CT-based size and shape determination of the craniofacial skeleton: A new scoring system to assess bony deformities in hemifacial microsomia

The purpose of this study was to design a better craniofacial classificatio n system for bony deformities in patients with hemifacial microsomia than t he existing ones. It was meant to incorporate the deformity of the craniofa cial skeleton other than that of the mandible. The "Mandibular Deformity Sc oring" System (MDS), the "Cranial Deformity Scoring" System (CDS), the the "Craniofacial Deformity Scoring" System (CFDS) are three newly developed cl assification systems, which are based on three-dimensional computed tomogra phy (3-D CT) reconstructions. The size and shape of the craniofacial struct ures of 34 children, 25 with hemifacial microsomia and 9 with minimal dyspl asia or trauma, were determined from CT scans, using 3-D image segmentation and rendering. Contiguous 1.5-mm CT scans were made using a Philips Tomosc an 350 and were processed using a Cemax 1500X 3-D workstation. The precisio n of the 3-D imaging was assessed by repeated determinations carried out by two observers (intra- and interreliability). Accuracy of the bone determin ation technique was assessed by comparing the interpretations of the cranio facial skeleton by 3-D CT reconstructions of laser-stereolithographic 3-D m odels. Correlations of the Pruzansky/Kaban classification system and the ne wly developed classification systems were demonstrated by the use of the Pe arson product moment correlation coefficients. The new CFDS (=CDS + MDS) pr ovides an adequate basis for assessment of bony structures using three-dime nsional imaging and demonstrates a high correlation with the known Fruzansk y/Kaban classification system. This new scoring system can handle the wide variety of individual variation of the deformity seen in patients with hemi facial microsomia better than the existing scoring systems.