[Comparison study of positron emission tomography, X-ray CT and MRI in parkinsonism with dementia].

In cases of Parkinson's disease, a high incidence of dementia and simultaneous pathologic changes of Alzheimer's type have been reported. X-ray CT and MRI have such good spatial resolution that they can be expected to be useful for evaluation of brain atrophy. Positron emission tomography (PET) used with 18F-2-deoxy-2-fluoro-D-glucose is considered to reflect regional function. By these techniques, brain atrophy and local cerebral metabolic rate of glucose (LCMR-glc) in patients with Parkinsonism with dementia was studied, and also compared with age-matched normal controls and senile dementia of Alzheimer type. In seven cases of Parkinson's disease with dementia, LCMRs-glc were statistically decreased in all regions in comparison with ten normal controls. LCMRs-glc in six Parkinson's disease without dementia were higher than those of demented Parkinson's disease, but significantly lower than normal controls in all regions except basal ganglia. Some aged normal controls presented cortical atrophy and a significant difference could not be seen in evaluation by MRI among these three groups. There was also no correlation between LCMR-glc and cortical atrophy. There was no significant difference of LCMR-glc between six Guamnian cases of Parkinsonism-Dementia complex (PD complex) without ALS and four cases of PD complex with ALS, and these values were significantly lower than five Guamanian and ten Caucasian normal controls. In PD complex with and without ALS, remarkable cortical atrophy and ventricular dilatation were recorded in comparison with normal controls, and correlation between decrement of LCMR-glc and cortical atrophy was indicated in frontal, parietal and temporal lobe. In Parkinson's disease with dementia and PD complex in Guam, LCMRs-glc in all regions of brain were generally lower than normal controls. These findings were different from Alzheimer's disease in which LCMR-glc have been reported to be low especially in cerebral cortex. On the other hand, cortical atrophy and ventricular dilatation evaluated by MRI and CT was apparent in PD complex, but these changes were not remarkable in Parkinson's disease. Cortical atrophy did not always correlate with the decrease of LCMR-glc and changes of LCMR-glc could reflect clinical signs such as Parkinsonism and dementia. Both PET as a functional imaging method and MRI, CT as an anatomical imaging method are useful to access the study of these diseases.