Abstract
For the evaluation of differential diagnosis and estimation of the functional prognosis for vascular dementia (VD), the usefulness of computed tomography (CT) and magnetic resonance imaging (MRI) in detecting cerebro-vascular lesions was compared. Then the correlations between the degrees of mental function (Hasegawa's dementia rating scale: HDRS, activity of daily living: ADL, troublesome behaviors: TB) and the CT findings of vascular dementia were examined retrospectively.
A hundred and seventeen dementia patients (male: 79 cases, female: 38 cases; mean-age 69.5 10.9 years old), diagnosed using DSM-III criteria, were scored according to Hachinski's ischemic score (I.S.) by clinical course and symptoms. Both MM and CT were carried out on 56 dementia cases (male: 21 cases, female: 35 cases; mean-age 78.0 7.4 years old) at the chronic stage of the cerebro-vascular accidents to compare the detectiveness of vascular lesions.
In 90 vascular dementia patients on whom only CT was carried out, the imagings were classified according to number, size, and localization. The correlation between these parameters and the degree of dementia were examined retrospectively.
MRI was more useful and sensitive than CT for differentiating VD from DAT (dementia of Alzheimer type), since MRI was superior to CT in detecting small infarcts or lacunaes on the perforating area or white matter.
Cases with positive findings on CT or MRI but clinically diagnosed as DAT by I.S. showed poorer ADL. Cases with negative findings on CT and MM but clinically diagnosed as MIX (mixed type of dementia) or VD by I.S. had more troublesome behaviors. However in MM positive cases, there was no correlation between the detectiveness of CT or MRI and age or degree of dementia.
CT was evaluated as the more specific imaging method for judging the mental functions. The size of CT lesions were revealed to be more significant in appreciating the degree of dementia in the chronic stage of cerebrovascular disease than the number, localization.
The present study showed that MRI should initially be used to detect small vascular lesions in differentiating VD from DAT, then CT to observe the size when anticipating the prognosis for vascular dementia.
