Volumetric Comparison Between CT Scans and Smartphone-Based Photogrammetry in Patients Undergoing Chin Augmentation Using Autologous Fat Graft

Abstract Background The most accurate methods for assessing fat grafted volume, such as CT scan and MRI, use 3D evaluation of the recipient area. Currently, other measurement techniques, such as photogrammetry (compilation of photos), are used. Objectives The present study aimed to compare 3D images obtained by CT scan with those obtained by photogrammetry in patients undergoing autogenous fat grafting to the chin. Methods A prospective longitudinal study assessed patients undergoing autologous fat grafting to the chin, capturing preoperative and postoperative (6 months) images with CT scan and photogrammetry. Captured images were submitted to 3D reconstruction using Blender image software. Results A total of 40 patients were submitted to surgery. Seventy-five percent were female. Median age and BMI were 26.5 years and 23.6 kg/m2, respectively. Median volume of fat grafted was 10 mL (IQR 8-12.25 mL). The study showed that the median preoperative volume measured by CT scan was larger compared to photogrammetry measurement (12.48 mL versus 12.01 mL, respectively, p < 0.001). Likewise, a larger volume was measured by CT scan compared to photogrammetry (15.54 mL versus 14.94 mL respectively, p < 0.001), six months postoperatively. However, there was no difference regarding the variation in volume between measurements made by CT scan and photogrammetry (p = 0.89). Conclusions There was no agreement in fat graft volume measurements obtained by 3D photogrammetry and CT scan techniques regarding absolute values of fat graft volume measurements, however no difference was found between the two methods when comparing preoperative and postoperative fat graft volume variation.