This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
[{'content': 'A patient presented with a 4 cm tumour in the left pariental lobe for which he underwent surgery and radiotherapy. After 2 months, he presented with headache and vomiting. Which of the following would best characterize the lesion in this patient?: \nSelect and explain. \nA. Gd-enhanced MRI, B. 99T-HNIPAO SPECT brain, C. Digital subtraction angiography with dual source CT scan, D. 18EDG PET Scan', 'role': 'user'}, {'content': 'Answer: D \nExplanation: D i.e. 18FDG PET Scan - 18 FDG-PET scan detects cerebral metabolism and is used for tumor grading, estimation of prognosis, localization of optimal biopsy site (most malignant areas show maximum F18 fluoro-deoxy-glucose uptake), assessment of response to therapy and detection of recurrence (versus radionecrosis)Q in brain tumor. 99mTcHMPAO-SPECT Scan detects uptake / distribution of lipophilic radio pharmaceutical (99mTcHMPAO) across functioning BBB propoional to cerebral blood flow (with no redistribution). It is indicated in acute cerebral infarct imaging before evidence of CT/MRI pathology (and gives positive finding with in 1 hr of event), stroke (shows flip flop phenomenon ie decreased aerial, equal capillary, and increased perfusion/activity in venous phase secondary to slow washout and late arrival of blood collaterals), dementia, seizure and blood brain barrier study.', 'role': 'assistant'}]