***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: PURPOSE To prospect ively compare oral contrast-enhanced T2-weighted half-Fourier rapid acquisition with relaxation enhancement ( RARE ) magnetic resonance ( MR ) imaging with T1-weighted gadolinium-enhanced fast low-angle shot ( FLASH ) MR and st and ard examinations in the evaluation of Crohn disease . MATERIAL S AND METHODS Institutional review board approval and informed consent were obtained . Fifty-nine patients with Crohn disease underwent MR imaging after oral administration of a superparamagnetic contrast agent ; RARE plain and fat-suppressed sequences and FLASH sequences were performed before and after intravenous injection of gadolinium chelate . References were endoscopic , small-bowel barium , computed tomographic , ultrasonographic , and clinical -biochemical scoring of disease activity . Two radiologists analyzed MR images for presence and extent of Crohn disease lesions , presence of strictures or other complications , and degree of local inflammation . MR findings were correlated with endoscopic , radiologic , and clinical data ( kappa statistic and Spearman rank correlation test ) . RESULTS T2-weighted MR was 95 % accurate , 98 % sensitive , and 78 % specific for detection of ileal lesions . Agreement between T1- and T2-weighted images ranged from 0.77 for ileal lesions to 1.00 for colic lesions . T2-weighted MR enabled detection of 26 of 29 severe strictures , 17 of 24 enteroenteric fistulas , and all adhesions and abscesses ; T1-weighted MR enabled detection of 20 of 29 severe strictures , 16 of 24 enteroenteric fistulas , and all adhesions and abscesses . Complications leading to surgery were found in 12 ( 20 % ) patients ; these were assessed correctly with either T1- or T2-weighted images . T2-weighted signal intensities of the wall and mesentery correlated with biologic activity ( P < .001 , r of 0.774 and 0.712 , respectively ) . Interobserver agreement was 0.642 - 1.00 for T2-weighted and 0.711 - 1.00 for T1-weighted images . CONCLUSION T2-weighted MR can depict Crohn disease lesions and help assess mural and transmural inflammation with the same accuracy as gadolinium-enhanced T1-weighted MR . Combination of gadolinium-enhanced T1- and T2-weighted sequences is useful in the assessment of Crohn disease Background : Studies comparing magnetic resonance enterography ( MRE ) and computerized tomography enterography ( CTE ) for Crohn 's disease ( CD ) are scarce . Methods : The aim of this study was to prospect ively compare the sensitivity , specificity , and accuracy of abdominal MRE and CTE to assess disease activity and complications ( fistulas , strictures ) in ileocolonic CD . A total of 44 patients ( 23 male ; 21 female ; mean age 44 ) with ileocolonic CD underwent both MR and CT  in a short time interval ( mean 5 days ) . A 16‐slice CT with intravenous contrast and an MRI with oral and paramagnetic intravenous contrast were performed . Ileocolonoscopy was used as the reference st and ard . Sensitivity values of CT and MR for detection of extraenteric signs of disease were compared with the McNemar test , with results of imaging studies , surgery , and physical examination as reference st and ards . Results : No significant differences in sensitivity , specificity , and accuracy were observed between MRE and CTE regarding the following parameters at the patient level : localization of CD ( P = 1.0 ) , bowel wall thickening ( P = 1.0 ) , bowel wall enhancement ( P = 1.0 ) , enteroenteric fistulas ( P = 0.08 ) , detection of abdominal nodes ( P = 1.0 ) , and perivisceral fat enhancement ( P = 0.31 ) . MR was significantly superior compared to CT in detecting strictures ( P = 0.04 ) . Per segment analysis showed that MRE was significantly superior to CTE in detecting ileal wall enhancement ( P = 0.02 ) . Conclusions : MR and CT are equally accurate to assess disease activity and bowel damage in CD . MR may be superior to CT in detecting intestinal strictures and ileal wall enhancement . MR may represent an alternative technique to CT in assessing ileocolonic CD . ( Inflamm Bowel Dis 2010 PURPOSE To evaluate activity staging of Crohn 's disease ( CD ) measured with MR-enterography using ileoscopy as reference st and ard . MATERIAL S AND METHODS A prospect i ve study was made of 61 patients with CD . All patients underwent MR-enterography and ileoscopy .  