Small bowel strictures in Crohn's disease: a quantitative investigation of intestinal motility using MR enterography

Small Bowel Motility Quantified by Cine MRI to Predict Longer-Term Response in Patients with Crohn's Disease Commencing Biological Therapy: The Motility Study

BACKGROUND

Small bowel Crohn's disease (SBCD) is increasingly treated with biological therapies. Predicting response or remission (RoR) for individual patients is difficult and complicates treatment strategy. We aimed to determine if motility magnetic resonance imaging (mMRI) is superior to CRP and fecal calprotectin (FC) for the prediction of RoR at 1 year in patients commencing biologics for SBCD.

METHODS

Prospective, multicenter (n = 13) cohort study of patients with active non-stricturing SBCD requiring anti-TNFα or anti-IL-12/23 treatment. We measured mMRI and CRP at baseline and post-induction (visit 2: 12-30 weeks), and FC in a subset. RoR was assessed at 1 year using clinical and structural magnetic resonance enterography parameters. We compared sensitivity, specificity, and area under the receiver operating characteristic curve (ROC-AUC) of changes in mMRI and CRP to predict RoR at 1 year. Secondary outcomes compared mMRI with FC, and prediction of improved quality of life (QoL).

RESULTS

Eighty-six participants completed all assessments. Stable or improved mMRI at visit 2 was more sensitive than normalization of CRP for RoR (mMRI:71.0%, 95%CI 52.0-85.8; CRP:45.2%, 95%CI 27.3-64.0%, P = .008) but less specific (mMRI:30.9%, 95%CI 19.1-44.8; CRP:67.3%, 95%CI 53.3-79.3%, P < .001). There was no significant difference in ROC-AUC (mMRI:0.48; CRP:0.53, P = .65). Similar results were obtained for FC. None of mMRI, CRP, or FC predicted patient QoL at 1 year.

CONCLUSIONS

Although improved mMRI is more sensitive than CRP and FC to predict RoR at 1 year, it is less specific. No factor predicted patient QoL. Motility MRI remains a marker of disease activity at given timepoints.

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.

Muscular hyperplasia in Crohn's disease strictures: through thick and thin

Fibrostenosing Crohn's disease (CD) represents a challenging clinical condition characterized by the development of symptomatic strictures within the gastrointestinal tract. Despite therapeutic advancements in managing inflammation, the progression of fibrostenotic complications remains a significant concern, often necessitating surgical intervention. Recent investigations have unveiled the pivotal role of smooth muscle cell hyperplasia in driving luminal narrowing and clinical symptomatology. Drawing parallels to analogous inflammatory conditions affecting other organs, such as the airways and blood vessels, sheds light on common underlying mechanisms of muscular hyperplasia. This review synthesizes current evidence to elucidate the mechanisms underlying smooth muscle cell proliferation in CD-associated strictures, offering insights into potential therapeutic targets. By highlighting the emerging significance of muscle thickening as a novel therapeutic target, this review aims to inform future research endeavors and clinical strategies with the goal to mitigate the burden of fibrostenotic complications in CD and other conditions.

Motility Mapping Quantification Using the Classical Optical Flow Algorithm for Small Bowel Crohn's Disease: Comparison with Balloon-assisted Enteroscopy Findings

PURPOSE

To quantify bowel motility shown on cine MRI using the classical optical flow algorithm and compare it with balloon-assisted enteroscopy (BAE) findings in patients with Crohn's disease (CD).

METHODS

This retrospective study included 29 consecutive patients with CD who had undergone MR enterocolonography (MREC) and BAE between March and May 2017. We developed computer software to present motion vector magnitudes between consecutive cine MR images as bowel motility maps via a classical optical flow algorithm using the Horn-Schunck method. Cine MR images were acquired with a balanced steady-state free precession sequence in the coronal direction to capture small bowel motility. The small bowels were divided into three segments. In total, 63 bowel segments were assessed via BAE and MREC. Motility scores on the maps, simplified MR index of activity (sMaRIA), and MREC score derived from a 5-point MR classification were assessed independently by two radiologists and compared with the CD endoscopic index of severity (CDEIS). Correlations were assessed using Spearman's rank coefficient. The areas under the receiver-operating characteristic curve (AUCs) of motility score for differentiating CDEIS was calculated; a P value < 0.05 was considered statistically significant.

RESULTS

Motility score was negatively correlated with CDEIS (r = -0.59 [P < 0.001] and -0.54 [P < 0.001]), and the AUCs of motility scores for detecting CDEIS ≥ 3 were 88.2% and 78.6% for observers 1 and 2, respectively. There were no significant differences in the AUC for detecting CDEIS ≥ 3 and CDEIS ≥ 12 between motility and sMaRIA or MREC score.

