resolution decreases

Fewer phase-encoding steps means less time to fill k-space (shorter scan) but larger voxels in the phase direction, reducing spatial resolution in that dimension.

Question 134: Under ARRT policy, which of the following must a registered MRI technologist report within 30 days?

A felony conviction or guilty plea (Correct answer)
Change of mailing address
Obtaining an additional college degree
Purchasing new MRI accessories

Correct answer: A felony conviction or guilty plea

ARRT's Standards of Ethics require technologists to report criminal convictions or guilty pleas within 30 days.

Question 135: Which MRI sequence is the standard for evaluating the internal structure of bone marrow and is most sensitive to marrow infiltration or edema?

Proton density without fat suppression
T2*-weighted gradient echo
T1-weighted spin-echo
STIR or fat-suppressed T2-weighted FSE (Correct answer)

Correct answer: STIR or fat-suppressed T2-weighted FSE

STIR and fat-suppressed T2 sequences null normal fatty marrow signal, making pathological edema, infiltration, or tumor stand out as high signal against the nulled fat background.

Question 136: What is the primary advantage of a 3T MRI scanner compared to a 1.5T scanner?

Shorter T1 relaxation times for all tissues
Higher SNR that can be traded for faster scans or higher spatial resolution (Correct answer)
Elimination of susceptibility artifacts
Lower SAR deposition in patients

Correct answer: Higher SNR that can be traded for faster scans or higher spatial resolution

Field strength doubling theoretically doubles SNR, which can be reinvested in thinner slices, smaller voxels, or reduced scan time.

Question 137: Which ligament of the knee is best seen on sagittal MRI images and connects the posterior femur to the anterior tibia?

Arcuate ligament
Anterior cruciate ligament (Correct answer)
Posterior cruciate ligament
Medial collateral ligament

Correct answer: Anterior cruciate ligament

The anterior cruciate ligament (ACL) runs from the posterior lateral femoral condyle to the anterior tibial spine and is best evaluated on sagittal MRI.

Question 138: FLAIR (Fluid-Attenuated Inversion Recovery) suppresses which signal and is most useful for detecting:

Blood signal; hemorrhage
CSF signal; periventricular and cortical lesions (Correct answer)
Muscle signal; soft tissue tumors
Fat signal; bone marrow edema

Correct answer: CSF signal; periventricular and cortical lesions

FLAIR uses an inversion pulse timed to null CSF, making periventricular lesions and cortical pathology (MS plaques, subarachnoid hemorrhage) visible against suppressed fluid.

Question 139: In MRI, what is k-space?

The raw data space containing spatial frequency information used to reconstruct images (Correct answer)
The physical space inside the magnet bore
A unit of measurement for gradient strength
The region of the brain studied in neuroimaging

Correct answer: The raw data space containing spatial frequency information used to reconstruct images

K-space is the mathematical domain that stores the raw MRI signal as spatial frequencies; a Fourier transform converts it into an image.

Question 140: Which artifact arises when signal from outside the FOV wraps around to the opposite side of the image?

Chemical shift artifact
Susceptibility artifact
Aliasing (wrap-around) artifact (Correct answer)
Gibbs ringing artifact

Correct answer: Aliasing (wrap-around) artifact

Aliasing occurs in the phase-encode direction when anatomy outside the FOV is undersampled, causing it to appear on the opposite side.

Question 141: Which type of MRI coil surrounds the entire body and is used to transmit RF energy uniformly?

Gradient coil
Surface coil
Body (volume) coil (Correct answer)
Phased-array coil

Correct answer: Body (volume) coil

The body (volume) coil is built into the bore and provides uniform RF transmission across the entire patient.

Question 142: Which labeling term indicates that an item has been tested and poses no known hazards in ALL MRI environments?

MR Approved
MR Safe (Correct answer)
MR Conditional
MR Compatible

Correct answer: MR Safe

The ASTM 'MR Safe' label means the item poses no known hazards in all MRI environments and is made of non-conductive, non-magnetic, non-RF-reactive materials.

Question 143: When performing MR arthrography of the hip, the patient is typically positioned with the hip in which orientation?

Maximum external rotation
30° internal rotation
Frog-leg lateral position
Neutral or slight internal rotation (Correct answer)

Correct answer: Neutral or slight internal rotation

Neutral to slight internal rotation during hip MR arthrography places the femoral neck parallel to the imaging plane and optimizes labral visualization.

Question 144: Which parameter directly controls the degree of T2 weighting in a spin echo sequence?

TR (repetition time)
Bandwidth
Flip angle
TE (echo time) (Correct answer)

Correct answer: TE (echo time)

TE determines how long transverse magnetization decays before sampling; a longer TE allows more T2 decay, increasing T2 contrast.

Question 145: Magnets that use liquid helium or cryogen to cool the wires after applying direct current to a coil of wire.

Permanent magnet
Resistive magnet
Superconducting (Correct answer)
Selenoid magnet

Correct answer: Superconducting

Superconducting magnets utilize special alloys that, when cooled to extremely low temperatures (near absolute zero) using cryogens like liquid helium, lose all electrical resistance. This allows a large current to flow indefinitely without power, creating very strong and stable magnetic fields. These magnets are essential for high-field MRI systems, typically operating at 1.5 Tesla and above.

Question 146: Which MRI screening form section is most critical for identifying implanted devices that may be MR Unsafe?

Medication list section
Implants and devices section (Correct answer)
Surgical history section
Allergies section

Correct answer: Implants and devices section

The implants and devices section identifies items such as pacemakers, cochlear implants, and aneurysm clips that may be MR Unsafe.

Question 147: A patient reports having a cardiac pacemaker. What is the standard MRI safety classification for most older pacemakers?

