A review of magnetic resonance enterography-based indices for quantification of Crohn's disease inflammation

Artificial Intelligence in Gastrointestinal Imaging: Advances and Applications

While artificial intelligence (AI) has shown considerable progress in many areas of medical imaging, applications in abdominal imaging, particularly for the gastrointestinal (GI) system, have notably lagged behind advancements in other body regions. This article reviews foundational concepts in AI and highlights examples of AI applications in GI tract imaging. The discussion on AI applications includes acute & emergent GI imaging, inflammatory bowel disease, oncology, and other miscellaneous applications. It concludes with a discussion of important considerations for implementing AI tools in clinical practice, and steps we can take to accelerate future developments in the field.

Quantified small bowel motility assessment on magnetic resonance enterography in paediatric inflammatory bowel disease - does it reflect clinical response?

BACKGROUND

Quantified small bowel motility assessment using cine magnetic resonance enterography (MRE) has shown promise as a biomarker in adult inflammatory bowel disease. Whether quantified motility corresponds to treatment response in paediatric inflammatory bowel disease is unknown.

OBJECTIVE

To test whether changes in motility reflect response.

MATERIALS AND METHODS

Local ethics approval was granted for this single-institution, retrospective study. All children < 18 years with confirmed inflammatory bowel disease, who had more than one MRE between Jan 2011-Jan 2022, were included. Simplified MaRIA (sMaRIA) and motility index (quantified motility) at all terminal ileum and diseased non-terminal ileum segments were independently assessed by two radiologists each with ≥ 9 years' experience. Change in (Δ) motility index was compared to clinical (gastroenterologist physician's global assessment) and consensus radiological reference standard (response = decrease in sMaRIA of more than or equal to 2 points) in responders versus non-responders using the Mann-Whitney test. Sensitivity and specificity of Δ motility index more than zero were compared to decrease in sMaRIA of 2 or more points for identifying clinical response.

RESULTS

Of 64 children aged 5-16, 21 out of 64 (33%) were responders, 37 out of 64 (58%) were non-responders and 6 out of 64 (9%) had inactive disease according to clinical reference standard. Δ Motility index by both radiologists was higher in responders (+ 16, + 39) than non-responders (-43, -44), P = 0.04, P = 0.01 each radiologist, respectively. Motility index was more sensitive (57% versus 24%), but less specific (67% versus 93%) than sMaRIA in identifying clinical response.

CONCLUSION

Motility index on cine MRE corresponds to clinical response, and is more sensitive at detecting response compared to sMaRIA in paediatric inflammatory bowel disease.

Crohn's disease management: translating STRIDE-II for UK clinical practice

Crohn's disease (CD) is a chronic inflammatory bowel disease (IBD) characterised by endoscopic inflammation, progressive bowel damage and gastrointestinal lesions. Although treatment strategies for CD have traditionally focused on a stepwise pharmacological approach to achieve clinical remission or symptom resolution, these treatment goals correlate poorly with disease activity. Thus, achieving full clinical remission and full endoscopic healing alone may be insufficient, as patients may remain at risk of inflammatory complications. Individualised 'treat-to-target' (T2T) pharmacological and treatment approaches represent a promising strategy for improving endoscopic remission and symptom resolution among patients with CD. The Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE) and STRIDE-II guidelines, launched in 2013 and later renewed, identified individualised targets for a T2T therapeutic approach for patients with IBD. These guidelines facilitate the individualisation of target treatment goals through evidence-based, long-term (health-related quality of life, absence of disability, endoscopic healing) and intermediate/short-term (abdominal pain, stool frequency, normalisation of biomarker levels) treatment targets, allowing patients and clinicians to consider the risk-to-benefit balance of goals and selected therapeutic strategies. This article aims to summarise the STRIDE-II guidelines and provide intellectual guidance for healthcare professionals to apply the STRIDE-II principles to current clinical practice in the United Kingdom (UK). Management recommendations for primary and secondary first-line non-responders are provided, along with suggestions for utilising the endoscopic outcomes scoring system in UK clinical practice.

Review article: Measuring disease severity in inflammatory bowel disease - Beyond treat to target

BACKGROUND

Inflammatory bowel disease (IBD) follows a heterogenous disease course and predicting a patient's prognosis is challenging. There is a wide burden of illness in IBD and existing tools measure disease activity at a snapshot in time. Comprehensive assessment of IBD severity should incorporate disease activity, prognosis, and the impacts of disease on a patient. This review investigates the concept of disease severity in adults with IBD to highlight key components contributing to this.

METHODS

To perform this narrative review, a Medline search was conducted for full-text articles available at 1st March 2024 using search terms which encompassed disease activity assessment, disease severity, prognosis, natural history of Crohn's disease (CD) and ulcerative colitis (UC), and the burden of IBD.

RESULTS

Current methods of disease assessment in IBD have evolved from a focus on the burden of symptoms to one that includes inflammatory targets, genetic, serological, and proteomic profiles, and assessments of quality-of-life (QoL), disability, and psychosocial health. Longitudinal studies of IBD suggest that the burden of illness is driven by disease phenotype, clinical markers of complicated disease course (previous intestinal resection, corticosteroid use, perianal disease in CD, recent hospitalisations in UC), gut inflammation, and the impact of IBD on the patient.

CONCLUSIONS

Disease severity in IBD can be difficult to conceptualise due to the multitude of factors that contribute to IBD outcomes. Measurement of IBD severity may better encapsulate the full burden of illness rather than gut inflammation alone at a single timepoint and may be associated with longitudinal outcomes.

The Relationship Between the Endoscopic Healing Index, Fecal Calprotectin, and Magnetic Resonance Enterography in Crohn's Disease

INTRODUCTION

The serum-based endoscopic healing index (EHI) test identifies endoscopic Crohn's disease (CD) activity. Data are lacking on the relationship between EHI with other endpoints. We assessed the relationship between EHI and the simplified Magnetic Resonance Index of Activity.

MATERIALS AND METHODS

Data were prospectively collected on patients with CD with either an EHI or fecal calprotectin (FCAL) within 90 days of magnetic resonance enterography (MRE). Diagnostic accuracy was assessed using area under the receiver operator characteristics. Proportions with any, severe, and terminal ileum MR inflammation were compared above/below identified thresholds for both EHI and FCAL.