MRI activity was measured by means of an ad hoc developed score , as well as by analysis of the imaging findings , and was compared with the SES-CD score obtained via ileoscopy . Examinations were performed using a 1.0 T scanner . RESULTS  MRI score discriminates between active and inactive disease with an area under the ROC curve of 0.941 . Overall correlation with the st and ard reference SES-CD score was moderate to strong ( Spearman 's r=0.62 p<0.001 ) . Agreement between both methods in staging patients with ileal CD as inactive , mild or moderate to severe was good ( Cohen 's κ=0.60 ) . Differences in means of the MRI activity scores of the three groups showed statistical significance ( p<0.01 ) . CONCLUSIONS The MRI score is a reliable predictor of activity in ileal CD and can stage patients in a way comparable to endoscopy . 1.0 T scans are valid for performing radiological evaluation of ileal Crohn 's disease BACKGROUND & AIMS Magnetic resonance ( MR ) enterography is a recommended imaging technique for detecting intestinal involvement in Crohn 's disease ( CD ) . However , the diagnostic accuracy of MR enterography has not been compared directly what that of enteroscopy of the jejunum and proximal ileum . We evaluated the usefulness of MR enterocolonography ( MREC ) by comparing its findings with those from balloon-assisted enteroscopy . METHODS In a prospect i ve study , MREC and enteroscopy were performed within 3 days of each other on 100 patients .  Ulcerative lesions and all mucosal lesions were evaluated . Physicians and radiologists were blinded to results from other studies . Findings from MREC were compared directly with those from enteroscopy ; the sensitivity and specificity with which MREC detected CD lesions were assessed . RESULTS MREC detected ulcerative lesions and all mucosal lesions in the small intestine with 82.4 % sensitivity ( 95 % confidence interval [ CI ] , 75.4%-87.7 % ) and 67.5 % sensitivity ( 95 % CI , 63.1%-70.0 % ) ; specificity values were 87.6 % ( 95 % CI , 83.7%-90.6 % ) and 94.8 % ( 95 % CI , 90.1%-97.5 % ) . MREC detected major stenosis with 58.8 % sensitivity ( 95 % CI , 37.6%-77.2 % ) and 90.0 % specificity ( 95 % CI , 88.4%-91.5 % ) and all stenoses with 40.8 % sensitivity ( 95 % CI , 30.8%-49.4 % ) and 93.7 % specificity ( 95 % CI , 91.1%-95.9 % ) . CONCLUSIONS MREC is useful for detecting active lesions in the small intestine . However , MR imaging is less sensitive for detecting intestinal damage , such as stenoses . Enteroscopy is preferred for identifying intestinal damage . Suitable imaging approaches should be selected to assess CD lesions in deep small intestine In the European Cooperative Crohn 's Disease Study patients from 14 centers were included in whom diagnosis was made within 2 years before study entry on the basis of generally accepted radiological , endoscopical and /or histological criteria or a combination of all . Reasons for exclusion were : diagnosis older than 2 years in patients who did not require active treatment , age less than 18 years , duration of symptoms less than 3 months , presence of complications which potentially required emergency surgery . Data on clinical features were obtained in 633 patients , of whom 452 were eligible to participate in the study . In 110 patients r and omized to placebo  the natural course of Crohn 's disease was studied . Patients with ileocolonic involvement were younger than patients with either colonic or small intestinal involvement only . Classic ileitis terminalis was present in 14 % of the patients . 49 % of the patients had combined involvement of both the small and large intestine . 30 % of patients had only small intestinal involvement , and in 21 % colonic disease was present . Small intestinal involvement was associated with a significantly lower Crohn 's Disease Activity Index ( CDAI ) than other anatomical locations of the disease . Perianal disease was more often associated with colonic than with small intestinal involvement . 