Identifying decreased peristalsis of abnormal small bowel segments in Crohn's disease using cine MR enterography: the frozen bowel sign

Multimodality Imaging of Small Bowel Crohn Disease

Computed tomography enterography, magnetic resonance enterography, and bowel ultrasound are complementary tools central to diagnosing and monitoring Crohn disease. These modalities can identify active inflammation, penetrating, and stricturing disease. Crohn disease must be monitored frequently to guide therapy, and resolution of inflammation on imaging correlates directly with steroid-free clinical remission. While disease activity assessment is qualitative, newer quantitative techniques to assess active inflammation are emerging. These as well as other techniques, such as contrast-enhanced ultrasound (US) and US elastography, will offer new tools for future radiologists.

Quantitative Analysis of Small Intestinal Motility in 3D Cine-MRI Using Centerline-Aware Motion Estimation

BACKGROUND

Currently available tools for noninvasive motility quantification of the small intestine are limited to dynamic 2D MRI scans, which are limited in their ability to differentiate between types of intestinal motility.

PURPOSE

To develop a method for quantification and characterization of small intestinal motility in 3D, capable of differentiating motile, non-motile and peristaltic motion patterns.

STUDY TYPE

Prospective.

SUBJECTS

Fourteen healthy volunteers (127 small intestinal segments) and 10 patients with Crohn's disease (87 small intestinal segments).

FIELD STRENGTH/SEQUENCE

3.0 T, 3D balanced fast field echo sequence, 1 volume per second.

ASSESSMENT

Using deformable image registration between subsequent volumes, the local velocity within the intestinal lumen was quantified. Average velocity and average absolute velocity along intestinal segments were used with linear classifiers to differentiate motile from non-motile intestines, as well as erratic motility from peristalsis. The mean absolute velocity of small intestinal content was compared between healthy volunteers and Crohn's disease patients, and the discriminative power of the proposed motility metrics for detecting motility and peristalsis was determined. The consensus of two observers was used as referenced standard.

STATISTICAL TESTS

Student's t-test to assess differences between groups; area under the receiver operating characteristic curve (AUC) to assess discriminative ability. P < 0.001 was considered significant.

RESULTS

A significant difference in the absolute velocity of intestinal content between Crohn's patients and healthy volunteers was observed (median [IQR] 1.06 [0.61, 1.56] mm/s vs. 1.84 [1.37, 2.43] mm/s), which was consistent with manual reference annotations of motile activity. The proposed method had a strong discriminative performance for detecting non-motile intestines (AUC 0.97) and discernible peristalsis (AUC 0.81).

DATA CONCLUSION

Analysis of 3D cine-MRI using centerline-aware motion estimation has the potential to allow noninvasive characterization of small intestinal motility and peristaltic motion in 3D.

EVIDENCE LEVEL

3 TECHNICAL EFFICACY: Stage 2.

Inflammatory Bowel Disease Drivers Revealed in Human Organ Chips

Inflammatory bowel disease (IBD) patients exhibit compromised intestinal barrier function and decreased mucus accumulation, as well as increased inflammation, fibrosis, and cancer risk, with symptoms often being exacerbated in women during pregnancy. Here, we show that these IBD hallmarks can be replicated using human Organ Chips lined by IBD patient-derived colon epithelial cells interfaced with matched fibroblasts cultured under flow. Use of heterotypic tissue recombinants revealed that IBD fibroblasts are the primary drivers of multiple IBD symptoms. Inflammation and fibrosis are accentuated by peristalsis-like motions in IBD Chips and when exposed to pregnancy-associated hormones in female IBD Chips. Carcinogen exposure also increases inflammation, gene mutations, and chromosome duplication in IBD Chips, but not in Healthy Chips. These data enabled by human Organ Chip technology suggest that the intestinal stroma and peristalsis-associated mechanical deformations play a key role in driving inflammation and disease progression in male and female IBD patients.

Intestinal organ chips for disease modelling and personalized medicine

Alterations in intestinal structure, mechanics and physiology underlie acute and chronic intestinal conditions, many of which are influenced by dysregulation of microbiome, peristalsis, stroma or immune responses. Studying human intestinal physiology or pathophysiology is difficult in preclinical animal models because their microbiomes and immune systems differ from those of humans. Although advances in organoid culture partially overcome this challenge, intestinal organoids still lack crucial features that are necessary to study functions central to intestinal health and disease, such as digestion or fluid flow, as well as contributions from long-term effects of living microbiome, peristalsis and immune cells. Here, we review developments in organ-on-a-chip (organ chip) microfluidic culture models of the human intestine that are lined by epithelial cells and interfaced with other tissues (such as stroma or endothelium), which can experience both fluid flow and peristalsis-like motions. Organ chips offer powerful ways to model intestinal physiology and disease states for various human populations and individual patients, and can be used to gain new insight into underlying molecular and biophysical mechanisms of disease. They can also be used as preclinical tools to discover new drugs and then validate their therapeutic efficacy and safety in the same human-relevant model.