RESULTS

A total of 241 MREs paired to either EHI or FCAL from 155 patients were included. Both EHI and FCAL had similar accuracy to diagnose inflammation (area under the receiver operator characteristics: EHI: 0.635 to 0.651, FCAL: 0.680 to 0.708). Optimal EHI values were 42 and 26 for inflammation on MRE and endoscopy, respectively. Patients with EHI ≥42 (100% vs. 63%, P =0.002), FCAL >50 µg/g (87% vs. 64%, P <0.001) and FCAL >250 µg/g (90% vs. 75%, P =0.02) had higher rates of simplified Magnetic Resonance Index of Activity ≥1 compared with lower values. EHI differentiated ileitis numerically more than FCAL (delta: 24% to 25% vs. 11% to 21%). Patients with FCAL ≥50 µg/g had higher rates of severe inflammation compared with FCAL <50 µg/g (75% vs. 47%, P <0.001), whereas smaller differentiation existed for EHI threshold of 42 (63% vs. 49%, P =0.35).

CONCLUSION

Both EHI and FCAL were specific in their confirmation of inflammation and disease activity on MRE in patients with CD. However, MRE-detected inflammation was frequently present in the presence of low EHI and FCAL in similar proportions.

Assessing quality of magnetic resonance enterography and its impact on disease assessment of ileal Crohn's disease

BACKGROUND/AIMS

Assessment of quality of magnetic resonance enterography (MRE) in small bowel Crohn's disease (CD) activity evaluation has received little attention. We assessed the impact of bowel distention and motion artifact on MRE activity indices in ileal CD.

METHODS

A cohort of patients who underwent contemporaneous MRE and colonoscopy for ileal CD assessment between 2014 and 2021 at 2 centers were audited. An abdominal radiologist blinded to clinical data reviewed each MRE, graded bowel distention and motion artifact upon a pre-specified 3-point scale and calculated the original magnetic resonance index of activity (MaRIA) and simplified MaRIA (sMaRIA), London index and CD MRE index (CDMI). Ileal endoscopic activity was graded via the Simplified Endoscopy Score for CD (SES-CD). The performance of MRE indices in discriminating active disease (SES-CD ≥3) stratified by MRE quality was measured by receiver operator characteristic analyses.

RESULTS

One hundred and thirty-seven patients had MRE and colonoscopy within a median of 16 days (range, 0-30 days) with 63 (46%) exhibiting active disease (SES-CD ≥3). Forty-four MREs (32%) were deemed low quality due to motion artifact and/or moderate to poor distention. Low-quality MREs demonstrated reduced discriminative performance between ileal SES-CD ≥3 and MRE indices (MaRIA 0.838 vs. 0.634, sMaRIA 0.834 vs. 0.527, CDMI 0.850 vs. 0.595, London 0.748 vs. 0.511, P<0.05 for all). Individually the presence of any motion artifact markedly impacted the discriminative performance (e.g., sMaRIA area under the curve 0.544 vs. 0.814, P<0.05).

CONCLUSIONS

Image quality parameters can significantly impact MRE disease activity interpretation. Quality metrics should be reported, enabling cautious interpretation in lower-quality studies.

Diagnostic value of apparent diffusion coefficient of psoas muscles for evaluating complications in patients with Crohn's disease

Aim

To assess the association of the apparent diffusion coefficient (ADC) of the psoas muscles and psoas muscle index (PMI) with the activity and behaviour of Crohn's disease (CD).

Material and methods

This was a retrospective study of 88 CD patients who underwent magnetic resonance enterography. Patients were classified according to the Montreal Classification in uncomplicated (non-stricturing, non-penetrating, B1), and complicated (structuring [B2] and penetrating disease [B3]). At the level of the third lumbar vertebra, the ADC and PMI were estimated. CD activity was analysed using the Magnetic Resonance Index of Activity (MaRIA), and depending on its values patients were categorized as high or low activity. Additionally, the presence of creeping fat (CrF) was used to evaluate activity. ADC and PMI were using Student's t-test.

Results

Our study included 47 males and 41 females (mean age of 38.69 ±14.4 years). The ADC in uncomplicated (B1, n = 45) and complicated disease (B2 + B3, n = 43) were 1.11 ±0.19 and 1.03 ±0.10 (10-3*mm2/s), respectively, (p = 0.02). ADC was significantly lower in patients with stricturing disease than in patients without strictures (1.02 ±0.11 and 1.10 ±0.18 [10-3 mm2/s], respectively, p = 0.01). The group with non-penetrating disease showed higher PMI than those with penetrating disease (5.71 ±1.88 vs. 4.42 ±1.55 cm2/m2, respectively, p = 0.10). There was no significant difference in PMI and ADC between patients with low and high MaRIA or positive and negative CrF.

Conclusions

The ADC of the psoas muscles is significantly lower in CD patients with uncomplicated disease, particularly those with stricturing disease. Therefore, ADC can be considered as an imaging biomarker of myopathic changes in CD patients.

Comparison of an Endoscopic Scoring System and the Simplified Magnetic Resonance Index of Activity in Patients with Small Bowel Crohn's Disease

Background/Aims

The newly derived simplified magnetic resonance index of activity (MARIAs) has not been verified in comparison to balloon-assisted enteroscopy (BAE) for patients with small bowel Crohn's disease (CD). We studied the correlation of MARIAs with simple endoscopic scores for CD (SES-CD) of the ileum based on magnetic resonance enterography (MRE) and BAE in patients with small bowel CD.

Methods

Fifty patients with small bowel CD who underwent BAE and MRE concurrently within 3 months from September 2020 to June 2021 were enrolled in the study. The primary outcome was the correlation between the active score of ileal SES-CD (ileal SES-CDa)/ileal SES-CD and MARIAs based on BAE and MRE. The cutoff value for MARIAs identifying endoscopically active/severe disease, defined as ileal SES-CDa/ileal SES-CD of 5/7 or more, was analyzed.