CONCLUSION

The motility map was feasible for locally quantifying the bowel motility. In addition, the motility score on the map reflected the endoscopic inflammatory activity of each small bowel segment in patients with CD; hence, it could be used as a tool in objectively interpreting cine MREC to predict inflammatory activity in CD.

Preoperative small bowel dilation is associated with ileus after right colectomy

Background

The relationship between preoperative bowel dysfunction and postoperative ileus has not been explored clinically. We hypothesized chronic partial obstruction, based on preoperative small bowel diameter, is associated with ileus after colon surgery.

Methods

This was a retrospective case-control study of patients undergoing right colectomy or ileocolic resection with primary anastomosis. Patients who developed ileus were compared to those who did not.

Results

Postoperative ileus occurred in 22 of 69 patients (32%). Preoperative small bowel dilation with maximum diameter >3 cm was present in 13 patients (19%) with 7 developing ileus (54%; p=0.06). In a multivariable model, small bowel dilation >3 cm (OR 4.6; 95% CI: 1.3-16.6) and preoperative weight loss >10 pounds (OR 9.8; 95% CI: 1.6-57.9) were independently associated with ileus.

Conclusions

Colorectal surgery patients with preoperative bowel dilation have an increased risk of postoperative ileus. This knowledge can better inform patient expectations for recovery and help guide perioperative nutritional management, particularly with patient selection for parenteral nutrition.

Impact of bowel dilation on small bowel motility measurements with cine-MRI: assessment of two quantification techniques

Objectives

To evaluate the effect of bowel dilation on cine-MRI small bowel motility measurements, by comparing a conventional motility score (including bowel wall and lumen) with a bowel wall-specific motility score in healthy and diseased populations.

Methods

Four populations were included: 10 Crohn's patients with a stricture and prestricture dilation for segmental motility analysis, and 14 mannitol-prepared healthy subjects, 15 fasted healthy subjects and eight chronic intestinal pseudo-obstruction (CIPO) patients (characterized by dilated bowel loops) for global small bowel motility analysis. All subjects underwent a cine-MRI scan from which two motility scores were calculated: a conventional score (including bowel wall and lumen) and a bowel wall-specific score. The difference between the two scores was calculated per population and compared between groups with a one-way ANOVA and Tukey-Kramer analysis.

Results

In Crohn's patients, the median (IQR) change between the conventional and wall-specific motility score was 0% (-2 to +4%) within the stricture and 0% (-1 to +7%) in the prestricture dilation. For the global small bowel, this was -1% (-5 to 0%) in mannitol-prepared healthy subjects, -2% (-6 to +2%) in fasted healthy subjects and +14% (+6 to+20%) in CIPO patients. The difference between the two motility scores in CIPO patients differed significantly from the four other groups (p = 0.002 to p < 0.001).

Conclusions

The conventional small bowel motility score seems robust in Crohn's disease patients and healthy subjects. In patients with globally and grossly dilated bowel loops, a bowel-wall specific motility score may give a better representation of small bowel motility.

Advances in knowledge

These findings support researchers and clinicians with making informed choices for using cine-MRI motility analysis in different populations.

Automatic detection of Crohn's disease using quantified motility in magnetic resonance enterography: initial experiences

AIM

To report initial experiences of automatic detection of Crohn's disease (CD) using quantified motility in magnetic resonance enterography (MRE).

MATERIALS AND METHODS

From 302 patients, three datasets with roughly equal proportions of CD and non-CD cases with various illnesses were drawn for testing and neural network training and validation. All datasets had unique MRE parameter configurations and were performed in free breathing. Nine neural networks were devised for automatic generation of three different regions of interests (ROI): small bowel, all bowel, and non-bowel. Additionally, a full-image ROI was tested. The motility in an MRE series was quantified via a registration procedure, which, accompanied with given ROIs, resulted in three motility indices (MI). A subset of the indices was used as an input for a binary logistic regression classifier, which predicted whether the MRE series represented CD.

RESULTS

The highest mean area under the curve (AUC) score, 0.78, was reached using the full-image ROI and with the dataset with the highest cine series length. The best AUC scores for the other two datasets were only 0.54 and 0.49.

CONCLUSION

The automatic system was able to detect CD in the group of MRE studies with lower temporal resolution and longer cine series showing potential in primary bowel disorder diagnostics. Larger ROI selections and utilising all available cine series for motility registration yielded slight performance improvements.

Objective evaluation for treat to target in Crohn's disease

BACKGROUND

Crohn's disease (CD) is a chronic and destructive bowel disease; continued disease activity can lead to penetrating complications. With the recent advent of effective medications, the importance of using a treat-to-target approach to guide therapy is becoming important.

METHODS

In this review, we reviewed the previous evidence for evaluating CD lesions.

