Characterization of Degree of Intestinal Fibrosis in Patients with Crohn Disease by Using Magnetization Transfer MR Imaging

A practical guide to dilating inflammatory bowel disease strictures

INTRODUCTION

Stricturing Crohn's disease is a common phenotype and treatment aims to improve symptoms, prevent complications, assess for proximal bowel disease activity, and screen for upstream neoplasm. Management is challenging due to diagnostic limitations, stricture composition, and recurrence rate.

AREAS COVERED

Categorizing a stricture as inflammatory or fibrotic is necessary to determine appropriate management. Inflammatory strictures are treated with medical therapy, and fibrostenotic strictures require endoscopic or surgical management. While EBD is increasingly utilized, stricture recurrence rates remain high, necessitating repeat endoscopic procedures or surgery. We performed a PubMed (MEDLINE database) search for the latest research on IBD-related stricture management, including detection, diagnosis, and medical and procedural therapies. We highlight the current literature on endoscopic techniques for the treatment of intestinal strictures and future areas of research.

EXPERT OPINION

The field of intestinal stricture management is expected to evolve in the coming years and will include enhanced imaging modalities, medication optimization, and increasing use of advanced endoscopic techniques.

Fibrosis: cross-organ biology and pathways to development of innovative drugs

Fibrosis is a pathophysiological mechanism involved in chronic and progressive diseases that results in excessive tissue scarring. Diseases associated with fibrosis include metabolic dysfunction-associated steatohepatitis (MASH), inflammatory bowel diseases (IBDs), chronic kidney disease (CKD), idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc), which are collectively responsible for substantial morbidity and mortality. Although a few drugs with direct antifibrotic activity are approved for pulmonary fibrosis and considerable progress has been made in the understanding of mechanisms of fibrosis, translation of this knowledge into effective therapies continues to be limited and challenging. With the aim of assisting developers of novel antifibrotic drugs, this Review integrates viewpoints of biologists and physician-scientists on core pathways involved in fibrosis across organs, as well as on specific characteristics and approaches to assess therapeutic interventions for fibrotic diseases of the lung, gut, kidney, skin and liver. This discussion is used as a basis to propose strategies to improve the translation of potential antifibrotic therapies.

Quantitative Magnetic Resonance Imaging (qMRI) of the Small Bowel in Crohn's Disease: State-of-the-Art and Future Directions

Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal tract in which repeated episodes of acute inflammation may lead to long-term bowel damage. Cross-sectional imaging is used in conjunction with endoscopy to diagnose and monitor disease and detect complications. Magnetic resonance imaging (MRI) has demonstrable utility in evaluating inflammatory activity. However, subjective interpretation of conventional MR sequences is limited in its ability to fully phenotype the underlying histopathological processes in chronic disease. In particular, conventional MRI can be confounded by the presence of mural fibrosis and muscle hypertrophy, which can mask or sometimes mimic inflammation. Quantitative MRI (qMRI) methods provide a means to better differentiate mural inflammation from fibrosis and improve quantification of these processes. qMRI may also provide more objective measures of disease activity and enable better tailoring of treatment. Here, we review quantitative MRI methods for imaging the small bowel in CD and consider the path to their clinical translation. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 2.

Circulating and Magnetic Resonance Imaging Biomarkers of Intestinal Fibrosis in Small Bowel Crohn's Disease

BACKGROUND

We previously identified circulating and MRI biomarkers associated with the surgical management of Crohn's disease (CD). Here we tested associations between these biomarkers and ileal resection inflammation and collagen content.

METHODS

Fifty CD patients undergoing ileal resection were prospectively enrolled at 4 centers. Circulating CD64, extracellular matrix protein 1 (ECM1), GM-CSF autoantibodies (GM-CSF Ab), and fecal calprotectin were measured by ELISA. Ileal 3-dimensional magnetization transfer ratio (3D MTR), modified Look-Locker inversion recovery (MOLLI) T1 relaxation, diffusion-weighted intravoxel incoherent motion (IVIM), and the simplified magnetic resonance index of activity (sMaRIA) were measured by MRI. Ileal resection specimen acute inflammation was graded, and collagen content was measured quantitatively using second harmonic imaging microscopy. Associations between biomarkers and ileal collagen content were tested.

RESULTS

Median (interquartile range [IQR]) age was 19.5 (16-33) years. We observed an inverse relationship between ileal acute inflammation and collagen content (r = -0.39 [95% confidence interval {CI}: -0.61, -0.10], P = .008). Most patients (33 [66%]) received biologics, with no variation in collagen content with treatment exposures. In the univariate analysis, CD64, GM-CSF Ab, fecal calprotectin, and sMaRIA were positively associated with acute inflammation and negatively associated with collagen content (P < .1). The multivariable model for ileal collagen content (R2 = 0.31 [95% CI: 0.11, 0.52]) included log CD64 (β = -.27; P = .19), log ECM1 (β = .47; P = .06), log GM-CSF Ab (β = -.15; P = .01), IVIM f (β = .29, P = .10), and IVIM D* (β = 1.69, P = .13).

CONCLUSIONS

Clinically available and exploratory circulating and MRI biomarkers are associated with the degree of inflammation versus fibrosis in CD ileal resections. With further validation, these biomarkers may be used to guide medical and surgical decision-making for refractory CD.

Quantitative Evaluation of Noncontrast Magnetic Resonance Enterography for Active Inflammation in Crohn Disease Using Native T 1 and T 2 Mapping

PURPOSE

The aim of this study was to investigate the utility of native T 1 and T 2 mapping in the bowel to evaluate disease activity in Crohn disease (CD) using endoscopy as the reference standard.

METHODS

This was a prospective study. Magnetic resonance imaging was performed by using a 1.5-T Philips scanner. We used a modified look-locker inversion recovery and a multiecho gradient-spin-echo sequences for single breath-hold native T 1 and T 2 maps, respectively, for the short-axis image of the intestine, and the measurement at the most severe site was compared with partial Simple Endoscopic Score for Crohn's Disease (pSES-CD, assessed by an expert endoscopist). A pSES-CD ≥ 4 indicated active disease. Statistical analyses were performed using the Student t test, Spearman correlation, and receiver operating characteristic curve analysis.

RESULTS

A total of 27 patients (mean age ± standard deviation, 37 ± 18 years; 20 men, 7 women) were included in this study. The native T 1 value of active disease was significantly higher than that of inactive disease (1170.8 ± 100.5 milliseconds vs 924.5 ± 95.3 milliseconds; P = 0.018), but the T 2 value was not significantly different between active and inactive disease (76.1 ± 7.8 milliseconds vs 69.3 ± 10.9 milliseconds; P = 0.424). A good correlation was found between native T 1 value and pSES-CD (ρ = 0.71; P < 0.001) but not between T 2 value and pSES-CD (ρ = 0.06; P = 0.790). The area under the receiver operating characteristic curve for differentiating the disease activity was 0.96 (95% confidence interval [CI]: 0.90-1.00) for T 1 values and 0.68 (95% confidence interval: 0.41-0.96) for T 2 values.

CONCLUSIONS

Native T 1 mapping could be potentially used as a noninvasive method to differentiate disease activity in patients with CD and may be superior to T 2 mapping for this purpose.

The role of molecular imaging in detecting fibrosis in Crohn's disease

Fibrosis is a pathological process that occurs due to chronic inflammation, leading to the proliferation of fibroblasts and the excessive deposition of extracellular matrix (ECM). The process of long-term fibrosis initiates with tissue hypofunction and progressively culminates in the ultimate manifestation of organ failure. Intestinal fibrosis is a significant complication of Crohn's disease (CD) that can result in persistent luminal narrowing and strictures, which are difficult to reverse. In recent years, there have been significant advances in our understanding of the cellular and molecular mechanisms underlying intestinal fibrosis in inflammatory bowel disease (IBD). Significant progress has been achieved in the fields of pathogenesis, diagnosis, and management of intestinal fibrosis in the last few years. A significant amount of research has also been conducted in the field of biomarkers for the prediction or detection of intestinal fibrosis, including novel cross-sectional imaging modalities such as positron emission tomography (PET) and single photon emission computed tomography (SPECT). Molecular imaging represents a promising biomedical approach that enables the non-invasive visualization of cellular and subcellular processes. Molecular imaging has the potential to be employed for early detection, disease staging, and prognostication in addition to assessing disease activity and treatment response in IBD. Molecular imaging methods also have a potential role to enabling minimally invasive assessment of intestinal fibrosis. This review discusses the role of molecular imaging in combination of AI in detecting CD fibrosis.