Results

Ileal SES-CDa/ileal SES-CD and MARIAs showed strong associations (R=0.76, p<0.001; R=0.78, p<0.001). The area under the receiver operating characteristic curve of MARIAs for ileal SES-CDa ≥5 and ileal SES-CD ≥7 was 0.92 (95% confidence interval, 0.88 to 0.97) and 0.92 (95% confidence interval, 0.87 to 0.97). The cutoff value of MARIAs for detecting active/severe disease was 3. A MARIAs index value of ≥3 identified ileal SES-CDa ≥5 with a sensitivity of 85% and specificity of 87% and detected ileal SES-CD ≥7 with a sensitivity of 87% and specificity of 86%.

Conclusions

This study validated the applicability of MARIAs compared to BAE-based ileal SES-CDa/SES-CD.

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.

Serum Ustekinumab Concentrations Are Associated With Improved Outcomes With the Magnetic Resonance Index of Activity for Crohn's Disease

Higher ustekinumab concentrations were associated with improved radiologic (Simplified Magnetic Resonance Index of Activity for Crohn’s Disease) and stringent biomarker (calprotectin) outcomes. The high concentration needed for these novel endpoints validates previous studies using the same assay.

Small Bowel Imaging from Stepchild of Roentgenology to MR Enterography, Part II: The Reliable Disclosure of Crohn's Disease and Non-Inflammatory Small Bowel Disorder Plot through MRI Findings

MRE has become a standard imaging test for evaluating patients with small bowel pathology, but a rigorous methodology for describing and interpreting the pathological findings is mandatory. Strictures, abscess, inflammatory activity, sinus tract, wall edema, fistula, mucosal lesions, strictures, and mesentery fat hypertrophy are all indicators of small bowel damage in inflammatory and non-inflammatory small bowel disease, and they are all commonly and accurately explained by MRE. MRE is a non-invasive modality that accurately assesses the intra-luminal, parietal, and extra-luminal small bowel. Differential MRE appearance allows us to distinguish between Crohn's disease and non-inflammatory small bowel disorder. The purpose of this paper is to present the MRE pathological findings of small bowel disorder.

Two-year real-world outcome data from a single tertiary centre shows reduced ustekinumab persistence in a non-bio-naïve Crohn's disease cohort with penetrating disease, -ostomies and sarcopenia

Background

Ustekinumab was approved in 2016 for the treatment of moderate-severe Crohn's disease (CD). Clinical trials and real-world studies have suggested ustekinumab to be a safe and effective treatment; however, studies to date infrequently use imaging techniques to predict response to biologics in CD.

Objectives

We assessed the 2-year real-world effectiveness and safety of ustekinumab in a tertiary CD cohort with the use of novel imaging techniques.

Design

Retrospective cohort study.

Methods

Retrospective data were collected between 2016 and 2021. Study end points included ustekinumab persistence, biological and/or clinical response and remission at 12, 18 and 24 months. Statistical analysis included demographic and inferential analyses.

Results

In all, 131 CD patients [57.3% female, median age of 26.0 (21.0-37.0)] were included. Patients were non-bio naïve, and the majority received ustekinumab as third- or fourth-line treatment. At 24 months, 61.0% (80/131) persisted with ustekinumab [52.7% (69/131) steroid free]. Clinical response was reported in 55.2% (37/67), clinical remission in 85.7% (57/67), biological response in 46.8% (22/47) and biological remission in 31.9% (15/47) of patients at 24 months. The low outcome numbers were attributable to missing data. Improvements in routine disease markers, including C-reactive protein and Harvey-Bradshaw Index, were also reflected in magnetic resonance imaging-derived disease scores. The presence of penetrating CD, an -ostomy and sarcopenia were all predictors of poorer ustekinumab outcomes (p < 0.05).

Conclusion

Ustekinumab is effective in non-bio-naïve CD patients with non-stricturing, non-penetrating disease with an unremarkable safety profile but may be less effective in those with penetrating disease, -ostomies and sarcopenia.

Comparison of the magnetic resonance scoring systems for Crohn's disease activity: MaRIA, simplified MaRIA, and Nancy scores

PURPOSE

The most widely used score for assessing the activity of Crohn's disease (CD) is the Magnetic Resonance Index of Activity (MaRIA) score, but it is time-consuming. The aim of this study was to compare the diagnostic accuracy of MaRIA score to the other two easily calculated scores.

METHODS

Between January 2011 and May 2021, 67 patients with CD who underwent MRE and ileocolonoscopy within 2 weeks were enrolled. The MRE-based scores including the MaRIA score, simplified MaRIA (sMaRIA) score, and Nancy score for each colonic segment and terminal ileum were calculated and correlated with the ileocolonoscopic findings. The simplified endoscopic score for Crohn's disease (SES-CD) was considered the gold standard.

RESULTS

A total of 343 intestinal segments were included in the analysis, of which 109 (31.8%) showed active inflammation on ileocolonoscopy. The areas under the receiver operating characteristic curve (AUC) of the MaRIA, sMaRIA, and Nancy scores for detecting active disease were 0.752, 0.764, and 0.765, respectively. In the sub-analysis for different indications, the MaRIA and sMaRIA scores showed a higher AUC (0.721 and 0.741) than the Nancy score (0.652) for disease monitoring.

CONCLUSION

The sMARIA and Nancy scores showed comparable diagnostic accuracy to the MaRIA score, and thus could be used as alternatives to the MaRIA score. Furthermore, considering the range of application, especially for disease monitoring, the sMaRIA score may be more suitable for use in clinical practice.

Parameters of body composition and creeping fat are associated with activity of Crohn's disease

AIM

This study aimed at assessing body composition parameters, creeping fat (CrF), and Crohn's disease's (CD) activity based on the Magnetic Resonance Index of Activity (MaRIA).

METHODS

114 CD patients who underwent magnetic resonance enterography (MRE) between June 2010 and April 2020 were retrospectively assessed. The semi-automated body composition segmentation, the qualitative evaluation of CrF, and MaRIA were performed. Based on their MaRIA score, patients were divided into two groups: mild-to-moderate disease (MaRIA <11, n = 50) and severe disease (MaRIA ≥11, n = 64). MRE parameters were analyzed between both groups. Patients were dichotomized according to body composition categories and the presence of CrF. Univariate regression analyses were performed to investigate the association between dichotomized variables and severe disease. Significant variables were incorporated into the multivariate logistic regression model.

