Application Of 16-slice Spiral CT: Study On Normal Greater Omentum

Objective: The purpose of this study was to analyze the appearance of the normal greater omentum on 16-slice spiral CT scan. Materials and methodsObjects of study: We reviewed the 16-slice spiral CT scans of 50 consecutive individuals who accorded with both the inclusion standards and the exclusion standards from Nov 2003 to Mar 2004 in West China Hospital. As far as this study was concerned, those individuals were supposed to be normal.CT scanner and scanning parameters: All of those individuals were scanned by using a Siemens sensation 16 CT after the oral administration of angiografin or water. All of them received 80-100mL of iodinated contrast material (Ultravist—Schering, Germany; Omnipaque-Nycomed, Norway) intravenously at a rate of 2.5mL/sec. Single-breath-hold scans were obtained through the entire abdomen with a detector-array of 16x0.75mm and a table-feed-speed of 12mm/rotation after a 60-second delay of intravenous contrast enhanced study. Coronal/sagittal and three-dimensional images were produced by computer stacking of a series of contiguous thin slices of 1mmwith the techniques of MPR and VR.Image interpretation: All of the images were reviewed and interpreted by three eligible radiologists and emphasis was placed on the following items: the issue of omental location; manifestation of the vasculature of the omentum; appearance of the fatty tissue within it; detecting lymph nodes.Results:The gastrocolic ligament: The gastrocolic ligament was visualized in 49(98%) cases. The gastroepiploic vessels could be easily discerned on axial, coronal and sagittal images of 16-slice spiral CT scans with a revealing rate of 100%, and the three-dimensional images of 5 cases were also able to demonstrate them. The gastroepiploic arteries could be distinguished from the accompanying veins in 42 (84%)cases on sagittal images and 36(72%) on coronal ones. Only single lymph node (less than 5mm in diameter) was noted in the gastrocolic ligament of one case. The attenuation of the fatty tissue within the gastrocolic ligament ranged from -80Hu to -124Hu, which was similar to that of the subcutaneous fat.The free-hanging portion: The visualization rate was 96%(48/50). The free-hanging portion in 9 of 48 cases was found to be located in the subphrenic spaces, which could be demonstrated on axiah coronal and sagittal images. The arcade formed by branches of gastroepiploic arteries(arch of Barkow) was seen in 6 of 50 cases (12%) on coronal images. No lymph nodule was shown in the free-hanging portion of the omentum. The CT appearance of the fatty tissue within it was homogeneous and similar to that of the gastrocolic ligament.Conclusion: Having advantages over conventional CT, 16-slice spiral CTis capable of producing excellent coronal/sagittal images and dynamic three-dimensional images which play an important role in demonstrating the normal greater omentum, including the location, the vasculature, the fatty tissue and so on.