MR Safe
MR Conditional
MR Compatible
MR Unsafe (Correct answer)

Correct answer: MR Unsafe

Most older pacemakers are classified MR Unsafe because the magnetic field can interfere with device function or cause heating.

Question 148: What is the Ernst angle in MRI?

The phase angle at which fat and water are in phase
The flip angle that maximizes signal for a given TR and T1 (Correct answer)
The gradient angle that minimizes eddy currents
The angle at which the slice becomes isotropic

Correct answer: The flip angle that maximizes signal for a given TR and T1

The Ernst angle (cos θ = e^(−TR/T1)) is the optimal flip angle for steady-state gradient echo imaging that maximizes SNR efficiency.

Question 149: In MRI, the term 'flip angle' refers to:

The phase angle accumulated during readout
The angle by which the net magnetization is rotated from B0 by the RF pulse (Correct answer)
The angle of the gradient coils relative to the main magnet
The angular difference between excitation and reception coils

Correct answer: The angle by which the net magnetization is rotated from B0 by the RF pulse

The flip angle is the degree of rotation of the net magnetization vector away from the longitudinal axis produced by an RF pulse.

Question 150: In a gradient echo sequence, what replaces the 180° refocusing pulse used in spin echo?

A second 90° RF pulse
A reversed readout gradient (Correct answer)
A slice-select gradient reversal
A phase-encoding rewinder gradient

Correct answer: A reversed readout gradient

Gradient echo sequences use a reversed readout gradient to rephase spins, making them sensitive to T2* rather than T2.

Question 151: The flip angle in an MRI sequence refers to which of the following?

The angular velocity of proton precession
The degree to which the net magnetization vector is rotated from B0 by the RF pulse (Correct answer)
The tilt of the gradient coil axis
The angle of the main magnetic field relative to the bore

Correct answer: The degree to which the net magnetization vector is rotated from B0 by the RF pulse

The flip angle is how far the net magnetization vector is tipped away from the longitudinal axis by the RF pulse.

Question 152: For temporomandibular joint (TMJ) MRI, images are obtained with the jaw in which two positions?

Supine and prone
Clenched and relaxed
Open and closed mouth (Correct answer)
Right lateral and left lateral

Correct answer: Open and closed mouth

TMJ MRI is performed with the mouth both open and closed to evaluate articular disc position and movement through the full range of condylar motion.

Question 153: The placement of the slice is established by the

The RF pulse's transmit frequency (Correct answer)
frequency of the RF pulse received
Radiofrequency coil's transmit frequency
phase difference

Correct answer: The RF pulse's transmit frequency

The placement of the slice in MRI is precisely established by the transmit frequency of the RF pulse. When a magnetic field gradient is applied, protons at different locations precess at different frequencies. By selecting a specific RF transmit frequency, only protons resonating at that exact frequency within the gradient field will be excited, thereby defining the slice's position.

Question 154: Which phase-encoding direction choice can help reduce motion artifact from breathing in abdominal MRI?

Use a larger FOV in the frequency direction
Orient phase encoding in the right-left direction so respiratory motion projects away from the anatomy of interest (Correct answer)
Orient phase encoding in the anterior-posterior direction to capture all motion
Increase the number of slices

Correct answer: Orient phase encoding in the right-left direction so respiratory motion projects away from the anatomy of interest

Placing phase encoding in the right-left direction directs respiratory ghosting away from critical abdominal structures, reducing diagnostic interference.

Question 155: Balanced steady-state free precession (SSFP) sequences have an advantage over conventional GRE sequences.

To create spin echoes, hold onto your transverse magnetization. (Correct answer)
Employ gradient spoilers to lessen transverse magnetization
To navigate k-space, use gradients of alternating magnetic fields.
To create spin echoes, use 180-degree pulses.

Correct answer: To create spin echoes, hold onto your transverse magnetization.

Balanced steady-state free precession (bSSFP) sequences have a key advantage over conventional spoiled GRE sequences by actively preserving transverse magnetization from previous excitations. Unlike spoiled GREs that use spoiler gradients to eliminate residual transverse magnetization, bSSFP sequences are designed to maintain both longitudinal and transverse magnetization in a steady state. This allows for the formation of both FID and echo signals, leading to high signal-to-noise ratio and characteristic T2/T1 contrast.

Question 156: Bilateral symmetric T2 hyperintensity in the basal ganglia of a child is most associated with which condition?

Multiple sclerosis
Glioblastoma multiforme
Wilson's disease or metabolic disorder (Correct answer)
Acute ischemic stroke

Correct answer: Wilson's disease or metabolic disorder

Bilateral symmetric basal ganglia T2 signal abnormality in a child raises concern for metabolic disorders such as Wilson's disease, mitochondrial disease, or toxic encephalopathy.

Question 157: Which SAR limit (Specific Absorption Rate) is the FDA guideline for whole-body RF energy deposition in a 15-minute period for non-controlled conditions?

2 W/kg
1.5 W/kg
4 W/kg (Correct answer)
3 W/kg

Correct answer: 4 W/kg

The FDA guideline for whole-body average SAR under normal operating mode is 4 W/kg over any 15-minute period.

Question 158: What is the recommended action when a patient with an unknown metallic implant cannot be identified before a clinically urgent MRI?

Cancel the exam without exception
Proceed with the scan at lowest SAR
Consult the radiologist and ordering physician to assess risk vs. benefit (Correct answer)
Perform the scan with a 0.5T open system only

Correct answer: Consult the radiologist and ordering physician to assess risk vs. benefit

The radiologist and referring physician must jointly assess whether clinical urgency outweighs the unquantified risk of scanning with an unknown implant.