RESULTS

The severe disease group exhibited higher serum C-reactive protein (CRP) levels compared to the mild-to-moderate disease group (p ≤0.001). In the mild-to-moderate disease group, a higher proportion of patients had a body mass index (BMI) ≥ 25 (kg/m2) (32.0%) compared to the severe disease group (16.5%) (p = 0.04). The subcutaneous adipose tissue index (SATI) was significantly higher in the mild-to-moderate disease group (p = 0.04). The visceral to subcutaneous adipose tissue (VAT/SAT) ratio tended to be higher in the severe disease group (p = 0.09). There was no significant difference between both groups regarding total adipose tissue index (TATI) (p = 0.10), visceral adipose tissue index (VATI) (p = 0.51), intramuscular adipose tissue index (IMATI) (p = 0.38), skeletal muscle index (SMI) (p = 0.83), and sarcopenia (p = 0.75). In the multivariate analysis, CrF was significantly associated with severe disease (odds ratio [OR] 11.50, 95% confidence interval [CI] 3.13-42.17; p ≤0.001). Additionally, a BMI ≥ 25 (kg/m2) was protective against severe disease (OR: 0.34, 95% CI 0.12-0.95; p = 0.04).

CONCLUSION

CrF is significantly associated with CD activity.

Replacing Endoscopy with Magnetic Resonance Enterography for Mucosal Activity Assessment in Terminal Ileal Crohn's Disease: Are We There Yet?

Crohn's disease (CD) is a chronic immune mediated disorder that most commonly affects the small bowel and/or the large bowel. Treatment targets in CD include mucosal healing assessed via ileocolonoscopy and transmural healing assessed through cross-sectional imaging modalities such as magnetic resonance enterography (MRE). More recently, histological healing in CD has emerged as a treatment target, though it is made cumbersome given its reliance on frequent endoscopic examinations. With expert guidelines now recommending regular objective assessments as part of a treat-to-target approach, accurate non-invasive assessment will become increasingly critical. MRE has an established role in the assessment of small bowel CD, with growing data supportive of its ability in detecting disease activity at mucosal and histological levels. This could therefore potentially reduce the need for serial endoscopic assessment. Thus, this review will assess the capacity of individual MRE parameters and MRE indices for detecting mucosal and histological small bowel CD activity. Furthermore, challenging scenarios, such as CD activity detection in post-operative clinical scenarios and abnormal findings in the context of a normal ileocolonoscopy, will be explored.

Integrating Radiomics With Clinicoradiological Scoring Can Predict High-Risk Patients Who Need Surgery in Crohn's Disease: A Pilot Study

BACKGROUND

Early identification of Crohn's disease (CD) patients at risk for complications could enable targeted surgical referral, but routine magnetic resonance enterography (MRE) has not been definitively correlated with need for surgery. Our objective was to identify computer-extracted image (radiomic) features from MRE associated with risk of surgery in CD and combine them with clinical and radiological assessments to predict time to intervention.

METHODS

This was a retrospective single-center pilot study of CD patients who had an MRE within 3 months prior to initiating medical therapy. Radiomic features were extracted from annotated terminal ileum regions on MRE and combined with clinical variables and radiological assessment (via Simplified Magnetic Resonance Index of Activity scoring for wall thickening, edema, fat stranding, ulcers) in a random forest classifier. The primary endpoint was high- and low-risk groups based on need for surgery within 1 year of MRE. The secondary endpoint was time to surgery after treatment.

RESULTS

Eight radiomic features capturing localized texture heterogeneity within the terminal ileum were significantly associated with risk of surgery within 1 year of treatment (P < .05); yielding a discovery cohort area under the receiver-operating characteristic curve of 0.67 (n = 50) and validation cohort area under the receiver-operating characteristic curve of 0.74 (n = 23). Kaplan-Meier analysis of radiomic features together with clinical variables and Simplified Magnetic Resonance Index of Activity scores yielded the best hazard ratio of 4.13 (P = (7.6 × 10-6) and concordance index of 0.71 in predicting time to surgery after MRE.

CONCLUSIONS

Radiomic features on MRE may be associated with risk of surgery in CD, and in combination with clinicoradiological scoring can yield an accurate prognostic model for time to surgery.

Body Composition Predictors of Complicated Crohn's Disease

BACKGROUND

High visceral adipose tissue (VAT) and creeping fat (CrF) in Crohn's disease (CD) have been widely recognized. The VAT to subcutaneous adipose tissue (SAT) ratio and sarcopenia have been associated with CD complications. Studies regarding the influence of body composition predictors on CD complications assessed with magnetic resonance enterography (MRE) are scarce.

AIM

The aim of this study was to assess body composition parameters and CrF in opportunistic MRE as predictors of complicated CD.

METHODS

This was a retrospective study of 114 patients with inflammatory (n = 54) and complicated (n = 60) CD. The semiautomated assessment of body composition and the qualitative evaluation of CrF were performed.

RESULTS

Body composition parameters did not differ between both groups regarding the body mass index (p = 0.50), total adipose tissue index (TATI) (p = 0.14), subcutaneous adipose tissue index (SATI) (p = 0.17), visceral adipose tissue index (VATI) (p = 0.33), VAT/SAT ratio (p = 0.77), intramuscular adipose tissue (p = 0.64), skeletal muscle index (p = 0.22), and sarcopenia (p = 0.50). 47 strictures, 18 fistulae, and seven abscesses were identified. Fistulae were more likely to occur in patients with CrF (odds ratio [OR] 5.07, 95% confidence interval [CI] 1.76-14.56; p=<0.001) and high VAT/SAT ratio (OR: 3.82, 95% CI 1.34-10.85; p = 0.01).

CONCLUSION

Body composition measurements in CD patients displayed no statistically significant difference between the groups of inflammatory and complicated disease. Nonetheless, CD patients stratified in the group of high VAT/SAT ratio and the presence of CrF should be recognized as risk groups for the occurrence of fistulae.

Development of a multimodal machine-learning fusion model to non-invasively assess ileal Crohn's disease endoscopic activity

BACKGROUND AND OBJECTIVE

Recurrent attentive non-invasive observation of intestinal inflammation is essential for the proper management of Crohn's disease (CD). The goal of this study was to develop and evaluate a multi-modal machine-learning (ML) model to assess ileal CD endoscopic activity by integrating information from Magnetic Resonance Enterography (MRE) and biochemical biomarkers.