RESULTS

We describe ileocolonoscopy's role in assessing disease activity, as well as recent progress in modalities, such as balloon-assisted endoscopy, capsule endoscopy, magnetic resonance enterography, computed tomography enterography, and ultrasonography. Advances in modalities have changed CD assessment, with small-bowel involvement becoming more important.

CONCLUSIONS

Proper optimization is necessary in clinical practice.

Will MRI of gastrointestinal function parallel the clinical success of cine cardiac MRI?

Cine cardiac MRI is generally accepted as the "gold-standard" for functional myocardial assessment. It only took a few years after the development of commercial MRI systems for functional cardiac imaging to be developed, with electrocardiogram (ECG)-gated cine imaging first reported in 1988. The function of the gastrointestinal (GI) tract is more complex to study compared to the heart. However, the idea of having a non-invasive tool to study the GI function that also allows the concurrent assessment of different aspects of this function has become more and more attractive in the gastroenterological field. This review summarises key literature of the last 5 years to describe the current status of MRI in respect to the evaluation of GI function, highlighting the gaps and challenges and the future prospects. As the clinical application of a new technique requires that its clinical utility is confirmed by demonstration of its ability to enable clinicians to make a diagnosis and/or predict the treatment response, this review also considers whether or not this has been achieved, and how MRI has been validated against techniques currently recognised as the gold standard in clinical practice.

Consensus Recommendations for Evaluation, Interpretation, and Utilization of Computed Tomography and Magnetic Resonance Enterography in Patients With Small Bowel Crohn's Disease

Computed tomography and magnetic resonance enterography have become routine small bowel imaging tests to evaluate patients with established or suspected Crohn's disease, but the interpretation and use of these imaging modalities can vary widely. A shared understanding of imaging findings, nomenclature, and utilization will improve the utility of these imaging techniques to guide treatment options, as well as assess for treatment response and complications. Representatives from the Society of Abdominal Radiology Crohn's Disease-Focused Panel, the Society of Pediatric Radiology, the American Gastroenterological Association, and other experts, systematically evaluated evidence for imaging findings associated with small bowel Crohn's disease enteric inflammation and established recommendations for the evaluation, interpretation, and use of computed tomography and magnetic resonance enterography in small bowel Crohn's disease. This work makes recommendations for imaging findings that indicate small bowel Crohn's disease, how inflammatory small bowel Crohn's disease and its complications should be described, elucidates potential extra-enteric findings that may be seen at imaging, and recommends that cross-sectional enterography should be performed at diagnosis of Crohn's disease and considered for small bowel Crohn's disease monitoring paradigms. A useful morphologic construct describing how imaging findings evolve with disease progression and response is described, and standard impressions for radiologic reports that convey meaningful information to gastroenterologists and surgeons are presented.

Consensus Recommendations for Evaluation, Interpretation, and Utilization of Computed Tomography and Magnetic Resonance Enterography in Patients With Small Bowel Crohn's Disease

Computed tomography and magnetic resonance enterography have become routine small bowel imaging tests to evaluate patients with established or suspected Crohn's disease, but the interpretation and use of these imaging modalities can vary widely. A shared understanding of imaging findings, nomenclature, and utilization will improve the utility of these imaging techniques to guide treatment options, as well as assess for treatment response and complications. Representatives from the Society of Abdominal Radiology Crohn's Disease-Focused Panel, the Society of Pediatric Radiology, the American Gastroenterological Association, and other experts, systematically evaluated evidence for imaging findings associated with small bowel Crohn's disease enteric inflammation and established recommendations for the evaluation, interpretation, and use of computed tomography and magnetic resonance enterography in small bowel Crohn's disease. This work makes recommendations for imaging findings that indicate small bowel Crohn's disease, how inflammatory small bowel Crohn's disease and its complications should be described, elucidates potential extra-enteric findings that may be seen at imaging, and recommends that cross-sectional enterography should be performed at diagnosis of Crohn's disease and considered for small bowel Crohn's disease monitoring paradigms. A useful morphologic construct describing how imaging findings evolve with disease progression and response is described, and standard impressions for radiologic reports that convey meaningful information to gastroenterologists and surgeons are presented. ^©2018, RSNA, AGA Institute, and Society of Abdominal Radiology This article is being published jointly in Radiology and Gastroenterology.

MRI assessment of the postprandial gastrointestinal motility and peptide response in healthy humans

BACKGROUND

Feeding triggers inter-related gastrointestinal (GI) motor, peptide and appetite responses. These are rarely studied together due to methodological limitations. Recent MRI advances allow pan-intestinal, non-invasive assessment of motility in the undisturbed gut. This study aimed to develop a methodology to assess pan-intestinal motility and transit in a single session using MRI and compare imaging findings to GI peptide responses to a test meal and symptoms in a healthy volunteer cohort.

