Gastric Bare Area Of ​​the Three-dimensional Tomography Perfusion Anatomy And Its Application In The Diagnosis Of Gastric Cancer Imaging

PurposeTo evaluate the morphology of radiological anatomy of the gastric bare area. To provide the bases for the continual studying on the image features of gastric cancer involving gastric bare area by observing the sectional anatomy of gastric bare area on cadavers and illuminating peritoneal reflection of GBA and its internal structures.Materials and Methods1. Research subjects6 formalin-fixed cadavers, of whom 4 male and 2 female, were studied. All of these embalmed cadavers were forced to meet the choosing criteria in order to make sure that the abdominal disease were ruled out.2. Sectional anatomyAfter frozen to -20℃for 5-7 days, the cadavers were performed anatomic dissection with transverse, saggital and coronary sections in 3, 2, 1 cases respectively. The thickness of cross sectional specimen was 1 cm, and of sagittally and coronarily 2 cm respectively. The dissected specimens were photogaphed and observed. The emphasis was put on the fascia boundaries of the GBA.3. Space perfusionRed latex with specific mixing proportion was injected into GBA space of anatomic dissection, 2 transaxially, 1 saggitally.4. Dynamic anatomyOne saggital section of GBA was chosed to dissect with the method of dynamic anatomy.ResultsGBA encroached upon the posterior surface of the gastric fundus and subcardial portion between the right and left layers of the gastrophrenic ligament, and lied between the superior and splenic recesses of the omental bursa. Left subphrenic retroperitoneal space was between the bare area of stomach and the diaphragm.GBA appeared at the esophageal-gastric conjunction, where the stomach contacts the diaphragm at the reflexions of the gastrophrenic and left gastropancreaatic folds, and disappeared at the hepatoduodenal ligament.The right and left border of GBA could be clearly depicted on the transverse or sagittal section, which presented at the gastric fundus and cardia. The superior and inferior border of GBA could be shown on the coronary dissection which appeared at the level of cardia. Red latex injected into GBA outlined these borders.In the GBA space between the stomach and the left diaphragm, gastric artery and vein, lymph nodes, adipose and connective tissue could be seen.ConclusionBare area of proximal stomach is not covered by visceral peritoneum and is located retroperitoneally. The stomach might be considered as one of the mesoperitoneal organs. OBJECTIVEGastric bare area (GBA) encroached upon the posterior surface of the gastric fundus and subcardial portion between the right and left layers of the gastrophrenic ligament. Bare area of proximal stomach is not covered by visceral peritoneum and is located retroperitoneally. To investigate the CT features of gastric bare area involvement by gastric carcinoma and their anatomic-pathological bases.MATERIALS AND METHODSThis prospective study was conducted at our university hospital between December 2002 to February 2005. 120 consecutive patients with gastroscopy biopsy proven PGC underwent MDCT scanning. 64 patients underwent chemotherapy after MDCT scan and were therefore excluded. The other 56 patients (40 men, 16 women; mean age 63 years, range 23～78 years) underwent radical gastric cancer surgery with extensive lymph node dissection were included in the study. The interval between MDCT examination and surgery was 3 day to 3 weeks ( mean, 8.7 days )Based on an initial scout image, the scanning range was planned from the diaphragmatic domes to inferior pole of the kidneys. All imaging was performed with an inspiratory breath hold. The MDCT imaging was started about 70 seconds after a bolus injection of intravenous contrast agent.Data analysis included as follows: MDCT depiction of tumors at specific sites, especially in relation to the GBA and the peritoneal reflection; the maximum depth of tumor extraluminal extension; the presence of gastrophrenic ligament invasion; and lymph nodes in the GBA or along the subphrenic retroperitoneal space.All patients underwent surgical resection and each surgical specimen was axially dissected. MDCT findings were compared with the pathology examination of each tumor bearing slice respectively. Findings from the surgical and histologic reports were used as the