MR Enterography for the Evaluation of Small-Bowel Inflammation in Crohn Disease by Using Diffusion-weighted Imaging without Intravenous Contrast Material: A Prospective Noninferiority Study

MRI radiomics enhances radiologists' ability for characterizing intestinal fibrosis in patients with Crohn's disease

OBJECTIVES

We aimed to develop MRI-based radiomic models (RMs) to improve the diagnostic accuracy of radiologists in characterizing intestinal fibrosis in patients with Crohn's disease (CD).

METHODS

This retrospective study included patients with refractory CD who underwent MR before surgery from November 2013 to September 2021. Resected bowel segments were histologically classified as none-mild or moderate-severe fibrosis. RMs based on different MR sequence combinations (RM1: T2WI and enhanced-T1WI; RM2: T2WI, enhanced-T1WI, diffusion-weighted imaging [DWI], and apparent diffusion coefficient [ADC]); RM3: T2WI, enhanced-T1WI, DWI, ADC, and magnetization transfer MRI [MTI]), were developed and validated in an independent test cohort. The RMs' diagnostic performance was compared to that of visual interpretation using identical sequences and a clinical model.

RESULTS

The final population included 123 patients (81 men, 42 women; mean age: 30.26 ± 7.98 years; training cohort, n = 93; test cohort, n = 30). The area under the receiver operating characteristic curve (AUC) of RM1, RM2, and RM3 was 0.86 (p = 0.001), 0.88 (p = 0.001), and 0.93 (p = 0.02), respectively. The decision curve analysis confirmed a progressive improvement in the diagnostic performance of three RMs with the addition of more specific sequences. All RMs performance surpassed the visual interpretation based on the same MR sequences (visual model 1, AUC = 0.65, p = 0.56; visual model 2, AUC = 0.63, p = 0.04; visual model 3, AUC = 0.77, p = 0.002), as well as the clinical model composed of C-reactive protein and erythrocyte sedimentation rate (AUC = 0.60, p = 0.13).

CONCLUSIONS

The RMs, utilizing various combinations of conventional, DWI and MTI sequences, significantly enhance radiologists' ability to accurately characterize intestinal fibrosis in patients with CD.

CRITICAL RELEVANCE STATEMENT

The utilization of MRI-based RMs significantly enhances the diagnostic accuracy of radiologists in characterizing intestinal fibrosis.

KEY POINTS

MRI-based RMs can characterize CD intestinal fibrosis using conventional, diffusion, and MTI sequences. The RMs achieved AUCs of 0.86-0.93 for assessing fibrosis grade. MRI-radiomics outperformed visual interpretation for grading CD intestinal fibrosis.

Comparative Assessment of Crohn's Disease Activity Using Magnetic Resonance Enterography and Endoscopy

Introduction Magnetic resonance enterography (MRE) has emerged as a promising technique for evaluating the extent and severity of Crohn's disease activity. To compare how we measure Crohn's disease activity with MRE and endoscopy. Material and methods We retrospectively reviewed MRE studies of 60 patients with suspicious Crohn's disease who underwent 1.5-T MRI examinations (T1-weighted images pre- and post-IV contrast medium administration and T2-weighted images) and endoscopy within one month, and they were evaluated by one radiology consultant with experience of 17 years. Endoscopy was used as the reference standard for diagnosing active Crohn's disease cases. Data analysis was performed using the websites (www.graphpad.com and www.medcalc.org) and Microsoft Excel (Microsoft® Corp., Redmond, USA). Results A total of 35 patients were included in the study. The remaining 25 patients were excluded either due to non-available data in the endoscopy report or cases of non-Crohn's disease. The MRI examinations were reviewed by one radiology consultant and revealed 27 active and eight non-active Crohn's disease cases compared to 30 active and five non-active Crohn's disease cases in endoscopy. The sensitivity of MRI in detecting active cases of Crohn's disease compared to endoscopy was 83.3% and the specificity of 60%. The strength of agreement between both methods was fair to good (Kappa = 0.347, p-value = 0.4497, Chi-squared = 0.571 with one degree of freedom). Conclusion MRE statistically has a good impact on the assessment of Crohn's disease as well as endoscopy with the parameters used in this study. Non-invasiveness and the changes of activity seen in the bowel proximal to the ileocecal junction undetectable by endoscopy make MRE more practically applicable in this aspect.

Influence of diffusion weighted imaging and contrast enhanced T1 sequences on the diagnostic accuracy of magnetic resonance enterography for Crohn's disease

OBJECTIVES

To evaluate the additional diagnostic benefit of diffusion weighted imaging (DWI) and contrast enhanced (CE) images during MR enterography (MRE) of Crohn's disease.

METHODS

Datasets from 73 patients (mean age 32; 40 male) (28 new-diagnosis, 45 relapsed) were read independently by two radiologists selected from a pool of 13. Radiologists interpreted datasets using three sequential sequence blocks: (1) T2 weighted and steady state free precession gradient echo (SSFP) images alone (T2^); (2) T2 weighted and SSFP images with DWI (T2 + DWI^) and; (3) T2 weighted images, SSFP, DWI and post-contrast enhanced (CE) T1 images (T2 + DWI + CE^), documenting presence, location, and activity of small bowel disease. For each sequence block, sensitivity and specificity (readers combined) was calculated against an outcome-based construct reference standard.

RESULTS

59/73 patients had small bowel disease. Per-patient sensitivity for disease detection was essentially identical (80 % [95 % CI 72, 86], 81 % [73,87], and 79 % [71,86] for T2^, T2 + DWI^and T2 + DWI + CE^respectively). Specificity was identical (82 % [64 to 92]). Per patient sensitivity for disease extent was 56 % (47,65), 56 % (47,65) and 52 % (43 to 61) respectively, and specificity was 82 % (64 to 92) for all blocks. Sensitivity for active disease was 97 % (90,99), 97 % (90,99) and 98 % (92,99), and specificity was also comparable between all sequence combination reads. Results were consistent across segments and newly diagnosed/relapse patients.

CONCLUSION

There is no additional diagnostic benefit of adding either DWI or CE to T2 FSE and SSFP sequences for evaluating small bowel Crohn's disease, suggesting MRE protocols can be simplified safely.

Technical Feasibility of Quantitative Measurement of Various Degrees of Small Bowel Motility Using Cine Magnetic Resonance Imaging

OBJECTIVE

Cine magnetic resonance imaging (MRI) has emerged as a noninvasive method to quantitatively assess bowel motility. However, its accuracy in measuring various degrees of small bowel motility has not been extensively evaluated. We aimed to draw a quantitative small bowel motility score from cine MRI and evaluate its performance in a population with varying degrees of small bowel motility.

MATERIALS AND METHODS

A total of 174 participants (28.5 ± 7.6 years; 135 males) underwent a 22-second-long cine MRI sequence (2-dimensional balanced turbo-field echo; 0.5 seconds per image) approximately 5 minutes after being intravenously administered 10 mg of scopolamine-N-butyl bromide to deliberately create diverse degrees of small bowel motility. In a manually segmented area of the small bowel, motility was automatically quantified using a nonrigid registration and calculated as a quantitative motility score. The mean value (MV) of motility grades visually assessed by two radiologists was used as a reference standard. The quantitative motility score's correlation (Spearman's ρ) with the reference standard and performance (area under the receiver operating characteristics curve [AUROC], sensitivity, and specificity) for diagnosing adynamic small bowel (MV of 1) were evaluated.

RESULTS

For the MV of the quantitative motility scores at grades 1, 1.5, 2, 2.5, and 3, the mean ± standard deviation values were 0.019 ± 0.003, 0.027 ± 0.010, 0.033 ± 0.008, 0.032 ± 0.009, and 0.043 ± 0.013, respectively. There was a significant positive correlation between the quantitative motility score and the MV (ρ = 0.531, P < 0.001). The AUROC value for diagnosing a MV of 1 (i.e., adynamic small bowel) was 0.953 (95% confidence interval, 0.923-0.984). Moreover, the optimal cutoff for the quantitative motility score was 0.024, with a sensitivity of 100% (15/15) and specificity of 89.9% (143/159).

CONCLUSION

The quantitative motility score calculated from a cine MRI enables diagnosis of an adynamic small bowel, and potentially discerns various degrees of bowel motility.

Diffusion-weighted imaging in Crohn's disease

BACKGROUND

Diffusion-weighted MRI (DWI) is routinely used in abdominal imaging. In addition to neoplastic diseases, inflammatory changes can be delineated and diagnosed based on diffusion restriction in DWI. DWI is also increasingly used in the context of MRI of the small and large intestine.

OBJECTIVE

This article focuses on the technical aspects of DWI and its role in the diagnosis of Crohn's disease (CD) as well as in the grading of disease severity and in treatment monitoring.

MATERIALS AND METHODS

Guidelines, basic research papers, and review articles were analyzed.

RESULTS

Diffusion-weighted MRI is a specialized MRI technique that visualizes the diffusion of water molecules in biological tissues. In the context of MRI of the small and large intestine, DWI facilitates the diagnosis of inflammatory bowel disease and assessment of treatment response. DWI enables detection of not only intra- and transmural changes, but also extramural pathologies and complications. However, DWI also has its limitations and challenges.

CONCLUSION

This article provides a comprehensive overview of the use of DWI for diagnostic evaluation of bowel wall changes and extramural complications in the setting of CD. It also summarizes the relevant evidence available in the literature.

