الفهرس 
Introduction and aim of the workOnly 14 pages are availabe for public view
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Abstract
IBDs are disorder with multifactorial aetiology in which genetics and environment are deeply involved in determining the manifestation of the disease. In fact, risk factors include genetic determinants and acquired determinants, such as a diet low in carbohydrates, smoking, use of non-steroidal anti-inflammatory drug (NSAIDs) and an altered intestinal microbiome.
In particular, MRE is widely considered the imaging modality of choice, taking advantage from the comprehensive evaluation of the small bowel as well as the abdominal cavity, the high contrast resolution of soft tissues, and the lack of ionizing radiation. It has been proposed as alternative procedure to CS in the evaluation of both ileo-colonic CD and UC.
Among the different sequences included within the MRE protocol, diffusion-weighted imaging (DWI) has gained increasing consent since it can deliver useful information about intestinal inflammation.
In this study we evaluated 50 patients referred from gastroenterology department of Assiut University for MRE examination with provisional diagnosis of IBD, 35 (70%) diagnosed as CD and 15 patients (30%) diagnosed as UC, at different age groups ranged from 9-72 years , all of them underwent colonoscopy and biopsy within one week before or after the MRE .
In CD patients , the following variables were analysed on MRE study ; restricted diffusion of most affected bowel segment and most affected LN and their ADC values , ADC value of normal psoas muscle , sMARIA , Clermont score also mural wall affection (mural thickness , intramural edema , mucosal ulceration , pseudo polyps and mass like lesions) , mesenteric inflammation ( fat stranding , comb sign , fibrofatty proliferation and LNs) and complications (entero enteric fistula , stricture perianal fistula and sinus).
In UC patients, the following variables were analysed on MRE study; restricted diffusion of most affected bowel segment and its ADC value, ADC value of normal psoas muscle, mural thickness , intramural edema , mucosal ulceration , pseudo polyps , lost haustrations , vascular engorgement , fat stranding and regional affected LNs also presence of perianal fistula.
A dichotomous qualitative analysis was performed with a b-value of 800 s/mm2 in the diffusion sequence of the wall of most affected segment. When there was high signal intensity in the DWI sequence and low signal intensity on the ADC map, the patient then had restricted diffusion. A quantitative evaluation of the ADC values was performed by drawing 10–30 mm2 region of interest (ROI) over the area with the highest signal intensity in the bowel wall.
We measured the mean ADC value at most affected segment (regarding diffusion signal); Mean± SD. was 0.98 ± 0.18 for CD group and 0.99 ± 0.11 for UC group with P value was 0.805 .ADC value at normal psoas muscle tissue both IBD groups ; 1.27 ± 0.10for CD and 1.26 ± 0.06 for UC with P value was 0.700. So, no statistically significant difference between the two groups regarding measured ADC values at most affected segment and normal psoas muscle. Statistical significant correlation between mean ADC value measured at most affected segment and grade of disease activity assessed by histopathological study of Colonoscopic biopsies in both CD patients was verified using Kendall rank correlation coefficient with P value 0.025 for UC patients 0.002 for CD patients, based on this statistical analysis we assessed the diagnostic performance of measured ADC value in total sample of IBD cases of our study based on histopathological disease activity grading to discriminate mild disease activity from moderate to severe cases, and we found significant discriminant performance of ADC (AUC .0741and P value 0.012*) at a cutoff point > 1.04 with sensitivity 75.0 and specificity 81.58, PPV 56.2 and NPV 91.2.
In the current study we determined the relation of these non-contrast dependent indices ;sMARIA and Clermont statistically to histopathological disease activity grading the median for Clermont score calculated for our 35 CD patients was 27.40 (18.50 – 30.25) and for sMARIA was 5.0 (3.0 – 5.0) , statistical analysis using Kruskal Wallis test , there was statistical significant corelation between theses indices and histopathological disease activity grading P value 0.004 for both indices which were significantly higher in moderate and severe cases than those of mild disease activity.
A good correlation is found between diffusion signal calculated ADC value and disease activity reported by Mayo Colonoscopic score using Pearson coefficient; r -0.539 , P value 0.038 , increased endoscopic score is associated with decrease in ADC value, so MRE DWI provides applicable radiological method for evaluating disease extent and activity in UC patients with less intestinal preparation than needed for colonoscopy.