FRCR FRCR Image Interpretation and Anatomy 2 — Questions and Answers
Question 1: Which radiological feature differentiates a simple renal cyst from a complex cystic renal mass on CT?
- Enhancing internal septations or nodules (Correct answer)
- High attenuation on non-contrast CT
- Dependent layering of fluid density
- Smooth thin wall without enhancement
Correct answer: Enhancing internal septations or nodules
Enhancing internal septations, nodularity, or thick walls (Bosniak categories III–IV) distinguish complex cystic masses requiring surgery from simple benign cysts (Bosniak I–II).
Question 2: On a lateral knee radiograph, which line is used to assess patellar height (patellar height index)?
- Insall-Salvati ratio (patellar tendon length to patellar length) (Correct answer)
- Blumensaat line relative to patellar inferior pole
- Sulcus angle on the trochlear groove
- Tibial tubercle-trochlear groove distance
Correct answer: Insall-Salvati ratio (patellar tendon length to patellar length)
The Insall-Salvati ratio compares patellar tendon length to patellar length on a lateral radiograph; a ratio >1.2 indicates patella alta and <0.8 indicates patella baja.
Question 3: What does the 'double bubble' sign on plain abdominal radiograph indicate in neonates?
- Duodenal atresia (Correct answer)
- Pyloric stenosis
- Jejunal atresia
- Malrotation with volvulus
Correct answer: Duodenal atresia
The double bubble sign — two air-fluid levels representing the stomach and dilated proximal duodenum — is pathognomonic of duodenal atresia, strongly associated with trisomy 21.
Question 4: On liver MRI, which enhancement pattern is characteristic of a hepatocellular carcinoma (HCC)?
- Arterial phase hyperenhancement with portal venous phase washout (Correct answer)
- Peripheral nodular enhancement progressing centrally
- Persistent delayed enhancement throughout all phases
- Homogeneous enhancement equal to liver parenchyma
Correct answer: Arterial phase hyperenhancement with portal venous phase washout
HCC shows arterial hyperenhancement (due to neoangiogenesis) followed by washout in the portal venous and delayed phases — a pattern called 'arterial hyperenhancement and washout' (LI-RADS criteria).
Question 5: Which vertebral level marks the bifurcation of the abdominal aorta into the common iliac arteries?
- L4 (Correct answer)
- L2
- L3
- L5
Correct answer: L4
The abdominal aorta bifurcates into the right and left common iliac arteries at the level of L4 (approximately at the level of the iliac crests).
Question 6: What does the Hounsfield unit (HU) value of approximately −100 HU indicate on CT?
- Fat tissue (Correct answer)
- Water
- Air
- Soft tissue
Correct answer: Fat tissue
Fat has a characteristic CT attenuation of approximately −50 to −150 HU, clearly distinguishing it from water (0 HU) and soft tissue (+20 to +80 HU).
FRCR FRCR Image Interpretation and Anatomy 2
Which radiological feature differentiates a simple renal cyst from a complex cystic renal mass on CT?