Intestinal MRI in Inflammatory Bowel Disease - Literature and Survey-Based Recommendations regarding Reporting by the German Radiological Society (DRG) and the German Competence Network for Inflammatory Bowel Diseases

BACKGROUND

MR-enterography/enteroclysis (MRE) is increasingly used for primary diagnosis, detection of complications, and monitoring of patients with inflammatory bowel disease (IBD). Standardization of reporting is relevant to ensure quality of the methodology and to improve communication between different faculties. The current manuscript describes the features that are required for optimized reporting of MRE in IBD.

METHODS

An expert consensus panel of radiologists and gastroenterologists conducted a systematic search of the literature. In a Delphi process, members of the German Radiological Society (DRG) and members of the Competence Network for Inflammatory Bowel Diseases voted on relevant criteria for the reporting of findings in MRE. Based on the voting results, statements were developed by the expert consensus panel.

RESULTS

Clinically relevant aspects of MRE findings have been defined to optimize reporting and to standardize terminology. Minimal requirements for standardized reporting are suggested. The statements focus on the description of disease activity as well as on complications of IBD. Attributes of intestinal inflammation are described and illustrated by exemplary images.

CONCLUSION

The current manuscript provides standardized parameters and gives practical recommendations on how to report and how to characterize MRE findings in patients with IBD.

KEY POINTS

· Systematic overview provides practice-oriented recommendations and names and evaluates the decisive criteria for reporting and interpretation of MRI in inflammatory bowel disease.. · Standardized terminology and reporting criteria for MRI in IBD improves interdisciplinary communication.. · Standardized collection and documentation of MRI findings in IBD helps to further establish the method and to improve care for IBD patients..

CITATION FORMAT

· Wessling J, Kucharzik T, Bettenworth D et al. Intestinal MRI in Inflammatory Bowel Disease - Literature and Survey-Based Recommendations regarding Reporting by the German Radiological Society (DRG) and the German Competence Network for Inflammatory Bowel Diseases. Fortschr Röntgenstr 2023; 195: 675 - 690.

Small bowel imaging in inflammatory bowel disease: updates for 2023

INTRODUCTION

Cross-sectional imaging techniques including MR and CT enterography and ultrasound are integral to Crohn's disease management, accurate, responsive, and well tolerated. They assess the full thickness of the bowel wall, perienteric environment, and distant complications. As we strive toward tighter disease control, imaging's role will expand further with transmural healing becoming an increasingly important therapeutic target.

AREAS COVERED

MEDLINE and Web of Science were searched from 2012 to 2023 inclusive. We review the evidence for cross-sectional imaging in assessing disease activity, phenotyping, and therapeutic response assessment. Emerging novel imaging applications such as quantifying enteric motility and fibrosis, prognostication, and potential utility of artificial intelligence will be covered. Recent international consensus statements highlight the need for standardized imaging reporting and definitions of transmural healing and remission. We will discuss how recent advances may be best integrated into patient care and highlight key outstanding research questions.

EXPERT OPINION

Cross-sectional imaging is established in Crohn's disease management. Research emphasis should be placed on optimal integration of imaging modalities in clinical care pathways, workforce training, definitions, and evidence for use of imaging based therapeutic targets such as transmural healing, better phenotyping of stricturing disease, and developing novel techniques, including integration of artificial intelligence.

Role of abbreviated non-contrast-enhanced MR-enterography in the evaluation of Crohn's disease activity and complications as an alternative for full protocol contrast-enhanced study: A systematic review and meta-analysis

Background

Crohn's disease (CD) is a chronic disorder that often starts at a young age and involves periods of remission and relapse. Prompt diagnosis of relapses through screening is crucial due to the potential morbid complications of untreated active inflammation. Magnetic resonance enterography (MRE) is a noninvasive technique to screen for active inflammation. The standard protocol involves intravenous injection of contrast agents with potential side effects. Some abbreviated non-contrast-enhanced MRE protocols are proposed as alternatives for conventional MRE to identify active inflammation. Currently, there is controversy regarding the applicability and accuracy of these protocols. This study aims to describe and compare these protocols and evaluate their accuracy in detecting active inflammation and CD complications.

Methods

Results from a systematic search of three databases in August 2022 were queried and screened by abstract and full text. Eligible studies were qualitatively and quantitatively analyzed by diagnostic test accuracy meta-analysis.

Results

59 studies entered the systematic review, and 37 were eligible for meta-analysis. Diffusion-weighted imaging (DWI) and fast T2-weighted (T2w) sequences were most frequently used in abbreviated protocols and showed non-inferior accuracy compared to the full protocol in detecting active inflammation. ADC and qualitative DWI had pooled sensitivity of 90% (CI: 82-95%) and 89% (CI:82-93%) and pooled specificity of 94% (CI: 88-97%) and 89% (CI: 79-94%), respectively for detecting active inflammation. Moreover, T2w and combined T2w+DWI sequences had pooled sensitivity of 80% (CI: 64-90%) and 76% (CI: 61-86%) and pooled specificity of 90% (CI: 80-95%) and 87% (CI: 74 - 94%), respectively. Unenhanced protocols show relatively poor diagnostic accuracy in detecting penetrating complications of CD. Magnetization transfer imaging (MTI) has demonstrated excellent accuracy in detecting fibrosis. High heterogeneity was observed in all subgroups, and accuracy was reported to be highly operator dependent in most studies.

Conclusion

An abbreviated protocol consisting of DWI and fast T2w imaging can potentially replace the full protocol MRE. Full protocol MRE will still have its role in identifying penetrating complications. MTI should be indicated in case of suspected fibrostenotic disease.

Validation of the simplified magnetic resonance index of activity by using DWI without gadolinium enhancement to evaluate bowel inflammation in Crohn's disease

OBJECTIVES

To validate the modified simplified magnetic resonance index of activity (sMARIA) score using DWI on non-contrast magnetic resonance enterography (MRE) to evaluate active inflammation in patients with Crohn's disease (CD), compared to the original sMARIA scoring system, with and without contrast enhancement.

METHODS

This retrospective study included 275 bowel segments from 55 CD patients who underwent ileocolonoscopy and MRE within a 2-week period. Two blinded radiologists evaluated original sMARIA on both conventional MRE (CE-sMARIA) and non-contrast MRE (T2-sMARIA). Modified sMARIA was then evaluated using non-contrast MRE, replacing ulcerations with DWI grades. Three scoring systems were compared for diagnostic accuracy of active inflammation, correlation with simple endoscopic score (SES)-CD, and interobserver reproducibility.

RESULTS

The AUC of modified sMARIA for detecting active inflammation (0.863, 95% confidence interval [0.803-0.923]) was significantly higher than T2-sMARIA (0.827 [0.773-0.881], p = 0.017), and comparable to CE-sMARIA (0.908 [0.857-0.959], p = 0.122). CE-sMARIA, T2-sMARIA, and modified sMARIA all showed moderate correlation with SES-CD (r = 0.795, 0.722, and 0.777, respectively). Interobserver reproducibility of diffusion restriction (κ, 0.686 [0.602-0.770]) was significantly better than ulcers on conventional MRE (κ, 0.382 [0.212-0.552]; p = 0.001) and T2-weighted image (κ, 0.312 [0.034-0.590]; p = 0.012).

CONCLUSIONS

Modified sMARIA using DWI can improve the diagnostic performance of sMARIA on non-contrast MRE, showing comparable performance to sMARIA using contrast-enhanced MRE.

KEY POINTS

• DWI can improve the diagnostic performance of non-contrast magnetic resonance enterography (MRE) for assessing active inflammation in patients with Crohn's disease. • Modified simplified magnetic resonance index of activity (sMARIA) using DWI grades in place of ulcers showed comparable diagnostic performance to sMARIA using conventional MRE with contrast-enhanced sequences.

A Novel Chronic Enteropathy Associated with SLCO2A1 Gene Mutation: Enterography Findings in a Multicenter Korean Registry

OBJECTIVE

Chronic enteropathy associated with SLCO2A1 gene (CEAS) is a recently recognized disease. We aimed to evaluate the enterographic findings of CEAS.

MATERIALS AND METHODS

Altogether, 14 patients with CEAS were confirmed based on known SLCO2A1 mutations. They were registered in a multicenter Korean registry between July 2018 and July 2021. Nine of the patients (37.2 ± 13 years; all female) who underwent surgery-naïve-state computed tomography enterography (CTE) or magnetic resonance enterography (MRE) were identified. Two experienced radiologists reviewed 25 and 2 sets of CTE and MRE examinations, respectively, regarding the small bowel findings.

RESULTS

In initial evaluation, eight patients showed a total of 37 areas with mural abnormalities in the ileum on CTE, including 1-4 segments in six and > 10 segments in two patients. One patient showed unremarkable CTE. The involved segments were 10-85 mm (median, 20 mm) in length, 3-14 mm (median, 7 mm) in mural thickness, circumferential in 86.5% (32/37), and showed stratified enhancement in the enteric and portal phases in 91.9% (34/37) and 81.8% (9/11), respectively. Perienteric infiltration and prominent vasa recta were noted in 2.7% (1/37) and 13.5% (5/37), respectively. Bowel strictures were identified in six patients (66.7%), with a maximum upstream diameter of 31-48 mm. Two patients underwent surgery for strictures immediately after the initial enterography. Follow-up CTE and MRE in the remaining patients showed minimal-to-mild changes in the extent and thickness of the mural involvement for 17-138 months (median, 47.5 months) after initial enterography. Two patients required surgery for bowel stricture at 19 and 38 months of follow-up, respectively.