Question 159: For MRI of the shoulder, the patient should be positioned with the arm in which orientation to best center the glenohumeral joint?

Arm in full internal rotation only
Arm crossed over the chest
Arm elevated above the head
Arm at the side in neutral or slight external rotation, shoulder centered in the coil (Correct answer)

Correct answer: Arm at the side in neutral or slight external rotation, shoulder centered in the coil

Positioning the shoulder with the arm at the side in neutral or slight external rotation and centering the glenohumeral joint within the dedicated shoulder coil optimizes image quality.

Question 160: Which section of the ARRT MRI content specifications covers pulse sequence selection and acquisition parameter optimization?

Physics and Instrumentation
Patient Care and Education
Procedures
Image Production (Correct answer)

Correct answer: Image Production

Image Production covers acquisition parameters, pulse sequences, and image quality optimization.

Question 161: The range of frequencies sampled during the process is represented by the receiver bandwidth.

gradient of frequency encoding (Correct answer)
phase difference
gradient for slice selection
gradient coils

Correct answer: gradient of frequency encoding

The receiver bandwidth in MRI represents the range of frequencies sampled during the signal acquisition process. This range of frequencies is directly linked to the frequency encoding gradient, which spatially encodes information along one dimension of the image. A wider bandwidth allows for faster acquisition but can lead to a reduction in signal-to-noise ratio (SNR).

Question 162: What is the maximum number of times a candidate may attempt the ARRT MRI registry examination?

6 times total (Correct answer)
Unlimited attempts
5 times within 5 years
3 times total

Correct answer: 6 times total

ARRT limits candidates to 6 total examination attempts for any given credential.

Question 163: Which MRI pulse sequence is most commonly used to perform MR angiography without contrast injection?

Spin echo with long TR/TE
Echo planar imaging (EPI)
Time-of-flight (TOF) angiography (Correct answer)
Inversion recovery with fat suppression

Correct answer: Time-of-flight (TOF) angiography

TOF MRA relies on flow-related enhancement: unsaturated blood flowing into a saturated imaging slice produces high signal relative to stationary tissue.

Question 164: When positioning a patient for a lumbar spine MRI, the technologist should place the patient in which position to reduce lumbar lordosis and improve image quality?

Prone with legs flat
Lateral decubitus position
Supine with knees flexed and supported by a foam wedge (Correct answer)
Seated upright

Correct answer: Supine with knees flexed and supported by a foam wedge

Flexing the knees with a foam wedge support flattens lumbar lordosis, reducing the curvature and aligning disc spaces parallel to axial slices for optimal visualization.

Question 165: To form a magnet field, wires are arranged side by side.

Resistive magnet
Permanent magnet
Superconducting
Selenoid magnet (Correct answer)

Correct answer: Selenoid magnet

A solenoid magnet is formed by coiling a wire into a cylindrical shape. When an electric current passes through this coiled wire, it generates a uniform magnetic field along the axis of the cylinder. This design is fundamental to many types of MRI magnets, particularly superconducting systems, where the solenoid configuration efficiently produces a strong, homogeneous field.

Question 166: A patient is claustrophobic and anxious before their MRI. Which non-pharmacological intervention is most appropriate first?

Use a stronger magnetic field to shorten scan time
Explain the procedure, offer a patient communication system, and consider feet-first entry (Correct answer)
Refuse the exam and reschedule
Immediately administer IV sedation

Correct answer: Explain the procedure, offer a patient communication system, and consider feet-first entry

Thorough patient education, reassurance, mirror/prism glasses, music headphones, and entering the bore feet-first can significantly reduce claustrophobia before pharmacological intervention.

Question 167: Which of the following is NOT an acceptable primary pathway for ARRT MRI registry eligibility?

Hold a primary ARRT certification in radiation therapy
Hold a primary ARRT certification in radiography
Hold an associate degree only with no primary ARRT credential (Correct answer)
Hold a primary ARRT certification in nuclear medicine technology

Correct answer: Hold an associate degree only with no primary ARRT credential

Candidates must hold a current primary ARRT certification in an approved discipline; an associate degree alone does not satisfy eligibility.

Question 168: Magnetization transfer contrast (MTC) in MRI is based on the exchange of magnetization between which two proton pools?

Arterial and venous blood
Fat protons and water protons
Free water protons and bound macromolecular protons (Correct answer)
Intracellular and extracellular water

Correct answer: Free water protons and bound macromolecular protons

MTC involves saturation of bound macromolecular protons, which transfer their saturation to free water protons, reducing signal in tissues with high macromolecular content.

Question 169: On MRI of the liver, a simple hepatic cyst is expected to show which signal characteristics?

T1 low, T2 low
T1 high, T2 high, with peripheral enhancement
T1 low, T2 high, no enhancement (Correct answer)
T1 high, T2 low

Correct answer: T1 low, T2 high, no enhancement

Simple hepatic cysts have low T1 signal, very high T2 signal due to pure fluid content, and show no contrast enhancement.

Question 170: Which gradient-echo sequence uses a very short TR and a spoiler gradient to eliminate residual transverse magnetization before the next RF pulse?

FIESTA
GRASS
Spoiled gradient echo (SPGR/FLASH) (Correct answer)
Steady-state free precession (SSFP/TrueFISP)

Correct answer: Spoiled gradient echo (SPGR/FLASH)

Spoiled GRE sequences (SPGR, FLASH) use RF or gradient spoiling to destroy residual transverse magnetization between pulses, producing T1-weighted images with high SNR efficiency.

Question 171: MR spectroscopy (MRS) of the brain identifies metabolites by their distinct chemical shifts. Which metabolite is elevated in tumors with high cell density and membrane turnover?

