Pelvic Peritoneum Radiological Anatomy Of The Extracellular Space

PurposeTo evaluate the methodology of Radiological Anatomy of Pelvic extraperitoneal spaces( PES).Methods and materials1. Anatomical study1) Research subjects16 cadavers, of whom 15 embalmed and 1 unembalmed, 8 male and 8 female, were studied. All of these cadavers were requested to meet the specific including criteria and excluding criteria in order to make sure that the abdominal and pelvic disease were ruled out. And the cause of death of those cadavers was referred to the non-abdominal-pelvic disease. According to our sequence of experiments, each cadaver was labeled as test 1 to test 16.2) Study methods and proceduresGross anatomy: test1 and test2, to observe the location, structure, reflection, fusion of the peritoneum and fascia of pelvis. Sectional anatomy: test 3 to test 8, 3 male, 3 female, were frozen to - 30℃ for 7 days, and then, the cadavers were performed anatomic dissection with transverse, saggital and coronary sections in 3,1,2cases respectively. The dissected specimens were photographed and observed. The emphasis was put on the fascia boundaries of the rectum and vesica.Spaces perfusion: test9-testl6, 4 male, 4 female, the PES was punctured and injected with specifically colored latex contrast agent (CLCA). The CLCA was a mixture of pigment, contrast media, latex, and water according to specific mixing proportion. The amount of injected CLCA was 200ml-400ml per one cadaver. Frozen and imaging: After injection, the abdominal cavity was cleaned and then the cadaver was positioned in supine for 24 hours. Then it was moved into a refrigerator and frozen under -30°C for 4-5 days. And then, the cadaver underwent CT scan with a Siemens Sensation 16 scanner. The scan parameter was as follows: 120kv, 250mA, 16xO.75mms, and reconstruction thickness lmm. The sagittal and coronary MPR were performed using a 2 mm slice and 1 mm interval.Anatomic dissection, The cadavers were refrozen for 3-4 days. All of the cadavers who received injection and frozen underwent anatomic dissection, 6 transaxially, 2 saggitally. The thickness of each section was approximately 1.0 cm and the thickness of tissue loss was about 0.2-0.3cm. 2. Vivi-imaging study1) Research subjects: 80 healthy individuals, 41 male and 39male, aged 15-78 years, underwent CT (40 cases) and MRI (40 cases), were included in our study.2) CT MRI scanner and scanning parameters: The extent of the CT and MRI scan was from the top of the diaphragm to the pelvis. The parameters of CT scan with Siemens Sensation 16 scanner were: 16 X 1.5mm, reconstruction slice 7mm. 18 cases underwent contrast enhanced study. The parameters of MRI scans (Toshiba 1.5 Ultra MRI scanner) were SE T1WI (TR 400 ms, TE 30 ms), T2WI (TR 3000 ms, TE 90 ms), 5-10 mm collimation, 256 x256 matrix.3. Histological study1) Two cadavers, test 7-test 8, 1 male and 1 female, were received histological study.2) The histological specimens were sampled from a transverxial dissection of the pelvis with thickness of 1.0 cm and sized inlcmXlcm. It includes a part of the rectum and vesica and their surrounding tissue. Then they were histologically dissected, stained by the way of Mallory and H.E methods, and photographed consequently. The emphasis was put on the surrounding tissue of the rectum and vesica, especially the fasciae.4. InterpretationAll of the anatomy specimens and CT/ MRI images were studied by three experienced abdominal radiologists and gained identical opinion, with emphasizing on the fusion and attachment of the fascia and the compartmentalignating spaces, and the proportion revealed by displaying CT and MRI.5. Statistical analysis:The incidence of the fascia and spaces on CT and MRI in healthyindividuals group was calculated. The P value less than 0.05 were regarded as significant correlation.Results1. The dissection specimens could reveal the distribution of fascia, the surrounding fat, and the peritoneal reflection of rectum, but could not show the communication of the subdivision of PES. However, the injected section could clearly show the communication and the defined ofPES.2. There was no significant difference between embalmed and unembalmed cadavers in our study. Moreover, the unembalmed cadavers could easily cause lots of unexpected infectious disease and the contaminated blood could affect the observation3. Opening abdomen and direct puncturing method could avoid contamination. Different puncture method could causes the different results.4. Low viscosity latex mixed with low dosage contrast medium was a suitable agent for the PES study because of its merits, such as minimal injection resistant, optiminal diffusion and no artifact in CT scan.5. There was no significant difference between the mulitdector-row CT and MRI in showing fascia and spaces.Conclusion1. This study is a integrative method, which consists of the gross anatomy, section anatomy, dissection specimens with spaces perfusion and CT scan, histological study and CT scan of cadaver and vivi-individuals, soit could provide comprehensive and accurate anatomy of PES.2. The stronger and younger cadaver which has not any type disease and operation history of abdomen and pelvis is had abundant fat tissue in the PES and easily to be punctured and get the best CT imaging.3. There is no significant difference between the embalmed and unembalmed cadavers in the study of PES.4. CLCA is the optimal perfusion agent to evaluate the anatimic distribution and communication of PES.5. Accurate puncture play a crucial role to study the anatomy of the PES.6. Mulitdector-row CT is the best imaging tool to study the PES.