CONCLUSION

CEAS of the small bowel typically manifested on enterography in varying numbers and lengths of abnormal ileal segments that showed circumferential mural thickening with layered enhancement without perienteric abnormalities. The lesions caused bowel strictures that required surgery in some patients.

Investigation of the Value of T 2 Mapping in the Prediction of Eosinophilic Chronic Rhinosinusitis With Nasal Polyps

OBJECTIVES

Patients with eosinophilic chronic rhinosinusitis with nasal polyps (eosCRSwNP) usually have more extensive sinus disease, severe symptoms, and poorer disease control compared with patients with non-eosCRSwNP. Separating these entities will be crucial for patient management. The purpose of this study is to investigate T 1, T 2 , and apparent diffusion coefficient (ADC) values of the nasal polyps in patients with CRSwNP and evaluate the usefulness of these parameters for differentiating these diseases.

METHODS

Sinonasal magnetic resonance imaging was performed in 36 patients with eosCRSwNP and 20 patients with non-eosCRSwNP (including T 1 mapping, T 2 mapping, and diffusion-weighted imaging) before surgery. The T 1 , T 2 , and ADC values were calculated and correlated with pathologically assessed inflammatory cells of nasal polyps.

RESULTS

Significant higher T 2 value, higher eosinophil count, and lower lymphocyte count of the nasal polyps were observed in eosCRSwNP than those in non-eosCRSwNP. There was no significant difference in T 1 or ADC values between the 2 groups. T 2 value was correlated with eosinophil count and lymphocyte count in CRSwNP. The area under the curve of T 2 value for predicting eosCRSwNP was 0.78 with 89.9% sensitivity and 60.0% specificity.

CONCLUSION

T 2 value is a promising imaging biomarker for predicting eosCRSwNP. It can help to distinguish eosCRSwNP from non-eosCRSwNP.

Apparent diffusion coefficient for assessing Crohn's disease activity: a meta-analysis

PURPOSE

To analyze relationships betweenapparent diffusion coefficient (ADC) and activity parameters of Crohn's disease, e.g., length and wall thickness, CRP, FCP, MaRIA, CDAI, SES-CD, histologic inflammatory activity score, and the histological fibrotic score, based upon published data.

MATERIALS AND METHODS

MEDLINE library, Scopus, and Embase databases were screened for association between ADC and activity parameters of Crohn's disease in patients with Crohn's disease up to Mai 2021. Overall, 21 studies with 1053 patients were identified. The following data were extracted from the literature: number of patients, correlation coefficients between ADC and length as well as wall thickness, CRP, FCP, MaRIA, CDAI, and SES-CD, inflammatory activity score, and fibrotic score. Associations between ADC and activity parameters were analyzed by Spearman's correlation coefficient. The studies' methodologic quality was evaluated by using the Quality Assessment of Diagnostic Studies (QUADAS 2) instrument, revealing a low risk of bias.

RESULTS

In the overall sample, the pooled correlation coefficient between ADC and CDAI was -0.8 (95% CI = [-0.94; -0.65]), between ADC and MaRIA -0.66 (95% CI = [-0.79; -0.53]). A strong association was observed between ADC and SES-CD with a pooled correlation of -0.66 (95% CI = [-0.87; -0.46]). The pooled sensitivity to discriminate between involved and non-involved bowel segments was 0.89, with an area under the curve of 0.89 CONCLUSIONS: ADC showed strong inverse correlations with CDAI, MaRIA, and SES-CD scores. However, the role of ADC in assessing fibrotic changes in the bowel wall is limited. ADC can reflect acute inflammatory reactions but not systemic inflammation.

KEY POINTS

• ADC value can reflect acute inflammatory reactions but not systemic inflammation. • ADC is inversely correlated with CDAI, MaRIA, and SES-CD. • The role of ADC in assessing fibrotic changes in the bowel wall is limited.

DWI ratios: New indexes for Crohn's disease activity at magnetic resonance enterography?

BACKGROUND

The aim of the study was to provide radiologists and clinicians a rapid tool for assessment of intestinal inflammation in Crohn's disease (CD) patients through quantification of diffusion-weighted imaging (DWI) signal intensity while performing magnetic resonance enterography (MRE).

MATERIALS AND METHODS

A monocentric retrospective study was conducted between September 2018 and July 2021 on CD patients who underwent MRE. Two radiologists measured signal intensity on DWI scans at the highest b-value (800 s/mm²) within pathologic intestinal walls, lymph nodes, spleen and psoas muscle and calculated the relative ratios. Spearman, Mann-Whitney and Jonckheere-Terpstra tests were applied for estimating correlation among ratios, significant differences between the two patient groups and determining the trend in relation to endoscopic classes. Wilcoxon's and Cronbach's alpha tests were employed for comparison of DWI measurements and ratios between the two observers.

RESULTS

Fifty-nine patients were enrolled in the study. In the non-surgical group, correlation has been found among Simple Endoscopic Score for Crohn's Disease (SES-CD) classes and the different ratios: bowel/spleen (p = 0.034), bowel/psoas (p = 0.008) and bowel/lymph node (p = 0.010). Within the surgical group, positive correlation was found only between bowel/lymph node ratio and bowel/psoas ratio (p = 0.014). The J-T test demonstrated an increasing monotonic trend for bowel/psoas ratio and bowel/lymph node ratio and SES-CD classes. Inter-reader evaluation demonstrated no statistical differences for DWI measurements and high degree of concordance for the final ratios.

CONCLUSION

DWI ratios correlate with endoscopic classes in non-surgical patients and have inter-observer reproducibility.

Clinical implication of radiologic complete remission on Crohn's Disease: Compared with endoscopic remission

OBJECTIVES

To determine the clinical implications of radiologic complete remission (CR) in Crohn's disease (CD) evaluated by computed tomography (CT) or magnetic resonance enterography (MRE) in comparison with endoscopic CR.

METHODS

Twenty-five CD patients who achieved endoscopic CR after medical treatment were retrospectively enrolled in this study. All patients underwent ileocolonoscopy, CT, or MRE at baseline, at the time of endoscopic CR, and during follow-up. Two radiologists assessed the mural and perienteric abnormalities on pre- and post-treatment CT or MRE in consensus. Patients were divided into radiologic CR and non-CR groups at the time of endoscopic CR. CD recurrence during subsequent follow-up periods was evaluated using clinical, laboratory, and CT/MRI findings. Statistical analysis was performed to assess whether there were significant differences in patient outcomes between the groups.

RESULTS

At the time of endoscopic CR, nine patients (mean age, 36.6 years) showed normalization of all radiologic features and were designated as the radiologic CR group. However, 16 patients (mean age: 32.9 years) showed residual CT/MRE abnormalities, suggesting persistent active inflammation, and were designated as the radiologic non-CR group. During follow-up, there was a significant difference between the groups regarding clinical outcomes (deep CR, 8/9 vs 5/16, P = 0.011; CD recurrence, 1/9 vs 14/16, P < 0.001). The mean fecal calprotectin level was significantly lower in the radiologic CR group (287.5 ug/g) than in the non-CR group (652.4 ug/g) (P = 0.023).

CONCLUSIONS

Radiologic CR can represent a better therapeutic endpoint in CD, showing superiority over endoscopic CR in predicting both clinical and biochemical outcomes.

MR Enterography in Crohn's Disease: Comparison of Contrast Imaging with Diffusion-weighted Imaging and a special Form of Color Coding

Purpose

We compared contrast-enhanced MR enterography with diffusion-weighted sequences to evaluate the validity of diffusion-weighted sequences for activity assessment in Crohnʼs disease compared to endoscopy. In addition, we investigated a new color-coded image post-processing technique in comparison with standard sequences and endoscopy.

Materials and Methods

Included were 197 MR enterographies (2015–2017) performed by using standardized examination protocols. The intestine was divided into 7 segments, which were compared separately. The accuracy of the MR examinations with regard to disease activity was validated using the Seo and MaRIA score and endoscopy findings. In addition, the image data were post-processed using a color-coded evaluation method (DCE tool on OsiriX).

Results

The comparison between contrast-enhanced and diffusion-weighted sequences showed a highly significant correlation for all bowel sections with a mean Spearman correlation coefficient of 0.876 (0.809–0.928). The color-coded image post-processing showed a sensitivity of 83.2 % and a specificity of 70.5 % in comparison with the MaRIA score. In comparison to endoscopy, a sensitivity of 81.3 % and a specificity of 70.5 %. In comparison with endoscopy, the MaRIA score showed a sensitivity of 80.2 % and a specificity of 84.0 % at a cut-off of 7. The visual score according to Seo showed a sensitivity of 85.7 % with a specificity of 77.0 % in the contrast-weighted examination and a sensitivity of 87.9 % and a specificity of 71.8 % for diffusion weighted images.

Conclusion

Diffusion-weighted sequences are as good as contrast-weighted sequences for assessing inflammatory activity in Crohnʼs disease. Contrast is often helpful for assessing complications, but this was not the purpose of this study. Visual imaging using color-coded data sets was similarly good at detecting inflammation.

