الفهرس 
Introduction
AIM OF WORKOnly 14 pages are availabe for public view
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Abstract
Recently, diffusion-weighted (DW) MRI has been introduced as a tool for the differential diagnosis of benign and malignant lesions of various organs. The idea to use this technique emerged from the concept that malignant lesions in different tissues show increased signal intensity on DW images due to restricted diffusion of water molecules in regions of hyper cellularity. Thus, we added DW imaging to the routine MRI examination of gastric tumors. Our purpose is to evaluate the role of the apparent diffusion coefficient (ADC) measurement made using diffusion-weighted magnetic resonance imaging (DW MRI) in the differential diagnosis of benign and malignant gastric wall thickening and compare these results to histopathological results of gastric masses. Between April 2015 and May 2016, we prospectively enrolled 26 cases - diagnosed with gastric mass either by upper endoscopy or MSCT abdomen after they had symptoms as persistent vomiting, loss of appetite and loss of weight - underwent MRI with diffusion before they underwent histopathological examination by endoscopic biopsy of gastric mass. Patient characteristics were: 15 males, 11 females, and their ages range from 23-75 years with mean age 53.4 years. Successful interpretation of MRI examination of the stomach requires: adequate opacification and proper distension for accurate estimation of gastric wall thickness. MR images were blindly evaluated without knowing the histopathological type of the gastric mass. Conventional T2W-TSE, T2W-SPAIR and T1 weighted images were assessed for the evaluation of the gastric mass (site, size and morphology), regional lymph nodes and intra-abdominal metastases. Now with the results of our study, * The mean ADC value were lower in patients with gastric malignancies (1.21+0.27 and 0.92+0.144) at b 400-800 and b 400,800-1000, respectively, compared to benign gastric diseases (2.53+ 0.67 and 1.95 + 0.56) at b 400-800 and b 400,800-1000 gradients (P < 0.0001). * We find the best cut-off value in ROC curve for differentiating gastric malignancy and benign gastric lesion according to ADC values, being 1.29 x10-3 mm²/sec, with a sensitivity of and specificity of 100%. * There was no significance between ADC values of adenocarcinoma and lymphoma cases (P = 0.681). * There was no significance among the ADC values of adenocarcinoma subgroups (P=0.232).