Amino Acid Uptake, Glucose Metabolism, and Neuroinflammation in John Cunningham Virus Associated Progressive Multifocal Leukoencephalopathy.

A 69-year-old woman presented with progressive dysarthria and cognitive deficits. On MRI, a T2-hyperintense, non-contrast-enhancing lesion was found in the left precentral area. 18F-FET and 18F-FDG PET scans revealed faint amino acid uptake and glucose hypometabolism of the lesion. To assess a neuroinflammatory component, TSPO PET with 18F-GE-180 was performed, where tracer uptake markedly exceeded the T2-hyperintense areas. Histology derived from a stereotactic biopsy findings confirmed John Cunningham virus-associated progressive multifocal leukoencephalopathy. This case underlines that TSPO PET comprises distinct imaging advantages over other established radioligands such as 18F-FET and 18F-FDG in progressive multifocal leukoencephalopathy.