Key points:

Citation Format

The Role of Magnetic Resonance Enterography in Crohn’s Disease: A Review of Recent Literature

Inflammatory bowel disease (IBD) is the term used to identify a form of chronic inflammation of the gastrointestinal tract that primarily contemplates two major entities: ulcerative colitis (UC) and Crohn’s disease (CD). The classic signs are abdominal pain and diarrhoea that correlate with the localization of gastro-enteric disease, although in this pathology extraintestinal symptoms may coexist. The diagnosis of CD relies on a synergistic combination of clinical, laboratory (stool and biochemical), cross-sectional imaging evaluation, as well as endoscopic and histologic assessments. The purpose of this paper is to prove the role of imaging in the diagnosis and follow-up of patients with CD with particular focus on recent innovations of magnetic resonance enterography (MRE) as a pivotal diagnostic tool, analysing the MRE study protocol and imaging features during the various phases of disease activity and its complications.

Capsule Endoscopy versus Magnetic Resonance Enterography for Evaluation of Pediatric Small Bowel Crohn’s Disease: Prospective Study

Background: Magnetic resonance enterography (MRE) and capsule endoscopy (CE) are currently used for the evaluation of small bowel involvement in pediatric Crohn’s disease (CD). Several studies have been conducted to investigate the usefulness and diagnostic accuracy of each test. However, only a few studies have been conducted to compare the performance of both tests in the assessment of pediatric small bowel CD upon diagnosis and during follow-up. Therefore, the purpose of this study was to assess the diagnostic accuracy and diagnostic consistency of CE and MRE for the evaluation of pediatric small bowel CD at the time of diagnosis and during follow-up. Methods: Fifteen patients with pediatric CD were recruited for this study. They underwent MRE and CE concomitantly at the time of diagnosis and 10–12 weeks and one year after induction therapy for CD. MRE was interpreted using MRE global score (MEGS) and bowel wall inflammation severity diffusion-weighted imaging score (BWI-DWIS), whereas CE was interpreted using Lewis’s score (LS). The two diagnostic modalities were then compared. Results: Eleven patients completed MRE and CE at the time of diagnosis. Analysis of the results showed that LS had a strong correlation with MEGS and BIS-DWIS (ρ = 0.633, p = 0.037, and ρ = 0.629, p = 0.038, respectively). Nine patients completed three MREs and three CEs. LS significantly decreased throughout the sessions (p = 0.044), whereas MEGS and BIS-DWIS did not show any statistically significant changes. When LS was compared with MEGS and BIS-DWIS, both MRE indicators showed statistically significant differences throughout the sessions. Conclusions: At the time of diagnosis, the severity indexes of MRE and CE showed very good agreement. However, throughout management, MRE and CE did not show consistent changes.

Diagnostic Performance of Diffusion-weighted Imaging for Evaluation of Bowel Inflammation in Paediatric Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

The diagnostic performance of diffusion-weighted imaging magnetic resonance enterography [DWI-MRE] has not been clearly established in a paediatric population. We systematically evaluated the diagnostic performance of DWI-MRE for the detection of bowel inflammation in paediatric patients with suspected or known inflammatory bowel disease [IBD].

METHODS

MEDLINE/PubMed, EMBASE, Web of science and the Cochrane library were searched for articles investigating the diagnostic performance of DWI-MRE for the detection of bowel inflammation in paediatric patients with suspected or known IBD up to December 31, 2020. Pooled sensitivity and specificity were calculated using a bivariate random-effects model. Pooled inter-reader agreement for the interpretation of DWI-MRE was also calculated. This study was registered as PROSPERO CRD42021228754.

RESULTS

Nine studies covering 400 paediatric patients were included. The pooled sensitivity and specificity of DWI-MRE for the detection of bowel inflammation were 0.93 (95% confidence interval [CI], 0.88-0.96) and 0.96 [95% CI, 0.87-0.99], respectively. Substantial heterogeneity was noted in both sensitivity [I2 = 66%; p < 0.01] and specificity [I2 = 94%; p < 0.01]. Meta-regression analysis identified that the use of spasmolytics contributed to higher specificity [0.89-0.99] and that quantitative assessment with an apparent diffusion coefficient cut-off value contributed to lower sensitivity [0.93-0.85] and specificity [0.98-0.72]. The pooled coefficient of inter-reader agreement, including four studies using visual assessment, was 0.97 [95% CI, 0.78-1.00].

CONCLUSIONS

DWI-MRE, especially when used with spasmolytics, is accurate for the detection of bowel inflammation in paediatric patients with suspected or known IBD. Quantitative measurement of ADC is not practical for this purpose.

MR-enterography: role in the assessment of suspected anastomotic recurrence of Crohn disease after ileocolic resection

PURPOSE

To determine the potential of magnetic resonance-enterography (MRE) in the assessment of the anastomotic status in patients with Crohn disease and prior ileocolic resection.

METHODS

A total of 62 MRE examinations obtained in 52 patients with Crohn disease who had previously undergone ileocolic resection were retrospectively reviewed by two readers in consensus. MRE features (anastomotic wall thickening, wall stratification, wall enhancement pattern and degree, DWI signal intensity, ADC values, lymph nodes, comb sign and complications) were compared to clinical, endoscopic and histological findings that served as standard of reference. Sensitivity, specificity and accuracy of MRE were calculated.

RESULTS

At univariate analysis, anastomotic wall thickening, anastomotic wall stratification, segmental wall enhancement, moderate wall enhancement, early and mucosal enhancement, and moderate/marked hyperintensity on diffusion-weighed imaging (DWI) were the most discriminative MRE features for differentiating between normal and abnormal anastomoses (p < 0.001 for all variables). Anastomotic wall thickening and segmental anastomotic wall enhancement were the two most sensitive and accurate MRE variables for the diagnosis of abnormal anastomosis with sensitivities of 82% (95% CI: 67-92%) and accuracies of 84% (95% CI: 72-92%). At univariate analysis, hyperintensity on DWI of the anastomotic site was the most sensitive finding for distinguishing between inflammatory recurrence and fibrostenosis (sensitivity, 89%; 95% CI: 67-99%).

CONCLUSIONS

MRE provides objective and relatively specific morphological criteria that help detect abnormal ileocolic anastomosis, but performances are lower when differentiating between inflammatory recurrence and fibrostenosis. DWI may be useful in identifying pathologic anastomosis and, in particular, in distinguishing between inflammatory recurrence and fibrostenosis.

Avoiding contrast-enhanced sequences does not compromise the precision of the simplified MaRIA for the assessment of non-penetrating Crohn's disease activity

OBJECTIVES

Patients with Crohn's disease (CD) require multiple assessments with magnetic resonance enterography (MRE) from a young age. Standard MRE protocols for CD include contrast-enhanced sequences. Gadolinium deposits in brain tissue suggest avoiding gadolinium could benefit patients with CD. This study aimed to compare the accuracy of the simplified Magnetic Resonance Index of Activity (sMaRIA) calculated with and without contrast-enhanced sequences in determining the response to biologic drugs in patients with CD.

METHODS

This post hoc analysis of a prospective study included patients with CD with endoscopic ulceration in ≥ 1 intestinal segment starting biologic drug therapy. Two blinded radiologists used the sMaRIA to score images obtained at baseline and week 46 of treatment first using only unenhanced sequences (T2-sMaRIA) and 1 month later using both unenhanced and enhanced images (CE-sMaRIA). We calculated the rates of agreement between T2-sMaRIA, CE-sMaRIA, and ileocolonoscopy for different conceptualizations of therapeutic response.

RESULTS

A total of 46 patients (median age, 36 years [IQR: 28-47]) were included. Agreement with ileocolonoscopy was similar for CE-sMaRIA and T2-sMaRIA in identifying ulcer healing (kappa = 0.74 [0.55-0.93] and 0.70 [0.5-0.9], respectively), treatment response (kappa = 0.53 [0.28-0.79] and 0.44 [0.17 - 0.71]), and remission (kappa = 0.48 [0.22-0.73] and 0.43 [0.17-0.69]). The standardized effect size was moderate for both CE-sMaRIA = 0.63 [0.41-0.85] p < 0.001 and T2-sMaRIA = 0.58 [0.36-0.80] p < 0.001.

CONCLUSIONS

sMaRIA with and without contrast-enhanced images accurately classified the response according to different therapeutic endpoints determined by ileocolonoscopy.

KEY POINTS

• The simplified Magnetic Resonance Index of Activity is accurate for the assessment of Crohn's disease activity, severity, and therapeutic response, using four dichotomic components that can be evaluated without the need of using contrast-enhanced sequences, representing a practical and safety advantage, but concerns have been expressed as to whether the lack of contrast sequences may compromise precision. • The simplified Magnetic Resonance Index of Activity can assess the response to biologic therapy in patients with Crohn's disease without the need for intravenous contrast agents obtaining comparable results without and with contrast-enhanced sequences. • Avoiding intravenous contrast agents could reduce the duration of the MRE examination and its cost and would increase the acceptance and safety of MRE in clinical research in patients with Crohn's disease.