Creatine (Cr)
Choline (Cho) (Correct answer)
Lactate
N-acetylaspartate (NAA)

Correct answer: Choline (Cho)

Choline is a marker of membrane synthesis and cellular turnover; elevated choline is characteristic of tumors, demyelination, and other high-proliferation states.

Question 172: Which coil type provides the best signal-to-noise ratio (SNR) for a specific small anatomy because it is placed closest to the structure?

Surface coil (Correct answer)
Head coil
Body coil
Volume coil

Correct answer: Surface coil

Surface coils are placed directly over the anatomy of interest; their proximity maximizes SNR for superficial or small structures compared to larger volume coils.

Question 173: A patient with a metallic foreign body in the eye should be evaluated with which imaging modality BEFORE entering the MRI suite?

Ultrasound
PET scan
CT scan (Correct answer)
Bone scan

Correct answer: CT scan

A CT scan of the orbits is used to detect metallic ocular foreign bodies before MRI because ferromagnetic metal near the eye is a contraindication.

Question 174: On MRI, cortical bone appears as which signal intensity on both T1 and T2 weighted images?

High signal
Intermediate signal
Low signal (signal void) (Correct answer)
Variable signal

Correct answer: Low signal (signal void)

Cortical bone has very few mobile protons and produces a signal void (low signal) on both T1 and T2 weighted MRI sequences.

Question 175: A patient develops nausea and vomiting during IV gadolinium infusion. The most appropriate immediate action is to:

Stop the infusion, assess the patient, and administer antiemetic if needed while monitoring for escalation (Correct answer)
Administer epinephrine immediately
Increase infusion rate to complete dosing faster
Continue the infusion as nausea is expected

Correct answer: Stop the infusion, assess the patient, and administer antiemetic if needed while monitoring for escalation

Nausea and vomiting may be physiologic reactions to GBCA; the injection should be stopped, the patient assessed, symptoms treated, and the reaction monitored for potential escalation to a more serious event.

Question 176: Which MRI zone is defined as the area containing the MRI scanner itself where the static magnetic field is always present?

Zone I
Zone III
Zone IV (Correct answer)
Zone II

Correct answer: Zone IV

Zone IV is the MRI scanner room where the magnet is always on and unrestricted ferromagnetic items pose immediate danger.

Question 177: Which sequence parameter directly controls the slice thickness in a 2D spin-echo acquisition?

TR duration
TE duration
Bandwidth of the readout gradient
Bandwidth of the RF pulse divided by the slice-select gradient amplitude (Correct answer)

Correct answer: Bandwidth of the RF pulse divided by the slice-select gradient amplitude

Slice thickness = RF pulse bandwidth ÷ slice-select gradient amplitude; thicker slices can be produced by widening the RF bandwidth or reducing the gradient strength.

Question 178: Which MRI technique uses magnetically labeled water protons as an endogenous tracer to measure cerebral blood flow without contrast injection?

Dynamic Susceptibility Contrast (DSC) MRI
Blood Oxygen Level Dependent (BOLD) fMRI
Dynamic Contrast Enhanced (DCE) MRI
Arterial Spin Labeling (ASL) (Correct answer)

Correct answer: Arterial Spin Labeling (ASL)

ASL uses RF inversion of arterial water protons proximal to the imaging plane as a flow tracer, enabling non-invasive perfusion measurement.

Question 179: For imaging the brachial plexus, which specialized MRI sequence is most useful for nerve visualization?

GRE in-phase
T1 axial post-contrast
Diffusion-weighted imaging
STIR or fat-suppressed T2 coronal (Correct answer)

Correct answer: STIR or fat-suppressed T2 coronal

Fat-suppressed T2 or STIR coronal images suppress the surrounding fat signal and highlight the high-water-content neural tissue of the brachial plexus.

Question 180: SSFP (steady-state free precession) sequences such as TrueFISP/FIESTA produce contrast that is proportional to which tissue property ratio?

TE/T2*
TR/T1
T2/T1 (Correct answer)
T1/T2

Correct answer: T2/T1

SSFP signal is proportional to T2/T1 ratio; tissues with high T2/T1 (like blood and fluids) appear very bright, making SSFP ideal for cardiac cine and vascular imaging.

Question 181: The quantity of determines the receiver bandwidth.

Phase changes within the matrix
Frequency samples in the matrix (Correct answer)

Correct answer: Frequency samples in the matrix

The receiver bandwidth in MRI is directly determined by the number of frequency samples (pixels) in the frequency encoding direction. A higher number of samples requires a wider bandwidth to accurately capture the range of frequencies present in the signal within the acquisition time. This ensures proper spatial resolution and minimizes aliasing artifacts in the resulting image.

Question 182: In MR imaging, the signal-to-noise ratio (SNR) improves with increasing field strength approximately as:

SNR is independent of field strength
As the square of B0 (B0²)
As the square root of B0
Linearly (proportional to B0) (Correct answer)

Correct answer: Linearly (proportional to B0)

SNR scales approximately linearly with B0 because both the equilibrium magnetization and the Larmor frequency (and thus the induced EMF) increase linearly with field strength.

Question 183: Zipper artifact on an MRI image appears as a line of alternating bright and dark pixels across the image, most often caused by:

Coil coupling artifact
Gradient switching noise
External RF interference from inadequate shielding or open RF cage door (Correct answer)
Patient movement

Correct answer: External RF interference from inadequate shielding or open RF cage door

Zipper artifact is caused by external radiofrequency interference entering the scan room, typically due to an open waveguide, broken shielding, or improperly closed scanner room door.

Question 184: Which vital sign parameter is most critical to monitor during MRI in a sedated pediatric patient?

