Comparison of Custom Cranial Implant Source Data: Manual, Mirrored and CAD generated skull surfaces

One of the objectives of performing cranioplasty is the creation of a satisfactory cosmetic outcome. The purpose of this work is to compare the accuracy of skull defect contours generated by CT volume mirroring and CAD. 3D multi-slice CT scanning was carried out on a cadaver before and after the creation of a large lateral defect. Two volume mirroring and two CAD methods were used to create customised repairs. 3D difference maps were used to compare the repair contour with the original skull. The CAD contour deviation ranged from 0.0 mm to 2.0 mm with 80% of the total defect area less than 0.66 mm as measured by difference maps whilst mirror imaging produced deviations of up to 3.0 mm from the original surface. CAD techniques can be used to produce contours for the repair of cranial defects with minimum deviation from the original skull contour.