Cross-Sectional Imaging Instead of Colonoscopy in Inflammatory Bowel Diseases: Lights and Shadows

International guidelines recommend a treat-to-target strategy with a close monitoring of disease activity and therapeutic response in inflammatory bowel diseases (IBD). Colonoscopy (CS) represents the current first-line procedure for evaluating disease activity in IBD. However, as it is expensive, invasive and poorly accepted by patients, CS is not appropriate for frequent and repetitive reassessments of disease activity. Recently, cross-sectional imaging techniques have been increasingly shown as reliable tools for assessing IBD activity. While computed tomography (CT) is hampered by radiation risks, routine implementation of magnetic resonance enterography (MRE) for close monitoring is limited by its costs, low availability and long examination time. Novel magnetic resonance imaging (MRI)-based techniques, such as diffusion-weighted imaging (DWI), can overcome some of these weaknesses and have been shown as valuable options for IBD monitoring. Bowel ultrasound (BUS) is a noninvasive, highly available, cheap, and well accepted procedure that has been demonstrated to be as accurate as CS and MRE for assessing and monitoring disease activity in IBD. Furthermore, as BUS can be quickly performed at the point-of-care, it allows for real-time clinical decision making. This review summarizes the current evidence on the use of cross-sectional imaging techniques as cost-effective, noninvasive and reliable alternatives to CS for monitoring patients with IBD.

Is the Mixed Use of Magnetic Resonance Enterography and Computed Tomography Enterography Adequate for Routine Periodic Follow-Up of Bowel Inflammation in Patients with Crohn's Disease?

OBJECTIVE

Computed tomography enterography (CTE) and magnetic resonance enterography (MRE) are considered substitutes for each other for evaluating Crohn's disease (CD). However, the adequacy of mixing them for routine periodic follow-up for CD has not been established. This study aimed to compare MRE alone with the mixed use of CTE and MRE for the periodic follow-up of small bowel inflammation in patients with CD.

MATERIALS AND METHODS

We retrospectively compared two non-randomized groups, each comprising 96 patients with CD. One group underwent CTE and MRE (MRE followed by CTE or vice versa) for the follow-up of CD (interval, 13-27 months [median, 22 months]), and the other group underwent MRE alone (interval, 15-26 months [median, 21 months]). However, these two groups were similar in clinical characteristics. Three independent readers from three different institutions determined whether inflammation had decreased, remained unchanged, or increased within the entire small bowel and the terminal ileum based on sequential enterography of the patients after appropriate blinding. We compared the two groups for inter-reader agreement and accuracy (terminal ileum only) using endoscopy as the reference standard for enterographic interpretation.

RESULTS

The inter-reader agreement was greater in the MRE alone group for the entire small bowel (intraclass correlation coefficient [ICC]: 0.683 vs. 0.473; p = 0.005) and the terminal ileum (ICC: 0.656 vs. 0.490; p = 0.030). The interpretation accuracy was higher in the MRE alone group without statistical significance (70.9%-74.5% vs. 57.9%-64.9% in individual readers; adjusted odds ratio = 3.21; p = 0.077).

CONCLUSION

The mixed use of CTE and MRE was inferior to MRE alone in terms of inter-reader reliability and could probably be less accurate than MRE alone for routine monitoring of small bowel inflammation in patients with CD. Therefore, the consistent use of MRE is favored for this purpose.

Current noninvasive modalities in Crohn's disease monitoring

Crohn’s disease (CD) is characterized by a remitting and relapsing course. Longstanding active CD may result in accumulating intestinal damage and disease-related complications. In contrast, mucosal healing is associated with significant improvement in the health-related quality of life, longer periods of disease remission and lower risk of disease progression, complications, hospitalizations, intestinal surgeries, as well as a lower risk of developing colorectal cancer. Mucosal healing, the new treatment endpoint in CD, made necessary the development of noninvasive, accurate, objective and reliable tools for the evaluation of CD activity. Ileocolonoscopy with biopsies remains the reference standard method for the evaluation of the colonic and terminal ileal mucosa. However, it is an invasive procedure with a low risk of complications, allowing the investigation of only a small part of the small bowel mucosa without being able to assess transmural inflammation. These disadvantages limit its role in the frequent follow up of CD patients. In this review, we present the currently available biomarkers and imaging modalities for the noninvasive assessment of CD activity.

Magnetic resonance enterography in Crohn's disease patients: current state of the art and future perspectives

INTRODUCTION

Crohn's disease (CD) is a major concern due to relatively high incidence and major complications like stricture or fistulas, often requiring surgical treatment. In recent years, magnetic resonance enterography (MRE) became a popular method of diagnosis and disease surveillance. The purpose of this review is to summarize and discuss the major and most recent advances in various aspects of MRE usage in diagnosong Crohn's disease, and to discuss advances in technique, disease activity monitoring and response to treatment.

METHODS

A literature search was performed and relevant publications were included, with emphasis on articles from the past decade.

AREAS COVERED

In this review we have presented articles with major advances in the field of MRE of CD patients such as proper sequence selection, recent advances in scoring of disease activity, differentiation between inflammation and fibrosis, response to treatment and technological advances such as the use of AI.

EXPERT OPINION

The main goal in improving MRE performance will be sequence selection aimed at differenting between inflammation and stricture while shortening the study length adjusted to patient compliance, and developing a standardized scoring system for MRE reporting assisted by artificial intelligence.

Multi-shot Diffusion-Weighted MRI With Multiplexed Sensitivity Encoding (MUSE) in the Assessment of Active Inflammation in Crohn's Disease

BACKGROUND

Single-shot diffusion-weighted imaging (ssDWI) has been shown useful for detecting active bowel inflammation in Crohn's disease (CD) without MRI contrast. However, ssDWI suffers from geometric distortion and low spatial resolution.

PURPOSE

To compare conventional ssDWI with higher-resolution ssDWI (HR-ssDWI) and multi-shot DWI based on multiplexed sensitivity encoding (MUSE-DWI) for evaluating bowel inflammation in CD, using contrast-enhanced MR imaging (CE-MRI) as the reference standard.

STUDY TYPE

Prospective.

SUBJECTS

Eighty nine patients with histological diagnosis of CD from previous endoscopy (55 male/34 female, age: 17-69 years). FIELD STRENGTH/SEQUENCES: ssDWI (2.7 mm × 2.7 mm), HR-ssDWI (1.8 mm × 1.8 mm), MUSE-DWI (1.8 mm × 1.8 mm) based on echo-planar imaging, T2-weighted imaging, and CE-MRI sequences, all at 1.5 T.

ASSESSMENT

Five raters independently evaluated the tissue texture conspicuity, geometry accuracy, minimization of artifacts, diagnostic confidence, and overall image quality using 5-point Likert scales. The diagnostic performance (sensitivity, specificity and accuracy) of each DWI sequences was assessed on per-bowel-segment basis.

STATISTICAL TESTS

Inter-rater agreement for qualitative evaluation of each parameter was measured by the intra-class correlation coefficient (ICC). Paired Wilcoxon signed-rank tests were performed to evaluate the statistical significance of differences in qualitative scoring between DWI sequences. A P value <0.05 was considered to be statistically significant.

RESULTS

Tissue texture conspicuity, geometric distortions, and overall image quality were significantly better for MUSE-DWI than for ssDWI and HR-ssDWI with good agreement among five raters (ICC: 0.70-0.89). HR-ssDWI showed significantly poorer performance to ssDWI and MUSE-DWI for all qualitative scores and had the worst diagnostic performance (sensitivity of 57.0% and accuracy of 87.3%, with 36 undiagnosable cases due to severe artifacts). MUSE-DWI showed significantly higher sensitivity (97.5% vs. 86.1%) and accuracy (98.9% vs. 95.1%) than ssDWI for detecting bowel inflammation.

DATA CONCLUSION

MUSE-DWI was advantageous in assessing bowel inflammation in CD, resulting in improved spatial resolution and image quality.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

Diagnosis of postoperative recurrence of Crohn disease with MR-enterography: Value of diffusion-weighted imaging

PURPOSE

To compare the diagnostic capabilities of MR enterography (MRE) using contrast-enhanced (CE) sequences with those of MRE using diffusion-weighted (DW) imaging for the diagnosis of postoperative recurrence at the neo-terminal ileum and/or anastomosis after ileocolonic resection in patients with Crohn disease (CD), and to clarify the role of additional DW imaging to CE-MRE in this context.

MATERIAL AND METHODS

Forty patients who underwent ileal resection for CD, and both endoscopy and MRE within the first year after surgery were included. There were 21 men and 19 women, with a mean age of 38 years±12 (SD) years (range: 18-67 years). MRE examinations were blindly analyzed independently by one senior (R1) and one junior (R2) radiologist for the presence of small bowel postoperative recurrence at the anastomotic site. During a first reading session, T2-, steady-state- and DW-MRE were reviewed (DW-MRE or set 1). During a separate distant session, T2-, steady-state- and CE-MRE were reviewed (CE-MRE or set 2). Lastly, all sequences were analyzed altogether (set 3). Performances of each reader for the diagnosis of postoperative recurrence were evaluated using endoscopic findings as the standard of reference (Rutgeerts score≥i2b).

RESULTS

Fifteen patients out of 40 (37.5%) had endoscopic postoperative recurrence at the anastomotic site. Sensitivity for the diagnosis of postoperative recurrence was 73% (95% CI: 51-96%) for R1 and 67% (95% CI: 43-91%) for R2 using set 1, and 80% (95% CI: 60-100%) for both readers using set 2. There was no significant differences in sensitivity between reading set 1 and reading set 2, for either R1 or R2 (R1, P> 0.99; R2, P=0.48). Specificity was 96% (95% CI: 88-100%) for both readers using set 1 or using set 2. Reading set 3 yielded an area under the ROC curve (AUC) of 0.93 (95% CI: 0.84-1) versus 0.89 (95% CI: 0.75-1) with set 1 (P=0.18) and versus 0.89 (95% CI: 0.78-1) with set 2 (P=0.21). No significant differences in AUC were found between set 1 or 2 and set 3 (P=0.18), nor between set 1 and 2 (P=0.76). Accuracies were 88% (95% CI: 74-95%) and 85% (95% CI: 71-93%) for DW-MRE for R1 and R2, respectively; 90% (95% CI: 77-96%) for CE-MRE for both readers; and 93% (95% CI: 80-97%) and 88% (95% CI: 74-95%) for R1 and R2 with set 3, respectively.

