Abstract
In order to establish baseline numerical figures on white and gray matters and their developmental trend during the neonatal period and the infancy, mean CT numbers and standard deviations of white and gray matters were calculated on thirteen nonpathological scans with the Hitachi CT-H 250 which were obtained from thirteen newborns and infants ranging from 17 days to 11 months of age (8 males, 5 females). The loci selected for the calculation were the preventricular frontal area as a representative of the white matter, and the thalamus and the head of caudate nucleus as those of the gray matter. Each region had an area of about 43.6 mm2 (36 pixels) except for the caudate nucleus where an area of abut 30.3 mm2 (25 pixels) was covered.
The mean CT number of the white matter was low especially in the neonatal period, increased rapidly by 3 months of age, remained relatively constant afterwards, till eleven months of age. The mean CT number from the two regions of the gray matter showed a similar developmental pattern but the changes were less conspicuous compared with those of the white matter. The difference between the average CT numbers of white and gray matters and also their ratio were smallest at the age of 2 months (the ratio 112).
The correlation of developmental changes of numbers, with the structural and functional changes in the developing brain and the clinical implication of the findings were discussed.
