Computed Tomography Test CT Anatomy and Clinical Applications 2 — Questions and Answers
Question 1: Which CT finding is characteristic of renal cell carcinoma (RCC)?
- Hypervascular solid renal mass with arterial phase enhancement ≥20 HU above baseline (Correct answer)
- Non-enhancing cyst with thin walls
- Calcified lesion with no enhancement
- Fat-containing lesion with negative HU values
Correct answer: Hypervascular solid renal mass with arterial phase enhancement ≥20 HU above baseline
RCC is highly vascular and shows significant enhancement (typically >20 HU increase) on arterial phase CT, distinguishing it from cysts and benign lesions.
Question 2: What is the CT appearance of a renal angiomyolipoma (AML)?
- Intralesional fat with HU values below −10 (macroscopic fat) (Correct answer)
- Purely cystic lesion
- Homogeneous solid mass without fat
- Ring-enhancing lesion with central necrosis
Correct answer: Intralesional fat with HU values below −10 (macroscopic fat)
Classic AMLs contain macroscopic fat (HU < −10), which is pathognomonic and allows diagnosis without biopsy in the appropriate clinical context.
Question 3: On a CT urogram, which phase of imaging is used to evaluate the collecting system, ureters, and bladder?
- Excretory (delayed) phase at 5–10 minutes (Correct answer)
- Arterial phase at 25 seconds
- Portal venous phase at 70 seconds
- Non-contrast phase
Correct answer: Excretory (delayed) phase at 5–10 minutes
The excretory phase captures opacified urine within the renal collecting system, ureters, and bladder after contrast is filtered and excreted by the kidneys.
Question 4: Which structure separates the right and left lobes of the liver and is identified by an imaginary line on CT?
- Main lobar fissure (Cantlie's line) from the gallbladder fossa to the middle hepatic vein (Correct answer)
- Falciform ligament
- Portal vein bifurcation
- Inferior vena cava
Correct answer: Main lobar fissure (Cantlie's line) from the gallbladder fossa to the middle hepatic vein
Cantlie's line is an imaginary line connecting the gallbladder fossa anteriorly to the middle hepatic vein posteriorly, dividing the liver into right and left functional lobes.
Question 5: A 'free air' (pneumoperitoneum) sign on CT of the abdomen following bowel perforation is best identified on which type of CT window?
- Lung window settings applied to abdominal images (Correct answer)
- Soft tissue window only
- Bone window
- Mediastinal window
Correct answer: Lung window settings applied to abdominal images
Free intraperitoneal air has the same HU as intraluminal air (−1000 HU) and is most conspicuous on lung window settings (wide width, low level) that make small gas pockets visible.
Question 6: What is the CT appearance of acute pancreatitis?
- Pancreatic edema, peripancreatic fat stranding, and possible fluid collections (Correct answer)
- Calcified pancreas with ductal dilation
- Hypervascular pancreatic mass
- Normal-appearing pancreas always
Correct answer: Pancreatic edema, peripancreatic fat stranding, and possible fluid collections
Acute pancreatitis on CT shows gland enlargement, decreased attenuation due to edema, peripancreatic inflammatory stranding, and in severe cases, necrosis or fluid collections.
Computed Tomography Test CT Anatomy and Clinical Applications 2
Which CT finding is characteristic of renal cell carcinoma (RCC)?