ADC Values for Detecting Bowel Inflammation and Biologic Therapy Response in Patients With Crohn Disease: A Post Hoc Prospective Trial Analysis.

BACKGROUND. New biologic agents for Crohn disease (CD) create a need for noninvasive disease markers. DWI may assess bowel inflammation without contrast agents. OBJECTIVE. The purpose of this study was to evaluate ADC values for identifying bowel inflammation and therapeutic response in patients with CD treated with biologic therapy. METHODS. This study entailed post hoc analysis of prospective trial data. Analysis included 89 patients (median age, 37 years; 49 women, 40 men) with CD treated by biologic therapy who underwent MR enterography (MRE) at baseline and 46 weeks after therapy, from March 2013 to April 2021; 43 patients underwent ileocolonoscopy at both time points. Analysis was conducted at the level of small-bowel and colorectal segments (586 segments analyzed). MR index of activity (MaRIA) score and presence of endoscopic ulcers were determined at both time points. One observer measured bowel wall ADC. Diagnostic performance was evaluated. Dichotomous ADC assessments used a threshold of 1301 × 10-6 mm2/s based on initial ROC analysis; dichotomous MaRIA score assessments used a threshold of 11 (moderate to severe inflammation). A second observer repeated ADC measurements in 15 patients. RESULTS. At baseline, ADC had AUC of 0.92, sensitivity of 78.6%, specificity of 91.4%, and accuracy of 88.2% for detecting segments with MaRIA score 11 or greater. At baseline, AUC for detecting endoscopic ulcers was 0.96 for MaRIA score versus 0.87 for ADC (p < .001); sensitivity, specificity, and accuracy were 70.8%, 90.2%, and 85.1% for ADC and 86.2%, 96.2%, and 93.6% for MaRIA score. At follow-up, ADC had AUC of 0.87, sensitivity of 75.4%, specificity of 83.6%, and accuracy of 80.0% for detecting improvement in MaRIA score to less than 11. At follow-up, AUC for detecting endoscopic ulcer healing was 0.94 for MaRIA score versus 0.84 for ADC (p = .01); sensitivity, specificity, and accuracy were 70.7%, 95.8%, and 84.4% for ADC and 90.2%, 100.0%, and 95.6% for MaRIA score. Interobserver agreement for ADC, based on intraclass correlation coefficient, was 0.70 at baseline and 0.65 at follow-up. CONCLUSION. The findings do not support use of ADC rather than MaRIA scores for detecting biologic therapy response. CLINICAL IMPACT. ADC may have an adjunct role in assessing bowel inflammation in CD, but showed limited performance for detecting biologic therapy response.

The Simplified MR Index of Activity Score in Pediatric Small-Bowel Crohn Disease: An Interreader Agreement and Responsiveness Study.

BACKGROUND. The simplified MR index of activity (MaRIA) score is used to assess the severity of small-bowel inflammation without use of IV contrast material. OBJECTIVE. The purposes of this study were to assess interreader agreement on the use of simplified MaRIA scores for evaluation of the inflammatory activity of terminal ileal Crohn disease in children and young adults and to assess whether simplified MaRIA scores change after biologic medical therapy. METHODS. This analysis was ancillary to a previously reported primary prospective research investigation. The study included 20 children and young adults with newly diagnosed ileal Crohn disease and 15 healthy control participants who underwent research small-bowel MRI examinations between December 2018 and October 2021. The participants with Crohn disease underwent baseline MRI and MRI 6 weeks and 6 months after beginning anti-tumor necrosis factor α-treatment as well as weighted pediatric Crohn disease activity index (wPCDAI) and C-reactive protein (CRP) assessment on the day of each examination. Control participants underwent one MRI examination. Four pediatric radiologists independently assigned simplified MaRIA scores using axial and coronal T2-weighted SSFSE images. Median simplified MaRIA score among readers was computed. Interreader agreement was assessed with Fleiss kappa coefficients and intra-class correlation coefficient (ICC). Analysis included the Mann-Whitney U test, Friedman test, and Spearman rank correlation. RESULTS. Simplified MaRIA scores (across time points and study groups) had substantial interreader agreement (κ = 0.65 [95% CI, 0.56-0.74]; ICC, 0.71 [95% CI, 0.63-0.78]). Median scores were higher in participants with Crohn disease at baseline than in healthy control participants (3.5 [IQR, 2.5-4.9] vs 0.5 [IQR, 0-2.0]; p < .001). Scores decreased after medical treatment in participants with Crohn disease (p = .005). The median score was 3.5 (IQR, 2.5-4.9) at baseline, 2.3 (IQR, 1.6-3.9) at 6 weeks, and 2.0 (IQR, 0.5-2.5) at 6 months. In participants with Crohn disease, median scores had significant correlations with wPCDAI (ρ = 0.46 [95% CI, 0.18-0.64]; p < .001) and CRP level (ρ = 0.48 [95% CI, 0.27-0.65]; p < .001). CONCLUSION. Radiologists had substantial agreement in use of simplified MaRIA scores to assess intestinal inflammation in ileal Crohn disease. Scores changed over time after medical therapy. CLINICAL IMPACT. The results support the simplified MaRIA score as an objective MRI-based clinical measure of intestinal inflammation in children and young adults with Crohn disease.

