CT measurements of cranial growth: alternative measurement method.

We have reported the growth pattern of cranium as measured by computed tomography (CT) from birth to 18 years [1] . In the previous report , the CT cranial area was obtained using a built-in cursor and manually tracing the outer edge of the subject's cranial vault. Proper selection of CT slice location and careful tracing provide values that reflect the maximum dimensions of the cranium. To ensure its precision, careful manual control during the tracing maneuver is required , and up to 1 min may be needed to complete one circle of the cranial vault. Although the absolute time needed (i.e. , less than 1 min) is tolerable , it interrupts the routine flow of diagnostic procedures. CT software with automatic edgedetection programs are readily available now and area measurements can easily be accomplished via keyboard controls, a task that can be incorporated into routine diagnostic and/ or filming procedures. In our experience, automatic tracing of boundaries can be accomplished more faithfully and more conveniently if we instruct the computer to trace the entire head area, that is , cranium plus the soft tissue of the subcu-