Are Magnetic Resonance Imaging-Generated 3Dimensional Models Comparable to Computed Tomography-Generated 3Dimensional Models for Orbital Fracture Reconstruction? An In-Vitro Volumetric Analysis

Magnetic resonance imaging (MRI) is being increasingly considered as an alternative for the evaluation and reconstruction of orbital fractures. No previous research has compared the orbital volume of an MRI-imaged, three-dimensional (3D), reconstructed, and virtually restored bony orbit to the gold standard of computed tomography (CT). To measure the orbital volumes generated from MRI-based 3D models of fractured bony orbits with virtually positioned prebent fan plates in situ and compare them to the volumes of CT-based virtually reconstructed orbital models. This retrospective in-vitro study used CT and MRI data from adult patients with orbital trauma assessed at the Royal Brisbane and Women's Hospital Outpatient Maxillofacial Clinic from 2011 to 2012. Only those with orbital blowout fractures were included in the study. The primary predictor variable was imaging modality, with CT- and MRI-based 3D models used for plate bending and placement. The primary outcome variable was the orbital volume of the enclosed 3D models. Additional data collected was age, sex, and side of fractured orbit. The effect of operator variability on plate contouring and orbital volume was quantified. The Wilcoxon signed rank test was used to assess differences between orbital volumes with a significance level P