Quantitative MRI in children with Crohn's disease - where do we stand?

Crohn's disease (CD) is a chronic inflammatory condition that affects the gastrointestinal tract, particularly the ileum and colon. This disease is characterized by recurrent bouts of intestinal inflammation with subsequent bowel wall damage, including scarring (i.e., fibrosis) and abnormal smooth muscle proliferation. MR enterography, an MRI examination tailored to assess the small bowel, is a first-line diagnostic tool for diagnosing CD in children, characterization and monitoring of disease severity and extent, and assessment of disease-related complications. To date, such MRI evaluations have been mostly qualitative, which can adversely impact diagnostic performance and inter-radiologist agreement. Quantitative MRI methods have been shown to aid in the evaluation of a variety of medical conditions and have been increasingly investigated in children and adults with CD. In CD, such objective techniques have been used to assist with diagnosis, assess treatment response, and characterize bowel wall histologic abnormalities. In the current work, we will review quantitative MRI methods for detecting and measuring intestinal active inflammation (MRI-based scoring systems, T1 relaxation mapping, diffusion-weighted imaging, intra-voxel incoherent motion, mesenteric phase contrast), bowel wall damage (magnetization transfer), and motility (quantitative cine imaging) in small bowel CD, with an emphasis on the pediatric population.

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

MRI-Based Characterization of Intestinal Motility in Children and Young Adults With Newly Diagnosed Ileal Crohn Disease Treated by Biologic Therapy: A Controlled Prospective Study

BACKGROUND. Changes in intestinal motility in patients with newly diagnosed Crohn disease have historically been evaluated primarily in a subjective manner. OBJECTIVE. The purpose of this study was to assess longitudinal changes in objective intestinal motility scores in children and young adults with newly diagnosed ileal Crohn disease treated with biologic (anti-tumor necrosis factor-α) medical therapy compared with those in control participants. METHODS. This prospective study included 20 children and young adults (eight female and 12 male patients; mean age, 14.6 ± 2.1 [SD] years) with newly diagnosed ileal Crohn disease who were recruited between December 2018 and October 2021 as well as 15 control participants without any known gastrointestinal conditions (eight female and seven male patients; mean age, 18.1 ± 4.4 years). All participants underwent research MRI examinations of the small bowel, including dynamic cine 2D SSFP sequences. Patients with Crohn disease underwent additional research MRI examinations performed at both 6 weeks and 6 months after initiation of biologic therapy. Two operators independently derived terminal ileal intestinal motility scores from the dynamic cine sequences by use of FDA-approved software (with higher scores indicating greater intestinal motility). Intestinal motility scores were compared between patient and control groups by use of t tests, whereas changes in intestinal motility scores after treatment were assessed using linear mixed models. Interoperator absolute agreement was assessed using the intra-class correlation coefficient (ICC). RESULTS. Mean terminal ileal intestinal motility scores were not significantly different between patients with newly diagnosed ileal Crohn disease and control participants (for operator 1, 180.9 ± 63.3 vs 229.7 ± 115.2, respectively [p = .12]; for operator 2, 175.0 ± 62.2 vs 236.4 ± 117.4, respectively [p = .05]). Mean intestinal motility scores changed over time compared with baseline in response to biologic therapy, for operator 1 (180.9 ± 63.3 at baseline, 248.1 ± 104.9 at 6 weeks after treatment initiation, and 249.1 ± 73.2 at 6 months after treatment initiation [p = .04]) and operator 2 (175.0 ± 62.2 at baseline, 247.8 ± 112.7 at 6 weeks after treatment initiation, and 239.6 ± 72.7 at 6 months after treatment initiation [p = .03]). Absolute agreement in intestinal motility scores was excellent between operators (ICC = 0.89). CONCLUSION. MRI measurements of intestinal motility are dynamic in children and adults with newly diagnosed small-bowel Crohn disease, showing early increases in response to biologic therapy. CLINICAL IMPACT. MRI-based intestinal motility scores may aid individualized assessment of disease activity and treatment response in patients with small-bowel Crohn disease.

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.