CONCLUSION

DW-MRE has diagnostic capabilities similar to those of CE-MRE for the diagnosis of postoperative recurrence of CD at the anastomotic site.

Emerging Imaging Biomarkers in Crohn Disease

ABSTRACT

In this review article, we present the latest developments in quantitative imaging biomarkers based on magnetic resonance imaging (MRI), applied to the diagnosis, assessment of response to therapy, and assessment of prognosis of Crohn disease. We also discuss the biomarkers' limitations and future prospects. We performed a literature search of clinical and translational research in Crohn disease using diffusion-weighted MRI (DWI-MRI), dynamic contrast-enhanced MRI (DCE-MRI), motility MRI, and magnetization transfer MRI, as well as emerging topics such as T1 mapping, radiomics, and artificial intelligence. These techniques are integrated in and combined with qualitative image assessment of magnetic resonance enterography (MRE) examinations. Quantitative MRI biomarkers add value to MRE qualitative assessment, achieving substantial diagnostic performance (area under receiver-operating curve = 0.8-0.95). The studies reviewed show that the combination of multiple MRI sequences in a multiparametric quantitative fashion provides rich information that may help for better diagnosis, assessment of severity, prognostication, and assessment of response to biological treatment. However, the addition of quantitative sequences to MRE examinations has potential drawbacks, including increased scan time and the need for further validation before being used in therapeutic drug trials as well as the clinic.

MR-enterography in Crohn's disease: what MRE mural parameters are associated to one-year therapeutic management outcome?

OBJECTIVE

To investigate the association of mural parameters of MR-enterography (MRE) with one-year therapeutic management of Crohn's disease (CD) patients.

METHODS

CD patients, undergone MRE with diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps between January 2017 and June 2018, were retrospectively enrolled. Extramural complications represented an exclusion criterion because of their potential influence on the intrinsic characteristic of the bowel wall. Two groups of patients were defined on the base of the therapeutic management adopted at 1-year follow-up: Medical-group and surgical-group. The following MRE parameters were evaluated: wall-thickening, longitudinal-extension, T2-fat-suppression-mural-signal, ulcers, mural-oedema, wall-enhancement-rate/pattern, DWI-scores, ADC-values, strictures.

RESULTS

70 CD patients were enrolled. 57/70 (81.4%) were included in Medical-group and 13/70 (18.6%) in Surgical-group. ADCmean and strictures resulted to be significantly (p < 0.01) different between the two groups. The ADCmean showed to be significantly associated to conservative management [p < 0.01; OR: 0.0003; 95% CI (0.00-0.13)], while the strictures to surgical management [p < 0.01; OR: 29.7; 95% CI (4.9-179.7)]. ROC curves for ADCmean showed that AUC was 0.717 [95% CI (0.607-0.810), p < 0.01] with an optimal cut-off value of 1.081 × 10^-3 mm² s^-1. A negative predictive value of 90.2% was observed associating ADCmean values > 1.081 × 10^-3 mm² s^-1 to conservative therapy. 13/17 (76%) strictures with an ADCmean > 1.081 × 10^-3 mm² s^-1 benefited of conservative therapy.

CONCLUSION

ADCmean values calculated on DWI-MRE may be associated to 1-year conservative medical therapy in patients with CD without extramural complications.

ADVANCES IN KNOWLEDGE

ADC maps may be proposed to select CD patients with a lower burden of mural active inflammatory cells and/or fibrosis benefiting of 1-year conservative treatment.

State of the Art MR Enterography Technique

ABSTRACT

Magnetic resonance enterography (MRE) is a well-established imaging technique that is commonly used for evaluating a variety of bowel diseases, most commonly inflammatory bowel disease which is increasing in prevalence. Inflammatory bowel disease is composed of 2 related, but distinct disease entities: Crohn disease (CD) and ulcerative colitis. In ulcerative colitis, inflammation is generally limited to the mucosa and invariably involves the rectum, and often the more proximal colon. CD is typified by transmural inflammation with skip lesions occurring anywhere from the mouth to anus, but characteristically involves the terminal ileum. The transmural involvement of CD may lead to debilitating ulceration and, ultimately, development of sinus tracts, which can be associated with abscesses and fistulae as extraenteric manifestations of the disease. Because much of the small bowel and extraenteric disease cannot be adequately assessed with conventional endoscopy, imaging plays a crucial role in initial diagnosis and follow-up. MRE does not use ionizing radiation which is important for these patients, many of which present earlier in life and may require multiple imaging examinations. In this article, we review the clinical indications, patient preparation, and optimal technique for MRE. We also discuss the role and proper selection of intravenous gadolinium-based contrast material, oral contrast material, and antiperistaltic agents, including pediatric considerations. Finally, we review the recommended and optional pulse sequence selection, including discussion of a "time-efficient" protocol, reviewing their utility, advantages, and limitations. Our hope is to aid the radiologist seeking to develop a robust MRE imaging program for the evaluation of bowel disease.

High b-value computed diffusion-weighted imaging for differentiating bowel inflammation in Crohn's disease

Purpose This study evaluated whether high b-value computed diffusion-weighted imaging (cDWI) can improve detection and differentiation of bowel inflammation in patients with Crohn's disease (CD). Methods Fifty-four consecutive CD patients who had undergone magnetic resonance enterography (MRE) and ileocolonoscopy (ICS) or balloon-assisted enteroscopy (BAE) were retrospectively studied; cDWI with a b-value = 1500s/mm² (cDWI1500) was generated using DWI acquired with b-values of 0 and 800 s/mm² (aDWI800). Overall, 366 bowel segments were evaluated. The signal intensities (SIs) of the bowel lumina were visually assessed on DWI. Bowel wall-to-iliopsoas muscle SI ratios on aDWI800 and cDWI1500 images and apparent diffusion coefficient (ADC) values were measured; visual assessments for lesion detection were performed using a 5-point Likert-like scale on plain MRE with aDWI800, plain MRE with cDWI1500, and contrast-enhanced (CE)-MRE without DWI. The area under the receiver-operating characteristic curve (AUC) was calculated to compare quantitative and qualitative assessments. Results SIs of the intraluminal fluid were shown as comparable to, or lower than background SIs on 157 (44.7 %) and 345 (98.3 %) of 351 segments on aDWI800 and cDWI1500, respectively. AUCs of SI ratios on cDWI1500 images (82.0 %, [95 % confidence interval: 76.6-87.3 %]) were greater than on aDWI800 (75.2 %, [68.2-82.3 %]; p < 0.001), and were close to the ADC values (81.5 % [76.3-86.7 %]; p = 0.76). The AUCs of CE-MRE images were largest, followed by plain MRE with cDWI1500, and plain MRE with aDWI800. Conclusions As it suppresses the SIs of intraluminal fluid and improves contrast between severe and non-severe inflammation, cDWI1500 helps with CD evaluation.

Magnetic resonance enterography compared with ultrasonography in newly diagnosed and relapsing Crohn's disease patients: the METRIC diagnostic accuracy study

BACKGROUND

Magnetic resonance enterography and enteric ultrasonography are used to image Crohn's disease patients. Their diagnostic accuracy for presence, extent and activity of enteric Crohn's disease was compared.

OBJECTIVE

To compare diagnostic accuracy, observer variability, acceptability, diagnostic impact and cost-effectiveness of magnetic resonance enterography and ultrasonography in newly diagnosed or relapsing Crohn's disease.

DESIGN

Prospective multicentre cohort study.

SETTING

Eight NHS hospitals.

PARTICIPANTS

Consecutive participants aged ≥ 16 years, newly diagnosed with Crohn's disease or with established Crohn's disease and suspected relapse.

INTERVENTIONS

Magnetic resonance enterography and ultrasonography.

MAIN OUTCOME MEASURES

The primary outcome was per-participant sensitivity difference between magnetic resonance enterography and ultrasonography for small bowel Crohn's disease extent. Secondary outcomes included sensitivity and specificity for small bowel Crohn's disease and colonic Crohn's disease extent, and sensitivity and specificity for small bowel Crohn's disease and colonic Crohn's disease presence; identification of active disease; interobserver variation; participant acceptability; diagnostic impact; and cost-effectiveness.

