Answer:

Explanation
1. Reports of hypermetabolism on 18FDG-PET exist for radiation necrosis. [18FDG-PET usually shows hypometabolism, but reports of hypermetabolism exist.]

2. Both 11C-MET PET and 123IMT SPECT show low uptake in necrosis with increased uptake in gliomas and lymphomas. [In general, while neoplastic lesions tend to have increased cerebral blood volume as well as increased glucose and amino acid metabolism, necrotic lesions should have reduced perfusion and be hypometabolic as reflected through MR perfusion, 18FDG-PET, 11C-MET PET and 123IMT SPECT studies]

3. Both toxoplasmosis and listerial or viral rhombencephalitis show decreased uptake on 99mTc SPECT. [Reduced uptake in nuclear imaging studies such as 18FDG-PET, 201Tl SPECT, 99mTc SPECT and sestamibi may be useful to distinguish toxoplasmosis from other entities, but larger prospective studies are required, and would not help to distinguish necrosis. 99mTc SPECT shows decreased uptake which can last for up to 6 months although residual findings on MRI may be minimal]

4. SPECT changes have been shown to last beyond residual MRI findings in listerial rhombencephalitis. [99mTc SPECT shows decreased uptake which can last for up to 6 months although residual findings on MRI may be minimal.]

5. 201Tl SPECT reflects a combination of these three parameters. [201Tl SPECT, which reflects a combination of blood flow, BBB permeability and cellular uptake, typically shows increased uptake in gliomas compared to necrosis]