This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nuclear medicine, Subject name: Radiology
Dye used in SPECT- 
Select and explain. 
A. O-14, B. Tc-99, C. Nitrogen-16, D. Iodine 124
B: Tc-99
Answer: B: Tc-99 
Explanation: SPECT imaging: It has a 360deg revolving gamma camera giving 3D images Tc99m radioisotope is used (t1/2 = 6 hrs) Tc99m - HMPAO: Lipophilic/Lipid soluble Crosses blood brain barrier Cerebral perfusion is evaluation