This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid, Subject name: Surgery
Most sensitive investigation of thyroid nodule: 
Select and explain. 
A. MRI, B. PET Scan, C. USG, D. Clinical examination
C: USG
Answer: C: USG 
Explanation: PET scan are not routinely used in the evaluation of thyroid nodules, however, they may show clinically occult thyroid lesions. USG is the most sensitive method for diagnosing intrathyroid lesions. CT and MRI are neither specific nor sensitive in diagnosing the intrathyroid lesions.