[Neuroradiological study of a possible progressive multifocal leukoencephalopathy using diffusion tensor imaging and proton magnetic resonance spectroscopy]

We report a possible case of progressive multifocal leukoencephalopathy (PML) that was attempted to evaluate the pathogenesis by a novel brain MRI techniques. A 72-year-old woman had developed subacute visual disturbance, right hemiparesis and sensory disturbance. Laboratory examinations revealed liver dysfunction and pancytopenia due to liver cirrhosis (type C) and preclinical status of multiple myeloma. Thus, this patient had these two underlying diseases, while anti-HIV antibody was negative. She was suspected with PML by detection of JCV-DNA in cerebrospinal fluid using with PCR. MRI showed multifocal T2-high signals in the bilateral parieto-occipital deep white matter, basal ganglia and right cerebellar hemisphere. No gadolinium enhancement was found. On FLAIR and diffusion weighted images (DWI), the lesion showed hyperintensity. The hyperintense areas on DWI showed various pattern on apparent diffusion coefficient (ADC) and fractional anisotropy (FA). In particular white matter changes, the course of FA reflected the clinical course more than ADC. Proton magnetic resonance spectroscopy (1H-MRS) in deep brain white matter showed ratios of reduced N-acetyl aspartate (NAA) and increased choline (Cho) to creatine. 1H-MRS by chemical shift imaging were undergone three times between 4 and 6 months after the onset. The change of these chemical markers correlated with her clinical course. We conclude that the approach of diffusion tensor imaging (DTI) and 1H-MRS are useful for evaluating neuropathologic observations and clinical course.