Diagnostic Imaging Techniques Flashcards

When performing an X-ray, what is considered the primary source of scatter radiation?

Answer: The patient's body

The patient's body is the main source of scatter radiation. When the primary X-ray beam enters the patient's tissues, some photons are absorbed, some pass through to the detector, and others are scattered in various directions through an interaction known as the Compton effect. This scattered radiation reduces image contrast and is the primary source of radiation exposure to personnel in the room.

A veterinarian suspects hip dysplasia in a 2-year-old Labrador Retriever and requests radiographs for official evaluation by the Orthopedic Foundation for Animals (OFA). Which of the following views is the required standard for this evaluation?

Answer: An extended-leg ventrodorsal view

The Orthopedic Foundation for Animals (OFA) requires a specific extended-leg ventrodorsal (VD) view for official hip dysplasia certification. This position involves placing the dog on its back, extending the rear limbs parallel to each other with the stifles rotated internally, and ensuring the pelvis is symmetrical.

A cat with chronic regurgitation is scheduled for a barium sulfate contrast study. What is the primary purpose of administering this positive contrast agent?

Answer: To outline the gastrointestinal tract to assess motility, and identify mucosal lesions or obstructions.

Barium sulfate is a positive contrast agent that is administered orally to coat the lining of the gastrointestinal (GI) tract. This allows for radiographic visualization of the esophagus, stomach, and intestines to evaluate their structure, function (motility), and to identify foreign bodies, masses, strictures, or mucosal irregularities.

During an abdominal ultrasound, the veterinarian points out the urinary bladder, which appears completely black on the screen. What is the correct term to describe this appearance?

Answer: Anechoic

The term 'anechoic' means without echo. Simple fluids, like urine in the bladder, do not reflect the ultrasound waves back to the transducer. Therefore, these structures appear black on the ultrasound image. 'Hyperechoic' means brighter than surrounding tissue (e.g., bone), 'hypoechoic' means darker than surrounding tissue (e.g., muscle), and 'isoechoic' means having the same brightness.

A dog is presented with acute onset of seizures. To best visualize the soft tissues of the brain and detect potential inflammation or a non-mineralized tumor, which imaging modality is superior?

Answer: Magnetic Resonance Imaging (MRI)

Magnetic Resonance Imaging (MRI) is the gold standard for imaging soft tissues, particularly the central nervous system. It provides excellent contrast between different soft tissue types, such as gray and white matter in the brain, making it superior for detecting inflammation (encephalitis), edema, and soft tissue tumors. CT is faster and better for imaging bone and acute hemorrhage.

A veterinary technician takes a thoracic radiograph of a dyspneic cat without sedation. The resulting image is blurry, and the cardiac silhouette and lung margins are indistinct. This loss of detail is most likely caused by which artifact?

Answer: Motion artifact

Motion artifact is a common cause of blurry radiographs and loss of detail. It occurs when the patient moves during the X-ray exposure, which is particularly common in awake, panting, or dyspneic animals. This movement causes the anatomical structures to be recorded across a range of positions, resulting in a blurred image.