Molecular Imaging and PET-CT Applications MCQs

Radiology · 16 free questions with answers & explanations.

1. 18F-FDG PET-CT is performed for staging of a 56-year-old man with newly diagnosed right lung adenocarcinoma. The SUVmax of the primary tumour is 8.2, and there is a solitary FDG-avid lesion in the right adrenal gland (SUVmax 6.5). A second primary adrenal adenoma is excluded. The staging implication is:
2. A patient with known lymphoma undergoes PET-CT after 4 cycles of chemotherapy. A residual mediastinal mass is present but shows no FDG uptake (SUVmax 1.8, same as background). According to the Deauville 5-point scale, this lesion scores:
3. Gallium-68 DOTATATE PET-CT is requested for a patient with a suspected neuroendocrine tumour (NET). Compared to 68Ga-DOTATATE, somatostatin receptor scintigraphy (octreotide scan), and 18F-FDG PET, the correct statement regarding NET imaging is:
4. Bone scan using 99mTc-MDP is performed for a patient with prostate cancer. The scan shows diffuse skeletal uptake with no renal excretion visible — so-called 'superscan.' This finding indicates:
5. An FDG PET-CT scan is performed in a patient with biopsy-proven mediastinal Hodgkin's lymphoma for staging. A mediastinal mass shows intense FDG uptake with SUVmax of 14. Two months after ABVD chemotherapy, a repeat PET-CT shows a residual mass but SUVmax has decreased to 2.0. According to Deauville criteria, this response would be scored as:
6. A 58-year-old man with biochemical recurrence of prostate cancer (PSA 0.8 ng/mL, negative conventional imaging) undergoes 68Ga-PSMA PET-CT. A focus of intense PSMA expression is identified in the right obturator lymph node. Which of the following best explains why PSMA PET-CT detects lesions at this PSA level when conventional imaging cannot?
7. On FDG PET-CT performed for lung cancer staging, the primary mass in the right upper lobe shows SUVmax 12. A 1.2 cm right hilar lymph node shows SUVmax 3.5. A focus of increased FDG uptake is also noted in the right cardiac ventricle wall. What is the most likely cause of this cardiac FDG uptake?
8. A 45-year-old woman with medullary thyroid carcinoma and rising calcitonin after thyroidectomy has negative conventional imaging. Which PET tracer is preferred over FDG for detecting recurrent medullary thyroid carcinoma?
9. A patient with recently treated Hodgkin lymphoma undergoes interim FDG-PET/CT after 2 cycles of ABVD. The mediastinal mass shows a Deauville score of 5 (markedly higher FDG uptake than the liver). What does this indicate?
10. In a patient with suspected phaeochromocytoma/paraganglioma syndrome with biochemical confirmation, which PET tracer has the highest sensitivity for localisation compared to MIBG scintigraphy?
11. A 70-year-old man with rising PSA after radical prostatectomy undergoes PSMA PET/CT. What does PSMA PET/CT detect compared to conventional CT and bone scan in this clinical scenario?
12. FDG-PET/CT shows a standardised uptake value (SUV) of 2.5 in a pulmonary nodule. What is the correct interpretation regarding malignancy?
13. A patient with newly diagnosed non-small cell lung cancer (NSCLC) undergoes FDG-PET/CT for staging. PET shows increased uptake in a right hilar node and an adrenal lesion. If the adrenal lesion has a CT attenuation of 5 HU on non-contrast CT and low FDG uptake (SUV 1.8), what is the most likely interpretation of the adrenal finding?
14. A patient with known Hodgkin's lymphoma undergoes 18F-FDG PET-CT for response assessment after 2 cycles of chemotherapy (interim PET). The Deauville score is assessed. A Deauville score of 1 or 2 at interim PET indicates:
15. 18F-FDG PET-CT is performed for staging of non-small cell lung cancer (NSCLC). Which of the following physiological uptake patterns can mimic mediastinal nodal metastasis and lead to a false-positive reading?
16. A patient with a known NET (neuroendocrine tumour) of the pancreas undergoes 68Ga-DOTATATE PET-CT. This tracer targets which receptor and what is its main advantage over 18F-FDG PET-CT for NETs?