Crohn's disease after multiple doses of rituximab treatment in a child with refractory nephrotic syndrome and an ATG2A mutation: a case report

De novo inflammatory bowel disease (IBD) in response to rituximab (RTX) has been documented on multiple occasions as a severe adverse effect. However, none of these reports mentioned any genetic variation associated with this complication. We describe the case of a 16-year-old patient with refractory nephrotic syndrome (NS) diagnosed at the age of 6 years, notably with a heterozygous mutation of the ATG2A gene, who developed Crohn's disease (CD) following ten administrations of RTX. Seventy months after the first and 6 months after the last RTX dose, the patient developed recurrent abdominal pain, hematochezia, oral aphthous ulcers and weight loss. On the basis of clinical evaluation and ileo-colonoscopy findings, the patient was diagnosed with CD and treated with mesalazine. A significant amelioration of clinical symptoms was achieved after 11 days of mesalazine treatment. A repeat ileo-colonoscopy performed 4 months later revealed near-complete resolution of the ulcers and marked mucosal healing. The underlying pathophysiology of RTX-induced IBD has not yet been clarified. Autophagy associated with ATG2A mutation is likely involved in the pathogenesis. This case underscores the need for vigilance in monitoring children with NS with gastrointestinal symptoms following RTX treatment, especially those who have hereditary susceptibility and have received multiple administrations.

MRI and Blood-based Biomarkers Are Associated With Surgery in Children and Adults With Ileal Crohn's Disease

BACKGROUND

Despite advances in medical therapy, many children and adults with ileal Crohn's disease (CD) progress to fibrostenosis requiring surgery. We aimed to identify MRI and circulating biomarkers associated with the need for surgical management.

METHODS

This prospective, multicenter study included pediatric and adult CD cases undergoing ileal resection and CD controls receiving medical therapy. Noncontrast research MRI examinations measured bowel wall 3-dimensional magnetization transfer ratio normalized to skeletal muscle (normalized 3D MTR), modified Look-Locker inversion recovery (MOLLI) T1 relaxation, intravoxel incoherent motion (IVIM) diffusion-weighted imaging metrics, and the simplified magnetic resonance index of activity (sMaRIA). Circulating biomarkers were measured on the same day as the research MRI and included CD64, extracellular matrix protein 1 (ECM1), and granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies (Ab). Associations between MRI and circulating biomarkers and need for ileal resection were tested using univariate and multivariable LASSO regression.

RESULTS

Our study sample included 50 patients with CD undergoing ileal resection and 83 patients with CD receiving medical therapy; mean participant age was 23.9 ± 13.1 years. Disease duration and treatment exposures did not vary between the groups. Univariate biomarker associations with ileal resection included log GM-CSF Ab (odds ratio [OR], 2.87; P = .0009), normalized 3D MTR (OR, 1.05; P = .002), log MOLLI T1 (OR, 0.01; P = .02), log IVIM perfusion fraction (f; OR, 0.38; P = .04), and IVIM apparent diffusion coefficient (ADC; OR, 0.3; P = .001). The multivariable model for surgery based upon corrected Akaike information criterion included age (OR, 1.03; P = .29), BMI (OR, 0.91; P = .09), log GM-CSF Ab (OR, 3.37; P = .01), normalized 3D MTR (OR, 1.07; P = .007), sMaRIA (OR, 1.14; P = .61), luminal narrowing (OR, 10.19; P = .003), log C-reactive protein (normalized; OR, 2.75; P = .10), and hematocrit (OR, 0.90; P = .13).

CONCLUSION

After accounting for clinical and MRI measures of severity, normalized 3D MTR and GM-CSF Ab are associated with the need for surgery in ileal CD.

Diagnostic value of MR and CT enterography in post-operative recurrence of Crohn's disease: a systematic review and meta-analysis

Post-operative recurrence is a critical issue in the surveillance of Crohn's disease after ileocecal resection. This meta-analysis aims to assess the diagnostic yield of enterography techniques in post-operative recurrence of Crohn's disease. A systematic electronic bibliographic databases search was conducted. The inclusion criteria of original articles were: Utilized MR enterography or CT enterography after ileocolonic resection; Documented recurrence by ileo-colonoscopy (Rutgeerts' score ≥ i2); Provided crude data of diagnostic performance. A random-effect method was used for analysis. Relative risk and diagnostic value of each imaging feature were calculated. Eleven studies (11 populations and 589 patients) were included (4 CTE and 7 MRE with 248 and 341 patients, respectively). The pooled sensitivity and specificity of the enterography were 91% (95% CI: 0.85-0.95) and 75% (95% CI: 0.56-0.87), respectively. The pooled sensitivity and specificity of CTE were 93% (95% CI: 0.87-0.96) and 67% (95% CI: 0.35-0.90), respectively. MRE revealed pooled sensitivity and specificity of 90% (95% CI: 0.78-0.96) and 78% (95% CI: 0.57-0.90), respectively. The inter-study heterogeneity was low for sensitivity (I2 = 29%, p-value = 0.17) and high for specificity (I2 = 85%, p-value < 0.01). Wall enhancement, anastomosis wall thickening, anastomosis stenosis, pre-anastomotic dilatation, penetrating lesion, comb sign, and perivisceral edema were significantly higher in POR patients. Wall thickening and penetrating lesion were the most sensitive (81%) and specific (97%) findings, respectively. MRE and CTE exhibit high sensitivity and acceptable specificity (especially MRE) for detection of recurrence in Crohn's disease which makes them an effective initial screening tool and reserves ileo-colonoscopy for those patients with inconclusive enterography results.

A proposal for analyzing the inflammatory and remodeling processes of mucosa in chronic rhinosinusitis with nasal polyposis through MRI

OBJECTIVES

Chronic Rhinosinusitis with Nasal Polyposis (CRSwNP) is a disease characterized by chronic inflammation and tissue remodeling process. The remodeling process in nasal polyps has mainly been studied by histology analysis. However, it is limited to a polyp fragment and requires tissue removal. The present study aims to evaluate the ability of Magnetic Resonance Imaging (MRI) to depict and characterize the remodeling process in patients with CRSwNP.

METHODS

30 patients that met clinical diagnostic criteria for CRSwNP, without previous history of rhinosinusitis surgery were submitted to MRI scan (conventional, diffusion-weighted and DCE MRI) and compared with polyp tissue histological findings, IL-6 concentrations in the tissue and eosinophil count in the blood. The examinations were evaluated, independently, by two radiologists blinded to other radiological and histological data. The pathologist, blinded to MRI results, also compared the tissue sample from the most central and the most peripheral portion of the polypoid tissue adjacent to the floor of the nasal fossa.

RESULTS

This study demonstrated a characteristic pattern of nasal polyps, whose peripheral portions of nasal polypoid tissue are edematous, whereas the central portions in the middle meatus and in the middle and upper ethmoid are predominantly fibrotic. ADC values found in the most anterior portion of the polyps may be a marker for radiological phenotyping the remodeling process. This non-invasive analysis presented a high degree of agreement in the fibrosis and edema rating by two radiologists and the histological analysis was concordant with the MRI findings. The polyps were characterized as eosinophilic, and no relationship was found between the severity of the eosinophilic inflammatory process or concentration of IL-6 and the remodeling process.

CONCLUSION

MRI by using T2-weighted imaging sequence and ADCs values allows tissue characterization and is an effective tool for the differentiation of edematous and fibrotic components in CRSwNP.