METHODS

We obtained MRE, biochemical and ileocolonoscopy data from the multi-center ImageKids study database. We developed an optimized multimodal fusion ML model to non-invasively assess terminal ileum (TI) endoscopic disease activity in CD from MRE data. We determined the most informative features for model development using a permutation feature importance technique. We assessed model performance in comparison to the clinically recommended linear-regression MRE model in an experimental setup that consisted of stratified 2-fold validation, repeated 50 times, with the ileocolonoscopy-based Simple Endoscopic Score for CD at the TI (TI SES-CD) as a reference. We used the predictions' mean-squared-error (MSE) and the receiver operation characteristics (ROC) area under curve (AUC) for active disease classification (TI SEC-CD≥3) as performance metrics.

RESULTS

121 subjects out of the 240 subjects in the ImageKids study cohort had all required information (Non-active CD: 62 [51%], active CD: 59 [49%]). Length of disease segment and normalized biochemical biomarkers were the most informative features. The optimized fusion model performed better than the clinically recommended model determined by both a better median test MSE distribution (7.73 vs. 8.8, Wilcoxon test, p<1e-5) and a better aggregated AUC over the folds (0.84 vs. 0.8, DeLong's test, p<1e-9).

CONCLUSIONS

Optimized ML models for ileal CD endoscopic activity assessment have the potential to enable accurate and non-invasive attentive observation of intestinal inflammation in CD patients. The presented model is available at https://tcml-bme.github.io/ML_SESCD.html.

Development, Validation, and Evaluation of the Pediatric Inflammatory Crohn's Magnetic Resonance Enterography Index From the ImageKids Study

BACKGROUND & AIMS

Cross-sectional imaging is important in the assessment of transmural inflammation in Crohn's disease (CD). Small bowel involvement is often more extensive in pediatric CD, requiring a panentering measuring tool. We undertook to develop a magnetic resonance enterography (MRE)-based index that would measure inflammation in all segments of the intestine, without rectal contrast.

METHODS

Children with CD underwent ileocolonoscopy and MRE and half were prospectively followed for 18 months when MRE was repeated. Item generation and reduction were performed by a Delphi panel of pediatric radiologists, a systematic literature review, a cross-sectional study of 48 MREs, and a steering committee. Formatting and weighting were performed using multivariate modeling adjusted by a steering committee. MREs were read locally and centrally. Reliability, validity, and responsiveness were determined using several clinimetric and psychometric approaches.

RESULTS

Thirty items were initially generated and reduced to 5 using regression analysis on 159 MREs: wall thickness, wall diffusion weighted imaging, ulcerations, mesenteric edema, and comb sign. In the validation cohort of 81 MREs, the weighted global PICMI correlated well with the radiologist global assessment (r = 0.85; P < .001) and with the simple endoscopic score in a subsample with ileocolonic disease (r = 0.63; P < .001). Interobserver and test-retest reliability were high (interclass correlation coefficients, 0.84; 95% confidence interval [CI], 0.79-0.87; and 0.81, 95% CI, 0.65-0.90, respectively; both P < .001). Excellent responsiveness was found at repeated visits (n = 116 MREs; area under the receiver operating characteristic curve 0.96; 95% CI, 0.93-0.99). Transmural healing was defined as PICMI ≤10 and response as a change of >20 points with excellent discriminative validity (area under the receiver operating characteristic curve = 0.96; 95% CI, 0.93-0.99).

CONCLUSIONS

The PICMI is a valid, reliable, and responsive index for assessing transmural inflammation in pediatric CD. It scores the entire bowel length and does not require intravenous contrast or rectal enema and, therefore, is suitable for use in children. (ClinicalTrials.gov, Number: NCT01881490.).

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.

Simplified Magnetic Resonance Index of Activity Is Useful for Terminal Ileal but not Colonic Disease in Pediatric Crohn Disease

BACKGROUND

Ileocolonoscopy (IC) detects mucosal inflammation and magnetic resonance enterography (MRE) detects transmural inflammation in Crohn disease (CD). We aimed to evaluate the relationship between the simplified magnetic resonance index of activity (MARIAs) and measures of inflammation by IC in children with newly diagnosed CD.

METHODS

Retrospective review of 140 patients 6-18 years of age with CD who had baseline IC and MRE within 5 weeks of diagnosis. MARIAs was calculated for each intestinal segment (terminal ileum [TI], ascending colon, transverse colon, descending colon, sigmoid colon, rectum), defined as (1 × thickness > 3 mm) + (1 × edema) + (1 × fat stranding) + (2 × ulcers). Sensitivity and specificity were derived using receiver operating characteristic (ROC) curves to compare MARIAs to IC findings.

RESULTS

Using IC as the reference standard, the cutoff MARIAs ≥1 identified TI segments with active inflammation with 84% sensitivity, 73% specificity, 85% positive predictive value (PPV), 70% negative predictive value (NPV), and area under the curve (AUC) 0.782 (95% confidence interval [CI] 0.689-0.876). The cutoff MARIAs ≥2 identified TI segments with severe lesions with 87% sensitivity, 76% specificity, 87% PPV, 76% NPV, and AUC 0.814 (95% CI 0.712-0.916). There was poor sensitivity for all colonic segments.

CONCLUSION

The MARIAs is feasible and accurate in reflecting disease activity in the TI, but not in the colon, in children with newly diagnosed CD. Although the MARIAs may be useful for monitoring TI disease activity over time, full assessment continues to require both IC and MRE.

Radiology plus ileocolonoscopy versus radiology alone in Crohn's disease: prognosis prediction and mutual agreement

BACKGROUND/AIMS

The optimal tools for monitoring Crohn's disease (CD) are controversial. We compared radiology plus ileocolonoscopy and radiology alone in terms of prognosis prediction and evaluated the agreement between radiologic and ileocolonoscopic findings in patients with CD.

METHODS

Patients with CD who were followed up with computed tomography enterography (CTE) or magnetic resonance enterography (MRE) alone or CTE or MRE plus ileocolonoscopy were retrospectively recruited. Time to relapse was investigated to evaluate the difference in prognosis using the log-rank and Cox regression tests, and the agreement between radiologic and ileocolonoscopic findings was determined using a kappa value.

