D146. Moving To 3D: Post-Surgical Cephalometric Changes and Surgical Planning Accuracy using Volumetric Analysis in Facial Feminization Surgery

PURPOSE: Facial feminization surgeries (FFS) aim to feminize facial features in transgender women. Assessing these changes is challenging due to their multi-dimensional nature, complicating the quantification of surgical accuracy in virtual surgical planning (VSP). The purpose of this study was to quantify skeletal changes in FFS using cephalometric and geometric morphometrics. METHODS: Patients undergoing FFS underwent preoperative and postoperative CT craniofacial bone scans. Cephalometrics and 3D skull reconstructions were created in 3D Slicer to measure preoperative-postoperative changes. Geometric morphometrics with PCA analysis were used to analyze genioplasty changes. Accuracy was assessed for patients where virtual surgical plans were available. RESULTS: 20 patients with 48 scans were chosen. Amongst frontal sinus setback patients, distance of frontal prominence landmark to the dorsum sellae was 81.42mm preoperatively and 79.79 postoperatively. 3D reconstructions revealed a change of 3mm in frontal sinus setback depth. Nasofrontal angle increased from 140.47 degrees to 147.57 degrees, nasofacial angle decreased from 33.6 degrees to 32.5 degrees, and frontal incline increased from 70.5 degrees to 74.9 degrees preoperatively to postoperatively. CONCLUSION: FFS changes can be quantified using 3D reconstruction software and cephalometrics to capture surgical changes in greater detail. Frontal sinus setback cephalometric changes demonstrate that skeletal changes can have diverse effects on soft tissue. Future work will compare these measurement parameters to soft tissue changes on volumetric facial imaging.