LEVEL OF EVIDENCE: 3

Combined Use of Magnetization Transfer Ratio and T2-Mapping to Evaluate Extraocular Muscle Pathophysiology in Myasthenia Gravis with Ophthalmoparesis

Background Myasthenia gravis (MG) is an autoimmune neuromuscular disorder that most frequently affects the extraocular muscles (EOMs), which causes symptoms such as ptosis and restricted eye movement. The EOMs in MG patients are representative of autoimmune inflammatory changes in muscle tissue. Currently, there is no reliable, and sensitive imaging technique for monitoring EOM changes to assist in the evaluation of underlying pathological changes. Methods This study included MG patients treated between March and November 2022 at the First Affiliated Hospital of Sun Yat-sen University. Healthy controls (matched by age and sex) were included. Participants underwent 3.0 T MRI with magnetization transfer imaging (MTI) and T2-mapping to measure the magnetization transfer ratio (MTR) and T2-mapping values in the superior, inferior, medial, and lateral rectus muscles. Comparisons were made between MG patients and healthy controls, and between MG subgroups with and without ophthalmoparesis. Results The MTR and T2-mapping values successfully reflected EOM fibrosis and inflammatory edema in MG patients. MG patients showed significantly higher MTR and T2-mapping values in the EOMs compared with healthy controls. MG patients with ophthalmoparesis exhibited a lower MTR but higher T2-mapping value compared with those without ophthalmoparesis. Combined MTR and T2-mapping values effectively distinguished between MG patients and healthy controls, and between different severities of EOM involvement, with a superior diagnostic accuracy compared with each parameter alone. Conclusion The combination of MTI and T2-mapping MRI techniques can provide key insight into the pathological changes in EOMs in MG patients. This approach enhances early diagnosis and treatment planning, and therefore may improve clinical outcomes.

Multiomics reveals microbial metabolites as key actors in intestinal fibrosis in Crohn's disease

Intestinal fibrosis is the primary cause of disability in patients with Crohn's disease (CD), yet effective therapeutic strategies are currently lacking. Here, we report a multiomics analysis of gut microbiota and fecal/blood metabolites of 278 CD patients and 28 healthy controls, identifying characteristic alterations in gut microbiota (e.g., Lachnospiraceae, Ruminococcaceae, Muribaculaceae, Saccharimonadales) and metabolites (e.g., L-aspartic acid, glutamine, ethylmethylacetic acid) in moderate-severe intestinal fibrosis. By integrating multiomics data with magnetic resonance enterography features, putative links between microbial metabolites and intestinal fibrosis-associated morphological alterations were established. These potential associations were mediated by specific combinations of amino acids (e.g., L-aspartic acid), primary bile acids, and glutamine. Finally, we provided causal evidence that L-aspartic acid aggravated intestinal fibrosis both in vitro and in vivo. Overall, we offer a biologically plausible explanation for the hypothesis that gut microbiota and its metabolites promote intestinal fibrosis in CD while also identifying potential targets for therapeutic trials.

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.

A global consensus on the definitions, diagnosis and management of fibrostenosing small bowel Crohn's disease in clinical practice

Fibrostenosis of the small bowel is common in patients with Crohn's disease. No consensus recommendations on definition, diagnosis and management in clinical practice are currently available. In this Consensus Statement, we present a clinical practice RAND/UCLA appropriateness study on the definition, diagnosis and clinical management of fibrostenosing Crohn's disease. It was conducted by a panel of 28 global experts and one patient representative. Following a systematic literature review, 526 candidate items grouped into 136 questions were generated and subsequently evaluated for appropriateness. Strictures are best defined as wall thickening, luminal narrowing and prestenotic dilation. Cross-sectional imaging is required for accurate diagnosis of fibrostenosing Crohn's disease, and it is recommended before making treatment decisions. It should also assess the degree of inflammation in the bowel wall. Multiple options for medical anti-inflammatory, endoscopic and surgical therapies were suggested, including follow-up strategies following therapy. This Consensus Statement supports clinical practice through providing guidance on definitions, diagnosis and therapeutic management of patients with fibrostenosing small bowel Crohn's disease.

Role of artificial intelligence in Crohn's disease intestinal strictures and fibrosis

Crohn's disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract. Intestinal fibrosis or stricture is one of the most prevalent complications in CD with a high recurrence rate. Manual examination of intestinal fibrosis or stricture by physicians may be biased or inefficient. A rapid development of artificial intelligence (AI) technique in recent years facilitates the detection of existing or possible intestinal fibrosis and stricture in CD through various modalities, including endoscopy, imaging examination, and serological biomarkers. We reviewed the articles on AI application in diagnosing intestinal fibrosis and stricture in CD during the past decade and categorized them into three aspects based on the detection methods, and found that AI helps accurate and expedient identification and prediction of intestinal fibrosis and stenosis in CD.

Reliability of CT Enterography for Describing Fibrostenosing Crohn Disease

Background Standardized methods to measure and describe Crohn disease strictures at CT enterography are needed to guide clinical decision making and for use in therapeutic studies. Purpose To assess the reliability of CT enterography features to describe Crohn disease strictures and their correlation with stricture severity. Materials and Methods A retrospective study was conducted in 43 adult patients with symptomatic terminal ileal Crohn disease strictures who underwent standard-of-care CT enterography at a tertiary care center at the Cleveland Clinic between January 2008 and August 2016. After training on standardized definitions, four abdominal radiologists blinded to all patient information assessed imaging features (seven continuous measurements and nine observations) of the most distal ileal stricture in two separate sessions (separated by ≥2 weeks) in random order. Features with an interrater intraclass correlation coefficient (ICC) of 0.41 or greater (ie, moderate reliability or better) were considered reliable. Univariable and multivariable linear regression analysis identified reliable features associated with a visual analog scale of overall stricture severity. Significant reliable features were assessed as components of a CT enterography-based model to quantitate stricture severity. Results Examinations in 43 patients (mean age, 52 years ± 16 [SD]; 23 female) were evaluated. Five continuous measurements and six observations demonstrated at least moderate interrater reliability (interrater ICC range, 0.42 [95% CI: 0.25, 0.57] to 0.80 [95% CI: 0.67, 0.88]). Of these, 10 were univariably associated with stricture severity, and three continuous measurements-stricture length (interrater ICC, 0.64 [95% CI: 0.42, 0.81]), maximal associated small bowel dilation (interrater ICC, 0.80 [95% CI: 0.67, 0.88]), and maximal stricture wall thickness (interrater ICC, 0.50 [95% CI: 0.34, 0.62])-were independently associated (P value range, <.001 to .003) with stricture severity in a multivariable model. These three measurements were used to derive a well-calibrated (optimism-adjusted calibration slope = 1.00) quantitative model of stricture severity. Conclusion Standardized CT enterography measurements and observations can reliably describe terminal ileal Crohn disease strictures. Stricture length, maximal associated small bowel dilation, and maximal stricture wall thickness are correlated with stricture severity. © RSNA, 2024 Supplemental material is available for this article. See also the article by Rieder et al in this issue. See also the editorial by Galgano and Summerlin in this issue.

Long-term outcomes and associated factors of Crohn's disease patients achieving transmural healing based on magnetic resonance enterography: a Chinese retrospective cohort study

Background

Transmural healing (TH) has emerged as a potential treatment goal for Crohn's disease (CD). However, further research is needed to confirm its benefits and risk factors associated with TH remain unclear.

Objectives

We aimed to assess the value of TH based on magnetic resonance enterography (MRE) in Chinese CD patients regarding the long-term outcomes and its associated factors.

Design

Retrospective, observational cohort study.

Methods

Patients with CD diagnosed by colonoscopy and MRE examination between 2015 and 2022 were included. All patients were evaluated with endoscopy together with MRE within 6-12 months after baseline and followed up for at least 6 months after evaluation. The primary endpoint was the occurrence of major outcomes during the follow-up, including drug escalation, hospitalization, and surgery. The cumulative probabilities of major outcomes were calculated using Kaplan-Meier survival curves. Logistic regression analyses were used to predict TH within 6-12 months after baseline.

Results

A total of 175 patients were included in the study. Of these, 69 (39.4%) patients achieved mucosal healing (MH), but only 34 (19.4%) of them achieved TH. The median follow-up duration was 17.4 months (interquartile range, 11.6-25.5), and major outcomes occurred in 58.3% of patients. A lower occurrence rate of major outcomes was noted in patients who achieved TH than in those who achieved MH only (p = 0.012). The baseline lymphocyte/C-reactive protein ratio (LCR) [odds ratio (OR), 1.60; 95% confidence interval (CI), 1.02-2.50; p = 0.039] and bowel wall thickness (BWT) (OR, 0.72; 95% CI, 0.59-0.90; p = 0.003) were independent predictors associated with TH. According to multivariate Cox regression analysis, low LCR [hazard ratio (HR), 2.34; 95% CI, 1.51-3.64; p < 0.001], and no healing (HR, 5.45; 95% CI, 2.28-13.00; p < 0.001) were associated with an increased risk of major outcomes.

Conclusion

Patients with CD who achieved TH showed improved prognosis compared to those who achieved MH only. Baseline LCR and BWT might predict TH.