RESULTS

Out of the 518 participants assessed, 335 entered the trial, with 51 excluded, giving a final cohort of 284 (133 and 151 in new diagnosis and suspected relapse cohorts, respectively). Across the whole cohort, for small bowel Crohn's disease extent, magnetic resonance enterography sensitivity [80%, 95% confidence interval (CI) 72% to 86%] was significantly greater than ultrasonography sensitivity (70%, 95% CI 62% to 78%), with a 10% difference (95% CI 1% to 18%; p = 0.027). For small bowel Crohn's disease extent, magnetic resonance enterography specificity (95%, 95% CI 85% to 98%) was significantly greater than ultrasonography specificity (81%, 95% CI 64% to 91%), with a 14% difference (95% CI 1% to 27%). For small bowel Crohn's disease presence, magnetic resonance enterography sensitivity (97%, 95% CI 91% to 99%) was significantly greater than ultrasonography sensitivity (92%, 95% CI 84% to 96%), with a 5% difference (95% CI 1% to 9%). For small bowel Crohn's disease presence, magnetic resonance enterography specificity was 96% (95% CI 86% to 99%) and ultrasonography specificity was 84% (95% CI 65% to 94%), with a 12% difference (95% CI 0% to 25%). Test sensitivities for small bowel Crohn's disease presence and extent were similar in the two cohorts. For colonic Crohn's disease presence in newly diagnosed participants, ultrasonography sensitivity (67%, 95% CI 49% to 81%) was significantly greater than magnetic resonance enterography sensitivity (47%, 95% CI 31% to 64%), with a 20% difference (95% CI 1% to 39%). For active small bowel Crohn's disease, magnetic resonance enterography sensitivity (96%, 95% CI 92% to 99%) was significantly greater than ultrasonography sensitivity (90%, 95% CI 82% to 95%), with a 6% difference (95% CI 2% to 11%). There was some disagreement between readers for both tests. A total of 88% of participants rated magnetic resonance enterography as very or fairly acceptable, which is significantly lower than the percentage (99%) of participants who did so for ultrasonography. Therapeutic decisions based on magnetic resonance enterography alone and ultrasonography alone agreed with the final decision in 122 out of 158 (77%) cases and 124 out of 158 (78%) cases, respectively. There were no differences in costs or quality-adjusted life-years between tests.

LIMITATIONS

Magnetic resonance enterography and ultrasonography scans were interpreted by practitioners blinded to clinical data (but not participant cohort), which does not reflect use in clinical practice.

CONCLUSIONS

Magnetic resonance enterography has higher accuracy for detecting the presence, extent and activity of small bowel Crohn's disease than ultrasonography does. Both tests have variable interobserver agreement and are broadly acceptable to participants, although ultrasonography produces less participant burden. Diagnostic impact and cost-effectiveness are similar. Recommendations for future work include investigation of the comparative utility of magnetic resonance enterography and ultrasonography for treatment response assessment and investigation of non-specific abdominal symptoms to confirm or refute Crohn's disease.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN03982913.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 42. See the NIHR Journals Library website for further project information.

Clinical-stage Approaches for Imaging Chronic Inflammation and Fibrosis in Crohn's Disease

The number of imaging-based indices developed for inflammatory bowel disease as research tools, objectively measuring ileocolonic and perianal activity and treatment response, has expanded in the past 2 decades. Created primarily to assess Crohn's disease (CD), there is increasing adoption of these indices into the clinical realm to guide patient care. This translation has been facilitated by validation in adult and pediatric populations, prompted by simplification of score calculations needed for practical application outside the research environment. The majority of these indices utilize magnetic resonance imaging (MRI), specifically MR enterography (MRE) and pelvic MRI, and more recently ultrasound. This review explores validated indices by modality, anatomic site and indication, including for documentation of the presence and extent of CD, disease progression, complications, and treatment response, highlighting those in clinical use or with the potential to be. As well, it details index imaging features used to quantify chronic inflammatory activity, severity, and to lesser extent fibrosis, in addition to their reference standards and any modifications. Validation in the pediatric population of indices primarily developed in adult cohorts such as the Magnetic Resonance Index of Activity (MaRIA), the Simplified Magnetic Resonance Index of Activity (MARIAs), and the MRE global score (MEGS), together with newly developed pediatric-specific indices, are discussed. Indices that may be predictive of disease course and investigational techniques with the potential to provide future imaging biomarkers, such as multiparametric MRI, are also briefly considered.

Toward Molecular Imaging of Intestinal Pathology

Inflammatory bowel disease (IBD) is defined by a chronic relapsing and remitting inflammation of the gastrointestinal tract, with intestinal fibrosis being a major complication. The etiology of IBD remains unknown, but it is thought to arise from a dysregulated and excessive immune response to gut luminal microbes triggered by genetic and environmental factors. To date, IBD has no cure, and treatments are currently directed at relieving symptoms and treating inflammation. The current diagnostic of IBD relies on endoscopy, which is invasive and does not provide information on the presence of extraluminal complications and molecular aspect of the disease. Cross-sectional imaging modalities such as computed tomography enterography (CTE), magnetic resonance enterography (MRE), positron emission tomography (PET), single photon emission computed tomography (SPECT), and hybrid modalities have demonstrated high accuracy for the diagnosis of IBD and can provide both functional and morphological information when combined with the use of molecular imaging probes. This review presents the state-of-the-art imaging techniques and molecular imaging approaches in the field of IBD and points out future directions that could help improve our understanding of IBD pathological processes, along with the development of efficient treatments.

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.

Which MRI Score and Technique Should Be Used for Assessing Crohn's Disease Activity?

Magnetic resonance (MR) enterography is assuming an increasingly important and central role in the management of patients with Crohn’s disease, as it is not only involved in diagnosis and staging of the disease but also allows for patients’ follow-up, evaluating the response to therapy, and predicting disease outcomes. Several MR scores have been developed but unfortunately there is no globally accepted score. The most widely used scores are the Magnetic Resonance Index of Activity (MaRIA) score, the London score, the Nancy score, and the Clermont score; however, there are multiple differences between these tools in terms of the assessed radiological items, fasting, administration of oral or intravenous contrast, and the use of diffusion-weighted images. Here we reviewed the main characteristics of each MR scoring system to clarify which is the most appropriate score for monitoring disease activity in both clinical practice and clinical trials.

Cross-sectional imaging for assessing intestinal fibrosis in Crohn's disease

More than 30% of patients with Crohn's disease (CD) develop fibrotic strictures in the bowel as the disease progresses. Excessive deposition of extracellular matrix components in the submucosa and smooth muscle hypertrophy or hyperplasia are the main features of fibrosis in CD. Cross-sectional imaging technology provides a wealth of information on the anatomy, histological composition, and physiological function of the bowel, allowing for a non-invasive and complete evaluation of associated abnormalities. This review summarizes recent advances in and the potential technologies of cross-sectional imaging for assessing intestinal fibrosis in CD, including ultrasound imaging, computed tomography, and magnetic resonance imaging.

Fast Magnetic Resonance Enterography Protocol for the Evaluation of Patients with Crohn's Disease: A Pilot Study

Objective

Magnetic resonance enterography has achieved an increasingly importance in the evaluation of patients with Crohn's disease, although it is limited by high costs and prolonged scanning times. The aim of our work was to design a "fast" abbreviated MRE protocol and to compare it with the standard one.

Materials and Methods

A single-center retrospective study was performed on 73 patients with Crohn's disease who underwent MRE with standard protocol over a 7-month period. The images of the standard protocol were separated from those included in the proposed abbreviated one and independently evaluated by two radiologists with different years of experience in MRE imaging. Statistical analysis was performed with the Cohen kappa (κ) value, used to assess the agreement in case of categorical variables, the Lin's concordance correlation coefficient and Bland-Altman plot, in assessing the degree of agreement between numerical measurements, while the non- parametric Mann-Whitney U-test was used in comparing the evaluation times of the two protocols.

Results

The intraobserver evaluation showed a perfect agreement between the two protocols for presence, number and extension of lesions, abdominal complications, and excellent/perfect in identification of active inflammation.The interobserver reproducibility was excellent for overall presence and number of lesions, for the presence and number of lesions in any abdominal quadrant, inflammation, intestinal and extraintestinal complications, and lesions extension.

Conclusion

The proposed protocol achieves comparable performance with standard MRE. Furthermore, it would carry potential benefits in terms of patient's comfort, time, and health-care costs savings.

Use of Cross-Sectional Imaging for Tight Monitoring of Inflammatory Bowel Diseases

A treat-to-target strategy with close monitoring of intestinal inflammation is recommended in inflammatory bowel disease (IBD). Ileocolonoscopy remains the gold standard for assessing disease activity in IBD but is a relatively invasive procedure and is impossible to repeat in the context of tight monitoring strategies. In addition to biomarkers, cross-sectional imaging increasingly is used in these patients. Computed tomography is limited by the use of radiation, while the use of magnetic resonance enterography (MRE) is limited by its cost and access. There is growing interest in bowel ultrasound that represents a cost-effective, noninvasive, and well-tolerated modality in clinical practice, but it is operator dependent. Compared with ileocolonoscopy and MRE, bowel US has been shown to have the same level of accuracy in assessing and monitoring disease activity for both CD and UC and thus can be considered a point-of-care test. Diffusion-weighted imaging (DWI) is a MR imaging technique that increasingly is used in both IBD and non-IBD conditions and has been shown to be a valuable and accurate tool for assessing and monitoring IBD activity. Compared with conventional MRE, DWI is quicker, less time consuming, may not require intravenous contrast agent, fasting, bowel cleansing, oral preparation, or rectal preparation. This review discusses the role of these cross-sectional imaging techniques for the management of patients with IBD. In the near future, the value of DWI and ultrasound in assessing IBD will require further investigation in the era of transmural healing in CD and complete mucosal healing, including histologic remission, in ulcerative colitis.

Radiologische Diagnostik chronisch-entzündlicher Darmerkrankungen bei Kindern und Jugendlichen

Dank der technischen Fortschritte nehmen bildgebende Methoden eine immer wichtigere Rolle sowohl in der Diagnostik als auch im klinischen Management chronisch-entzündlicher Darmerkrankungen (CED), insbesondere in der Pädiatrie, ein. Dieser Beitrag fokussiert charakteristische Erscheinungsformen der CED und jeweils relevante bildgebende Verfahren (Ultraschall und MRT). Außerdem werden Forschungstrends und aktueller Wissensstand zu verschiedenen bildgebenden Modalitäten dargestellt.

