Oncology MCQs
Practice questions on PET/CT imaging in oncology, FDG biodistribution, and interpretation.
18F-FDG is an analog of:
Explanation: FDG (Fludeoxyglucose) is an analog of Glucose. It is transported into cells via GLUT transporters and phosphorylated by hexokinase but cannot be metabolized further, leading to metabolic trapping.
Which organ typically shows the HIGHEST physiologic uptake of FDG?
Explanation: The brain is an obligate glucose user and shows intense physiologic uptake. The bladder also shows intense activity due to renal excretion, but the brain’s metabolic demand is constant.
Brown fat uptake on FDG-PET is typically located in the:
Explanation: Brown adipose tissue (BAT) uptake is often seen in the neck, supraclavicular, axillary, and paraspinal regions, especially in cold patients or those who are anxious.
Standardized Uptake Value (SUV) is normalized for:
Explanation: SUV is Activity Concentration / (Injected Dose / Body Weight). It normalizes for the amount injected and the patient’s size (usually weight, but lean body mass or surface area can also be used).
Which condition typically causes false-negative FDG-PET in lung cancer?
Explanation: Carcinoid tumors (and bronchoalveolar/mucinous carcinomas) often have low metabolic activity and low FDG avidity, leading to false negatives.
Metformin therapy can cause increased FDG uptake in the:
Explanation: Metformin causes intense, diffuse uptake in the bowel (colon and small intestine), which can mask lesions or mimic pathology. It is often withheld for 48h prior to scanning if possible.
Bone marrow uptake that is diffuse and homogeneous usually indicates:
Explanation: Diffuse marrow uptake is seen after G-CSF therapy (e.g., Neulasta) or recent chemotherapy reaction (marrow rebound). Metastatic disease is typically focal or multifocal.
Deauville Score is used for response assessment in:
Explanation: The Deauville Score (5-point scale) is the standard for interpreting FDG-PET in Lymphoma (Hodgkin and NHL), comparing uptake to mediastinum and liver reference pools.
Maximum glucose level generally recommended before FDG injection is:
Explanation: Guidelines typically recommend serum glucose < 150-200 mg/dL. High glucose competes with FDG for transport and increases insulin which drives FDG into muscle, degrading image quality.
The ‘flare phenomenon’ on bone scan refers to:
Explanation: Increased uptake in healing bone metastases shortly after starting effective therapy, which can mimic progression. It is due to osteoblastic healing response.