Radiology of fibrosis part II: abdominal organs

Fibrosis is the aberrant process of connective tissue deposition from abnormal tissue repair in response to sustained tissue injury caused by hypoxia, infection, or physical damage. It can affect almost all organs in the body causing dysfunction and ultimate organ failure. Tissue fibrosis also plays a vital role in carcinogenesis and cancer progression. The early and accurate diagnosis of organ fibrosis along with adequate surveillance are helpful to implement early disease-modifying interventions, important to reduce mortality and improve quality of life. While extensive research has already been carried out on the topic, a thorough understanding of how this relationship reveals itself using modern imaging techniques has yet to be established. This work outlines the ways in which fibrosis shows up in abdominal organs and has listed the most relevant imaging technologies employed for its detection. New imaging technologies and developments are discussed along with their promising applications in the early detection of organ fibrosis.

A novel multidisciplinary machine learning approach based on clinical, imaging, colonoscopy, and pathology features for distinguishing intestinal tuberculosis from Crohn's disease

OBJECTIVES

Differentiating intestinal tuberculosis (ITB) from Crohn's disease (CD) remains a diagnostic dilemma. Misdiagnosis carries potential grave implications. We aim to establish a multidisciplinary-based model using machine learning approach for distinguishing ITB from CD.

METHODS

Eighty-two patients including 25 patients with ITB and 57 patients with CD were retrospectively recruited (54 in training cohort and 28 in testing cohort). The region of interest (ROI) for the lesion was delineated on magnetic resonance enterography (MRE) and colonoscopy images. Radiomic features were extracted by least absolute shrinkage and selection operator regression. Pathological feature was extracted automatically by deep-learning method. Clinical features were filtered by logistic regression analysis. Diagnostic performance was evaluated by receiver operating characteristic (ROC) curve and decision curve analysis (DCA). Delong's test was applied to compare the efficiency between the multidisciplinary-based model and the other four single-disciplinary-based models.

RESULTS

The radiomics model based on MRE features yielded an AUC of 0.87 (95% confidence interval [CI] 0.68-0.96) on the test data set, which was similar to the clinical model (AUC, 0.90 [95% CI 0.71-0.98]) and higher than the colonoscopy radiomics model (AUC, 0.68 [95% CI 0.48-0.84]) and pathology deep-learning model (AUC, 0.70 [95% CI 0.49-0.85]). Multidisciplinary model, integrating 3 clinical, 21 MRE radiomic, 5 colonoscopy radiomic, and 4 pathology deep-learning features, could significantly improve the diagnostic performance (AUC of 0.94, 95% CI 0.78-1.00) on the bases of single-disciplinary-based models. DCA confirmed the clinical utility.

CONCLUSIONS

Multidisciplinary-based model integrating clinical, MRE, colonoscopy, and pathology features was useful in distinguishing ITB from CD.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

CRITICAL RELEVANCE STATEMENT

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

KEY POINTS

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

Comparative analysis of [18F]F-FAPI PET/CT, [18F]F-FDG PET/CT and magnetization transfer MR imaging to detect intestinal fibrosis in Crohn's disease: A prospective animal model and human cohort study

PURPOSE

Accurately and early detection of intestinal fibrosis in Crohn's disease (CD) is crucial for clinical management yet remains an unmet need. Fibroblast activation protein inhibitor (FAPI) PET/CT has emerged as a promising tool to assess fibrosis. We aimed to investigate the diagnostic capability of [18F]F-FAPI PET/CT in detecting intestinal fibrosis and compared it with[18F]F-FDG PET/CT and magnetization transfer MR imaging (MTI).

METHODS

Twenty-two rats underwent TNBS treatment to simulate fibrosis development, followed by three quantitative imaging sessions within one week. Mean and maximum standardized uptake values (SUVmean and SUVmax) were calculated on[18F]F-FAPI and [18F]F-FDG PET/CT, along with normalized magnetization transfer ratio on MTI. Intestinal fibrosis was assessed pathologically, with MTI serving as imaging standard for fibrosis. The diagnostic efficacy of imaging parameters in fibrosis was compared using pathological and imaging standards. Ten patients with 34 bowel strictures were prospectively recruited to validate their diagnostic performance, using the identical imaging protocol.

RESULTS

In CD patients, the accuracy of FAPI uptake (both AUCs = 0.87, both P ≤ 0.01) in distinguishing non-to-mild from moderate-to-severe fibrosis was higher than FDG uptake (both AUCs = 0.82, P ≤ 0.01) and comparable to MTI (AUCs = 0.90, P ≤ 0.001). In rats, FAPI uptake responded earlier to fibrosis development than FDG and MTI; consistently, during early phase, FAPI uptake showed a stronger correlation (SUVmean: R = 0.69) with pathological fibrosis than FDG (SUVmean: R = 0.17) and MTI (R = 0.52).

CONCLUSION

The diagnostic efficacy of [18F]F-FAPI PET/CT in detecting CD fibrosis is superior to [18F]F-FDG PET/CT and comparable to MTI, exhibiting great potential for early detection of intestinal fibrosis.

Contemporary Imaging Assessment of Strictures and Fibrosis in Crohn Disease, With Focus on Quantitative Biomarkers: From the AJR Special Series on Imaging of Fibrosis

Patients with Crohn disease commonly have bowel strictures develop, which exhibit varying degrees of inflammation and fibrosis. Differentiation of the distinct inflammatory and fibrotic components of strictures is key for the optimization of therapeutic management and for the development of antifibrotic drugs. Cross-sectional imaging techniques, including ultrasound, CT, and MRI, allow evaluation of the full thickness of the bowel wall as well as extramural complications and associated mesenteric abnormalities. Although promising data have been reported for a range of novel imaging biomarkers for detection of fibrosis and quantification of the degree of fibrosis, these biomarkers lack sufficient validation and standardization for clinical use. Additional methods, including PET with emerging radiotracers, artificial intelligence, and radiomics, are also under investigation for stricture characterization. In this review, we highlight the clinical relevance of identifying fibrosis in Crohn disease, review the histopathologic aspects of strictures in Crohn disease, summarize the morphologic imaging findings of strictures, and explore contemporary developments in the use of cross-sectional imaging techniques for detecting and characterizing intestinal strictures, with attention given to emerging quantitative biomarkers.

Recent advances in intestinal fibrosis

Despite many progresses have been made in the treatment of inflammatory bowel disease, especially due to the increasing number of effective therapies, the development of tissue fibrosis is a very common occurrence along the natural history of this condition. To a certain extent, fibrogenesis is a physiological and necessary process in all those conditions characterised by chronic inflammation. However, the excessive deposition of extracellular matrix within the bowel wall will end up in the formation of strictures, with the consequent need for surgery. A number of mechanisms have been described in this process, but some of them are not yet clear. For sure, the main trigger is the presence of a persistent inflammatory status within the mucosa, which in turn favours the occurrence of a pro-fibrogenic environment. Among the main key players, myofibroblasts, fibroblasts, immune cells, growth factors and cytokines must be mentioned. Although there are no available therapies able to target fibrosis, the only way to prevent it is by controlling inflammation. In this review, we summarize the state of art of the mechanisms involved in gut fibrogenesis, how to diagnose it, and which potential targets could be druggable to tackle fibrosis.

Cross-sectional imaging: current status and future potential in adult celiac disease

Celiac disease (CD), triggered by exposure to gluten in genetically susceptible individuals, is an immune-mediated small bowel disease affecting about 1% of the population worldwide. But the prevalence of CD varies with age, sex, and location. A strict gluten-free diet remains the primary treatment for CD, currently. Most of patients with CD respond well to gluten-free diet with good prognosis, while some patients fail to get symptomatic relief or histological remission (e.g., nonresponsive or refractory CD). Because of heterogeneous clinical appearance, the diagnosis of CD is difficult. Moreover, malignant complications and poor outcomes accompanied with refractory CD present great challenges in disease management. Over the past three decades, cross-sectional imaging techniques (computed tomography [CT] and magnetic resonance imaging [MRI]) play an important role in small bowel inflammatory and neoplastic diseases. Compared with endoscopic techniques, cross-sectional imaging permits clearly presentation of both intraluminal and extraluminal abnormalities. It provides vascular and functional information, thus improving the possibility as diagnostic and follow-up tool. The value of cross-sectional imaging for patients with suspected or confirmed CD has been gradually demonstrated. Studies revealed that certain features suggested by cross-sectional imaging could help to establish the early diagnosis of CD. Besides, the potential contributions of cross-sectional imaging may lie in the evaluation of disease activity and severity, which helps guiding management strategies. The purpose of this review is to provide current overviews and future directions of cross-sectional imaging in adult CD, thus facilitating the understanding and application in clinical practice. CLINICAL RELEVANCE STATEMENT: In this review, we systematically summarized the existing knowledge of cross-sectional imaging in adult CD and analyzed their possible roles in clinical practice, including disease diagnosis, complication identification, treatment evaluation, and prognostic prediction. KEY POINTS: • Regarding a condition described as "celiac iceberg", celiac disease remains underdiagnosed and undertreated. • Cross-sectional imaging is helpful in clinical management of celiac disease, including disease diagnosis, complication identification, treatment evaluation, and prognostic prediction. • Cross-sectional imaging should be considered as the valuable examination in patients suspected from celiac disease.

