[Complex maxillofacial trauma: diagnostic contribution of multiplanar and tridimensional spiral CT imaging].

INTRODUCTION

Adequate radiologic assessment of the maxillofacial trauma patient is the basis for planning reparative surgery. We investigated the yield of the integration of axial CT with multiplanar (MP) and three-dimensional (3D) reconstructions with the Spiral technique.

MATERIAL AND METHODS

Thirty-five patients (21 men and 14 women, mean age: 31.2 years) with complex maxillofacial traumas were submitted to Spiral CT. Images were acquired with 2-3-mm collimation, 1:1 to 2:1 pitch, 210 mAs, 120 kV, 15-24 s Spiral scan, RI = 1. 3D reconstructions were always obtained and used to guide MPRs targeted on the single injury. The examinations were retrospectively given a score, namely 1 if 3D and MPR yielded no more important diagnostic information than axial CT, 2 if 3D and MPR permitted better detailing of some axial CT findings and thus improved image reading, and 3 if 3D and MPR showed new injuries missed on axial images. Then, a radiologist and a maxillofacial surgeon reviewed the 3D images together only to assess in which cases they were useful to optimize surgical planning.

RESULTS

Nine cases (25.7%) scored 1, seventeen (48.6%) scored 2 and nine (25.7%) scored 3. MP and 3D reconstructions were useful or determinant (2 + 3) in over 74% of cases. 3D images made surgical planning easier in 15 of 32 surgical patients (46.8%), allowing the surgeon a better panoramic view of the complex fracture.

CONCLUSIONS

The greatest advantage of multiplanar imaging is the improved depiction of skeletal injuries along a horizontal plane, paralleling that of axial scans. The depiction of fractures of cribrum and of orbital roof and floor was particularly useful from a clinical viewpoint. MPRs clearly depicted herniation and incarceration of the lower rectus muscle in blow-out fractures. MP and 3D reconstructions better defined the presence and grade of displaced bone fragments in nearly vertical structures, such as the upward branches and coronoid apophysis of the mandible. 3D images alone never showed any more fractures than those seen on axial and MP images. 3D images are especially useful to the surgeon because they permit the panoramic depiction of the fracture complex, which facilitates treatment planning. The radiologist can use 3D reconstructions to guide the acquisition of targeted MP reconstructions, for better diagnostic yield. The Spiral technique, with its pitch increases up to 2, permits to limit the radiation dose while preserving the quality of postprocessing reconstructions. Finally, decreasing the execution time is important in multiple trauma patients who are often clinically unstable or have damaged vital organs.