Comparison of Sensitivity Encoding (SENSE) and Compressed Sensing-SENSE for Contrast-Enhanced T1-Weighted Imaging in Patients With Crohn Disease Undergoing MR Enterography.

BACKGROUND. Long acquisition times for breath-hold contrast-enhanced (CE) T1-weighted imaging in MR enterography (MRE) protocols result in reduced image quality. OBJECTIVE. The purpose of this study was to compare CE T1-weighted imaging performed using sensitivity encoding (SENSE) and compressed sensing-SENSE (CS-SENSE) in terms of image quality and diagnostic performance for active inflammation in Crohn disease (CD). METHODS. This retrospective study included 41 patients (31 men, 10 women; mean age, 34 ± 12 [SD] years) who underwent MRE for known or suspected CD between June 2020 and September 2020. MRE was performed in one of two scanning rooms depending on scheduling availability. Per institutional protocol, in one room, the enteric phase was acquired using SENSE (acceleration factor, 3) and the portal phase was acquired using CS-SENSE (acceleration factor, 5); this order was reversed in the other room. Two radiologists independently assessed sequences for subjective image quality measures at the patient level and for active inflammation at the bowel-segment level. Mean image quality scores between readers were computed. Diagnostic performance for active inflammation was compared between SENSE and CS-SENSE using generalized estimating equations; a separate experienced radiologist reviewed the full MRE protocol to establish the reference standard. RESULTS. The mean acquisition time of CE T1-weighted imaging was 17.2 ± 1.1 seconds for SENSE versus 11.5 ± 0.8 seconds for CS-SENSE (p < .001). CS-SENSE scored significantly better than SENSE in overall image quality (4.2 ± 0.7 vs 3.7 ± 1.1; p = .02), motion artifacts (4.0 ± 0.8 vs 3.6 ± 1.2; p = .006), and aliasing artifacts (4.8 ± 0.4 vs 4.2 ± 0.6; p < .001). CS-SENSE scored significantly worse than SENSE in synthetic appearance (4.6 ± 0.5 vs 4.8 ± 0.4; p = .003). Contrast, sharpness, and blurring were not different between sequences (p > .05). For reader 1, CS-SENSE, compared with SENSE, showed a sensitivity of 86% versus 81% (p = .09), specificity of 88% versus 83% (p = .08), and accuracy of 87% versus 82% (p = .56). For reader 2, CS-SENSE, compared with SENSE, showed a sensitivity of 92% versus 79% (p = .006), specificity of 90% versus 98% (p = .16), and accuracy of 91% versus 86% (p = .002). CONCLUSION. Use of CS-SENSE for CE T1-weighted imaging in MRE protocols results in reduced scan times with reduced artifact and improved image quality. CLINICAL IMPACT. The benefits of CS-SENSE in MRE protocols may improve the diagnostic performance for active inflammation in CD.

Bowel Wall Visualization Using MR Enterography in Relationship to Bowel Lumen Contents and Patient Demographics.

BACKGROUND: MR enterography (MRE) is generally performed without bowel preparation, but the frequency and extent by which bowel contents affect bowel wall visualization are poorly described in the literature. PURPOSE: To evaluate MRE bowel wall visualization quality relative to bowel lumen contents and patient demographics. STUDY TYPE: Retrospective, single-center. POPULATION: One hundred and four consecutive patients (mean age 29 years, range 5-76 years) without prior bowel resection who had undergone MRE. FIELD STRENGTH/SEQUENCE: 3 T (N = 87) or 1.5 T (N = 17)/T2-weighted single-shot spin echo (T2WI) and fat-saturated T1-weighted gradient echo (T1WI) without and with gadolinium. ASSESSMENT: For the proximal and distal jejunum and ileum and colon, three readers independently categorized bowel lumen signal (water = bright T2 dark T1, T1-bright, or air = dark T2 and T1 signal) and scored distension (0 = poor, 1 = moderate, 2 = well) and wall enhancement (0 = unclear, 1 = perceptible, 2 = clear) based upon gadolinium enhanced T1WI for the 104 MRE exams). The bowel visualization score was the sum of the wall enhancement and distension scores and was considered adequate if ≥3. STATISTICAL TESTS: Wilcoxon signed-rank test. RESULTS: The bowel lumen content was water signal in 93% (97/104 scans), 92% (95/104), 98% (102/104), and 93% (92/104) of the proximal and distal jejunum and proximal and distal ileum, respectively, but only in 12.5% (13/104) of the colon. There was adequate bowel visualization of 53.8%, 77.8%, 84.6%, 90.4% of the proximal and distal jejunum and proximal and distal ileum, respectively, but only 19.2% of the colon. In children (age < 18 years), the visualization score of the ileum was lower when the adjacent colon contained air (2.4 ± 0.97) compared to water (3.75 ± 0.29, P < 0.05) or T1-bright material (3.21 ± 0.82, P < 0.05). DATA CONCLUSION: Without bowel preparation, colon wall visualization was often unsatisfactory at MRE, and air-filled colon also degraded small bowel visualization, particularly in children. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY: Stage 1.