Comprehensive review and update of stricturing Crohn's disease

Up to 50% of patients with Crohn's disease develop a stricture within 10 years of diagnosis. Crohn's strictures can compose of inflammation, fibrosis or smooth muscle expansion and usually a combination of these. There have been numerous new developments in imaging modalities in determining the composition of Crohn's strictures. Magnetic resonance imaging remains the best upfront imaging modality to characterize Crohn's strictures. Gastrointestinal ultrasound (GIUS) has an increasing role in clinical practice, particularly for monitoring stricture response as a treat-to-target tool. Novel imaging techniques to differentiate between fibrosis and inflammatory strictures have been developed including contrast-enhanced GIUS, strain or shear wave elastography with GIUS and multiple new magnetic resonance imaging (MRI) protocols, including diffusion weighted, delayed contrast enhancement and magnetization transfer MR protocols. However, these techniques require further validation and standardization. Regarding therapeutics, anti-tumor necrosis agents with a treat-to-target strategy have the highest quality evidence in treating strictures and can lead to stricture regression in some cases. Endoscopic balloon dilatation remains a mainstay in the treatment algorithm of treating predominantly fibrostenotic Crohn's strictures, particularly those which are symptomatic, < 5 cm in length and not causing prestenotic dilatation. Endoscopic balloon dilatation has greater effectiveness in anastomotic strictures. Surgery remains an important treatment option in Crohn's strictures, with segmental resection and stricturoplasty having their own advantages and disadvantages. Kono-S anastomosis may be superior to conventional anastomosis for endoscopic recurrence; however, further high-quality studies are required to confirm this. Using risk stratification models such as the BACARDI risk model is important to guide management decisions between a medical and surgical approach. Early post-operative medical prophylaxis with an advanced therapy is an important consideration to prevent disease recurrence. This review expands on the above topics, highlights research gaps and provides a suggested investigation and management pathway in stricturing Crohn's disease.

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

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

Adiabatic null passage for on-resonance magnetization transfer preparation

PURPOSE

We propose a novel RF pulse providing an adiabatic null passage (ANP) for magnetization transfer preparation with improved insensitivity toB 1 + $$ {\mathrm{B}}_1^{+} $$ and B0 inhomogeneities and mitigated direct saturation and T2 effects.

METHOD

The phase modulation function of a 6-ms time-resampled frequency offset-corrected pulse was modified to achieve zero flip angle at the end of the pulse. The spectral response was simulated, and its insensitivity to B0 andB 1 + $$ {\mathrm{B}}_1^{+} $$ was investigated and compared with a phase-inverted (12 ¯ $$ \overline{2} $$ 1-1 ¯ $$ \overline{1} $$ 21 ¯ $$ \overline{1} $$ ) binomial pulse. The proposed pulse was implemented in a 2D-EPI pulse sequence to generate magnetization transfer (MT) contrast and MT ratio (MTR) maps. In vivo experiments were performed on 3 healthy participants with power-matched settings for ANP and the binomial pulse with the following parameters: 6-ms binomial pulse with a flip angle of 107° (shortest element) and pulse repetition period (PRP) of TRslice  = 59 ms, three experiments with 6-ms ANP and constant MT used overdrive factor (OF)/PRP values of 1/TRslice ,2 $$ \sqrt{2} $$ /2TRslice , and3 $$ \sqrt{3} $$ /3TRslice .

RESULTS

At gray matter (white matter) in vivo, the MTR decreased from 61% (64%) at OF = 1 to 38% (42%) applying ANP with an OF =3 $$ \sqrt{\mathsf{3}} $$ and PRP = 3 TRslice , demonstrating the mitigation of T2 /direct effect by 22% (22%). Bloch-McConnell simulations gave similar values. In vivo experiments showed significant improvement in the MTR values for areas with high B0 inhomogeneity.

CONCLUSION

ANP pulse was shown to be advantageous over its binomial counterpart in providing MT contrast by mitigating the T2 effect and direct saturation of the liquid pool as well as reduced sensitivity toB 1 + $$ {\mathrm{B}}_1^{+} $$ and B0 inhomogeneity.

Evaluating the diagnostic accuracy of magnetic resonance imaging in distinguishing strictures in Crohn's disease: a systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis sought to assess the diagnostic accuracy of magnetic resonance imaging (MRI) in distinguishing fibrotic from inflammatory strictures in Crohn's disease (CD) patients.

METHODS

A rigorous and systematic exploration of five key databases yielded studies that met predefined criteria. Data were extracted for a comprehensive meta-analysis using MetaDiSC and MetaDTA software, providing diagnostic accuracy measures. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool was utilized for evaluating the methodological quality and potential bias within the studies.

RESULTS

The systematic review involved the evaluation of 7437 records, culminating in the inclusion of 22 studies. In detecting fibrotic strictures in CD patients, MRI exhibited a pooled sensitivity of 85.20% (95% CI: 76.10-91.20%) and specificity of 96.00% (95% CI: 87.80-98.70%). For differentiating fibrotic strictures from inflammatory stenosis, the sensitivity was 81.5% (95% CI: 70.2-89.20%), and the specificity was 97.2% (95% CI: 90.0-99.3%). In terms of assessing the severity of strictures, sensitivity stood at 90.4% (95% CI: 78.1-96.1%) and specificity at 89.4% (95% CI: 57.4-98.2%). The consistency of the diagnostic accuracy was observed across different geographical locations and the various reference tests applied in the studies.

CONCLUSIONS

The results of this meta-analysis underscore the robust diagnostic accuracy of MRI in detecting fibrotic strictures, distinguishing between fibrotic and inflammatory strictures, and evaluating stricture severity in CD patients. These findings support the integration of MRI into standard diagnostic protocols for patients with CD. Further large-scale, multicenter trials are warranted to confirm these results and to identify any potential limitations associated with the application of MRI in this clinical setting.

MRI texture analysis of T2-weighted images is preferred over magnetization transfer imaging for readily longitudinal quantification of gut fibrosis

OBJECTIVES

To investigate the value of magnetization transfer (MT) MRI and texture analysis (TA) of T2-weighted MR images (T2WI) in the assessment of intestinal fibrosis in a mouse model.

METHODS

Chronic colitis was induced in mice by cyclic administration of dextran sodium sulphate (DSS) resulting in chronic inflammation and progressive bowel fibrosis. Mice underwent 7-T MR imaging at various time points. Bowel wall MT ratio (MTR) and textural features (skewness, kurtosis, entropy), extracted by a filtration histogram technique, were correlated with histopathology. Performance of both techniques were validated using antifibrotic therapy. Finally, a retrospective study was conducted in five patients with Crohn's disease (CD) who underwent bowel surgery.

RESULTS

MTR and texture entropy correlated with histopathological fibrosis (r = .85 and .81, respectively). Entropy was superior to MTR for monitoring bowel fibrosis in the presence of coexisting inflammation (linear regression R2 = .93 versus R2 = .01). Furthermore, texture entropy was able to assess antifibrotic therapy response (placebo mice versus treated mice at endpoint scan; Δmean = 0.128, p < .0001). An increase in entropy was indicative of fibrosis accumulation in human CD strictures (inflammation: 1.29; mixed strictures: 1.4 and 1.48; fibrosis: 1.73 and 1.9).

CONCLUSION

MT imaging and TA of T2WI can both noninvasively detect established intestinal fibrosis in a mouse model. However, TA is especially useful for the longitudinal quantification of fibrosis in mixed inflammatory-fibrotic tissue, as well as for antifibrotic treatment response evaluation. This accessible post-processing technique merits further validation as the benefits for clinical practice as well as antifibrotic trial design would be numerous.

