[Cerebral blood flow and brain size in healthy subjects--sensitivity to age and gender]

Cerebral blood flow was measured in 56 healthy subjects who ranged in age from 1.3 to 80 years. The Xe-133 inhalation method with ring type single photon emission computed tomography (SPECT); HEADTOME was used. The cerebral blood flow were calculated by the method of Kanno & Lassen. Then the value were corrected for end-tidal CO2 concentration that had an excellent correlation with PaCO2 and was one of the most sensitive factors to change cerebral blood flow. The brain-size index was obtained by measuring the lateral and antero-posterior diameters from the SPECT images. The mean cerebral blood flow in children less than five years of age was 90-100 ml/100 g/min that was approximately twice that found in adults. The mean cerebral blood flow decreased rapidly with age until 24.0 years of age in male and 21.7 in female. Thereafter, there was a slow decrease and a negative correlation with age was found. In adults, the mean value of the cerebral blood flow of females was slightly higher than that of males (p less than 0.01). In contrast, the brain-size index of females was significantly smaller than that in males (p less than 0.01). There was a significant negative correlation to an inverse proportionality of cerebral blood flow and brain-size index (p less than 0.002). But, there was no significant correlation between total flow index that obtained to multiplied mean flow by brain-size index and brain-size index or gender.