Diagnostic performance of CT, MPR and 3DCT imaging in maxillofacial trauma

CT imaging of complex maxillofacial fractures is common practice now, but the relative diagnostic value of spiral computed tomography (CT), multiplanar reformations (MPR), and three-dimensional (3D) reconstructions in evaluating maxillofacial fractures is not established with independent validation of correct diagnosis. We studied these modalities and measured their diagnositc value in a carefully controlled observer based rated response experiment. Multiple fractures were created by blunt experimental trauma in nine adult cadaver heads (five males, four females). Spiral CT scans were performed on all specimens before (control) and after trauma. Axial slices (CT), sagittal and coronal multiplanar reconstructions (MPR), and 3D volumetric reconstructions views were generated. Truth was determined by defleshing the specimens and direct inspection of the traumatized skull. Three expert readers separately interpreted CT, MPR and 3D film hard copy images presented in random order blinded to patient identification or experimental conditions. We measured the time to diagnose each case as recorded by a monitor who was present while evaluations were performed. Twenty-eight facial regions were evaluated using rated response and free response illustrative formats. Each region was considered separately. Sensitivity and specificity were calculated to measure observer performance. We found that 3D and CT had a similar performance in fracture detection and both were markedly better than MPR. For free response illustrative data, CT correctly identified 10% more orbital fractures than 3D, and approximately 10% fewer zygomatic fractures. Fracture localization was best with 3D. Reader confidence was highest with CT, but assessment time was faster with 3D. We conclude that CT and 3D are comparable in detecting midfacial fractures and both are superior to MPR. 3D reconstructions are superior for localization of complex fractures involving multiple planes.