KEY POINTS

• Magnetization transfer MRI and texture analysis of T2-weighted MR images can detect established bowel fibrosis in an animal model of gut fibrosis. • Texture entropy is able to identify and monitor bowel fibrosis progression in an inflammatory context and can assess the response to antifibrotic treatment. • A proof-of-concept study in five patients with Crohn's disease suggests that texture entropy can detect and grade fibrosis in human intestinal strictures.

Feasibility of in vivo magnetic resonance elastography of mesenteric adipose tissue in Crohn's disease

Background

Although there is growing evidence that functional involvement and structural changes of mesenteric adipose tissue (MAT) influence the course of Crohn's disease (CD), its viscoelastic properties remain elusive. Therefore, we aimed to investigate the viscoelastic properties of MAT in CD using magnetic resonance elastography (MRE), providing reference values for CD diagnosis.

Methods

In this prospective proof-of-concept study, 31 subjects (CD: n=11; healthy controls: n=20) were consecutively enrolled in a specialized care center for inflammatory bowel diseases (tertiary/quaternary care). Inclusion criteria for the CD patients were a clinically and endoscopically established diagnosis of CD based on the clinical record, absence of other concurrent bowel diseases, scheduled surgery for the following day, and age of at least 18 years. Diagnoses were confirmed by histological analysis of the resected bowel the day after MRE. Subjects were investigated using MRE at 1.5-T with frequencies of 40-70 Hz. To retrieve shear wave speed (SWS), volumes of interest (VOIs) in MAT were drawn adjacent to CD lesions (MATCD) and on the opposite side without adjacent bowel lesions in patients (MATCD_Opp) and controls (MATCTRL). The presented study is not registered in the clinical trial platform.

Results

A statistically significant decrease in mean SWS of 7% was found for MATCD_Opp vs. MATCTRL (0.76±0.05 vs. 0.82±0.04 m/s, P=0.012), whereas there was a nonsignificant trend with an 8% increase for MATCD vs. MATCD_Opp (0.82±0.07 vs. 0.76±0.05 m/s, P=0.098) and no difference for MATCD vs. MATCTRL. Preliminary area under the receiver operating characteristic curve (AUC) analysis showed diagnostic accuracy in detecting CD to be excellent for SWS of MATCD_Opp [AUC =0.82; 95% confidence interval (CI): 0.64-0.96] but poor for SWS of MATCD (AUC =0.52; 95% CI: 0.34-0.73).

Conclusions

This study demonstrates the feasibility of MRE of MAT and presents preliminary reference values for CD patients and healthy controls. Our results motivate further studies for the biophysical characterization of MAT in inflammatory bowel disease.

Small bowel imaging in inflammatory bowel disease: updates for 2023

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

How to Evaluate Fibrosis in IBD?

In this review, we will describe the importance of fibrosis in inflammatory bowel disease (IBD) by discussing its distinct impact on Crohn's disease (CD) and ulcerative colitis (UC) through their translation to histopathology. We will address the existing knowledge on the correlation between inflammation and fibrosis and the still not fully explained inflammation-independent fibrogenesis. Finally, we will compile and discuss the recent advances in the noninvasive assessment of intestinal fibrosis, including imaging and biomarkers. Based on the available data, none of the available cross-sectional imaging (CSI) techniques has proved to be capable of measuring CD fibrosis accurately, with MRE showing the most promising performance along with elastography. Very recent research with radiomics showed encouraging results, but further validation with reliable radiomic biomarkers is warranted. Despite the interesting results with micro-RNAs, further advances on the topic of fibrosis biomarkers depend on the development of robust clinical trials based on solid and validated endpoints. We conclude that it seems very likely that radiomics and AI will participate in the future non-invasive fibrosis assessment by CSI techniques in IBD. However, as of today, surgical pathology remains the gold standard for the diagnosis and quantification of intestinal fibrosis in IBD.

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

Background

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

Methods

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

Results

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

Conclusion

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

Early transmural healing and its predictors assessed by magnetic resonance enterography in patients with Crohn's disease receiving ustekinumab

Background

Transmural healing (TH) is a potential therapeutic goal of Crohn's disease (CD) and is associated with better clinical outcomes. However, few studies have described early TH and its predictors.

Objectives

We aimed to evaluate early TH and its predictors using magnetic resonance enterography (MRE) in patients with CD receiving ustekinumab (UST).

Design

This was a retrospective observational study.

Methods

Patients with active CD treated with UST and their intestinal segments with bowel wall thickness (BWT) ⩽ 3 mm at baseline were included. Clinical characteristics, laboratory indicators, endoscopic manifestations, and MRE indices were evaluated at baseline and week 26 (W26) of the therapy. The following MRE parameters were assessed: BWT, edema, apparent diffusion coefficient (ADC), Clermont score, Magnetic Resonance Index of Activity score, fat stranding, comb sign, and stricture. TH was defined as BWT ⩽ 3 mm without any signs of inflammation (i.e., ulceration, edema, diffusion-weighted hyperintensity, and increased contrast enhancement) at W26.

Results

The study included 37 patients with 106 intestinal segments (including 15 proximal small intestines, 33 terminal ilea, and 58 colons). Clinical features, laboratory indicators, endoscopic results, and MRE parameters at W26 were significantly improved after UST treatment in both patient-based and intestinal segment-based analysis. Seven (18.9%) patients and 26 (24.5%) intestinal segments achieved TH at W26. Baseline BWT [odds ratio (OR) = 0.287, 95% confidence interval (CI), 0.090-0.918, p = 0.035] and ADC (OR = 2.997, 95% CI, 1.009-8.908, p = 0.048) predict TH of patients at W26. Baseline ADC (OR = 2.857, 95% CI, 1.285-6.349, p = 0.010) and presence of stenosis (OR = 0.196, 95% CI, 0.052-0.735, p = 0.016) were associated with TH of segments at W26.

Conclusion

Early TH assessed by MRE was observed in nearly one-fifth of patients with CD and intestinal segments after UST treatment for 26 weeks. Baseline MRE indices such as BWT and presence of stenosis might negatively predict TH, while ADC might positively predict early TH.

The Role of Radiomics in Fibrosis Crohn's Disease: A Review

Inflammatory bowel disease (IBD) is a global health concern that has been on the rise in recent years. In addition, imaging is the established method of care for detecting, diagnosing, planning treatment, and monitoring the progression of IBD. While conventional imaging techniques are limited in their ability to provide comprehensive information, cross-sectional imaging plays a crucial role in the clinical management of IBD. However, accurately characterizing, detecting, and monitoring fibrosis in Crohn's disease remains a challenging task for clinicians. Recent advances in artificial intelligence technology, machine learning, computational power, and radiomic emergence have enabled the automated evaluation of medical images to generate prognostic biomarkers and quantitative diagnostics. Radiomics analysis can be achieved via deep learning algorithms or by extracting handcrafted radiomics features. As radiomic features capture pathophysiological and biological data, these quantitative radiomic features have been shown to offer accurate and rapid non-invasive tools for IBD diagnostics, treatment response monitoring, and prognosis. For these reasons, the present review aims to provide a comprehensive review of the emerging radiomics methods in intestinal fibrosis research that are highlighted and discussed in terms of challenges and advantages.

Fibro-Stenosing Crohn's Disease: What Is New and What Is Next?

Fibro-stenosing Crohn's disease (CD) is a common disease presentation that leads to impaired quality of life and often requires endoscopic treatments or surgery. From a pathobiology perspective, the conventional view that intestinal fibro-stenosis is an irreversible condition has been disproved. Currently, there are no existing imaging techniques that can accurately quantify the amount of fibrosis within a stricture, and managing patients is challenging, requiring a multidisciplinary team. Novel therapies targeting different molecular components of the fibrotic pathways are increasing regarding other diseases outside the gut. However, a large gap between clinical need and the lack of anti-fibrotic agents in CD remains. This paper reviews the current state of pathobiology behind fibro-stenosing CD, provides an updated diagnostic and therapeutic approach, and finally, focuses on clinical trial endpoints and possible targets of anti-fibrotic therapies.

