Usefulness of 11C-methionine-positron emission tomography for the diagnosis of progressive multifocal leukoencephalopathy
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Progressive multifocal leukoencephalopathy (PML) is a subacute demyelinating disease of the brain caused by the JC virus that occurs mainly in immunocompromised patients. The prognosis is very poor. As the lesion looks like non- specific leukoencephalopathy, making a diagnosis at the early stage is very difficult. We report three PML cases in which there was a mismatch between 11C-methionine-positron emission tomography (MET-PET) uptake and 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) uptake. All three cases demonstrated the hyper-uptake of MET around the white matter lesions and hypo-uptake of FDG inside the lesions. We speculate that the infection had ended inside the white matter lesions of these patients, while JC virus infection was ongoing around the lesions, resulting in the increase of methionine metabolism, and the glucose metabolism was reduced or intermediate because inflammatory cells infiltrate PML lesions rarely. Two patients who were diagnosed and treated with mefloquine while the JC virus was at a low level in the cerebrospinal fluid are still alive. We suggest the usefulness of MET-PET for the early diagnosis of PML and early treatment with mefloquine.
KeywordsProgressive multifocal leukoencephalopathy 11C-methionine-positron emission tomography 18F-fluorodeoxyglucose-positron emission tomography Mefloquine
This work was partly supported by Grants-in-Aid for Research on HIV/AIDS (H24-AIDS-Wakate-002) and the Research Committee of Prion Disease and Slow Virus Infection (H23-Nanchi-Ippan-013) from the Ministry of Health, Labor, and Welfare of Japan.
Conflicts of interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
This study was approved by the Institutional Review Board of Hokkaido University.