Blood pressure only
Temperature with a mercury thermometer
Heart rate via standard ECG only
Oxygen saturation via MR-compatible pulse oximetry (Correct answer)

Correct answer: Oxygen saturation via MR-compatible pulse oximetry

Continuous oxygen saturation monitoring via MR-compatible pulse oximetry is essential in sedated pediatric patients to detect respiratory compromise caused by sedation.

Question 185: Pulsatile flow artifact from a vessel typically appears as ghost images displaced in which direction?

Both frequency and phase directions equally
Frequency-encoding direction
Slice-selection direction
Phase-encoding direction (Correct answer)

Correct answer: Phase-encoding direction

Pulsatile flow ghosts appear in the phase-encoding direction because pulsatile variations in spin phase occur between TR intervals during phase-encode data collection.

Question 186: Multiple sclerosis (MS) plaques in the brain are classically found in which location on MRI?

Periventricular white matter, corpus callosum, and juxtacortical regions (Correct answer)
Cerebellum exclusively
Gray matter of the cortex only
Basal ganglia bilaterally

Correct answer: Periventricular white matter, corpus callosum, and juxtacortical regions

MS demyelinating plaques characteristically occur in periventricular white matter, corpus callosum (Dawson fingers), juxtacortical, and infratentorial regions.

Question 187: What is the main biological risk associated with rapidly switching gradient magnetic fields during an MRI scan?

Radiofrequency burns
Peripheral nerve stimulation (Correct answer)
Hypothermia
Acoustic damage

Correct answer: Peripheral nerve stimulation

Rapidly switching gradients can induce electrical currents in body tissue, causing peripheral nerve stimulation (PNS).

Question 188: During inversion recovery, the null point (TI) for fat suppression (STIR) is set to:

TI = TE × T1(fat)
TI = T2(fat) × 0.693
TI = TR / 2
TI = T1(fat) × ln(2) (Correct answer)

Correct answer: TI = T1(fat) × ln(2)

The null point occurs when the recovering longitudinal magnetization of fat passes through zero, which is at TI ≈ T1(fat) × ln(2) ≈ 0.693 × T1(fat).

Question 189: On MRI of the prostate using PI-RADS scoring, which sequence is the most dominant sequence for peripheral zone lesions?

Diffusion-weighted imaging (DWI) (Correct answer)
T1-weighted
MR spectroscopy
Dynamic contrast-enhanced (DCE)

Correct answer: Diffusion-weighted imaging (DWI)

DWI is the dominant sequence for peripheral zone lesion characterization in the PI-RADS v2.1 scoring system for prostate MRI.

Question 190: Which MRI sequence is used to visualize flowing blood as bright signal ('bright blood') without contrast injection by exploiting the inflow of unsaturated spins into the imaging slice?

VIBE
Time-of-flight (TOF) MRA (Correct answer)
Contrast-enhanced MRA
Phase contrast MRA

Correct answer: Time-of-flight (TOF) MRA

TOF MRA uses gradient echo with short TR to saturate stationary tissue; fresh unsaturated blood flowing into the slice appears bright due to the inflow enhancement effect.

Question 191: Spin echo sequence is modified by rapid spin echo sequence by

Gradient additions for spoilers
Adding repeated pulses of 90 degrees
Adding 180-degree pulses in succession (Correct answer)
progressively adding gradients encoded with frequencies

Correct answer: Adding 180-degree pulses in succession

The rapid spin echo (also known as Fast Spin Echo or Turbo Spin Echo) sequence modifies the conventional spin echo by applying a train of multiple 180-degree refocusing pulses after a single 90-degree excitation pulse. Each 180-degree pulse generates a separate echo, allowing multiple lines of k-space to be acquired within a single TR period. This significantly shortens scan times compared to conventional spin echo sequences.

Question 192: Traditional GRE order

Maintain transverse magnetization for additional attempts
Reduce the impact of residual transverse magnetization by using spoiler gradients. (Correct answer)
To lessen the impact of residual transverse magnetization, use long TR.

Correct answer: Reduce the impact of residual transverse magnetization by using spoiler gradients.

In traditional (spoiled) Gradient Echo (GRE) sequences, spoiler gradients are applied at the end of each TR period. The primary purpose of these gradients is to intentionally dephase any residual transverse magnetization. This prevents the magnetization from contributing to the signal in subsequent TRs, ensuring that the signal primarily reflects T1 weighting and maintains consistent image contrast by avoiding contamination from previous excitations.

Question 193: Require the employment of solenoid coils because of the B0's orientation; these coils are more effective than linear coils and can be electrically combined with other coils to enhance signal homogeneity across an area of interest.

Phased array
Helmholtz pair
Quadrature
Vertical (Correct answer)

Correct answer: Vertical

Vertical coils are specifically designed for MRI systems where the main magnetic field (B0) is oriented vertically, often found in open or permanent magnet systems. These coils are more effective than linear coils in this orientation and can be electrically combined with other coils to enhance signal homogeneity across the area of interest, optimizing signal reception for vertical field systems.

Question 194: What is the relationship between magnetic field strength (B0) and the Larmor frequency?

Larmor frequency is proportional to B0²
Larmor frequency is directly proportional to B0 (ω₀ = γ·B0) (Correct answer)
Larmor frequency is independent of B0
Larmor frequency is inversely proportional to B0

Correct answer: Larmor frequency is directly proportional to B0 (ω₀ = γ·B0)

The Larmor equation states ω₀ = γ·B0, so doubling the field strength doubles the resonance frequency (e.g., 63 MHz at 1.5T, 128 MHz at 3T for hydrogen).

