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: Medicine
Investigation of choice in pheochromocytoma is: 
Select and explain. 
A. CT scan, B. Urinary catecholamines, C. MIBG scan, D. MRI Scan
B: Urinary catecholamines
Answer: B: Urinary catecholamines 
Explanation: Answer is B (Urinary Catecholamines): Pheochromocytomas synthesize and store catecholamines which include norepinephrine, epinephrine and dopamine. The investigation of choice for diagnosis of Pheochromocytomas is determination of elevated levels of catecholamines and their methylated metabolites (metanephrines) in the plasma and urine. CT scan, MRI and MBIG Scintography are all useful diagnostic modalities for localization of pheochromocytoma once the diagnosis is established.