This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Medicine
Investigation of choice for leptomeningeal carcinomatosis 
Select and explain. 
A. PET, B. SPECT, C. Gd enhanced MRI, D. CT scan
C: Gd enhanced MRI
Answer: C: Gd enhanced MRI 
Explanation: To detect leptomeningeal metastases, gadolinium-enhanced MRI is more sensitive than CT scanning. The sensitivity of MRI is nearly 70% while that of CT scan is around 30%. The most common MRI findings consist of typical nodules in the subarachnoid and parenchymal regions, parenchymal volume loss and sulcal/dural enhancement CT-myelography is not indicated due to low sensitivity, whereas the value of FDG PET ,SPECT scan is still under investigation Ref Harrison20th edition pg 2234