60 % of placebo patients with active disease at entry achieved at least a transient remission within the initial 5 months of study . After 2 years , 23 % of patients with active disease at entry and 68 % of patients with quiescent disease had reached or maintained a remission , respectively . By stepwise multiple linear regression analysis long duration of disease between diagnosis and r and omization , normal serum albumin and combined involvement of small intestine and colon were identified as predictors of a more favorable outcome of patients treated with placebo . In contrast , extensive small bowel disease , treatment with steroids and bowel resection prior to study entry correlated with a less favorable outcome . However , by life table analysis outcome of previously untreated and treated patients in the placebo group was similar Objectives To prospect ively compare conventional MRI sequences , dynamic contrast enhanced ( DCE ) MRI and diffusion weighted imaging ( DWI ) with histopathology of surgical specimens in Crohn ’s disease . Methods 3-T MR enterography was performed in consecutive Crohn ’s disease patients scheduled for surgery within 4 weeks . One to four sections of interest per patient were chosen for analysis . Evaluated parameters included mural thickness , T1 ratio , T2 ratio ; on DCE-MRI maximum enhancement ( ME ) , initial slope of increase ( ISI ) , time-to-peak ( TTP ) ; and on DWI apparent diffusion coefficient ( ADC ) . These were compared with location-matched histopathological grading of inflammation ( AIS ) and fibrosis ( FS ) using Spearman correlation , Kruskal – Wallis and Chi-squared tests . Results Twenty patients ( mean age 38 years , 12 female ) were included and 50 sections ( 35 terminal ileum , 11 ascending colon , 2 transverse colon , 2 descending colon ) were matched to AIS and FS . Mural thickness , T1 ratio , T2 ratio , ME and ISI correlated significantly with AIS , with moderate correlation ( r = 0.634 , 0.392 , 0.485 , 0.509 , 0.525 , respectively ; all P < 0.05 ) . Mural thickness , T1 ratio , T2 ratio , ME , ISI and ADC correlated significantly with FS ( all P < 0.05 ) . Conclusions Quantitative parameters from conventional , DCE-MRI and DWI sequences correlate with histopathological scores of surgical specimens . DCE-MRI and DWI parameters provide additional information . Key points• Conventional MR enterography can be used to assess Crohn ’s disease activity.• Several MRI parameters correlate with inflammation and fibrosis scores from histopathology.• Dynamic contrast enhanced imaging and diffusion weighted imaging give additional information.• Quantitative MRI parameters can be used as biomarkers to evaluate Crohn ’s disease activity Guidelines for clinical practice are intended to suggest preferable approaches to particular medical problems as established by interpretation and collation of scientifically valid research , derived from extensive review of published literature . When data that will withst and objective scrutiny are not available , a recommendation may be made based on a consensus of experts . Guidelines are intended to apply to the clinical situation for all physicians without regard to specialty . Guidelines are intended to be flexible , not necessarily indicating the only acceptable approach , and should be distinguished from st and ards of care that are inflexible and rarely violated . Given the wide range of choices in any health-care problem , the physician should select the course best suited to the individual patient and the clinical situation presented . These guidelines are developed under the auspices of the American College of Gastroenterology and its Practice Parameters Committee . Expert opinion is solicited from the outset for the document . The quality of evidence upon which a specific recommendation is based is as follows : Grade A : Homogeneous evidence from multiple well- design ed r and omized ( therapeutic ) or cohort ( descriptive ) controlled trials , each involving a number of participants to be of sufficient statistical power . Grade B : Evidence from at least one large well- design ed clinical trial with or without r and omization , from cohort or case – control analytic studies , or well- design ed meta- analysis . Grade C : Evidence based on clinical experience , descriptive studies , or reports of expert committees . The Committee review s guidelines in depth , with participation from experienced clinicians and others in related fields . The final recommendations are based on the data available at the time of the production of the document and may be up date d with pertinent scientific developments at a later time Background : We developed novel magnetic resonance enterocolonography ( MREC ) for simultaneously evaluating both small and large bowel lesions in patients with Crohn 's disease ( CD ) . The aim of this study was to evaluate the diagnostic performance of MREC by comparing results of 
    Output:
    
MR imaging provides a reliable alternative in detecting small bowel activity in patients with Crohn 's disease .
Its advantages include high diagnostic accuracy and no radiation exposure while its disadvantages include high cost and limited availability