METHODS

Fifteen healthy volunteers (29.3±2.7 years and BMI 20.1±1.2 kg m^-2 ) underwent baseline and postprandial MRI scans, symptom questionnaires, and blood sampling (for subsequent GI peptide analysis, Glucagon-like peptide-1 [GLP-1], Polypeptide YY [PYY], Cholecystokinin [CCK]) at intervals for 270 minutes following a 400 g soup meal (204 kcal, Heinz, UK). Gastric volume, gall bladder volume, small bowel water content, small bowel motility, and whole gut transit were measured from the MRI scans.

KEY RESULTS

(mean±SEM) Small bowel motility index increased from fasting 39±3 arbitrary units (a.u.) to a maximum of 87±7 a.u. immediately after feeding. PYY increased from fasting 98±10 pg mL^-1 to 149±14 pg mL^-1 at 30 minutes and GLP-1 from fasting 15±3 μg mL^-1 to 22±4 μg mL^-1 . CCK increased from fasting 0.40±0.06 pmol mL^-1 to 0.94±0.1 pmol mL^-1 . Gastric volumes declined with a T_1/2 of 46±5 minute and the gallbladder contracted from a fasting volume of 19±2 mL^-1 to 12±2 mL^-1 . Small bowel water content increased from 39±2 mL^-1 to 51±2 mL^-1 postprandial. Fullness VAS score increased from 9±5 mm to 41±6 mm at 30 minutes postprandial.

CONCLUSIONS AND INFERENCES

The test meal challenge was effective in inducing a change in MRI motility end-points which will improve understanding of the pathophysiological postprandial GI response.

Evaluation of gastrointestinal motility with MRI: Advances, challenges and opportunities

Dynamic magnetic resonance imaging (MRI) of gastrointestinal motility has developed rapidly over the past few years. The non-invasive and non-ionizing character of MRI is an important advantage together with the fact that it is fast and can visualize the entire gastrointestinal tract. Advances in imaging and quantification techniques have facilitated assessment of gastric, small intestinal, and colonic motility in a clinical setting. Automated quantitative motility assessment using dynamic MRI meets the need for non-invasive techniques. Recently, studies have begun to examine this technique in patients, including those with IBD, pseudo-obstruction and functional bowel disorders. Remaining challenges for clinical implementation are processing the large amount of data, standardization and validation of the numerous MRI metrics and subsequently assessment of the potential role of dynamic MRI. This review examines the methods, advances, and remaining challenges of evaluation of gastrointestinal motility with MRI. It accompanies an article by Khalaf et al. in this journal that describes a new protocol for assessment of pan-intestinal motility in fasted and fed state in a single MRI session.

Magnetic resonance evaluation for small bowel strictures in Crohn's disease: comparison with balloon enteroscopy

BACKGROUND

Magnetic resonance (MR) imaging is the recommended technique for detection of small bowel lesions in Crohn's disease. We aimed to evaluate the impact of stricture findings obtained by MR imaging on patient outcomes using balloon-assisted enteroscopy (BAE) as a reference.

METHODS

Two hundred Crohn's disease patients undergoing both MR enterocolonography and BAE were prospectively followed up for at least 1 year. The presence of strictures detected by MR enterocolonography was compared with endoscopic findings. Moreover, the relationship between MR findings and surgery was evaluated.

RESULTS

The accuracy of MR imaging for detection of small bowel strictures was defined by a sensitivity of 60.6% and a specificity of 93.4%. Major strictures (diameter less than 10 mm or with internal fistula), long strictures (length 10 mm or greater), and prestenotic dilatation were predictors of stricture detection by MR imaging (P = 0.001, 0.017, and 0.002 respectively). Surgery was performed in 31.6% of patients (18 of 57) in the MR-positive-BAE-positive stricture group and in 10.8% of patients (4 of 37) in the MR-negative-BAE-positive stricture group. Multiple regression analysis showed MR-positive-BAE-positive strictures were an independent risk factor for surgery (P = 0.002 at 6 months and P < 0.001 at 1 year). The surgery-free rate in the MR-negative-BAE-positive stricture group was significantly lower than that in nonstricture group at 1 year (P = 0.001).

CONCLUSIONS

The specificity of MR imaging for detection of small bowel strictures was clinically sufficient, and the MR procedure could detect critical strictures, which was a predictive factor for surgery. But MR-negative-BAE-positive strictures were also associated with an increased risk compared with no strictures after 1 year of follow-up.

