[Multiplanar imaging in the retroperitoneum: noninvasive diagnosis with a new spiral CT technique--anatomy and pathology].

Both anatomic and pathologic structures are often not documented in sufficient detail to provide overall information in axial scans, and magnetic resonance imaging does not always provide the required spatial resolution. The spiral CT technique, in contrast, with use of the secondary image reconstruction is capable of clearly documenting these interrelations. We have examined 45 patients with pathologic changes in the retroperitoneum by means of a spiral CT scanner and used the secondary image reconstruction in the coronary and sagittal plane in all cases. The scan times ranged between 45 and 60 seconds at a selected slice thickness of 3 mm and a table feed of 4.5 mm. Up to 30 cm of the crania-caudal length of the patients could thus be documented. From the basic data, up to 170 overlapping images were calculated for a multiplanar image reconstruction, and every third axial scan was photographed. The post-processing time was 10 to 15 minutes. The patients received 120 ml of a non-ionic contrast medium, intravenous at a flow rate of 2.5 ml per second. The spiral CT examination was started 40 seconds after the injection had been begun. It could be performed in all patients under inspiration, without problems. The chosen scan times did not lead to significant overshadowing due to motion artefacts. The vascular structures of the aorta and its main branches as well as the vena cava and the portal vein could be identified in their whole lengths. The peritoneal duplications and the renal fascia could be clearly documented. The lymph nodes could be identified in all of them. In cases of tumours with metastases, the extent of the tumor was excellently visible in the multiplanar reconstructions and a thickened peritoneum could be differentiated in such cases. This standardized examination procedure offers a uniform and reproducible diagnostic basis with short examination times. The early detection even of small recurrences in the axial slices and the identification of pathologic changes of the lymph nodes enable a timely tumor treatment for curative purposes.