CT measurements of cranial growth: normal subjects.

Growth patterns of the cranium measured directly as head circumference have been well documented. With the availability of computed tomography (CT), cranial dimensions can be obtained easily. The objective of this project was to establish the mean values and their normal variance of CT cranial area of subjects at different ages. Cranial areas and its long and short axes were measured on CT scans for 215 neurologic patients of a wide age range who presented no evidence of abnormal growth of head size. Growth patterns of the cranial area as well as the numeric product of its linear dimensions were determined via a curve fitting process. The patterns resemble that of the head circumference growth chart, with the most rapid growth observed in the first 12 months of age and reaching full size during adolescence. It is believed that the availability of such reference, in addition to the head circumference measurement, will be valuable to the CT reviewer in determining the growth status of head size.