Question 195: Which structure in the knee joint is best evaluated with MRI and appears as a low-signal-intensity triangular structure?

Articular cartilage
Patellar tendon
Anterior cruciate ligament
Medial meniscus (Correct answer)

Correct answer: Medial meniscus

The medial meniscus is best visualized on MRI as a low-signal-intensity fibrocartilaginous triangular structure on coronal and sagittal images.

Question 196: Positive susceptibility is present in these materials, however when exposed to an external magnetic field, they will stay magnetized even after the field is removed.

Ferromagnetic (Correct answer)
Diamagnetic
Paramagnetic
Superpapmagnetic

Correct answer: Ferromagnetic

Ferromagnetic materials are characterized by strong positive susceptibility and the ability to retain their magnetization even after the external magnetic field is removed. This property makes them suitable for creating permanent magnets. Examples include iron, nickel, and cobalt, which are strongly attracted to magnets and can become permanently magnetized.

Question 197: Echo planar imaging (EPI) is used in which MRI techniques due to its extremely fast acquisition speed?

Conventional T1 spin echo and MRCP
STIR and inversion recovery sequences
DWI, fMRI, and perfusion imaging (Correct answer)
MR arthrography and spectroscopy

Correct answer: DWI, fMRI, and perfusion imaging

EPI acquires an entire k-space in a single excitation, enabling the speed needed for diffusion-weighted imaging, fMRI BOLD imaging, and dynamic perfusion studies.

Question 198: What is the effect of increasing the echo time (TE) on T2-weighted images?

Increases T2 weighting by allowing more transverse relaxation (Correct answer)
Increases T1 weighting
Has no effect on tissue contrast
Decreases T2 weighting by increasing signal

Correct answer: Increases T2 weighting by allowing more transverse relaxation

A longer TE allows more time for T2 decay, so tissues with short T2 lose more signal, increasing contrast between tissues with different T2 values.

Question 199: Parallel imaging techniques such as GRAPPA and SENSE reduce scan time by:

Applying stronger gradient pulses
Using multiple receiver coil elements to partially fill k-space and reduce phase encoding steps (Correct answer)
Increasing the magnetic field strength
Eliminating the need for radiofrequency pulses

Correct answer: Using multiple receiver coil elements to partially fill k-space and reduce phase encoding steps

Parallel imaging exploits spatial sensitivity information from multiple coil elements to skip phase encoding lines, reconstructing the full image and reducing acquisition time.

Question 200: When imaging the lumbar spine, which position best opens the intervertebral foramina and reduces lumbar lordosis for improved visualization?

Lateral decubitus
Supine with legs elevated on a cushion (knees and hips flexed) (Correct answer)
Prone with pillow under abdomen
Prone with legs extended

Correct answer: Supine with legs elevated on a cushion (knees and hips flexed)

Flexing the hips and knees while supine flattens lumbar lordosis, opens intervertebral foramina, and improves disc and nerve root visualization.

Question 201: What is the primary purpose of fat saturation techniques in MRI?

To eliminate chemical shift artifact entirely
To increase the signal from fat-containing tissues
To reduce T1 relaxation time of fat
To suppress the fat signal so adjacent structures are more conspicuous (Correct answer)

Correct answer: To suppress the fat signal so adjacent structures are more conspicuous

Fat saturation applies a frequency-selective RF pulse to null the fat signal, improving visibility of adjacent enhancing or edematous tissue.

Question 202: What is the term for the MRI safety classification that indicates a device has been tested and found safe under specified conditions?

MR Conditional (Correct answer)
MR Compatible
MR Unsafe
MR Safe

Correct answer: MR Conditional

MR Conditional means the device poses no known hazards when used within the specific conditions (field strength, SAR, gradient limits) stated by the manufacturer.

Question 203: Which MRI artifact appears as a ghosting or smearing of bright structures in the phase-encoding direction?

Motion (ghosting) artifact (Correct answer)
Gibbs (truncation) artifact
Chemical shift artifact
Susceptibility artifact

Correct answer: Motion (ghosting) artifact

Motion artifact manifests as ghost images displaced in the phase-encoding direction because phase-encoding samples data over many TR intervals while frequency encoding is instantaneous.

Question 204: What is the purpose of applying a saturation band in MRI?

To increase SNR from the target anatomy
To improve spatial resolution in the phase direction
To shorten the overall scan time
To suppress signal from specified tissue or flowing blood to reduce artifacts (Correct answer)

Correct answer: To suppress signal from specified tissue or flowing blood to reduce artifacts

Saturation bands apply an RF pulse to a defined region, nulling its magnetization so it contributes no signal, which suppresses motion or flow-related artifacts.

Question 205: In MRI, what does the term 'bandwidth' typically refer to in clinical practice?

The RF pulse duration in milliseconds
The range of flip angles used in a sequence
The range of frequencies sampled during readout, affecting SNR and chemical shift (Correct answer)
The number of phase-encode steps acquired

Correct answer: The range of frequencies sampled during readout, affecting SNR and chemical shift

Receiver bandwidth is the range of frequencies digitized during readout; wider bandwidth reduces chemical shift and distortion but decreases SNR.

Question 206: Which phenomenon causes the chemical shift artifact in MRI, and in which direction does it occur?

Resonance frequency difference between fat and water; frequency-encode direction (Correct answer)
Susceptibility differences between tissues; phase-encode direction
B1 field inhomogeneity; slice-select direction
T1 differences between tissues; readout direction

Correct answer: Resonance frequency difference between fat and water; frequency-encode direction

Fat protons resonate at ~3.5 ppm lower frequency than water, causing spatial misregistration along the frequency-encoding direction.