Evaluation of Crohn Disease Activity Using a Potential Abbreviated MRE Protocol Consisting of Balanced Steady-State Free Precession MRI Only Versus Full-Protocol MRE.

OBJECTIVE. The purpose of the present study was to compare the diagnostic performance of an abbreviated MR enterography (MRE) protocol consisting of balanced steady-state free-precession (b-SSFP) imaging only versus standard full-protocol MRE for the evaluation of Crohn disease activity. MATERIALS AND METHODS. This single-center retrospective study included 112 patients with Crohn disease (66 women and 46 men; age range, 18-84 years) who underwent MRE between January 2017 and March 2018. Utilizing binary and 5-point Likert confidence scales, two blinded readers independently interpreted and scored disease activity on b-SSFP sequences only and on full-protocol MRE images. Interreader and intrareader agreement on confidence regarding disease activity were calculated using weighted kappa indexes. Correlation between MRE findings of Crohn disease and the Harvey-Bradshaw index was also performed. RESULTS. Perfect intrareader agreement and strong interreader agreement on disease activity were observed (intrareader agreement: κ = 0.97, 0.96, and 0.96 for reader A, reader B, and both readers combined; interreader agreement: κ = 0.82 for b-SSFP imaging only and κ = 0.81 for MRE). For detecting active Crohn disease, b-SSFP sequences had a sensitivity and specificity of 97% and 100%, respectively, for reader A and 98% and 86%, respectively, for reader B. Strong-to-perfect intrareader agreement was achieved between b-SSFP imaging only and MRE for identification of penetrating disease (κ = 0.80 and 0.97) and stenosing disease (κ = 0.87 and 0.95). Perfect intrareader agreement was also obtained between b-SSFP imaging only and MRE for detecting abnormal bowel segments (κ = 0.91 for reader A; κ = 0.98 for reader B). Weak agreement was noted between both b-SSFP imaging only and MRE versus the Harvey-Bradshaw index (κ = 0.08 of reader A; κ = 0.04 for reader B). CONCLUSION. Robust agreement was observed between b-SSFP imaging only and full-protocol MRE for the assessment of Crohn disease activity and complications. An abbreviated MRE protocol that exclusively uses b-SSFP sequences appears feasible and has significant implications for health care resources.

Prevalence and clinical significance of incidental extra-intestinal findings in MR enterography: experience of a single University Centre.

PURPOSE: To determine the incidence and clinical relevance of extra-intestinal incidental findings (IF) in a cohort of patients with proven or suspected Crohn disease (CD) examined with magnetic resonance enterography (MR-E) in a single University Centre. METHODS: Between January 2018 and June 2019, 182 patients with proven or suspected CD with a planned first MR-E examination, were retrospectively included in this study. Incidental findings were considered as any abnormality identified in the absence of previous clinically suspected or known disease. IF were categorized as unremarkable, benign or potentially relevant findings requiring further imaging or specific treatment. RESULTS: Of the 182 revised MR-E, extra-intestinal IF were recorded in 70 cases (38.5%); 35 (50%) incidental lesions were recognized as non-significant, 24 (34%) as benign and 11 (16%) as clinically relevant. Moreover, there was a positive correlation between IF and patients' age (p < 0.0001). CONCLUSIONS: In our experience, a high number of IF (38.5%) was found, with a prevalence that increases with patients' age. Clinically relevant findings were found in 16% of MR-E. This means that MR-E is a useful tool to detect IF, therefore, the presence of a radiologist during the image acquisition is crucial in adding sequences to the examination.

Potential MR Enterography Features to Differentiate Primary Small Intestinal Lymphoma From Crohn Disease.