RESULTS

A total of 501 patients with CD in clinical remission who underwent CTE or MRE and/or ileocolonoscopy were analyzed. Of these, 372 (74.3%) patients underwent CTE or MRE alone and 129 (25.7%) patients underwent CTE or MRE plus ileocolonoscopy. The cumulative maintenance rate of clinical remission between the two groups was not significantly different (p = 0.526, log-rank test). In multivariate analysis, age <40 years (hazard ratio [HR], 2.756; 95% confidence interval [CI], 1.263 to 6.013) and a history of steroid use (HR, 2.212; 95% CI, 1.258 to 3.577) were found to independently predict an increased risk for clinical relapse in patients with CD in clinical remission. Radiologic and ileocolonoscopic findings had a moderate degree of agreement (κ = 0.401, -0.094 to 0.142). The comparison of agreement between radiologic and ileocolonoscopic findings was the highest in the anastomotic site (κ = 0.749, -0.168 to 0.377).

CONCLUSION

Radiology plus ileocolonoscopy was not superior to radiology alone in predicting the prognosis of CD.

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.

Monitoring established Crohn's disease with pan-intestinal video capsule endoscopy in Europe: clinician consultation using the nominal group technique

OBJECTIVE

Monitoring established Crohn's disease (CD) through a "treat-to-target" strategy aims to reduce and prevent long-term bowel damage and disability. Despite the availability of different monitoring techniques, there is a current lack of integrated evidence to guide optimal monitoring in terms of appropriate tools and timing. Pan-intestinal video capsule endoscopy (PCE) enables non-invasive and direct visualization of the entire intestinal tract with proven safety and efficacy. This study aims to generate insights on the value of PCE for monitoring established CD from the physician's perspective.

METHODS

The Nominal Group Technique (NGT) was used to create discussion around pre-defined research questions aimed at identifying target patient populations for PCE, benefits of PCE in terms of improving disease management, comparative benefits of PCE over standard of care, research priorities to ratify the use of PCE, and hurdles to PCE utilization. A NGT panel was held in Brussels, Belgium in October 2018 with 9 gastroenterology experts. Data were collected from multiple rankings of statements to the research questions and analyzed descriptively.

RESULTS

Consensus indicated that PCE is differentiated from other diagnostic tools, allowing for non-invasive and direct visualization of the luminal intestinal tract in one single procedure. Participants agreed that PCE is beneficial for mapping and grading established CD in all patients, enabling individual and tailored treatment decision-making. Time required to read PCE results was identified as the main utilization hurdle by participants. Well-designed studies are needed to confirm improved outcomes amongst patients with CD managed through a PCE-guided approach.

CONCLUSIONS

This study, using the NGT, generated expert opinion on the value of PCE for monitoring established CD in terms of target patient populations and benefits compared to other diagnostic modalities. Participants perceived PCE to facilitate a "treat-to-target" strategy for CD management. Further research is needed to support this value perception.

Magnetic resonance imaging in the management of Crohn's disease: a systematic review and meta-analysis

Objectives

Crohn’s disease (CD) is a condition that can occur in any part of the gastrointestinal tract, although usually forms in the colon and terminal ileum. Magnetic resonance imaging (MRI) has become a beneficial modality in the evaluation of small bowel activity. This study reports on a systematic review and meta-analysis of magnetic resonance enterography for the prediction of CD activity and evaluation of outcomes and possible complications.

Methods

Following the PRISMA guidelines, a total of 25 low-risk studies on established CD were selected, based on a QUADAS-II score of ≥ 9.

Results

A sensitivity of 90% was revealed in a pooled analysis of the 19 studies, with heterogeneity of χ² = 81.83 and I² of 80.3%. Also, a specificity of 89% was calculated, with heterogeneity of χ² = 65.12 and I² of 70.0%.

Conclusion

It was concluded that MRI provides an effective alternative to CT enterography in the detection of small bowel activity in CD patients under supervision of radiologist for assessment of disease activity and its complications. Its advantages include the avoidance of radiation exposure and good diagnostic accuracy.

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.

Qualitative sonographic assessment of transmural ileal inflammation in Crohn's disease: a comparison with MRI activity score

BACKGROUND

Intestinal ultrasound (IUS) is an accurate tool for monitoring Crohn's disease. To date, there is no clinically used validated quantitative ultrasonographic score for assessing disease activity. For magnetic resonance enterography (MRE), the magnetic resonance index of activity (MaRIA) is most used. The goal of this study was to devise a new quantitative IUS score for assessing Crohn's disease inflammation, by using a partial MaRIA score as a reference.

METHODS

This was a retrospective cohort study. The study cohort included patients with Crohn's disease followed between January 2016 and December 2018. Inclusion criteria were age >18 and <3 months between MRE and IUS. Linear/logistic regression was performed for the correlation of ultrasonographic parameters with MaRIA score. Ultrasonograpic features included: bowel wall thickness, disrupted bowel wall stratification, mesenteric fat proliferation, presence of lymph nodes, hypervascularity present on color Doppler flow, and the presence of complications (strictures, inflammatory mass, and fistula).

RESULTS

Forty-two patients were included. A stepwise multiple regression model was constructed to predict MaRIA score using ultrasound features. Two variables were found to be independently significant: terminal ileum (TI) thickness (r = 0.68, P = 0.001) and mesenteric fat proliferation (r = 0.45, P = 0.019). A model was constructed as follows: MaRIA = 7 + 2.5 * TI US thickness (mm) + 7 * US fat proliferation (0 = no, 1 = yes). This model has an R2 of 0.51 for explaining the variability in the results.

CONCLUSIONS

IUS measurements are significantly correlated with MaRIA score in the terminal ileum and a simple computational model can be constructed.

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.

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.

Comparison between Diffusion-Weighted Sequences with Selective and Non-Selective Fat Suppression in the Evaluation of Crohn's Disease Activity: Are They Equally Useful?

