الفهرس 
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Abstract
Elicobacter pylori (H. pylori) infects about half of the world’s population. It is now well accepted as a crucial factor in the multistep carcinogenic process of gastric cancer and gastric ulcer. There is considerable interest in diagnostic methods for H. pylori infection both before and after treatment. Generally, H. pylori infection can be diagnosed by invasive (endoscopy and biopsy) and non-invasive techniques (e.g., serology, urea breath test, stool test). It was first isolated from the antral mucosa in 1983 by Marshall and Warren. Interest in this organism has developed because of a close relationship between H. Pylori infection and various gastrointestinal disorders. It has been established a major cause of chronic gastritis affecting approximately 50% of the world population and is important in the pathogenesis of gastric adenocarcinoma and gastric lymphoma. The prevalence ranges from less than 15% in some populations to virtually 100%, depending on socio-economic status and country development, more in low socio-economic population. On standard endoscopy, H. pylori-negative mucosa usually shows numerous minute points throughout the gastric body. On closer observation, the points are shown to be star-fish like arrangements of vessels, and this endoscopic finding was termed “regular arrangement of collecting venules (RAC)”. It is often observed in the gastric body, especially in young patients. RAC was considered a characteristic endoscopic feature of H. pylori negative normal stomach. i-Scan is based on the post processing of reflected light Because of a new computed spectral estimation technology, it is not dependent on optical filters also no significant difference in diagnostic sensitivity was observed between white light magnifying endoscopy and magnifying I-Scan, but the accuracy and specificity were significantly higher for magnifying I-Scan than for white light magnifying endoscopy (accuracy: 94.0% vs 84.5%, and specificity: 93.5% vs80.6%). I-Scan may provide a better image quality for H. pylori infection. However, i-scan consists of three types of algorithms: surface enhancement, contrast enhancement, and tone enhancement (TE). TE contains a variety of modes such as TE-g for gastric lesion, TE-v for vessel changes, and TE-e for pit patterns), which make it easier to recognize the subtle structure of the mucosal Surface. The aim of this study was to assess mucosal changes associated with H. pylori related gastritis by i-scan compared to white light endoscopy (WLE) in patients with dyspepsia, recurrent nausea and vomiting, recurrent epigastric pain or with H-pylori infection. All patients were subjected to full history taking and clinical examination. A total of 65 patients (32 men, 33 women; mean age 41.415 years, range 23-60 years) were enrolled in the study. Regarding mucosal assessment by I scan, 33.8%, 20%, 33.8%, 6.2% and 6.2% were classified as having types A, B, C, D and E respectively. There is statistically significant positive relation between presence of H. pylori bacilli by biopsy and grades detected by I scan. All patients with grades D and E had positive H. pylori in biopsy taken. About 91% of those with grade C had positive H. pylori bacilli in biopsy. Out of 33 patients with H. pylori infection, 29 patients were classified as having it by WLE. Sensitivity was 87.9%, specificity 84.4%, positive predictive value 85.3%, negative predictive value 87.1% and accuracy 86.2%. There is significant substantial agreement between WLE by biopsy and presence of H. pylori as confirmed by biopsy. Out of 33 patients with H. pylori infection, 20 patients were classified as having type C. Sensitivity was 60.6%, specificity 93.8%, positive predictive value 90.9%, negative predictive value 69.8%, and accuracy 76.9%. There is significant moderate agreement between type C by I scan and presence of H. pylori as confirmed by biopsy. Four patients were classified as having type D. Sensitivity was 12.1%, specificity 100%, positive predictive value 100%, negative predictive value 52.5% and accuracy 55.4%. There is significant slight agreement between type D by I scan and presence of H. pylori as confirmed by biopsy. Also, four patients were classified as having type E. Sensitivity was 12.1%, specificity 100%, positive predictive value 100%, negative predictive value 52.5% and accuracy 55.4%. There is significant slight agreement between type D by I scan and presence of H. pylori as confirmed by biopsy. In this study, there is statistically significant positive correlation between WLE and I scan grades. High grades were significantly present in those with positive lesion on WLE. On comparing result of WLE and presence of C, D, or E grades of I scan in diagnosis of h. pylori infection, I scan had lower sensitivity (84.8% versus 87.9% in WLE), yet higher specificity (93.8% versus 84.8% in WLE) and accuracy (89.2% versus 86.2% in WLE). Yet it is also superior to WLE in grading mucosal affection.