Question 207: Which MRI contrast agent class is associated with the highest risk of nephrogenic systemic fibrosis (NSF)?

Manganese-based agents
Blood pool agents
Macrocyclic ionic agents
Linear non-ionic agents (Correct answer)

Correct answer: Linear non-ionic agents

Linear non-ionic (and some linear ionic) gadolinium agents release free Gd³⁺ more readily and carry the highest NSF risk in patients with severe renal impairment.

Question 208: The echo time (TE) in gradient-echo sequences affects which type of contrast?

TR governs all contrast in GRE sequences
Proton density contrast only
T2* contrast — longer TE increases T2* weighting and susceptibility effects (Correct answer)
T1 contrast only

Correct answer: T2* contrast — longer TE increases T2* weighting and susceptibility effects

In gradient-echo sequences, TE controls T2* contrast; longer TE allows greater T2* dephasing, increasing susceptibility effects from blood products, iron, and air-tissue interfaces.

Question 209: What is the mechanism of action of gadolinium-based contrast agents (GBCAs) in MRI?

They increase T2 relaxation time, increasing signal on T2-weighted images
They block radiofrequency pulses to create contrast
They directly emit radio waves that increase signal
They shorten T1 relaxation time of nearby water protons, increasing signal on T1-weighted images (Correct answer)

Correct answer: They shorten T1 relaxation time of nearby water protons, increasing signal on T1-weighted images

Gadolinium shortens the T1 relaxation time of surrounding water protons through dipole-dipole interactions, causing increased signal intensity on T1-weighted sequences.

Question 210: EPI (echo planar imaging) sequences are particularly prone to which artifact caused by off-resonance spins accumulating phase during the long readout?

Susceptibility artifact only in GRE
Truncation artifact
Magic angle artifact
Chemical shift (N/2 ghost or Nyquist ghost) and geometric distortion (Correct answer)

Correct answer: Chemical shift (N/2 ghost or Nyquist ghost) and geometric distortion

EPI's long readout makes it sensitive to field inhomogeneity, causing geometric distortion along the phase-encode direction and N/2 ghosting from alternating echo phase inconsistencies.

Question 211: Which of the following best describes the purpose of placing the frequency-encoding gradient in the anterior-posterior direction for spine MRI?

To shorten scan time
To reduce susceptibility artifact
To reduce phase wrap (aliasing) from anterior abdominal structures (Correct answer)
To increase SNR

Correct answer: To reduce phase wrap (aliasing) from anterior abdominal structures

Placing frequency encoding AP moves phase wrap artifact (aliasing) to the AP direction, preventing anterior abdominal fat from wrapping onto the spine.

Question 212: Which type of question format is exclusively used on the ARRT MRI registry computer-based examination?

Multiple choice with one best answer (Correct answer)
Fill-in-the-blank
True/False
Matching

Correct answer: Multiple choice with one best answer

The ARRT MRI exam uses only multiple-choice questions with four options and one best answer.

Question 213: When is a candidate's ARRT MRI registry exam score report typically available?

Six weeks after the exam window closes
Within 3–5 business days via the ARRT website (Correct answer)
Immediately on screen at the testing center
After 30 days by postal mail only

Correct answer: Within 3–5 business days via the ARRT website

ARRT posts official score reports to the candidate's online account within approximately 3–5 business days after testing.

Question 214: This kind of magnetic shielding confines the main magnet's field by using other magnets and their corresponding magnetic fields.

Passive
Active (Correct answer)

Correct answer: Active

Active magnetic shielding uses additional superconducting coils, placed around the main magnet, that generate opposing magnetic fields. These opposing fields effectively cancel out the main magnet's fringe field at a certain distance. This method significantly reduces the extent of the stray magnetic field outside the scanner, making it a more complex but often more effective and lighter shielding solution than passive methods.

Question 215: In MR angiography, time-of-flight (TOF) technique produces vascular signal by exploiting which physical principle?

T2 prolongation of blood
T1 shortening by gadolinium contrast
Inflow enhancement: unsaturated blood entering a saturated imaging slab (Correct answer)
Chemical shift between blood and surrounding fat

Correct answer: Inflow enhancement: unsaturated blood entering a saturated imaging slab

TOF MRA relies on flow-related enhancement: flowing unsaturated blood entering a slice that has saturated stationary tissue appears bright relative to background.

Question 216: Susceptibility-weighted imaging (SWI) is particularly sensitive to which types of tissue or substances?

Myelinated white matter
Gadolinium-enhanced tissue
Fat and water interfaces
Blood products (hemosiderin, deoxyhemoglobin), calcium, and iron-containing structures (Correct answer)

Correct answer: Blood products (hemosiderin, deoxyhemoglobin), calcium, and iron-containing structures

SWI exploits magnetic susceptibility differences between tissues; hemosiderin, deoxyhemoglobin, calcium, and iron create local field distortions that appear as marked hypointensity on SWI images.

Question 217: Fast spin-echo (FSE/TSE) sequences acquire multiple lines of k-space per TR using which approach?

Multiple 90° pulses with a single 180° refocusing pulse
A single 90° pulse followed by multiple 180° refocusing pulses (echo train) (Correct answer)
Using a series of partial flip-angle pulses
Rapidly toggling the frequency-encoding gradient

Correct answer: A single 90° pulse followed by multiple 180° refocusing pulses (echo train)

FSE uses an echo train (RARE principle): after a 90° excitation, a series of 180° pulses generates multiple spin echoes, each phase-encoded differently, filling multiple k-space lines per TR.

Question 218: How does increasing the echo train length (ETL) in a fast spin echo (FSE) sequence affect image quality?