Background: We compared the efficiency of two MRI diffusion weighted imaging (DWI) techniques: DWI with SPIR (DWI_SPIR) and DWI with STIR (DWI_STIR), to estimate their eligibility for quantitative assessment of Crohn’s disease activity in children and adults. Methods: In inflamed terminal ileum segments (n = 32 in adults, n = 46 in children), Magnetic Resonance Index of Activity (MaRIA) was calculated, ADC values of both DWI techniques were measured, and the corresponding Clermont scores calculated. ADC values of both DWI techniques were compared between both and within each patient group, assessing their mutual correlation. Correlations between MaRIA and the corresponding ADC values, and Clermont scores based on both DWI techniques were estimated. Results: No correlation between ADC of DWI_SPIR and DWI_STIR was observed (rho = 0.27, p = 0.13 in adults, rho = 0.20, p = 0.17 in children). The correlation between MaRIA and Clermont scores was strong in both techniques—in SPIR, rho = 0.93; p < 0.0005 in adults, rho = 0.98, p < 0.0005 in children, and, in STIR, rho = 0.89; p < 0.0005 in adults, rho = 0.95, p < 0.0005 in children. The correlation between ADC and MaRIA was moderate negative for DWI_STIR (rho = 0.93, p < 0.0005 in adults, rho = 0.95, p < 0.0005 in children), but, in DWI_STIR, no correlation between ADC and MaRIA score was observed in adults (rho = −0.001, p = 0.99), whereas children presented low negative correlation (rho = −0.374, p = 0.01). Conclusions: DWI_STIR is not suitable for quantitative assessment of Crohn’s disease activity both in children and adult patients.

Crohn's disease: prevalence, MR features, and clinical significance of enteric and colonic sinus tracts

Objectives

Enteric and colonic sinus tracts are inflammatory complications that precede intestinal fistulas in patients with Crohn’s disease (CD). The aim of this study was to retrospectively determine the prevalence, morphologic features, and outcome of sinus tracts using MR imaging.

Methods

A consecutive cohort of 642 patients with known CD, referred for MR enterography or MR enteroclysis (study period 01/2014–09/2019), was evaluated retrospectively for the presence of sinus tracts, their locations, presence and length of coexisting strictures, bowel wall thickness, CDMI score, upstream dilation, and bowel distension. Clinical outcome was assessed using medical records. For metric data, means and standard deviation, as well as one-way ANOVA and Pearson’s correlation coefficient, were calculated.

Results

In 36/642 patients with CD undergoing MRE, 49 sinus tracts (forty in small intestine, nine in left-sided colon) were detected with a prevalence of 6.9% in patients with MR-visible signs of CD (n = 519, overall prevalence of 5.6%). Mean segmental bowel wall thickness was 8.9 mm, and mean CDMI score was 9.3. All sinus tracts were located within a stenotic segment, showing mesenteric orientation within the small bowel and upstream dilation in 13 patients. Of 36 patients, 19 underwent immediate surgery and seven developed clinical progression within the segment containing the sinus tract.

Conclusions

Sinus tracts occur in 6.9% of patients with visible signs of CD. They are located within stenotic, severely thickened bowel segments with high MR inflammation scores. Their detection is clinically important, because they indicate a more aggressive phenotype and, if left untreated, may show severe progression.

Key Points

• Sinus tracts occur in 6.9% of patients with MR-visible signs of Crohn’s disease.

• Sinus tracts are a radiological indicator of early penetrating Crohn’s disease, with a high risk of progression, and require dedicated treatment.

• Sinus tracts can be recognized by characteristic findings and typically occur in stenotic, severely thickened bowel segments with high MR inflammation scores.

Quantitative evaluation of Crohn's disease using dynamic contrast-enhanced MRI in children and young adults

OBJECTIVES

To evaluate the clinical usefulness of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in children and young adults with Crohn's disease.

METHODS

From August 2017 to October 2018, 30 patients with Crohn's disease (21 males and 9 females; mean age 15.1 ± 2.5 years) underwent DCE-MRI with MRI enterography. We assessed the endoscopic finding, pediatric Crohn's disease activity index (PCDAI), C-reactive protein (CRP) level (mg/dL), Crohn's disease MR index (CDMI) score, and the perfusion parameters of DCE-MRI (K^trans, K^ep, and V^e) at the ileocecal region between the inactive and active groups based on the histopathologic status.

RESULTS

The active Crohn's disease group showed higher PCDAI, CRP, and CDMI scores than the inactive group (22.2 ± 18.8 vs. 6.3 ± 6.4, p = 0.027; 1.32 ± 1.79 vs. 0.10 ± 0.13, p = 0.005; 7.4 ± 3.9 vs. 4.5 ± 3.0, p = 0.047, respectively). The active Crohn's disease group showed a higher K^trans value than the inactive group (0.31  ±  0.12 vs. 0.16 ±  0.46 min^-1, p = 0.002). Endoscopic finding; PCDAI, CRP, and CDMI scores; and K^trans value were significant parameters in the identification of the active Crohn's disease (p = 0.002, p < 0.001, p = 0.029, p = 0.006, and p < 0.001, respectively). K^trans value was the most significant value for identifying active Crohn's disease in the multivariate logistic regression analysis (p = 0.013).

CONCLUSION

K^trans value could discriminate between inactive and active Crohn's diseases. K^trans value may have the potential to monitor the pediatric Crohn's disease activity.

KEY POINTS

• With dynamic contrast-enhanced MRI, we can quantitatively monitor the Crohn's disease status in pediatric patients and provide proper management plans to clinicians. • The K^transvalue of dynamic contrast-enhanced MRI perfusion parameter, as well as the clinical pediatric Crohn's disease activity index, C-reactive protein level, the endoscopic score, and the Crohn's disease MR index, was higher in the active Crohn's disease than in the inactive group based on the histopathologic status. • The K^transvalue among the dynamic contrast-enhanced MRI perfusion parameters was the most significant differentiating parameter for the active Crohn's disease from inactive status among those parameters (p = 0.013).

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.

Lemann Index for Assessment of Crohn's Disease: Correlation with the Quality of Life, Endoscopic Disease Activity, Magnetic Resonance Index of Activity and C- Reactive Protein

AIM

Crohn's disease (CD) is characterized by continuing inflammation and progressive gut damage. Despite many scoring indices of CD, there is a lack of more global assessment tools for the evaluation of the total disease impact on the gut.