OBJECTIVE. The purpose of this study was to assess the MR enterographic features of primary small intestinal lymphoma (PSIL) and compare them with active Crohn disease (CD) presenting with severe (≥ 10 mm) mural thickening of the small bowel. MATERIALS AND METHODS. This retrospective study included 15 patients with pathologically proven PSIL and 15 patients with active inflammatory CD with severe mural thickening. Various morphologic, enhancement, and diffusion parameters were compared between the two groups at MR enterography. The ratios of the upstream to involved luminal diameter and mural thickness to luminal diameter in the involved segment were calculated. An attempt was made to define a predictive model (morphologic score) for discriminating PSIL from CD with severe mural thickening. RESULTS. Patients with PSIL were more likely than those with CD to have unifocal disease (66.7% vs 20.0%, p = 0.025), circumferential involvement (86.7% vs 26.7%, p < 0.001), luminal dilatation (60.0% vs 7.0%, p = 0.005), and an attenuated fold pattern (53.3% vs none, p < 0.001). They were less likely to have serosal surface involvement (40.0% vs 100%, p = 0.001) and mesenteric fat infiltration (33.3% vs 100%, p < 0.001). Median upstream to involved luminal diameter ratio (1.5 vs 9.6, p < 0.001) and mural thickness to involved luminal diameter ratio (1.1 vs 4.3, p = 0.044) were significantly lower in patients with PSIL than in those with CD with severe mural thickening. No significant difference was observed in enhancement and diffusion measures. Morphologic score was based on the presence of luminal dilatation, unifocal involvement, mesenteric fat infiltration, and luminal stricture, yielding accuracy of 98% for differentiation between PSIL and CD with severe mural thickening. CONCLUSION. Morphologic features seen at MR enterography rather than enhancement or diffusion parameters may be valuable for differentiation of PSIL from active CD with severe mural thickening with significantly lower ratios of upstream to involved luminal diameter and mural thickness to involved luminal diameter in PSIL.

Prospective comparison of diffusion-weighted magnetic resonance enterography and contrast enhanced computed tomography enterography for the detection of ileocolonic Crohn's disease.

BACKGROUND AND AIMS: Crohn's disease (CD) is a chronic and relapsing course with various status of different segments, and there were no investigations comparing the lesion detection between magnetic resonance (MR) and computed tomography (CT) in term of the severity of CD. We aim to assess the performances of diffusion-weighted MR enterography (DW-MRE) and contrast enhanced CT enterography (CTE) for detecting different grade lesions in ileocolonic CD. METHODS: Forty-one consecutive patients finally diagnosed with ileocolonic CD were included. All the patients prospectively underwent DW-MRE, contrast enhanced CTE, and ileocolonoscopy within 2 weeks. DW-MRE and CTE images were interpreted for the presence or absence of active CD segments by two experienced radiologists independently. Ileocolonic segments (terminal ileum, right colon, transverse colon, left colon, and rectum) were graded as inactive (0-2), mild (3-6), or moderate-severe (≥ 7) by the simplified endoscopic score for CD (SES-CD). Diagnostic efficiencies of DW-MRE and CTE for mild and/or moderate-severe CD segments were calculated and compared, using ileocolonoscopy as reference standard. RESULTS: According to SES-CD, 190 ileocolonic segments from 41 CD patients were scored as 91 inactive, 68 mild, and 31 moderate-severe CD lesions. The sensitivity of DW-MRE for detecting active from inactive segments was higher than that of CTE, and the specificities of them had no significant differences. As for the subgroup analysis, DW-MRE was more sensitive for mild CD lesions than CTE (76.5% vs 60.3%; P = 0.019), while the sensitivities for moderate-severe CD were similar between these two modalities (96.8% for DW-MRE and 93.5% for CTE; P = 1.00). CONCLUSIONS: Both DW-MRE and CTE had comparably excellent performances for moderate-severe CD detection; DW-MRE demonstrated better sensitivity in mild lesions compared with CTE and could be more suitable for the diagnosis of mild CD.

Detection of Crohn's disease with diffusion images versus contrast-enhanced images in pediatric using MR enterography with histopathological correlation.

