A continuous point measure for quantifying skull deformation in medical diagnostics

Deformational plagiocephaly (DP) manifests in a deformed skull primarily caused by retaining a constant sleeping position in infants. Manual measures of skull asymmetry based on MRI or CT scans combined with the cranial vault asymmetry index (CVAI) provides information on the extent of asymmetry. CVAI uses four points on the skull as markers for the asymmetry index but tends to underestimate the deformity because of the lack of sampling points. Computer-based continuous-point methods may be a more objective measure with better sensitivity for the skull contour. The outline of the skull circumference of infants with confirmed cranial deformity was obtained from the literature and analysed applying the mean bending energy (MBE) obtained from the Hermitian wavelet. MBE was shown to correlate with CVAI in the current sample and has the potential to add both quantitative and visual information in 2D or 3D space for the clinician to diagnose DP. Waveletbased continuous-point estimation of skull asymmetry is a useful method as it is more sensitive to mild deformation anywhere along the skull outline and in assessing slow but progressive improvement as a result of treatment. The broader significance is that this method can be applied to other structural pathology analysis in clinical practice.