Established and emerging methods for assessment of small and large intestinal motility

BACKGROUND

Gastrointestinal symptoms are common in the general population and may originate from disturbances in gut motility. However, fundamental mechanistic understanding of motility remains inadequate, especially of the less accessible regions of the small bowel and colon. Hence, refinement and validation of objective methods to evaluate motility of the whole gut is important. Such techniques may be applied in clinical settings as diagnostic tools, in research to elucidate underlying mechanisms of diseases, and to evaluate how the gut responds to various drugs. A wide array of such methods exists; however, a limited number are used universally due to drawbacks like radiation exposure, lack of standardization, and difficulties interpreting data. In recent years, several new methods such as the 3D-Transit system and magnetic resonance imaging assessments on small bowel and colonic motility have emerged, with the advantages that they are less invasive, use no radiation, and provide much more detailed information.

PURPOSE

This review outlines well-established and emerging methods to evaluate small bowel and colonic motility in clinical settings and in research. The latter include the 3D-Transit system, magnetic resonance imaging assessments, and high-resolution manometry. Procedures, indications, and the relative strengths and weaknesses of each method are summarized.

A Fixed Stricture on Routine Cross-sectional Imaging Predicts Disease-Related Complications and Adverse Outcomes in Patients with Crohn's Disease

BACKGROUND

Patients with Crohn's disease (CD) typically undergo multiple cross-sectional imaging exams including computed tomography and magnetic resonance enterography during the course of their disease. The aim was to identify imaging findings that predict future disease-related poor outcomes.

METHODS

This was a retrospective, case control study at a single tertiary center. Cases were CD patients diagnosed with complications (bowel obstruction, perforation, internal fistula, or abscess); controls were CD patients without complications. Two radiologists blinded to clinical outcomes, independently scored cross-sectional imaging examinations obtained before the complication.

RESULTS

One hundred eight patients (67 F; 41 M) with CD (51 cases; 57 controls) were included. For the cases, 21 had internal fistulae, 15 had bowel obstructions, 13 had abdominal abscesses, and 2 developed bowel perforations. Patients with complications were more likely to have a fixed small bowel stricture on cross-sectional imaging (P = 0.01). A patient with a stricture and upstream dilatation was 3.4 times more likely to develop a complication in the next 2 years. When present in the setting of hypervascularity and/or evidence of active inflammation, the risk increased further to 15-fold. Cases were more likely to be active smokers (29% versus 12%, P = 0.033). Cases had more evidence of inflammation based on higher Harvey Bradshaw Index values and inflammatory biomarkers and lower hemoglobin values.

CONCLUSIONS

Information from radiologic studies, especially the presence of fixed strictures, can predict future CD complications. These findings, along with smoking and ongoing inflammation, should alert the clinician to the possibility of future complications.

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

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

Magnetic resonance enterography for the evaluation of the deep small intestine in Crohn's disease

For the control of Crohn's disease (CD) a thorough assessment of the small intestine is essential; several modalities may be utilized, with cross-sectional imaging being important. Magnetic resonance (MR) enterography, i.e., MRE is recommended as a modality with the highest accuracy for CD lesions. MRE and MR enteroclysis are the two methods performed following distension of the small intestine. MRE has sensitivity and specificity comparable to computed tomography enterography (CTE); although images obtained using MRE are less clear compared with CTE, MRE does not expose the patient to radiation and is superior for soft-tissue contrast. Furthermore, it can assess not only static but also dynamic and functional imaging and reveals signs of CD, such as abscess, comb sign, fat edema, fistula, lymph node enhancement, less motility, mucosal lesions, stricture, and wall enhancement. Several indices of inflammatory changes and intestinal damage have been proposed for objective evaluation. Recently, diffusion-weighted imaging has been proposed, which does not need bowel preparation and contrast enhancement. Comprehension of the characteristics of MRE and other modalities is important for better management of CD.

MR enterography-histology comparison in resected pediatric small bowel Crohn disease strictures: can imaging predict fibrosis?

BACKGROUND

Crohn disease is a chronic inflammatory condition that can lead to intestinal strictures. The presence of fibrosis within strictures alters optimal management but is not reliably detected by current imaging methods.

OBJECTIVE

To correlate the MRI features of surgically resected small-bowel strictures in pediatric Crohn disease with histological inflammation and fibrosis scoring.

MATERIALS AND METHODS

We included children with Crohn disease who had symptomatic small-bowel strictures requiring surgical resection and had preoperative MR enterography (MRE) within 3 months of surgery (n = 20). Two blinded radiologists reviewed MRE examinations to document stricture-related findings. A pediatric pathologist scored stricture histological specimens for fibrosis (0-4) and inflammation (0-4). MRE findings were correlated with histological data using Spearman correlation (ρ) and exact logistic regression analysis.