The purpose of this study was to determine whether MRE performed with diffusion-weighted imaging (DWI) sequences is comparable to contrast-enhanced MRE in the detection of active small-bowel inflammation in pediatric patients with Crohn's disease (CD). We included in our study 68 patients with diagnosis of CD between April 2015 and June 2018 that underwent MRE examination. Examination protocol includes coronal and axial FISP, T2-w half-Fourier RARE and DWI sequences, a baseline coronal T1-w fat-saturated ultrafast (GRE) sequence followed by contrast 3D T1-w GRE. All images were assessed by two radiologists who graded each of bowel segments for the presence of inflammation on a four-point confidence scale on the basis of wall thickening and wall signal on DWI and ADC maps and comparing their results with post-contrast images. When considering all bowel segments, we found 41 true positive and 25 true negative on DWI. One false positive case corresponded to the absence of inflammatory histopathology changes at the level of the terminal ileum in a 15-year-old male, and one false negative case was in a 10-year-old female with only jejunal lesion. The corresponding sensitivity, specificity, PPV, NPV and accuracy were 97.6% (95% CI 67.7-99.7), 96.1% (95% CI 66.7-98.5), 97.6% (95% CI 70.8-98.4), 96.1% (95% CI 64.2-90.6) and 97% (95% CI 84.2-97.5), respectively. Analyzing the gadolinium-enhanced set, 35 true positive and 25 true negative results were found. One false positive case was found, and it was the same as with DWI. The corresponding sensitivity, specificity, PPV, NPV and accuracy were 83.3% (95% CI 65.9-86.7), 96.1% (95% CI 68.7-88.9), 97.2% (95% CI 84.3-98.7), 78.1% (95% CI 27.9-72.1) and 88.2% (95% CI 41.2-85.6), respectively. Sensitivity for the detection of active IBD lesion was significantly better with DWI than with CE-T1-w imaging (p = 0.002), whereas the specificity was similar (p = 0.743). Our study has shown that DWI sequences have a high accuracy in detecting the bowel segment affected by CD. These results emphasize the utility to include the DWI/ADC in standard MR enterography protocols and suggest that DWI could replace T1-weighted post-contrast sequences.

The Influence of Bowel Preparation on ADC Measurements: Comparison between Conventional DWI and DWIBS Sequences.

Background and objectives: The aim of the study was to assess whether there were differences between apparent diffusion coefficient (ADC) values of diffusion-weighted imaging (DWI) and diffusion-weighted imaging with background body signal suppression (DWIBS) sequences in non-prepared and prepared bowels before and after preparation with an enteric hyperosmolar agent, to assess whether ADC measurements have the potential to avoid bowel preparation and whether ADC-DWIBS has advantages over ADC-DWI. Materials and Methods: 106 adult patients without evidence of inflammatory bowel disease (IBD) underwent magnetic resonance (MR) enterography before and after bowel preparation. ADC-DWI and ADC-DWIBS values were measured in the intestinal and colonic walls demonstrating high signal intensity (SI) at DWI tracking images of b = 800 s/mm2 before and after preparation. Results: There were significant difference (p < 0.0001) in both ADC-DWI and ADC-DWIBS results between non-prepared and prepared jejunum for DWI being 1.09 × 10-3 mm2/s and 1.76 × 10-3 mm2/s, respectively, and for DWIBS being 0.91 × 10-3 mm2/s and 1.75 × 10-3 mm2/s, respectively. Both ADC-DWI and DWIBS also showed significant difference between non-prepared and prepared colon (p < 0.0001), with DWI values 1.41 × 10-3 mm2/s and 2.13 × 10-3 mm2/s, and DWIBS-1.01 × 10-3 mm2/s and 2.04 × 10-3 mm2/s, respectively. No significant difference between ADC-DWI and ADC-DWIBS was found in prepared jejunum (p = 0.84) and prepared colon (p = 0.58), whereas a significant difference was found in non-prepared jejunum and non-prepared colon (p = 0.0001 in both samples). Conclusions: ADC between DWI and DWIBS does not differ in prepared bowel walls but demonstrates a difference in non-prepared bowel. ADC in non-prepared bowel is lower than in prepared bowel and possible overlap with the ADC range of IBD is possible in non-prepared bowel. ADC-DWIBS has no advantage over ADC-DWI in regard to IBD assessment.

[18F]FDG PET/MR enterography for the assessment of inflammatory activity in Crohn's disease: comparison of different MRI and PET parameters.

PURPOSE: To evaluate the diagnostic performance of integrated whole-body positron emission tomography (PET)/magnetic resonance (MR) enterography in patients with Crohn's disease (CD). METHODS: Fifty patients with known CD and recurrent symptoms underwent ileocolonoscopy (reference standard) as well as PET/MR enterography. Seven ileocolonic segments were endoscopically analysed using the Simplified Endoscopic Activity Score for Crohn's Disease (SES-CD) and additionally classified into three categories of inflammation (none, mild to moderate and severe ulcerative inflammation). A total of 14 PET/MR parameters were applied for the assessment of inflamed segments. Contingency tables and the chi-squared test were used for the analysis of qualitative parameters, and the Mann-Whitney U test and receiver operating characteristic (ROC) curve for the analysis of quantitative parameters. The PET/MR parameters were ranked according to their diagnostic value by random forest classification. Correlations between PET/MR parameters and the severity of inflammation on endoscopy and SES-CD were tested using Spearman's rank correlation test. RESULTS: A total of 309 segments could be analysed. Based on multivariate regression analysis, wall thickness and the comb sign were the most important parameters for predicting segments with active inflammation of any type. SUVmax ratio of the bowel segment (relative to SUVmax of the liver) was the most important parameter for detecting segments with severe ulcerative inflammation. Wall thickness was the only parameter that moderately correlated with inflammation severity on endoscopy as well as with SES-CD (ρ = 0.56 and 0.589, both p < 0.001). CONCLUSION: PET/MR enterography is an excellent noninvasive diagnostic method, and both MR parameters and PET findings provided high accuracy in detecting inflamed segments.

