Diagnostic Imaging & Radiology Flashcards

Which MRI sequence is most sensitive for detecting acute cerebral ischemia within the first few hours of onset?

Answer: Diffusion-weighted imaging (DWI)

DWI detects restricted diffusion caused by cytotoxic edema in acute ischemia, making it positive within minutes of stroke onset.

On a chest X-ray, the 'silhouette sign' is caused by:

Answer: Air-space consolidation obliterating a normally visible border

The silhouette sign occurs when two structures of equal radiodensity are in contact, causing loss of the normal visible interface between them.

Which imaging modality is the gold standard for evaluating the rotator cuff for full-thickness tears?

Answer: MRI

MRI provides excellent soft tissue contrast and multiplanar imaging, making it the gold standard for rotator cuff tear assessment.

A 'target sign' on bowel ultrasound typically indicates:

Answer: Intussusception

The target sign on transverse ultrasound view represents layers of bowel wall telescoping into itself in intussusception.

What is the primary advantage of using gadolinium-based contrast agents in MRI over iodinated contrast in CT?

Answer: Significantly lower risk of anaphylaxis

Gadolinium-based agents have a significantly lower rate of severe anaphylactic reactions compared to iodinated CT contrast agents.

On mammography, which feature is MOST suspicious for malignancy?

Answer: Irregular mass with spiculated margins

Spiculated margins on mammography are highly associated with malignancy due to desmoplastic reaction pulling surrounding tissue inward.

The 'double bubble' sign on abdominal X-ray in a neonate is characteristic of:

Answer: Duodenal atresia

Duodenal atresia produces two air-filled bubbles representing the stomach and proximal duodenum, with no distal bowel gas.