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

Abstract

The most accurate methods for assessing fat grafted volume, such as computed tomography (CT) scan and magnetic resonance imaging, use 3-dimensional (3D) evaluation of the recipient area. Currently, other measurement techniques such as photogrammetry (compilation of photos) are employed. The aim of the present study was to compare 3D images obtained by CT scan with those obtained by photogrammetry in patients undergoing autogenous fat grafting to the chin. A prospective longitudinal study was undertaken to assess 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 with Blender image software. 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 (interquartile range 8-12.25 mL). Results showed that the median preoperative volume measured by CT scan was larger than the photogrammetry measurement (12.48 mL vs 12.01 mL, respectively, P < .001). Likewise, a larger volume was measured by CT scan than by photogrammetry (15.54 mL vs 14.94 mL respectively, P < .001) 6 months postoperatively. However, there was no difference between CT scan and photogrammetry measurements of the change in volume from preoperatively to postoperatively (P = .89). There was no agreement between fat graft volume measurements obtained by 3D photogrammetry and CT scan techniques with regard to absolute values of fat graft volume measurements, however no difference was found between the 2 methods when comparing preoperative with postoperative fat graft volume variation.