Anatomical Road Mapping Using CT and MR Enterography for Ultrasound Molecular Imaging of Small Bowel Inflammation in Swine.

OBJECTIVES: To evaluate the feasibility and time saving of fusing CT and MR enterography with ultrasound for ultrasound molecular imaging (USMI) of inflammation in an acute small bowel inflammation of swine. METHODS: Nine swine with ileitis were scanned with either CT (n = 3) or MR (n = 6) enterography. Imaging times to load CT/MR images onto a clinical ultrasound machine, fuse them to ultrasound with an anatomical landmark-based approach, and identify ileitis were compared to the imaging times without anatomical road mapping. Inflammation was then assessed by USMI using dual selectin-targeted (MBSelectin) and control (MBControl) contrast agents in diseased and healthy control bowel segments, followed by ex vivo histology. RESULTS: Cross-sectional image fusion with ultrasound was feasible with an alignment error of 13.9 ± 9.7 mm. Anatomical road mapping significantly reduced (P < 0.001) scanning times by 40%. Localising ileitis was achieved within 1.0 min. Subsequently performed USMI demonstrated significantly (P < 0.001) higher imaging signal using MBSelectin compared to MBControl and histology confirmed a significantly higher inflammation score (P = 0.006) and P- and E-selectin expression (P ≤ 0.02) in inflamed vs. healthy bowel. CONCLUSIONS: Fusion of CT and MR enterography data sets with ultrasound in real time is feasible and allows rapid anatomical localisation of ileitis for subsequent quantification of inflammation using USMI. KEY POINTS: • Real-time fusion of CT/MRI with ultrasound to localise ileitis is feasible. • Anatomical road mapping using CT/MRI significantly decreases the scanning time for USMI. • USMI allows quantification of inflammation in swine, verified with ex vivo histology.

Intestinal Behçet Disease: Evaluation With MR Enterography-A Case-Control Study.

OBJECTIVE: The purposes of this study were to discern imaging findings that distinguish Behçet disease from small-bowel Crohn disease, to find initial performance estimates for these findings, and to evaluate the diagnostic value of MR enterography (MRE) for detecting intestinal Behçet disease. MATERIALS AND METHODS: The MRE examinations of 30 consecutively registered patients with established intestinal Behçet disease were reviewed by two blinded readers. The frequencies of MRE findings were compared with those obtained for 30 control subjects with small-bowel Crohn disease who were matched for sex and age. The performance estimates were generated with ileocolonoscopic and histopathologic findings as the reference standard. RESULTS: Polypoid pattern and homogeneous mural enhancement were the findings seen more frequently in Behçet disease (p = 0.000) than in Crohn disease (p = 0.003). Stricture formation, long-segment disease, and involvement of more proximal ileal segments favored small-bowel Crohn disease. The ROC AUCs for polypoid pattern and homogeneous mural enhancement in the detection of intestinal Behçet disease were 0.806 and 0.779. The accuracy of MRE was 70.00% (95% CI, 50.60-85.27%); sensitivity, 57.14% (95% CI, 34.02-78.18%), and specificity, 100% (95% CI, 66.37-100%). CONCLUSION: MRE has potential for use as a radiation-free alternative for clarifying the cause of nonspecific gastrointestinal symptoms in patients with known Behçet disease. However, additional studies are needed to determine the actual value of MRE in patients with Behçet disease and to validate the clinical usefulness of the technique in the detection of unknown intestinal Behçet disease.

Utility of MR enterography and ultrasound for the investigation of small bowel Crohn's disease.

Cross sectional Imaging plays an increasingly important role the diagnosis and management of Crohn's disease. Particular emphasis is placed on MRI and Ultrasound as they do not impart ionising radiation. Both modalities have reported high sensitivity for disease detection, activity assessment and evaluation of extra-luminal complications, and have positive effects on clinical decision making. International Guidelines now recommend MRI and Ultrasound in the routine management of Crohn's disease patients. This article reviews the current evidence base supporting both modalities with an emphasis on the key clinical questions. We describe current protocols, basic imaging findings and highlight areas in need of further research. LEVEL OF EVIDENCE: 5 Technical Efficacy: Stage 4 J. MAGN. RESON. IMAGING 2017;45:1573-1588.

MR enterography in nonresponsive adult celiac disease: Correlation with endoscopic, pathologic, serologic, and genetic features.