RESULTS

There was significant positive correlation between histological bowel wall fibrosis and inflammation in resected strictures (ρ = 0.55; P = 0.01). Confluent transmural histological fibrosis was associated with pre-stricture upstream small-bowel dilatation >3 cm at univariate (odds ratio [OR] = 51.7; 95% confidence interval [CI]: 7.6- > 999.9; P = 0.0002) and multivariate (OR = 43.4; 95% CI: 6.1- > 999.9; P = 0.0006, adjusted for age) analysis. The degree of bowel wall T2-weighted signal intensity failed to correlate with histological bowel wall fibrosis or inflammation (P-values >0.05). There were significant negative correlations between histological fibrosis score and patient age at resection (ρ = -0.48, P = 0.03), and time from diagnosis to surgery (ρ = -0.73, P = 0.0002).

CONCLUSION

Histological fibrosis and inflammation co-exist in symptomatic pediatric Crohn disease small-bowel strictures and are positively correlated. Pre-stenotic upstream small-bowel dilatation greater than 3 cm is significantly associated with confluent transmural fibrosis.

Aberrant Motility in Unaffected Small Bowel is Linked to Inflammatory Burden and Patient Symptoms in Crohn's Disease

BACKGROUND

Inflammation-related enteric dysmotility has been postulated as a cause for abdominal symptoms in Crohn's disease (CD). We investigated the relationship between magnetic resonance imaging-quantified small bowel (SB) motility, inflammatory activity, and patient symptom burden.

METHODS

The Harvey-Bradshaw index (HBI) and fecal calprotectin were prospectively measured in 53 patients with CD (median age, 35; range, 18-78 years) the day before magnetic resonance enterography, which included a dynamic (cine), breath-hold motility sequence, repeated to encompass the whole SB volume. A validated registration-based motility quantitation technique produced motility maps, and regions of interest were drawn to include all morphologically normal SB (i.e., excluding diseased bowel). Global SB motility was correlated with calprotectin, HBI, and symptom components (well-being, pain, and diarrhea). Adjustment for age, sex, smoking, and surgical history was made using multivariate linear regression.

RESULTS

Median calprotectin was 336 (range, 0-1280). Median HBI, motility mean, and motility variance were 3 (range, 0-16), 0.33 (0.18-0.51), and 0.01 (0.0014-0.034), respectively. Motility variance was significantly negatively correlated with calprotectin (rho = -0.33, P = 0.015), total HBI (rho = -0.45, P < 0.001), well-being (rho = -0.4, P = 0.003), pain (rho = -0.27, P = 0.05), and diarrhea (rho = -0.4, P = 0.0025). The associations remained highly significant after adjusting for covariates. There was no association between mean motility and calprotectin or HBI (P > 0.05).

CONCLUSIONS

Reduced motility variance in morphologically normal SB is associated with patient symptoms and fecal calprotectin levels, supporting the hypothesis that inflammation-related enteric dysmotility may explain refractory abdominal symptoms in CD.

Magnetic resonance imaging to evaluate gastrointestinal function

Magnetic resonance imaging of gastrointestinal (GI) function has advanced substantially in the last few years. The ability to obtain high resolution images of the undisturbed bowel with tunable tissue contrast and using no ionizing radiation are clear advantages, particularly for children and women of reproductive age. Barriers to diffusion in clinical practice so far include the need to demonstrate clinical value and the burden of data processing. Both difficulties are being addressed and the technique is providing novel insights into both upper and lower GI disorders of function at an ever increasing rate.

Magnetic resonance imaging biomarkers of gastrointestinal motor function and fluid distribution

Magnetic resonance imaging (MRI) is a well established technique that has revolutionized diagnostic radiology. Until recently, the impact that MRI has had in the assessment of gastrointestinal motor function and bowel fluid distribution in health and in disease has been more limited, despite the novel insights that MRI can provide along the entire gastrointestinal tract. MRI biomarkers include intestinal motility indices, small bowel water content and whole gut transit time. The present review discusses new developments and applications of MRI in the upper gastrointestinal tract, the small bowel and the colon reported in the literature in the last 5 years.

Quantitative assessment of small bowel motility in patients with Crohn's disease using dynamic MRI

BACKGROUND

Assessment of motility alterations by functional magnetic resonance imaging (MRI) contributes to improved evaluation of inflammatory bowel disease. The aim of the study was to quantify motility in inflammatory bowel segments and to compare motility alterations with MR-based parameters for activity of inflammation in Crohn's disease (CD).

METHODS

Thirty consecutive patients with CD underwent bowel MRI which included a dynamic sequence for automatic generation of parametric maps facilitating quantification of bowel motility. Mean motility score (MMS) of small bowel segments with signs of inflammation was measured and compared with MMS of the whole gastrointestinal tract (GI tract). MRI-based score of inflammatory activity and lesion length were correlated with the MMS ratio of inflammatory small bowel lesion and whole GI tract.