Mucosa-Associated Oscillospira sp. Is Related to Intestinal Stricture and Post-Operative Disease Course in Crohn's Disease

Intestinal stricture remains one of the most intractable complications in Crohn's disease (CD), and the involved mechanisms are poorly understood. Accumulating evidence suggests that the gut microbiota contributes to the pathogenesis of intestinal fibrosis. In this study, we investigated specific mucosa-associated microbiota related to intestinal strictures and their role in predicting postoperative disease course. Twenty CD patients who had undergone operative treatments were enrolled and followed up. Intestinal mucosa and full-thickness sections from stenotic and non-stenotic sites were sterilely collected. DNA extraction and bacterial 16s rRNA gene sequencing were conducted. Radiological and histological evaluations were performed to assess fibrosis. Microbial alpha diversity was significantly decreased in stenotic sites (p = 0.009). At the genus level, Lactobacillus, Oscillospira, Subdoligranulum, Hydrogenophaga, Clostridium and Allobaculum were decreased in stenotic segments (p < 0.1). The difference in Oscillospira sp. (stenotic vs. non-stenotic) was negatively correlated with the erythrocyte sedimentation rate (correlation coefficient (CC) -0.432, p = 0.057) and white blood cell count (CC -0.392, p = 0.087) and positively correlated with serum free fatty acids (CC 0.575, p < 0.05). This difference was negatively associated with intestinal fibrosis evaluated by imagological and histological methods (CC -0.511 and -0.653, p < 0.05). Furthermore, CD patients with a higher abundance of Oscillospira sp. in the residual intestine might experience longer remission periods (p < 0.05). The mucosa-associated microbiota varied between stenotic and non-stenotic sites in CD. Most notably, Oscillospira sp. was negatively correlated with intestinal fibrosis and postoperative disease course. It could be a promising biomarker to predict post-operative disease recurrence and a microbial-based therapeutic target.

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.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

KEY POINTS

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

Inflammatory bowel disease cross-sectional imaging: What's new?

Cross-sectional imaging-ultrasonography, computed tomography enterography, and magnetic resonance enterography-is a routine and indispensable tool for patients with Crohn's disease (CD) that helps to detect or monitor disease characteristics before, during, and after CD treatment. New emerging radiological technologies may have further clinical applications in the management of CD. In this review article, we focus on the latest developments in cross-sectional imaging in CD research, including its role in intra- and extra-luminal lesion detection, intestinal inflammation and fibrosis grading, therapeutic response assessment and outcome prediction, postoperative recurrence detection and prediction, and the gut-brain axis.

Recent advances in clinical practice: advances in cross-sectional imaging in inflammatory bowel disease

Endoscopy remains the reference standard for the diagnosis and assessment of patients with inflammatory bowel disease (IBD), but it has several important limitations. Cross-sectional imaging techniques such as magnetic resonance enterography (MRE) and intestinal ultrasound (IUS) are better tolerated and safer. Moreover, they can examine the entire bowel, even in patients with stenoses and/or severe inflammation. A variety of cross-sectional imaging activity scores strongly correlate with endoscopic measures of mucosal inflammation in the colon and terminal ileum. Unlike endoscopy, cross-sectional techniques allow complete visualisation of the small-bowel and assess for extraintestinal disease, which occurs in nearly half of patients with IBD. Extramural findings may predict outcomes better than endoscopic mucosal assessment, so cross-sectional techniques might help identify more relevant therapeutic targets. Coupled with their high sensitivity, these advantages have made MRE and IUS the primary non-invasive options for diagnosing and monitoring Crohn's disease; they are appropriate first-line investigations, and have become viable alternatives to colonoscopy. This review discusses cross-sectional imaging in IBD in current clinical practice as well as research lines that will define the future role of these techniques.

Advanced imaging and Crohn's disease: An overview of clinical application and the added value of artificial intelligence

PURPOSE

The purpose of this narrative review is to describe the clinical applications of advanced computed tomography (CT) and magnetic resonance (MRI) techniques in patients affected by Crohn's disease (CD), giving insights about the added value of artificial intelligence (AI) in this field.

METHODS

We performed a literature search comparing standardized and advanced imaging techniques for CD diagnosis. Cross-sectional imaging is essential for the identification of lesions, the assessment of active or relapsing disease and the evaluation of complications.

RESULTS

The studies reviewed show that new advanced imaging techniques and new MRI sequences could be integrated into standard protocols, to achieve a reliable quantification of CD activity, improve the lesions' characterization and the evaluation of therapy response. These promising tools are: dual-energy CT (DECT) post-processing techniques, diffusion-weighted MRI (DWI-MRI), dynamic contrast-enhanced MRI (DCE-MRI), Magnetization Transfer MRI (MT-MRI) and CINE-MRI. Furthermore, AI solutions show a potential when applied to radiological techniques in these patients. Machine learning (ML) algorithms and radiomic features prove to be useful in improving the diagnostic accuracy of clinicians and in attempting a personalized medicine approach, stratifying patients by predicting their prognosis.

CONCLUSIONS

Advanced imaging is crucial in the diagnosis, lesions' characterisation and in the estimation of the abdominal involvement in CD. New AI developments are promising tools that could support doctors in the management of CD affected patients.

Intestinal fibrosis classification in patients with Crohn's disease using CT enterography-based deep learning: comparisons with radiomics and radiologists

OBJECTIVES

Accurate evaluation of bowel fibrosis in patients with Crohn's disease (CD) remains challenging. Computed tomography enterography (CTE)-based radiomics enables the assessment of bowel fibrosis; however, it has some deficiencies. We aimed to develop and validate a CTE-based deep learning model (DLM) for characterizing bowel fibrosis more efficiently.

METHODS

We enrolled 312 bowel segments of 235 CD patients (median age, 33 years old) from three hospitals in this retrospective study. A training cohort and test cohort 1 were recruited from center 1, while test cohort 2 from centers 2 and 3. All patients performed CTE within 3 months before surgery. The histological fibrosis was semi-quantitatively assessed. A DLM was constructed in the training cohort based on a 3D deep convolutional neural network with 10-fold cross-validation, and external independent validation was conducted on the test cohorts. The radiomics model (RM) was developed with 4 selected radiomics features extracted from CTE images by using logistic regression. The evaluation of CTE images was performed by two radiologists. DeLong's test and a non-inferiority test were used to compare the models' performance.

RESULTS

DLM distinguished none-mild from moderate-severe bowel fibrosis with an area under the receiver operator characteristic curve (AUC) of 0.828 in the training cohort and 0.811, 0.808, and 0.839 in the total test cohort, test cohorts 1 and 2, respectively. In the total test cohort, DLM achieved better performance than two radiologists (*1 AUC = 0.579, *2 AUC = 0.646; both p < 0.05) and was not inferior to RM (AUC = 0.813, p < 0.05). The total processing time for DLM was much shorter than that of RM (p < 0.001).

CONCLUSION

DLM is better than radiologists in diagnosing intestinal fibrosis on CTE in patients with CD and not inferior to RM; furthermore, it is more time-saving compared to RM.

KEY POINTS

• Question Could computed tomography enterography (CTE)-based deep learning model (DLM) accurately distinguish intestinal fibrosis severity in patients with Crohn's disease (CD)? • Findings In this cross-sectional study that included 235 patients with CD, DLM achieved better performance than that of two radiologists' interpretation and was not inferior to RM with significant differences and much shorter processing time. • Meaning This DLM may accurately distinguish the degree of intestinal fibrosis in patients with CD and guide gastroenterologists to formulate individualized treatment strategies for those with bowel strictures.

Imaging Evaluation of Inflammatory Bowel Disease Complications

Inflammatory bowel disease (IBD) is a chronic inflammatory condition that can progress to fibrostenotic and penetrating complications. Cross-sectional imaging is often needed for accurate diagnosis of IBD complication and for planning the appropriate management strategy. Computed tomography enterography, magnetic resonance enterography, and IBD ultrasound have become key tools for clinicians and interventional endoscopists. This article highlights and discusses various radiologic imaging techniques and their application to the diagnosis and management of IBD complications.

Intestinal Ultrasound for Differentiating Fibrotic or Inflammatory Stenosis in Crohn's Disease: A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

Intestinal ultrasound [IUS] has been increasingly reported to distinguish inflammatory or fibrotic intestinal stenosis in Crohn's disease [CD] patients. However, the diagnostic value is unclear. This systematic review and meta-analysis aimed to assess the diagnostic role of different modes of IUS parameters.

METHODS

We searched PubMed, Embase, Web of Science, and Cochrane Library from inception to August 2021. Regarding effect sizes, weighted mean differences [WMDs] or standardised mean differences [SMDs] were used. We pooled data using a random-effects or fixed-effects model according to heterogeneity. The diagnostic accuracy of IUS for distinguishing fibrosis was pooled.

