[Complex maxillofacial trauma: diagnostic contribution of multiplanar and tridimensional spiral CT imaging]. / Traumi complessi del massiccio facciale: apporto diagnostico dell'imaging TC multiplanare e tridimensionale ottenuto con tecnica spirale.

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.

Infiltrative subcutaneous metastases from ovarian carcinoma after paracentesis: CT findings.

Implantation subcutaneous metastases from ovarian cancer are an uncommon event in surgery, and diagnostic procedures such as laparoscopy, fine-needle biopsy, and intraperitoneal catheter access are usually used. Findings of tumor implantations are rarely reported with diagnostic imaging techniques. In this case, an infiltrative subcutaneous metastasis appeared on computed tomography 4 months after paracentesis in a patient with untreated ovarian cancer. Differential diagnostic problems are discussed.

The use of spiral computed tomography in the localization of impacted maxillary canines.

PURPOSE: To compare spiral CT with conventional radiography in planning the orthodontic treatment of impacted permanent maxillary canines. METHODS: Nineteen patients with 29 malpositioned permanent maxillary canines (15 palatal and 12 buccal impactions, one ectopic and one transposition) were examined with conventional panoramic and lateral cephalometric radiography and with spiral CT (at 1 mm slice thickness, and 1:1 or 2:1 pitch) using multiplanar (MPR) and 3D reconstruction. RESULTS: Conventional radiography failed to depict root resorption especially on the buccal surfaces of the incisor teeth. CT located impacted teeth better. Contact between impacted maxillary canines and incisor roots was demonstrated in 26 cases and root resorption in eight. MPR proved to be superior for the orientation of impacted teeth, and, in two cases, confirmed the presence of minimal root lesions for which axial images had proved inconclusive. The 3D reconstructions were useful in targeting the MPR. CONCLUSIONS: CT facilitates the treatment of impacted canine especially when the teeth are very oblique to the arch. Root resorption is better demonstrated especially on the palatal and buccal surfaces of the adjacent incisors. Spiral CT reduces examination time and risk of accidental movement, thus optimizing MPR quality. Examination at 2:1 pitch enables a significant reduction in radiation exposure without loss of image quality.

Use of spiral computed tomography for multiplanar dental reconstruction.

OBJECTIVE: To compare spiral with conventional CT for multiplanar reconstruction (MPR) prior to dental implant placement. METHODS: Ten patients underwent conventional and then Spiral CT at 1 mm slice thickness. In six patients (Group A) the pitch was 1:1; the other four (Group B) it was 2:1. Image quality and clinical features were evaluated separately on axial and reconstructed images by two experienced radiologists who scored each parameter from 1 (poor, non-diagnostic) to 3 (good, diagnostic). RESULTS: Loss of spatial resolution with spiral CT was not significant and the diagnostic yield poorer only for trabecular bone structure. The MPRs were better and depiction of the mandibular canal more reliable. CONCLUSIONS: We recommend the use of spiral CT instead of conventional CT for dental MPR because examination time is shorter and patient comfort is improved. Use of a pitch of 2:1 permits a marked reduction in X-ray dose with no loss of image quality.