This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Microbiology
[{'content': 'Most sensitive investigation for preoperative localization of abnormal parathyroid glands is \nSelect and explain. \nA. Neck ultrasound, B. (99mTc) labelled Sestamibi isotope scan, C. CT scan, D. MRI', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Neck ultrasound locates glands in approximately 75% of cases. (99mTc) labelled Sestamibi isotope scans identify approximately 80% of abnormal parathyroid glands.CT & MRI is not indicated prior to first-time neck exploration.', 'role': 'assistant'}]