FRCR MCQ 5 — Questions and Answers
Question 1: On CT pulmonary angiography (CTPA), which feature is most specific for chronic pulmonary embolism rather than acute PE?
- Eccentric filling defect forming an obtuse angle with the vessel wall (Correct answer)
- Central filling defect forming an acute angle with the vessel wall
- Complete occlusion of a pulmonary artery
- Bilateral lower lobe distribution of defects
Correct answer: Eccentric filling defect forming an obtuse angle with the vessel wall
Chronic PE shows eccentric mural thrombus forming an obtuse angle with the vessel wall due to organisation and adherence, contrasting with the acute PE 'polo mint' or acute angle sign.
Question 2: Which sequence is most appropriate for evaluating articular cartilage integrity in the knee on MRI?
- Proton density fat-saturated (PDFS) sequence (Correct answer)
- T1-weighted spin echo
- T2* gradient echo without fat saturation
- STIR sequence
Correct answer: Proton density fat-saturated (PDFS) sequence
Proton density fat-saturated sequences provide optimal contrast between cartilage and adjacent tissues, making them the sequence of choice for cartilage evaluation.
Question 3: A 60-year-old smoker has a 1.2 cm solid pulmonary nodule on CT. According to Fleischner Society guidelines (2017), what is the recommended follow-up?
- CT at 3 months, then 18-24 months if stable (Correct answer)
- No follow-up required
- CT at 12 months only
- PET-CT immediately
Correct answer: CT at 3 months, then 18-24 months if stable
For high-risk patients (smoker) with solid nodules 6–8 mm, Fleischner 2017 recommends initial CT at 3 months, then 18–24 months if stable; for >8 mm nodules, CT at 3 months, PET or biopsy is appropriate.
Question 4: Which of the following is the most common site of metastatic disease in the brain from a primary lung carcinoma?
- Grey-white matter junction of the cerebral hemispheres (Correct answer)
- Corpus callosum
- Cerebellar vermis
- Basal ganglia
Correct answer: Grey-white matter junction of the cerebral hemispheres
Haematogenous metastases preferentially lodge at the grey-white matter junction where vessel calibre abruptly decreases, trapping tumour emboli.
Question 5: Which radiological feature best distinguishes a hepatic adenoma from focal nodular hyperplasia (FNH) on MRI?
- Absence of a central scar and presence of intracellular fat or haemorrhage in adenoma (Correct answer)
- Homogeneous T2 hypointensity in adenoma
- Spoke-wheel arterial pattern in adenoma
- Hepatobiliary phase retention of gadoxetate in adenoma
Correct answer: Absence of a central scar and presence of intracellular fat or haemorrhage in adenoma
Hepatic adenomas may contain intracellular fat or areas of haemorrhage and typically show no hepatobiliary phase uptake, whereas FNH retains gadoxetate on hepatobiliary phase due to functional bile canaliculi.
Question 6: In the context of radiation protection, what is the primary purpose of the dose length product (DLP) in CT?
- To estimate effective dose from a CT examination for patient dose monitoring (Correct answer)
- To set the maximum tube current for a single CT slice
- To calculate the surface entrance dose at the skin
- To determine the peak voltage required for CT acquisition
Correct answer: To estimate effective dose from a CT examination for patient dose monitoring
DLP (mGy·cm) integrates CTDIvol over the scan length and is used with conversion factors (k-factors) to estimate effective dose and monitor patient radiation exposure in CT.
Question 7: A 50-year-old woman with known breast cancer presents with low back pain. Bone scintigraphy shows multiple foci of increased uptake in the axial skeleton. What pattern on plain radiograph would be expected?
- Sclerotic metastases in the vertebrae and pelvis (Correct answer)
- Purely lytic lesions throughout the spine
- Diffuse osteopaenia with vertebral fractures
- No abnormality, as plain radiographs are always normal in bone metastases
Correct answer: Sclerotic metastases in the vertebrae and pelvis
Breast carcinoma most commonly produces sclerotic (osteoblastic) metastases, which appear as areas of increased density on plain radiography and show increased tracer uptake on bone scintigraphy.
FRCR MCQ 5
On CT pulmonary angiography (CTPA), which feature is most specific for chronic pulmonary embolism rather than acute PE?