PURPOSE: To assess small bowel abnormalities on magnetic resonance enterography (MRE) in adult patients with nonresponsive celiac disease (CD) and investigate their associations with endoscopic, histopathologic, serologic, and genetic features. MATERIALS AND METHODS: This prospective study was carried out between September 2012 and August 2013. After approval by the Ethics Committee of our institution, informed consent was acquired from all participants. Forty consecutive patients with nonresponsive CD, aged 17-76 years, underwent MRE using a 1.5T unit. Sequences included T2 -HASTE, True-FISP, pre- and postcontrast VIBE to assess the quantitative (number of ileal and jejunal folds) and qualitative (fold pattern abnormalities, mural thickening, increased enhancement, bowel dilatation, or intussusception) measures. Endoscopic manifestations were categorized as normal/mild vs. severe. Histopathological results were divided into mild and severe. Genotyping of HLA-DQ2 and DQ8 was performed. Serum levels of tissue-transglutaminase, endomysial, and gliadin antibodies were also determined. Logistic regression analysis and receiver operating characteristic (ROC) curve were used. RESULTS: Twenty-nine (72.5%) cases showed abnormal MRE. Reversed jejunoileal fold pattern had significant association with severe endoscopic (odds ratio [OR] = 8.38, 95% confidence interval [CI] 1.73-40.5) and pathologic features (OR = 7.36, 95% CI 1.33-40.54). An increased number of ileal folds/inch was significantly associated with severe MARSH score and positive HLA-DQ8. (P < 0.001 and P = 0.026, respectively). Ileal fold number had the highest areas under the curve for prediction of severe endoscopic (AUC: 0.75, P = 0.009) and pathologic (AUC: 0.84, P < 0.001) findings and positive anti-transglutaminase antibody (AUC: 0.85, P = 0.027). CONCLUSION: Fold pattern reversal on MRE is highly associated with endoscopic and pathologic features of refractory celiac disease (RCD). Increased ileal folds showed higher correlation with endoscopic-pathologic features, HLA-DQ8, and anti-transglutaminase level. MRE might be more sensitive for detection of increased ileal folds in CD rather than reduction of duodenal and jejunal folds due to better distension of ileal loops. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2017;46:1096-1106.

MR Enterography Assessment of Bowel Inflammation Severity in Crohn Disease Using the MR Index of Activity Score: Modifying Roles of DWI and Effects of Contrast Phases.

OBJECTIVE: The purpose of this article is to appraise the use of the MR index of activity (MaRIA) score in evaluating Crohn disease (CD) on present-day MR enterography images, with an emphasis on determining the modifying roles of DWI and the effects of different contrast enhancement phases. SUBJECTS AND METHODS: Fifty patients prospectively underwent MR enterography, including DWI and enteric and portal phase scans, and ileocolonoscopy with segmental CD endoscopic index of severity (CDEIS) scoring within a week. Thirty-nine terminal ilea and 40 right-sided colons (mean [± SD] segmental CDEIS score, 14.3 ± 12.1) from 42 patients with CD (mean age, 27 ± 6.2 years) were finally analyzed by three independent readers. Original and modified (ulcer replaced with DWI grade) MaRIA scores were compared regarding their correlation with segmental CDEIS score, accuracy in diagnosing active (segmental CDEIS score ≥ 3) and severe (segmental CDEIS score ≥ 12) inflammation, and interobserver reproducibility. The primary analysis used portal phase data, and the agreement between portal and enteric phase scores was analyzed. RESULTS: MaRIA and modified MaRIA scores correlated similarly with CDEIS scores (r = 0.737 and 0.742; p = 0.387) and did not significantly differ in terms of AUC values for the diagnosis of active (0.909 and 0.903; p = 0.571) or severe (0.907 and 0.892; p = 0.443) inflammation. The intraclass correlation coefficient was significantly higher for modified MaRIA than for MaRIA (0.845 and 0.701; p < 0.001). The mean difference between portal and enteric phase scores (i.e., portal minus enteric) was 0.33-0.36 score points for individual readers, and the Bland-Altman repeatability coefficient was 0.9-1.42 score points. CONCLUSION: Interobserver reproducibility in evaluating the severity of bowel inflammation in CD using the MaRIA score can be improved by modification with DWI. MaRIA scoring provides steady results across enteric and portal phases.

Diffusion-weighted MRI in Crohn's disease: Current status and recommendations.

Over the past years, technological improvements and refinements in magnetic resonance imaging (MRI) hardware have made high-quality diffusion-weighted imaging (DWI) routinely possible for the bowel. DWI is promising for the detection and characterization of lesions in Crohn's disease (CD) and has been advocated as an alternative to intravenous gadolinium-based contrast agents. Furthermore, quantification using the apparent diffusion coefficient may have value as a biomarker of CD activity and has shown promise. In this article we critically review the literature pertaining to the value of DWI in CD for detection, characterization, and quantification of disease activity and complications. Although the body of supportive evidence is growing, it is clear that well-designed, multicenter studies are required before the role of DWI in clinical practice can be fully established. J. Magn. Reson. Imaging 2016;44:1381-1396.

