SPEX SPEX Radiology and Imaging 4

Question 1

A patient with a GFR of 28 mL/min requires contrast-enhanced CT. Which strategy best minimizes the risk of contrast-induced nephropathy?

Accepted Answer

Prehydrate with IV normal saline and use the lowest effective iodine dose

Answer

IV hydration with isotonic saline before and after contrast administration and minimizing contrast volume are the cornerstones of CIN prevention in patients with reduced GFR.

Question 2

On a PA chest radiograph, which finding is most consistent with a left lower lobe collapse?

Accepted Answer

Elevation of the left hemidiaphragm with leftward mediastinal shift and a triangular retrocardiac opacity

Answer

Left lower lobe collapse produces a triangular retrocardiac density, elevated left hemidiaphragm, and ipsilateral mediastinal shift due to volume loss.

Question 3

Which MRI sequence is most sensitive for detecting acute cerebral ischemia within the first 6 hours of symptom onset?

Accepted Answer

Diffusion-weighted imaging (DWI)

Answer

DWI detects cytotoxic edema from restricted water diffusion within minutes of ischemia onset, making it the most sensitive early sequence.

Question 4

During fluoroscopy-guided lumbar spine injection, the operator notices the C-arm beam is delivered in a steep oblique angle for extended periods. The most appropriate dose-reduction measure is to:

Accepted Answer

Use pulsed fluoroscopy at the lowest frame rate that provides adequate visualization

Answer

Pulsed fluoroscopy reduces cumulative dose by delivering radiation only in pulses rather than continuously, with minimal loss of procedural guidance.

Question 5

A 35-year-old pregnant woman at 28 weeks gestation presents with right flank pain. What is the preferred initial imaging modality?

Accepted Answer

Renal ultrasound

Answer

Ultrasound is the first-line modality in pregnancy because it carries no ionizing radiation and can diagnose hydronephrosis and renal calculi without fetal risk.

SPEX Exam Practice Test

SPEX Exam Practice Test

SPEX SPEX Radiology and Imaging 4