KEY RESULTS

Inflammatory bowel segments showed a mean value of MMSs of 1080, whereas the whole GI tract showed a mean value of MMSs of 2839 (p < 0.0001). Decrease in motility ranged between 20 and 87% in inflammatory bowel segments compared to the MMS of the whole GI tract. The MMS ratio of an inflammatory small bowel segment and whole GI tract showed negative correlation with MR activity score (r = -0.5921, p = 0.0003) and length of the lesion (r = -0.3495, p = 0.0462).

CONCLUSIONS & INFERENCES

Quantitative assessment of motility alterations by means of motility scoring in small bowel segments affected by CD provides additional information on inflammatory activity.

Indications and selection of MR enterography vs. MR enteroclysis with emphasis on patients who need small bowel MRI and general anaesthesia: results of a survey

Aims

To survey the perceived indications for magnetic resonance imaging of the small bowel (MRE) by experts, when MR enteroclysis (MREc) or MR enterography (MREg) may be chosen, and to determine how the approach to MRE is modified when general anaesthesia (GA) is required.

Materials and methods

Selected opinion leaders in MRE completed a questionnaire that included clinical indications (MREg or MREc), specifics regarding administration of enteral contrast, and how the technique is altered to accommodate GA.

Results

Fourteen responded. Only the diagnosis and follow-up of Crohn’s disease were considered by over 80 % as a valid MRE indication. The remaining indications ranged between 35.7 % for diagnosis of caeliac disease and unknown sources of gastrointestinal bleeding to 78.6 % for motility disorders. The majority chose MREg over MREc for all indications (from 100 % for follow-up of caeliac disease to 57.7 % for tumour diagnosis). Fifty per cent of responders had needed to consider MRE under GA. The most commonly recommended procedural change was MRI without enteral distention. Three had experience with intubation under GA (MREc modification).

Conclusion

Views were variable. Requests for MRE under GA are not uncommon. Presently most opinion leaders suggest standard abdominal MRI when GA is required.

Main messages

• Experts are using MRE for various indications.

• Requests for MRE under general anaesthesia are not uncommon.

• Some radiologists employ MREc under general anaesthesia; others do not distend the small bowel.

Magnetic resonance enterography: state of the art

Crohn's disease is a chronic inflammatory bowel disease of the gastrointestinal tract manifested by frequent periods of relapses and remissions of symptoms. The small bowel is most frequently affected. Progression of transmural inflammation can lead to stricturing or penetrating complications. At the time of diagnosis, approximately 10% of patients have disease beyond the reach of the colonoscope. Imaging can aid in clinical evaluation by depicting small bowel involvement and extraenteric disease. Magnetic resonance enterography (MRE) has emerged as a valuable tool and is being used with increasing frequency for the diagnosis and management of Crohn's disease. This article will discuss the current state of the art in MRE. In addition to reviewing the literature reporting its utility, we will present case examples illustrating how MRE best depicts the various findings of Crohn's disease within 4 imaging categories of disease: active inflammatory, fibrostenotic, fistulizing/perforating, and reparative or regenerative. We will present additional important clinical considerations in routine use of MRE, including implications for monitoring disease activity and response to treatment, cost-effectiveness, and appropriate use in the context of the American College of Radiology Appropriateness Criteria.

Imaging techniques in IBD and their role in follow-up and surveillance

The assessment of extent and severity of IBD is crucial for directing treatment decisions. Clinical symptoms alone are neither sensitive nor specific for the assessment of lesion severity in IBD. Cross-sectional imaging techniques, as well as small-bowel capsule endoscopy (SBCE) and device-assisted enteroscopy, have a high accuracy for assessing the extent of mucosal lesions, and are reliable alternatives to ileocolonoscopy. New endoscopic techniques and devices are emerging for improved follow-up and surveillance. In this Review, we discuss different imaging techniques that are used to assess IBD activity and to survey patients with IBD, and highlight the latest developments in each area. Moreover, technical improvements and new tools that aim to measure intestinal fibrosis, postoperative recurrence, activity indices and endoscopic features are analysed. All of these imaging techniques are aimed at changing the paradigm from symptom-driven to lesion-driven treatment of IBD.

The challenge of segmental small bowel motility quantitation using MR enterography

OBJECTIVE

Analysis of "cine" MRI using segmental regions of interest (ROIs) has become increasingly popular for investigating bowel motility; however, variation in motility in healthy subjects both within and between scans remains poorly described.

METHODS

20 healthy individuals (mean age, 28 years; 14, males) underwent MR enterography to acquire dynamic motility scans in both breath hold (BH) and free breathing (FB) on 2 occasions. Motility data were quantitatively assessed by placing four ROIs per subject in different small bowel segments and applying two measures: (1) contractions per minute (CPM) and (2) Jacobian standard deviation (SD) motility score. Within-scan (between segment) variation was assessed using intraclass correlation (ICC), and repeatability was assessed using Bland-Altman limits of agreement (BA LoA).