RESULTS

A total of 19 studies were retained for qualitative analysis, and 14 were included in the meta-analysis [with 511 total subjects and 635 bowel segments]. In patients with fibrotic stenosis, the pooled WMDs for bowel wall thickness were 1.30 mm (95% confidence interval [CI]: 0.69-1.91) thicker than in patients with inflammatory stenosis, and the pooled SMDs for strain value and strain ratio were 0.80 [95% CI: 0.41-1.20] and 1.08 [95% CI: 0.55-1.60] harder than in patients with inflammatory stenosis, respectively. The percentage of maximal enhancement of fibrotic stenosis was lower than that of inflammatory stenosis [WMD -10.03; 95% CI: -17.91- -2.16]. The diagnostic accuracy of IUS was not performed because only a few studies provided relevant diagnostic indicators, and these studies used different modes and parameters.

CONCLUSIONS

IUS currently is inaccurate to differentiate fibrotic or inflammatory stenosis in CD patients, and more studies assessing the significance of each parameter and its cut-off value in different modes of IUS are needed to be conducted in the future.

Visceral adipose volume is correlated with surgical tissue fibrosis in Crohn's disease of the small bowel

Background

This study explored the diagnostic performance of visceral adiposity to predict the degree of intestinal inflammation and fibrosis.

Methods

The patients with Crohn’s disease (CD) who underwent surgical small bowel resection at the First Affiliated Hospital of Sun Yat-sen University (Guangzhou, China) between January 2007 and December 2017 were enrolled. We evaluated the intestinal imaging features of computed tomography enterography (CTE), including mesenteric inflammatory fat stranding, the target sign, mesenteric hypervascularity, bowel wall thickening, lymphadenopathy, stricture diameter, and maximal upstream diameter. We used A.K. software (Artificial Intelligence Kit, version 1.1) to calculate the visceral fat (VF) and subcutaneous fat (SF) volumes at the third lumbar vertebra level. Pathological tissue information was recorded. Diagnostic models were established based on the multivariate regression analysis results, and their effectiveness was evaluated by area under the curve (AUC) and decision curve analyses.

Results

Overall, 48 patients with CD were included in this study. The abdominal VF/SF volume ratio (odds ratio, 1.20; 95% confidence interval, 1.05–1.38; P = 0.009) and the stenosis diameter/upstream intestinal dilatation diameter (ND) ratio (odds ratio, 0.90; 95% confidence interval, 0.82–0.99; P = 0.034) were independent risk factors for the severe fibrosis of the small intestine. The AUC values of the VF/SF ratio, the ND ratio, and their combination were 0.760, 0.673, and 0.804, respectively. The combination of the VS/SF volume ratio and ND ratio achieved the highest net benefit on the decision curve.

Conclusion

The VF volume on CTE can reflect intestinal fibrosis. The combination of the VF/SF volume ratio and ND ratio of CD patients assessed using CTE can help predict severe fibrosis stenosis of the small intestine.

Preliminary Application of Magnetization Transfer Imaging in the Study of Normal Uterus and Uterine Lesions

PURPOSE

The aim of this study is to evaluate the utility of magnetization transfer (MT) imaging in the study of normal uterus and common uterine lesions.

METHODS

This prospective study enrolled 160 consecutive patients with suspected uterine lesions. MT ratio (MTR) map was obtained by pelvic MT imaging on a 3.0T MRI scanner. Patients confirmed by pathology were divided into microscopic lesion group and lesion group, according to whether the maximum diameter of the lesion was less than 5 mm. After evaluating and eliminating patients with poor image quality by a three-point Likert scale, MTR values of lesions and normal endometrium, myometrium, and cervix were independently measured on the MTR map by two radiologists. Inter-reader agreement was evaluated. MTR values were compared among different uterine lesions and normal uterine structures using the Mann-Whitney U test with Bonferroni correction. Receiver operating characteristic curve was performed. The correlations between age and MTR values were explored by Pearson correlation analyses.

RESULTS

A total of 96 patients with 121 uterine lesions in the lesion group and 41 patients in the microscopic lesion group were measured. The MTR values among normal endometrium, myometrium, and cervix were statistical significant differences (P < 0.05). There were significant differences between endometrial cancer and normal endometrium and between cervical cancer and normal cervix (both P ≤ 0.001). Area under the curve (AUC) for diagnosing endometrial and cervical cancer were 0.73 and 0.86. Myometrial lesions had significantly higher MTR values than endometrial lesions and cervical cancer (both P < 0.001), and the AUC for differentiating myometrial lesions from them were 0.89 and 0.94. MTR values of endometrial cancer were significantly higher than those of cervical cancer (P = 0.02). There was a critical correlation between age and MTR values in endometrial cancer (r = 0.81, P = 0.04).

CONCLUSIONS

MTR values showed significant differences among normal uterine structures. It was valuable for diagnosing and differentiating uterine cancer. MTR values could differentiate myometrial lesions from endometrial or cervical lesions.

Reverse translation approach generates a signature of penetrating fibrosis in Crohn's disease that is associated with anti-TNF response

OBJECTIVE

Fibrosis is a common feature of Crohn's disease (CD) which can involve the mesenteric fat. However, the molecular signature of this process remains unclear. Our goal was to define the transcriptional signature of mesenteric fibrosis in CD subjects and to model mesenteric fibrosis in mice to improve our understanding of CD pathogenesis.

DESIGN

We performed histological and transcriptional analysis of fibrosis in CD samples. We modelled a CD-like fibrosis phenotype by performing repeated colonic biopsies in mice and analysed the model by histology, type I collagen-targeted positron emission tomography (PET) and global gene expression. We generated a gene set list of essential features of mesenteric fibrosis and compared it to mucosal biopsy datasets from inflammatory bowel disease patients to identify a refined gene set that correlated with clinical outcomes.

RESULTS

Mesenteric fibrosis in CD was interconnected to areas of fibrosis in all layers of the intestine, defined as penetrating fibrosis. We found a transcriptional signature of differentially expressed genes enriched in areas of the mesenteric fat of CD subjects with high levels of fibrosis. Mice subjected to repeated colonic biopsies showed penetrating fibrosis as shown by histology, PET imaging and transcriptional analysis. Finally, we composed a composite 24-gene set list that was linked to inflammatory fibroblasts and correlated with treatment response.

CONCLUSION

We linked histopathological and molecular features of CD penetrating fibrosis to a mouse model of repeated biopsy injuries. This experimental system provides an innovative approach for functional investigations of underlying profibrotic mechanisms and therapeutic concepts in CD.

Magnetic Resonance Enterography and Histology in Patients With Fibrostenotic Crohn's Disease: A Multicenter Study

INTRODUCTION

Magnetic resonance enterography (MRE) is useful for detecting bowel strictures, whereas a number of imaging biomarkers may reflect severity of fibrosis burden in Crohn's disease (CD). This study aimed to verify the association of MRE metrics with histologic fibrosis independent of inflammation.

METHODS

This prospective European multicenter study performed MRE imaging on 60 patients with CD with bowel strictures before surgical resection. Locations of 61 histological samples were annotated on MRE examinations, followed by central readings using the Chiorean score and measurement of delayed gain of enhancement (DGE), magnetization transfer ratio, T2-weighted MRI sequences (T2R), apparent diffusion coefficient (ADC), and the magnetic resonance index of activity (MaRIA). Correlations of histology and MRE metrics were assessed. Least Absolute Shrinkage and Selection Operator and receiver operator characteristic (ROC) curve analyses were used to select composite MRE scores predictive of histology and to estimate their predictive value.

RESULTS

ADC and MaRIA correlated with fibrosis (R = -0.71, P < 0.0001, and 0.59, P < 0.001) and more moderately with inflammation (R = -0.35, P < 0.01, and R = 0.53, P < 0.001). Lower or no correlations of fibrosis or inflammation were found with DGE, magnetization transfer ratio, or T2R. Least Absolute Shrinkage and Selection Operator and ROC identified a composite score of MaRIA, ADC, and DGE as a very good predictor of histologic fibrosis (ROC area under the curve = 0.910). MaRIA alone was the best predictor of histologic inflammation with excellent performance in identifying active histologic inflammation (ROC area under the curve = 0.966).

DISCUSSION

MRE-based scores for histologic fibrosis and inflammation may assist in the characterization of CD stenosis and enable development of fibrosis-targeted therapies and clinical treatment of stenotic patients.