The Comparative Study Between MSCT Imaging Anatomy And Systemic Anatomy Of The Omental Bursa

Because of the specificity of omental bursa in its adjacent relationship, composition and involvement in many diseases, it shows an very important clinical significance. The combination of original and post-processing images of multislice spiral computed tomography (MSCT) is very good in displaying the status, extended position, adjacent relation of main component ligaments and areas of omental bursa. It is a relatively useful and reliable examination method to diagnose the diseases of omental bursa and related areas. As the omental bursa can't be displayed in physiological conditions, there is little study on its imaging anatomy in home or abroad, and is lack of detailed comparison between imaging anatomy and systemic anatomy. Objective: To study the display, extended position, adjacent relation of the main ligament and each component of omental bursa with MSCT examination, try to provide imaging anatomy basis for observing omental bursa and omental bursa areas.Subjects and Methods: There were 100 cases collected in physiological conditions of the omental bursa, range of age: 20-60 years old, average age: 42years old, during the period from September, 2009 to March,2010; 89 cases in effusion conditions of the omental bursa, range of age: 20-78 years old, average age: 47.5 years old, during the period from September, 2007 to July, 2010. All the subjects, who had been fasting for 6-8 hours before examination and drank 0~600ml warm water 10 minutes before the scan (depending on the subject's condition of the disease),were scaned by Siemens dual source or 64-slice spiral CT. All of them took supine position. 80-100ml non-ionic contrast media omnipaque(370mg/l) or ultavist(350mg/l) was injected by automatic high pressure injector at a speed of 3.5ml/s. The delay time of arterial phase, venous phase and balance phase was 29s,40s and 80s after injected, respectively. Scan range: including the entire omental bursa areas, holding breath. Scanning parameters: collimation 64×0.625, slice thickness 5mm, slice distance 5mm,table speed 12mm/s, tube voltage 120KV, tube current 260-320mAs, rotation time 0.7s. The original scanning data was reconstructed to 1mm thickness, including the coronal and sagittal images, then transmitted to the workstation and observed in abdomen window with combination of axial images, multiplanar reconstruction(MPR),volume rendering(VR), maximum intensity projection(MIP), maximum intensity projection thin(MIP thin).All the data was observed and analyzed in these aspects: the display status, direction, adjacent relation, extended position of the main ligament of omental bursa in physiological, effusion conditions and when the omental bursa filling well; the display of omental foramen and macroporous in physiological and effusion conditions on CT; the applicability of systemic anatomy markers of omental bursa on CT images; and the influencing factors of observing omental bursa.Results:In physiological conditions, the display rate of left gastric artery and vein, hepatic artery, portal vein, common bile duct, splenic artery and veins near splenic hilum was 100%, and was better on enhanced scan. For some thin vessels, such as left gastroepiploic artery, gastroepiploic artery arch, right gastric artery, short gastric artery, were difficult to display on plain scan , but display rates were 92%,71%,73%, 36%on enhanced scan. Some lymph nodes and connective tissue could be displayed too, but we didn't find any lymph nodes which its diameter>0.5cm in each ligament;the density of fat between the main component ligament of omental bursa was same with peritoneal cavity; the attachment and transitional points of each ligament couldn't be observed well. In effusion conditions, in addition to vessels, the display of fat in ligament was also useful in imaging anatomy of omental bursa. Because of the effusion, which increased the natural contrast among soft tissue, fluid and fat , the attachment points, direction, boundary of ligament could be observed well. And when there was effusion in omental bursa, the relationship between component areas and adjacent viscera could be displayed clearly with well extended sac. In addition, when effusion existed, the omental foramen and macroporous which couldn't be observed in normal condition could be displayed by connection of effusion.Conclusion:The examination of omental bursa with MSCT can provide satisfied images. The anatomic landmarks of omental bursa can be showed well both in physiological and effusion conditions, which is consistent with the systematic anatomy; when there is effusion in omental bursa, the filling level, extened position, adjacent relation of omental bursa can be showed well, which is consistent with the systematic anatomy; the amount of abdominal fat, the extent of omental bursa effusion, whether the effusion is encapsulated, the filling degree of stomach and congenital form are the main influencing factors of observing the omental bursa.