Asymmetrical FDG-PET and MRI findings of striatonigral system in multiple system atrophy with hemiparkinsonism

The asymmetry of the local cerebral metabolic rate for glucose (lCMRglc) and magnetic resonance (MR) imaging was studied in five patients with multiple system atrophy (MSA) presenting hemiparkinsonism. lCMRglc was measured with 18F-2-fluoro-2-deoxy-D-glucose and positron emission tomography (PET) in these patients and five normal control subjects. MR images were obtained in five patients and 11 control subjects. In all patients, T2-weighted MR images showed hypointense areas in the posterior lateral putamen. They were bigger or lower in intensity on the contralateral side than on the ipsilateral side. Significant glucose hypometabolism was found in the posterior putamen on the contralateral side to hemiparkinsonism. A significant decrease in size was found in the contralateral putamen, caudate nucleus, and pars compacta of the substantia nigra. However, no significant correlation was seen between PET and MRI data. In the control subjects, no apparent asymmetry was observed. PET and MR imaging demonstrated the characteristic asymmetry corresponding to the pathological findings reported in MSA.