standard of reference and were conelated with the MDCT findings. MDCT findings-pathologic correlation was performed. A true-positive lesion was one found at surgery and on MDCT scannings. A false-negative lesion was one missed on MDCT scannings, but found at surgery. A false-positive finding was one demonstrated on MDCT scannings but not found at surgery or histopathologic examination.RESULTSFifty-six cases had GBA involvement at surgery and proved by pathology. Gastroscopy and gastrointestinal barium examination didn't offer help in detecting GBA involvement.The lesion appeared as mass in bare area in 46 cases and as metastatic lymphadenopathy in 10 cases. CT features of GBA involvement included: 1) Gastric bare area was widened. The thin fat strip between gastric wall and diaphragm obscured, or even disappeared. 2) Soft tissue density mass with heterogeneous enhancement or round lymphonodes was seen in GBA. 3) Left diaphragmatic crus or gastrophrenic ligament irregularly thickening was presented and could not be separated from mass tissue. 4) Other metastatic lymphonodes located in subphrenic extroperitoneal space might also be revealed.CONCLUSIONGBA involvement by gastric carcinomas shows some characteristic CT signs. GBA involvement by gastric carcinoma attributes to anatomic location and lymphatic drainage of PGC, also may be relevant to poor prognosis. PurposeGastric cancer mortality rates have remained relatively uncnanged over the past 30 years, and gastric cancer continues to be one of the leading causes of cancer-related death. Well-conducted studied have stimulated changes to surgical decision-making and technique. One of the most important factors that affects the prognosis in patients with gastric cancer is lymph node involvement and lymphadenectomy. Our aim to evaluate the efficacy of the detection of metastatic lymph nodes in patients with gastric cancer using 64-detector row CT.Materials and MethodsFrom June 2006 to January 2007, 56 consecutive patients diagnosed as gastric cancer were examined with 64-detector row helical CT before surgery at West China Hospital. Each patient fasted for at least 6 hours and was given more than 1000 mL tap water orally before the examination. All patients received 100 mL of nonionic contrast material intravenously by means of a power injector at a rate of 3 mL/sec.Scans were acquired with the following parameters: detector collimation 64×0.625, table feed of 10 mm per rotation, section width of 5 mm, reconstruction increment of 0.7 mm with 1～2mm sections, pitch of 0.98; tube current of 120 kVp and 250～320 mAs.Two radiologists independently evaluated the N staging on the axial MDCT images in combination with the MPR images. Perigastric and extragastric lymph nodes were considered to be involved when the short-axial diameter was≥5 mm. The UICC and GRGCS classification were independently used. Differences in staging accuracy for N staging were assessed using the McNemar test. P-value less than 0.05 were considered statistically significant.Results322 lymph nodes were resected at surgery. Of the 256 lymph nodes larger than 5 mm and included in the analysis, 210 were positive and 46 negative for metastasis. 240(94%)of 256 lymph nodes larger than 5 mm and 200(95%)of 210 positive for metastasis were detected at 64-detector row helical CT.The accuracy of 64-detector row helical CT examination in detecting perigastric and extragastric metastatic lymph nodes were analyzed. The accuracy rate of CT examination was higher in finding perigastric goups(1, 2, 3, 4) and paravessel groups(7, 9, 11, 14, 15, 16).For the evaluation of subsection N staging: the sensitivity of GRGCS was 83% for N0, 88% for N1, 58% for N2 and 75% for N3; the sensitivity of UICC was 83% for N0, 81% for N1, 67% for N2.The overall accuracy for N staging of nodal involvement was 80% for GRGCS and 77% for UICC classification. Overstaging of the N stage occurred in 8(14%) of 56 cases with GRGCS and 5(9%) of 56 cases with UICC classification, whereas understaging in 3(6%) of 56 cases with GRGCS and 8(14%) of 56 cases with UICC classification. The difference in staging between GRGCS and UICC was not statistically significant(p＞0.05).Conclusion64-detector row helical CT is effective for detection of metastatic lymphadenopathy and provides valuable results regarding N staging in patients with gastric cancer.