Application Of Mri In The Diagnosis And Staging Of Advanced Gastric Cancer Before Surgery

Objective: To evaluate the role of MRI in the preoperative diagnosis and staging of advanced gastric carcinoma. Material and methods: MR imaging was performed in 11 normal cases subjects and 34 cases of gastric carcinoma with a 0.5-T MR imager and body-array coil. SE T1WI before and after contrast enhanced; SE high-weighed T2WI and SPIR images were obtained with a matrix of 153256,and a section thickness of 0.6cm. 11 normal cases were for control group, who were fasted for 8-12 hours and given 10mg of 654-2 ten minutes before study, and drank 800-1000ml water immediately before study. The same MR scanning was conducted in 34 patients with advanced gastric carcinoma. We evaluated the thickness, interruption (or not) of the low signal intensity bands, and enhancement pattern of the cancerous wall and normal gastric wall. We prospectively evaluated the depth of cancer invasion, perigastric infiltration (extraserosal invasion), perigastric organ invasion, and regional lymph nodes and determined tumor staging on MR images. T and N stages were classified according to the International Union Against Cancer classification. These MR evaluations including MR-determined staging were correlated with the surgicopathologic findings, results: Gastric anatomy was clearly demonstrated on MRI. Though each layer of gastric wall can not be specify by MRI, the serosa can show as a low-signal-intensity band in any sequence. Two layers of the gastric wall were visible in 4 normal cases. The gastriccarcinoma shows middle-signal-intensity and irregular thickened wall in SE T1WI; higher signal-intensity in SE high-weighed T2WI and much higher in SPIR images which can be differentiated to the normal gastric wall. 34 cases of gastric carcinoma including Borrman's type. I (3 cases), II(12 cases),III (11 cases) and IV(6 cases).The degree of extraserosal invasion may be classified by the appearance of low-signal-intensity band. The accuracy in evaluating T1,T2,T3 and T4 classes was 90.65%,84.38%,90.63% and 96.88%,respectively; The sensitivity in evaluating T1,T2,T3 and T4 classes was 40%,89.47%,83.33% and 100%,respectively; The sensitivity was excellent in evaluating extraserosal invasion. The specificity in evaluating T1,T2,T3 and T4 classes was 100%,76.92%,92.31% and 96,67%.MRI determined the overall N staging with 66.67% sensitivity,72.73% specificity,68.75% accuracy,82.35% positive predictive value, and 53.33% negative predictive value, moreover, it had a very high accuracy in distance of invasion. The sensitivity, specificity and accuracy of M staging was 85.71%, 100% and 100%, respectively. The overall accuracy of MRI in determining TNM-staging and respectability was 84.38% and 93.75% respectively. Conclusion: MRI can well show the gastric wall thickness, anatomic structure and surrounding anatomy. For the advanced gastric carcinoma, MRI can demonstrate not only all its morphologic features, such as mass, thickened wall and invasion of adjacent organs, but also adenopathy,metastasis in abdominal cavity and viscera. MRI is very helpful in the diagnosis and staging of gastric carcinoma.