Magnetic resonance enterography/enteroclysis in acquired small bowel diverticulitis and small bowel diverticulosis.

PURPOSE: Small bowel (SB) diverticulosis is a rare disorder that may entail serious complications, including SB diverticulitis. Both are often missed in imaging. Magnetic resonance enterography/enteroclysis (MRE) is increasingly used to assess SB disease; awareness of the appearance of SB diverticulitis is essential to ensure appropriate management. Our aim was to systematically describe imaging characteristics of SB diverticulosis and diverticulitis in MRE. METHODS: This retrospective, HIPAA-compliant study identified 186 patients with suspected SB diverticulosis/diverticulitis in medical databases of two tertiary medical centres between 2005 and 2011. Patients with surgically confirmed diagnoses of SB diverticulosis/diverticulitis were included. Two observers analyzed MR images for the presence, location, number, and size of diverticula, wall thickness, and mural and extramural patterns of inflammation. RESULTS: Seven patients were recruited. MRI analysis showed multiple diverticula in all (100 %). Diverticular size ranged from 0.5 to 6 cm. Prevalence of diverticula was higher in the proximal than the distal SB (jejunum 86 %, ileum 57 %, distal ileum43%). Diverticulitis occurred in 3/7 patients (43 %) showing asymmetric bowel wall thickening and focal mesenteric inflammation. CONCLUSION: SB diverticulitis demonstrates characteristic MRE imaging features to distinguish this rare disorder from more common diseases. Asymmetric, focal mesenteric and mural inflammation and presence of multiple diverticula are keys to diagnosis. KEY POINTS: • Small bowel diverticulosis and diverticulitis is rare and often missed in imaging • Acquired small bowel diverticula are variable in size and number • Small bowel diverticulitis demonstrates characteristic features on MR enterography/enteroclysis • A focal or segmental asymmetric small bowel inflammation should prompt the search for diverticula.

DWI at MR Enterography for Evaluating Bowel Inflammation in Crohn Disease.

OBJECTIVE: The purpose of this article is to provide a comprehensive review regarding DWI enterography used for evaluating Crohn disease and to summarize the relevant evidence. CONCLUSION: Active bowel inflammation in Crohn disease causes restricted diffusion on MR enterography with DWI. Enterographic DWI to evaluate Crohn disease is increasingly drawing attention for both academic research and clinical practice and has shown potential as a quantitative tool for assessing bowel inflammation. DWI enterography also has multiple unresolved issues and limitations.

MR Enterographic Findings as Biomarkers of Mucosal Healing in Young Patients With Crohn Disease.

OBJECTIVE: The purpose of this study was to investigate the MR enterographic findings that best correlate with mucosal healing assessed with ileocolonoscopy. MATERIALS AND METHODS: Patients with Crohn disease who underwent two ileocolonoscopic examinations and also underwent MR enterography close in time to the second endoscopic examination were included in a retrospective study. Two pediatric gastroenterologists blinded to the imaging findings reviewed the endoscopic examinations to assess for mucosal healing, defined as resolution of inflammation within a bowel segment at subsequent ileocolonoscopy. Two radiologists blinded to endoscopic and clinical data interpreted the MR enterographic images. Sensitivity, specificity, and accuracy for mucosal healing were calculated for several imaging features. RESULTS: A total of 30 patients (15 female patients, 15 male patients; age range, 8-24 years; mean, 17.2 ± 3.2 years) with pediatric-onset Crohn disease were examined. The average time between MR enterography and the second ileocolonoscopic examination was 12.7 ± 7.9 days. A total of 202 bowel segments from the terminal ileum to rectum were evaluated in the 60 ileocolonoscopic examinations. Forty-four bowel segments exhibited mucosal healing, and 37 segments exhibited persistent inflammation. At imaging, the MR index of activity score in mucosal healing segments was 6.6 ± 3.4, compared with 13.7 ± 9.7 in segments without mucosal healing (p = 0.0001). The average bowel wall thickness in healing segments was 2.7 ± 0.9 mm compared with 4.7 ± 3.1 mm in persistently inflamed segments (p = 0.0004). An MR index of activity score less than 8 had the highest accuracy for mucosal healing (accuracy, 74%; sensitivity, 84%; specificity, 62%; p < 0.0001). Mucosal hyperenhancement (72%, 98%, 41%), mesenteric hypervascularity (72%, 98%, 41%), bowel wall edema (72%, 93%, 46%), and bowel wall thickness less than 4 mm (72%, 84%, 57%) were also strongly associated with mucosal healing (p < 0.0003). CONCLUSION: In this study MR enterography was accurate for assessing mucosal healing, an important therapeutic endpoint in pediatric patients with Crohn disease.