[CT study in senile dementia of Alzheimer type]

In order to evaluated the utility of cranial CT in diagnosis of senile dementia of Alzheimer type (SDAT) various CT findings were studied. CT scans of 62 cases with SDAT (83 +/- 6 years old) were compared with those of 357 aged cases (means 78 +/- 8 years old) with out psychiatric and/or neurological illness (normal control NC). The methods of evaluating CT findings were linear measurements of the ventricle (Huckman number, Evans' ratio, lateral body ratio), observation of sulci (Sylvian fissure, cingulate sulcus and central sulcus), brain atrophy ranking of microscopic observation (I; absent, II; mild, III; mild to moderate, IV; moderate, V; maximum) and presence of periventricular lucency. When SDAT were compared with NC the cases were divided into two groups by the age (the eighth decade, 80 years old and over) in order to avoid the influence of physiological brain atrophy. The results were as follows: 1) In SDAT there was a positive correlation between the volume of the lateral ventricle in autopsy brain and each index which demonstrates the size of the lateral ventricle on CT (r = 0.65, p less than 0.001). 2) In SDAT the incidence of cases with more than III degree in brain atrophy ranking was significantly higher than in NC (p less than 0.001). It was 82.6% in SDAT, 15.7% in NC in the eighth decade and 92.3% in SDAT, 32.1% in NC in 80 years and over. 3) The mean values of indexes of lateral ventricle enlargement (Huckman number, Evans' ratio, lateral body ratio) in SDAT increased more than those in NC significantly (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)