RESULTS

Within-scan segmental variation: BH CPM and Jacobian SD metrics between the four segments demonstrated ICC R = 0.06, p = 0.100 and R = 0.20, p = 0.027 and in FB, the CPM and Jacobian SD metrics demonstrated ICC R = -0.26, p = 0.050 and R = 0.19, p = 0.030. Repeatability: BH CPM for matched segments ranged between 0 and 14 contractions with BA LoA of ±8.36 and Jacobian SD ranged between 0.09 and 0.51 with LoA of ±0.33. In FB data, CPM ranged between 0 and 10 contractions with BA LoA of ±7.25 and Jacobian SD ranged between 0.16 and 0.63 with LoA = ±0.28.

CONCLUSION

The MRI-quantified small bowel motility in normal subjects demonstrates wide intersegmental variation and relatively poor repeatability over time.

ADVANCES IN KNOWLEDGE

This article presents baseline values for healthy individuals of within- and between-scan motility that are essential for understanding how this process changes in disease.

Involvement of interleukin-17A-induced hypercontractility of intestinal smooth muscle cells in persistent gut motor dysfunction

BACKGROUND AND AIM

The etiology of post-inflammatory gastrointestinal (GI) motility dysfunction, after resolution of acute symptoms of inflammatory bowel diseases (IBD) and intestinal infection, is largely unknown, however, a possible involvement of T cells is suggested.

METHODS

Using the mouse model of T cell activation-induced enteritis, we investigated whether enhancement of smooth muscle cell (SMC) contraction by interleukin (IL)-17A is involved in postinflammatory GI hypermotility.

RESULTS

Activation of CD3 induces temporal enteritis with GI hypomotility in the midst of, and hypermotility after resolution of, intestinal inflammation. Prolonged upregulation of IL-17A was prominent and IL-17A injection directly enhanced GI transit and contractility of intestinal strips. Postinflammatory hypermotility was not observed in IL-17A-deficient mice. Incubation of a muscle strip and SMCs with IL-17A in vitro resulted in enhanced contractility with increased phosphorylation of Ser19 in myosin light chain 2 (p-MLC), a surrogate marker as well as a critical mechanistic factor of SMC contractility. Using primary cultured murine and human intestinal SMCs, IκBζ- and p38 mitogen-activated protein kinase (p38MAPK)-mediated downregulation of the regulator of G protein signaling 4 (RGS4), which suppresses muscarinic signaling of contraction by promoting inactivation/desensitization of Gαq/11 protein, has been suggested to be involved in IL-17A-induced hypercontractility. The opposite effect of L-1β was mediated by IκBζ and c-jun N-terminal kinase (JNK) activation.

CONCLUSIONS

We propose and discuss the possible involvement of IL-17A and its downstream signaling cascade in SMCs in diarrheal hypermotility in various GI disorders.

Correlation between morphological expansion and impairment of intra- and prelesionary motility in inflammatory small bowel lesions in patients with Crohn's disease - preliminary data

INTRODUCTION

The aim of this study is to investigate if alterations of intra- and prelesionary motility in inflamed small-bowel segments correlate with length, wall-thickness and prelesionary dilatation of inflammatory small bowel lesions in patients suffering from Crohn's disease assessed with MRI.

METHODS AND MATERIALS

This retrospective IRB approved study included 25 patients (12 males, 18-77y) with inflammatory lesions examined using (MRE) magnetic resonance imaging enterography. Cine MRE was performed using a coronal 2D steady-state free precession sequence (TR 2.9, TE 1.25) on a 1.5T MRI scanner. Small bowel motility was examined using a dedicated MR-motility assessment software (Motasso, Vers. 1.0, Sohard AG, Bern, Switzerland). Motility patterns (contraction frequency, relative occlusion rate and mean diameter) were assessed in correlation to wall thickness, length and prelesionary dilatation of the lesions. Statistical analysis was performed by calculation of the Pearson's-Correlation coefficient.

RESULTS

The length of the inflammatory segments, the wall thickening and prelesionary dilatation did not correlate with the frequency of the contractions (r=0.17, p=0.477; r=0.316, p=0.123; r=0.161, p=0.441) or the impairment of luminal occlusion (r=0.274, p=0.184; r=0.199, p=.0339; r=0.015, p=0.945) and only the prelesionary dilatation (r=0.410, p=0.042) correlated to the mean luminal diameter of the segment.

CONCLUSION

The degree of motility impairment within inflammatory small bowel lesions does not significantly correlate with the extent of the lesion but with the motility measured in prelesionary, non-affected segments, suggesting an interdependent functional aspect of inflammation even in morphologically non-affected small bowel segments.