METHODS

Fift y-three adult patients with proven CD underwent magnetic resonance enterocolonography (MR-EC), colonoscopy, and clinical activity assessment, including CRP. Quality of life was assessed using IBDQ. MR-EC was used to evaluate the Magnetic Resonance Index of Activity (MaRIA- global (G)) and the Lemann Index (LI). The CD Endoscopic Index of Severity (CDEIS) was used to score the endoscopic activity of the disease.

RESULTS

A signifi cant correlation between the LI and IBDQ was found (r=-0.812, P<0.01). LI and MaRIA-G correlated moderately, while the LI did not correlate significantly with CRP and CDEIS. For the detection of endoscopically active CD, MaRIA-G was more sensitive and specific (83.3%; 73.3%) compared to the LI (66.7%; 60.0%). There was a moderate correlation between CRP and MaRIA-G, as well as CRP and CDEIS (r=0.496; r=0.527,<0.01).

CONCLUSION

A signifi cant negative correlation between the LI and quality of life, measured by IBDQ, was found in our study, suggesting that the LI could resemble more global features of the disease, besides inflammatory activity of the gut.

Chronic Granulomatous Disorder-Associated Colitis Can Be Accurately Evaluated with MRI Scans and Fecal Calprotectin Level

Purpose

Colitis is a common and serious complication of chronic granulomatous disorder (CGD) and requires assessment. Colonoscopy is invasive and carries risks of serious complication. We therefore assessed non-invasive monitoring via magnetic resonance imaging (MRI). We also evaluated fecal calprotectin (FCP), the Harvey-Bradshaw index (HBI) clinical score, and serum cytokines.

Methods

We recruited 10 patients with CGD (8 males, mean age 29.6 years), scored a modified HBI, and obtained stool for FCP. The following day we took blood for cytokine measurement via Luminex, performed MR enterography (scored by two independent radiologists using three systems: London score, CDMI, and MaRIA) followed by colonoscopy with disease activity measurement via ulcerative colitis endoscopic index of severity (UCEIS). We assessed patient experience after each investigation and overall preference with follow-up questionnaires.

Results

MRI scores correlated well with colonoscopic gold standard (for London score R² 0.91, p < 0.0001; for CDMI R² 0.83, p = 0.0006; for MaRIA R² 0.89, p = 0.0002). MRI was better tolerated and generally preferred, quicker, and visualized the entire large bowel whereas colonoscopy did not reach the terminal ileum in 3 participants. Elevated FCP accurately differentiated patients with colitis from those without, and log(calprotectin) correlated well with disease activity (R² 0.71, p = 0.009). Serum interleukin (IL)-12 concentration correlated with colitis activity but IL-1β and TNF did not. Harvey-Bradshaw index did not correlate with colitis activity.

Conclusions

MRI and fecal calprotectin are useful methods for monitoring CGD colitis and should reduce the need for colonoscopy in these patients. IL-12 may represent an appropriate target for treatment.

Electronic supplementary material

The online version of this article (10.1007/s10875-019-00651-2) contains supplementary material, which is available to authorized users.

Faecal Calprotectin and Magnetic Resonance Enterography in Ileal Crohn's Disease: Correlations Between Disease Activity and Long-Term Follow-Up

BACKGROUND AND AIMS

Magnetic resonance enterography [MRE] is the gold standard for assessing ileal inflammation in Crohn's disease [CD]. The aim of the present study was to correlate faecal calprotectin [FC] to MRE via a simple score in an exclusive ileal cohort with long-term follow-up for association with time to surgery or biologic therapy.

METHODS

In total, 150 MRE studies with matched FC [±30 days] were identified from the Edinburgh FC Register [2008-12; n = 18138]. Scans were re-read blinded to clinical data, independently, by two expert gastrointestinal radiologists, to generate a simple MRE score [range 0-10] from assessment of the worst intestinal segment plus total disease extent.

RESULTS

In total, 119 MRE scans were evaluated from 104 patients with ileal CD [L1 or L3 with panproctocolectomy]. Receiver operating characteristic analysis showed an area under the curve of 0.77 [0.67-0.87, p < 0.0001] for FC and MRE score >1, with an optimal cut-off of 145 μg/g for severe inflammation on MRE with 69.3% [57.6-79.5] sensitivity and 71.4% [53.7-85.4] specificity. Long-term follow-up over a median [interquartile range] of 2086 days [1786-2353] revealed FC ≥ 145 μg/g was associated with reduced biologic-free survival until 3 years following MRE, whereas MRE score [severe vs absent] was associated with reduced surgery- and biologic-free survival throughout follow-up. Backwards stepwise logistic regression revealed that length of ileal disease (odds ratio [OR] 3.8, 1.1-13.2, p = 0.034) and increased bowel wall thickness at MRE [OR 4.2, 1.6-10.7, p < 0.0001] or female sex [OR 5.2, 1.5-18.7, p = 0.011] increased the risk of biologic use or surgery, respectively.

CONCLUSIONS

FC correlates well with MRE assessment of ileal CD with MRE parameters associated with long-term biologic- and surgery-free remission.

Treat-to-target in Crohn's disease: Will transmural healing become a therapeutic endpoint?

Crohn's disease (CD) represents a chronic transmural inflammatory condition of the gastrointestinal tract, which usually leads to structural damage and significant disability. Deep remission - defined by both clinical and endoscopic remission, signifying mucosal healing - represents the current endpoint in the treat-to-target strategy, significantly improving patients' long-term outcomes. Transmural healing (TH) could be a more effective target, but this possibility remains unclear. This narrative review aims to critically review and summarize the available literature relating TH to long-term outcomes, being the first of its kind and to the best of the author's knowledge. A systematic literature search (from inception to March 31 2018) was performed, using multiple databases, and identifying seven full-text manuscripts. In those studies, long-term favorable outcomes (≥ 52 wk) included sustained clinical remission, as well as fewer therapeutic changes, CD-related hospitalizations, and surgeries. Despite heterogeneous design and methodological limitations, six of the studies demonstrated that TH or intestinal healing (TH plus mucosal healing) were predictive for the aforementioned favorable outcomes. Therefore, TH may become a reasonable therapeutic target and be included in the concept of deep remission. Further prospective, well-designed, multicenter trials aiming to better define the role of TH in personalized therapy for CD and to determine the long-term influence of TH on bowel damage and disability are warranted.