remature fusion of the sagittal suture results in inhibited perpendicular biparietal expansion and parallel anterior and posterior compensatory elongation. 1 The resulting head shape is described by a classic dysmorphology: scaphocephaly. 2 Attempts to measure this abnormality globally have led to the widespread adoption of the cephalic index and its derivatives. 3,4 The cephalic index is limited by its 2-dimensionality and an inability to regionalize dysmorphology. [4][5][6][7][8][9] For example, 2 patients with sagittal craniosynostosis (SC) and identical cephalic indices, as depicted in Figure 1, may have vastly different shape abnormalities (eg, either predominance of frontal bossing or an occipital bullet), each potentially necessitating different surgical approaches. The recently described frontal bossing index (FBI; Fig. 2, above) and occipital Background: The recently described frontal bossing index (FBI) and occipital bullet index (OBI) allow for quantification of scaphocephaly. A similar index examining biparietal narrowing has not been described. Addition of such an index measuring width would allow for direct evaluation of the primary growth restriction in sagittal craniosynostosis and the formation of an optimized global width/length measure. Methods: Computed tomography scans and three-dimensional photographs were used to recreate scalp surface anatomy. Equidistant axial, sagittal, and coronal planes were overlaid, creating a Cartesian grid. Points of intersection were analyzed for population trends in biparietal width. Using the most descriptive point coupled with the sellion protrusion to control for head size, the vertex narrowing index is formed. By combining this index with the FBI and OBI, the scaphocephalic index (SCI) is created as a tailored width/length measure. Results: Using 221 controls and 360 individuals with sagittal craniosynostosis, the greatest difference occurred superiorly and posteriorly at a point 70% of the head's height and 60% of the head's length. This point had an area under the curve of 0.97 and sensitivity and specificity of 91.2% and 92.2%, respectively. The SCI has an area under the curve of 0.9997, sensitivity and specificity greater than 99%, and interrater reliability of 0.995. The correlation coefficient between computed tomography imaging and three-dimensional photography was 0.96. Conclusions: The vertex narrowing index, FBI, and OBI evaluate regional severity, while the SCI is able to describe global morphology in patients with sagittal craniosynostosis. These measures allow for superior diagnosis, surgical planning, and outcome assessment, independent of radiation. (Plast.

Background: Sagittal craniosynostosis (SC) is associated with scaphocephaly, an elongated narrow head shape. Assessment of regional severity in the scaphocephalic head is limited by the use of serial CT imaging or complex computer programing. Three-dimensional measurements of cranial surface morphology provide a radiation-free alternative for assessing cranial shape. This study describes the creation of an Occipital Bulleting Index (OBI), a novel tool using surface morphology to assess the regional severity in patients with SC. Methods: Surface imaging from CT scans or 3D photographs of 360 individuals with sagittal craniosynostosis and 221 normocephalic individuals were compared to identify differences in morphology. Cartesian grids were created on each individual’s surface mesh using equidistant axial and sagittal planes. Area under the curve (AUC) analyses were performed to identify trends in regional morphology and create measures capturing population differences.Results: The largest differences were located in the medial regions posteriorly. Using these population trends, a measure was created maximizing AUC. The Occipital Bullet index has an AUC of 0.72 with a sensitivity of 74% and a specificity of 61%. When the Frontal Bossing Index is applied in tandem, the two have a sensitivity of 94.7% and a specificity of 93.1%. Correlation between the two scores in individuals with SC was found to be negligible with an intraclass correlation coefficient of 0.018. Severity was found to be independent of age under 24 months, sex, and imaging modality.Conclusions: This index creates a tool for differentiating control head shapes from those with sagittal craniosynostosis, and has the potential to allow for objective evaluation of the regional severity, outcomes of different surgical techniques, and tracking shape changes in individuals over time, without the need for radiation.