Diffusion-weighted imaging and apparent diffusion coefficient values for evaluating terminal ileitis in patients with Crohn's disease

Objective:

To determine the accuracy of diffusion-weighted imaging (DWI) in identifying terminal ileitis in patients with Crohn’s disease.

Materials and Methods:

This was a retrospective study of 38 consecutive patients with Crohn’s disease who underwent magnetic resonance enterography with DWI in a 3.0 T scanner. The patients were divided into two groups, on the basis of colonoscopy and biopsy findings: active inflammation; and inactive disease. Apparent diffusion coefficient (ADC) values were determined, as were the magnetic resonance index of activity (MaRIA) and the Clermont score.

Results:

Of the 38 patients evaluated, 18 (47%) had active inflammation. The patients with active inflammation showed greater restricted diffusion, more pronounced mucosal edema, greater wall thickening, a higher MaRIA, and a higher Clermont score than did those with inactive disease. The level of interobserver agreement (intraclass correlation coefficient) was excellent for the MaRIA and the Clermont score, whereas it was substantial for the ADC values. For identifying colonoscopy-proven inflammation, the best ADC cut-off point was 2.1 × 10⁻³ mm²/s, which had a sensitivity of 88.8% and a specificity of 95.0%, whereas DWI presented an overall accuracy of 89.4%, with a sensitivity of 88.9% and a specificity of 90.0%.

Conclusion:

Visual analysis of the DWI sequence has good accuracy in detecting terminal ileitis in patients with Crohn’s disease. In addition, low ADC values have good sensitivity for detecting colonoscopy-proven inflammation.

Can diffusion weighted imaging be used as an alternative to contrast-enhanced imaging on magnetic resonance enterography for the assessment of active inflammation in Crohn disease?

The present study aimed to investigate the potential use of T2-weighted sequences with diffusion weighted imaging (DWI) in magnetic resonance (MR) enterography instead of conventional contrast-enhanced MR imaging (MRI) sequences for the evaluation of active inflammation in Crohn disease.Two-hundred thirteen intestinal segments of 43 patients, who underwent colonoscopy within 2 weeks before or after MR enterography were evaluated in this retrospective study. DWI sequences, T2-weighted sequences, and contrast-enhanced T1-weighted sequences were acquired in the MR enterography scan after cleaning of the bowel and using an oral contrast agent. First, the intestinal segments that had active inflammation in MR enterography were qualitatively evaluated in T2-weighted and contrast-enhanced T1-weighted sequences and then MR activity index (MRAI 1) and MRAI 2 were formed with and without contrast-enhanced sequences in 2 separate sessions.The correlation coefficient between contrast enhanced and DWI MR enterography scores (MRAI 1 and MRAI 2) of intestinal inflammation was 0.97 for all segments. In addition, separate correlation coefficients were calculated for terminal ileum, right colon, transverse colon, left colon, and rectum, and there was a strong correlation between the MRAI 1 and MRAI 2 scores of each segment (r = 0.86-0.97, P < .001). On the other hand, MR enterography had 88.7% sensitivity, 97.9% specificity, 95.5% positive predictive value, 94.6% negative predictive value, and 94.8% accuracy for detection of active inflammation in all intestinal segments in Crohn disease.DWI and T2-weighted sequences acquired with cleaning of the bowel can be used instead of contrast-enhanced MRI sequences for the evaluation of active inflammation in Crohn disease.

Noninferiority testing for matched-pair ordinal data with misclassification

New treatments that are noninferior or equivalent to-but not necessarily superior to-the reference treatment may still be beneficial to patients because they have fewer side effects, are more convenient, take less time, or cost less. The noninferiority test is widely used in medical research to provide guidance in such situation. In addition, categorical variables are frequently encountered in medical research, such as in studies involving patient-reported outcomes. In this paper, we develop a noninferiority testing procedure for correlated ordinal categorical variables based on a paired design with a latent normal distribution approach. Misclassification is frequently encountered in the collection of ordinal categorical data; therefore, we further extend the procedure to account for misclassification using information in the partially validated data. Simulation studies are conducted to investigate the accuracy of the estimates, the type I error rates, and the power of the proposed procedure. Finally, we analyze one substantive example to demonstrate the utility of the proposed approach.

Magnetic resonance enterography

Crohn's disease is a condition of chronic inflammation that may involve any part of the gastrointestinal tract, although it more frequently affects the terminal ileum. Longstanding inflammation may lead to several bowel complications including obstruction, stricture, fistula and abscesses which often necessitate surgery. Cross-sectional imaging methods such as computed tomography and magnetic resonance imaging are being utilized more frequently to assess mural and extramural inflammatory bowel disease manifestations. Magnetic resonance enterography (MRE) for assessment of small bowel is optimal because of absence of ionizing radiation, better soft tissue contrast, development of motion-free sequences and high resolution images. A typical protocol includes pre and postcontrast sequences utilizing an enteric contrast agent for adequate bowel distention and an antiperistaltic agent. Overall, MRE allows the evaluation of disease activity, extraenteric complication and response to therapy with a great impact on patient management. In this review we discuss the features of MRE from patient's preparation and exam protocol to pathological findings.

Noninvasive Multimodal Methods to Differentiate Inflamed vs Fibrotic Strictures in Patients With Crohn's Disease

Fibrotic strictures occur in 30% of patients with Crohn's disease (CD). However, there are no therapeutic agents that prevent or reverse fibrotic strictures. Strictures are treated by endoscopic dilatation procedures and surgical procedures, but there are high rates of recurrence. Two antifibrotic agents (nintedanib and pirfenidone) recently were approved for the treatment of idiopathic pulmonary fibrosis and inhibitors of Rho-associated protein kinases 1 and 2 reversed fibrosis in mice with chronic intestinal inflammation. Cross-sectional imaging techniques, such as magnetic resonance (MR) enterography, computed tomography enterography, and bowel ultrasound, are used to assess small-bowel and CD-related complications, including strictures. It is important to be able to determine the degree of inflammation and fibrosis in strictures to select the best therapy; this can be a challenge because inflammation and fibrosis co-exist to varying degrees in a damaged bowel segment. Delayed gadolinium enhancement, magnetization transfer MR imaging, and ultrasound elastography seem to be promising tools for assessing fibrosis in patients with CD. We review noninvasive techniques for fibrosis assessment, including analyses of genetic, epigenetic, and protein markers. We discuss the potential of imaging techniques such as diffusion-weighted and magnetization transfer MR imaging, strain elastography, shear-wave imaging, and positron emission tomography to guide therapeutic decisions for patients with stricturing CD.

Evaluation of Intravoxel Incoherent Motion Diffusion-Weighted Magnetic Resonance Imaging for Detection of Bowel Inflammation in Patients With Crohn Disease

OBJECTIVES

This study aimed to evaluate the feasibility of intravoxel incoherent motion diffusion-weighted magnetic resonance imaging (DW-MRI) in detecting bowel inflammation in patients with Crohn disease (CD).

METHODS

Sixteen patients who underwent intravoxel incoherent motion DW-MRI for CD and colonoscopy were recruited. Seventy-nine bowel segments were selected, and their mean D, D*, f, and apparent diffusion coefficient (ADC) values were measured. The receiver operating characteristic curve was performed to distinguish inflamed from normal bowel.

RESULTS

The mean D, D*, f, and ADC values of inflamed bowel were significantly lower than those of normal bowel (P < 0.05). The area under the receiver operating characteristic curve for f (0.906) and ADC values (0.924) was greater than that for D (0.709) or D* values (0.686) for differentiating inflamed bowel from normal bowel (P < 0.05).

CONCLUSIONS

Intravoxel incoherent motion DW-MRI is a feasible technique for detecting inflammation in CD patients. The ADC and f values have more potential than the D and D* values.

Potential of diffusion-weighted imaging in magnetic resonance enterography to identify neoplasms in the ileocecal region: Use of ultra-high b-value diffusion-weighted imaging

Patients with chronic inflammatory bowel disease have an increased risk of colorectal cancer, and the differentiation between neoplastic and inflammatory lesions often poses a clinical dilemma. The aim of the present study was to investigate whether diffusion-weighted (DW) magnetic resonance (MR) enterography with ultra-high b-value facilitates the identification of neoplastic lesions in the ileocecal region. A total of 76 patients (22 patients with neoplasms, 26 inflammatory lesions and 28 normal subjects) from 292 cases of suspected bowel disorders were included in the present study. All patients were examined with conventional MR enterography and DW imaging (DWI) with seven different b-values (400, 600, 800, 1,000, 1,200, 1,500 and 3,000 sec/mm²) in a 3T MR scanner. DWI scans with different b-values were analyzed independently by two radiologists for the presence of ileocecal lesions. The signal intensity of the majority of inflammatory lesions and normal bowel segments gradually decreased to the background intensity with increasing b-values; however, neoplastic lesions demonstrated relative hyperintensity compared with the background. In addition, ~76% of the positive findings from b=3,000 sec/mm² DWI were neoplasms. In conclusion, a lesion with consistently high signal intensity from DWI images with b-values increasing to 3,000 sec/mm² indicated the presence of neoplasms. The results suggested that ultra-high b-value (3,000 sec/mm²) imaging may aid the clinical differentiation of neoplasms from benign conditions.