SNR improves proportional to ETL
Scan time decreases but T2 blurring may increase (Correct answer)
T1 contrast increases significantly
Spatial resolution improves in all directions

Correct answer: Scan time decreases but T2 blurring may increase

Longer ETL fills k-space faster (reducing scan time) but each echo has progressively more T2 decay, causing blurring particularly of edges and fine detail.

Question 219: A small bandwidth makes _slices possible.

Slimmer (Correct answer)
Dicker

Correct answer: Slimmer

In MRI, the slice selection gradient, in conjunction with the radiofrequency (RF) pulse, determines the slice thickness. A smaller receiver bandwidth means that a narrower range of frequencies is sampled. This corresponds to a smaller range of magnetic field strengths along the slice selection gradient, resulting in the selection of a thinner, or 'slimmer,' slice.

Question 220: What happens to image contrast when the echo time (TE) is increased in a T2-weighted sequence?

Tissues appear uniformly bright
T1 contrast increases
T2 contrast increases as tissues with short T2 decay faster (Correct answer)
SNR improves due to longer signal collection

Correct answer: T2 contrast increases as tissues with short T2 decay faster

Longer TE allows more T2 decay to occur, so tissues with short T2 lose signal faster and appear darker, enhancing T2 contrast between tissues.

Question 221: On brain MRI, the hippocampus is best evaluated for atrophy (as in Alzheimer's disease) on which plane?

Coronal, especially perpendicular to the long axis of the hippocampus (Correct answer)
Oblique axial
Sagittal only
Axial only

Correct answer: Coronal, especially perpendicular to the long axis of the hippocampus

Coronal T1-weighted images perpendicular to the long axis of the hippocampus provide the best visualization of hippocampal volume and atrophy.

Question 222: Which type of MRI coil provides the best SNR for imaging a small, superficial structure?

Small surface coil placed directly over the region of interest (Correct answer)
Large volume (birdcage) coil surrounding the patient
Solenoid body coil at isocenter
Phased-array coil designed for the spine

Correct answer: Small surface coil placed directly over the region of interest

A small surface coil placed close to the target anatomy maximizes signal reception from that area while minimizing noise from surrounding regions.

Question 223: The magnetic field's intensity is varied from head to foot by this gradient coil.

X
Z (Correct answer)
Y

Correct answer: Z

In most MRI systems, the main magnetic field (B0) is oriented along the Z-axis, which typically runs from the patient's head to foot. The Z-gradient coil is specifically designed to create a linear variation in the magnetic field strength along this Z-axis. This allows for precise slice selection and spatial encoding in the head-to-foot dimension.

Question 224: The signal-to-noise ratio (SNR) in MRI is proportional to which of the following?

1 / (TR × TE)
Field of view / matrix size only
Voxel volume × √(NEX) × √(scan time factors) (Correct answer)
Flip angle / repetition time

Correct answer: Voxel volume × √(NEX) × √(scan time factors)

SNR increases with larger voxel volume, more signal averages (NEX), and longer acquisition times that allow more k-space sampling.

Question 225: The ARRT MRI registry exam content specification places approximately what percentage of questions in the 'Procedures' domain?

20%
35% (Correct answer)
10%
50%

Correct answer: 35%

Approximately 35% of the MRI registry exam covers Procedures, making it one of the largest content areas.

Question 226: Which of the following parameters most directly controls T1 contrast in a spin echo sequence?

Echo time (TE)
Repetition time (TR) (Correct answer)
Flip angle in gradient echo
Bandwidth

Correct answer: Repetition time (TR)

TR determines how much longitudinal relaxation occurs between excitations; a short TR emphasizes T1 differences because tissues with shorter T1 recover faster.

Question 227: Which breathing technique is recommended for upper abdominal MRI (liver, pancreas) to minimize respiratory motion artifact?

Breath-hold acquisitions combined with respiratory-triggered sequences for longer scans (Correct answer)
Free breathing throughout all sequences
Hyperventilation before each sequence
Continuous shallow breathing

Correct answer: Breath-hold acquisitions combined with respiratory-triggered sequences for longer scans

Breath-hold sequences minimize diaphragmatic motion for dynamic contrast imaging; respiratory triggering or navigator gating is used for longer acquisitions that cannot be completed in a single breath-hold.

Question 228: A 'blooming' artifact on gradient echo (GRE) MRI is caused by which substance?

Fat
Cerebrospinal fluid
Hemosiderin or calcification (Correct answer)
Gadolinium contrast

Correct answer: Hemosiderin or calcification

Hemosiderin, calcium, and other susceptibility-inducing substances cause local field inhomogeneities that appear as signal loss blooming on GRE sequences.

Question 229: Which inversion recovery technique is used to suppress fat signal in musculoskeletal MRI?

MPRAGE
VIBE
FLAIR
STIR (Short TI Inversion Recovery) (Correct answer)

Correct answer: STIR (Short TI Inversion Recovery)

STIR uses a short inversion time timed to null the longitudinal magnetization of fat, suppressing fat signal uniformly regardless of field inhomogeneity.

Question 230: What does 'isotropic voxel' mean in MRI acquisition?

Voxel aligned with the main magnetic field
Voxel with equal dimensions in all three spatial directions (Correct answer)
Voxel that produces equal signal in T1 and T2 sequences
Voxel with equal field strength in all dimensions

Correct answer: Voxel with equal dimensions in all three spatial directions

An isotropic voxel has identical length, width, and height, allowing high-quality multiplanar reformats without resolution loss.

ARRT MRI Exam

The ARRT Magnetic Resonance Imaging examination certifies technologists in MRI, assessing competency in patient care, MRI safety, image production physics and sequences, and clinical imaging procedures.

230

Questions

240 min

Time Limit

75%

To Pass

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