Diagnostic accuracies of MR enterography and CT enterography in symptomatic Crohn's disease

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.

Assessment of activity and severity of inflammatory bowel disease in cross-sectional imaging techniques: a systematic review

BACKGROUND AND AIMS

Cross-sectional imaging techniques, including intestinal ultrasonography (IUS), computed tomography enterography (CTE), magnetic resonance enterography (MRE), are increasingly used for the evaluation of inflammatory bowel diseases (IBD). We aimed to systematically review literature evidence on the assessment of disease activity, and/or severity through cross-sectional imaging in IBD patients, and to offer guidance on their most effective utilization.

METHODS

We performed a systematic review of PubMed, EMBASE, and Scopus to identify citations pertaining to the assessment of disease activity and/or severity at cross-sectional imaging techniques compared to a reference standard (ie, other radiological techniques, endoscopy, histopathology, and surgery) in IBD patients published until December 2023.

RESULTS

Overall, 179 papers published between 1990 and 2023 were included, with a total of 10 988 IBD patients (9304 Crohn's disease [84.7%], 1206 ulcerative colitis [11.0%], 38 IBD-U [0.3%], 440 unspecified [4.0%]). Of the 179 studies, 39 investigated IUS, 22/179 CTE, and 101/179 MRE. In the remaining papers, 2 techniques were addressed together. In 81.6% of the papers, endoscopy (with or without histopathology) was used as a reference standard. All studies included evaluated disease activity, while just over half (100/179, 55.8%) also evaluated disease severity of the addressed cross-sectional methodology. Pooled sensitivity, specificity, and overall accuracy of IUS, MRE, and CTE compared to the reference standard were 60%-99%, 60%-100%, and 70%-99%, respectively.

CONCLUSIONS

All cross-sectional imaging techniques demonstrated moderate-to-good accuracy in assessing disease activity and severity of IBD. This finding highlights the potential, especially for MRE and IUS to be widely utilized in managing IBD in both clinical practice and clinical trials.

Anti-fibrotics in inflammatory bowel diseases: Challenges and successes

Stricture formation leading to obstruction in Crohn's disease (CD) remains one of the largest unmet needs in the field of inflammatory bowel diseases (IBD). Despite this need no selective anti-stricture drug has been approved for use in CD patients. This contrasts with other fibrotic diseases, such as in the lung, liver or kidney, where multiple drug development programs crossed the starting line and two anti-fibrotics are now being approved for pulmonary fibrosis. Strictures are composed of a mix of inflammation, excessive deposition of extracellular matrix (ECM) and smooth muscle hyperplasia, likely all ultimately being responsible for the luminal narrowing driving patient symptoms. Our understanding of the pathogenesis of stricturing CD has evolved and indicates a multifactorial process involving immune and non-immune cells and their soluble mediators. This understanding has rendered target pathways for anti-stricture drug development. Significant progress was made in creating consensus definitions and tools to enable clinical trials with two clinical development programs having been conceived to date. In this chapter, we discuss stricture pathogenesis with a focus on the pathways being tested in clinical trials, and clinical trial endpoints developed for this indication.

The Utility of Patency Capsule in Patients With Crohn's Disease

BACKGROUND

Video capsule retention is a complication that can have serious consequences in patients with Crohn's disease (CD). The patency capsule was developed to detect small bowel strictures. The usefulness of patency capsules in patients who do not have evidence of small bowel disease on imaging is uncertain.

STUDY

This is a multicenter retrospective study of patients with suspected or confirmed CD who underwent a patency capsule study between January 2017 and February 2023. We excluded patients who were lost to follow-up or did not have computerized tomography or magnetic resonance imaging of the abdomen within 180 days before or after the patency capsule study.

RESULTS

A total of 105 patients met the inclusion criteria with 69% having a confirmed CD diagnosis. The majority of patients (95/105; 90.5%) passed their patency capsule. A total of 91 patients had their subsequent video capsule endoscopy (VCE), with 96.7% (88/91) successfully passing the capsule. Out of those who passed the VCE, 2 patients had patency capsule retention. Both had normal small bowel imaging. Meanwhile, the 3 patients who had VCE retention had evidence of small bowel disease in their imaging scans. The presence of abnormal small bowel wall thickening or stricture on imaging had a statistically significant association with VCE retention ( P =0.02).

CONCLUSION

Our study demonstrated a statistically significant association between small bowel disease on imaging and retention of both patency capsules and VCE. Small bowel imaging in patients with suspected or documented CD had a negative predictive value of 100% for VCE retention.

Clinical utility of multi-row spiral CT in diagnosing hepatic nodular lesions, gastric cancer, and Crohn's disease: a comprehensive meta-analysis

A retrieval of relevant literature on hepatic nodular lesions, gastric cancer (GC), and Crohn's disease (CD) was conducted from Chinese and English databases. Meta-analysis was performed using Review Manager 5.4 software and the MIDAS package in Stata 18.0. Results from 11 studies comprising 1847 patients were synthesized. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio with 95% confidence intervals were: 0.91 (0.84-0.95), 0.73 (0.65-0.79), 3.30 (2.60-4.30), 0.13 (0.07-0.23), and 26.00 (12.00-53.00), respectively. Significant statistical heterogeneity was found in sensitivity and specificity (P<0.05), with specificity heterogeneity originating from n, type, and mode (P<0.05). Sensitivity and specificity for n, type, object, and mode were non-heterogeneous (P>0.05). The combined AUC from SROC curve analysis of the 11 studies was 0.85. Deeks' funnel plot asymmetry test yielded a p-value of 0.01, indicating potential bias across studies in the diagnostic odds ratio funnel plot. Fagan's nomogram demonstrated that using CT for diagnostic modeling increased the post-test probability of correctly diagnosing hepatic nodular lesions, GC, and CD from 50.00% to 77.00%. Overall, multi-detector CT shows good diagnostic value for hepatic nodular lesions, GC, and CD, supporting its clinical flexibility based on patient-specific considerations.

Fibrosis in IBD: from pathogenesis to therapeutic targets

BACKGROUND

Intestinal fibrosis resulting in stricture formation and obstruction in Crohn's disease (CD) and increased wall stiffness leading to symptoms in ulcerative colitis (UC) is among the largest unmet needs in inflammatory bowel disease (IBD). Fibrosis is caused by a multifactorial and complex process involving immune and non-immune cells, their soluble mediators and exposure to luminal contents, such as microbiota and environmental factors. To date, no antifibrotic therapy is available. Some progress has been made in creating consensus definitions and measurements to quantify stricture morphology for clinical practice and trials, but approaches to determine the degree of fibrosis within a stricture are still lacking.

OBJECTIVE

We herein describe the current state of stricture pathogenesis, measuring tools and clinical trial endpoints development.

DESIGN

Data presented and discussed in this review derive from the past and recent literature and the authors' own research and experience.

RESULTS AND CONCLUSIONS

Significant progress has been made in better understanding the pathogenesis of fibrosis, but additional studies and preclinical developments are needed to define specific therapeutic targets.

Diagnostic accuracy of different cross-sectional imaging techniques for disease location and activity in Crohn's disease and external validation and comparison of MARIAs and IBUS-SAS

PURPOSE

The comparative accuracy of cross-sectional imaging techniques for evaluating Crohn's disease (CD) remains uncertain. This study aimed to assess diagnostic accuracy of disease location and activity in different cross-sectional images and validate and compare International Bowel Ultrasound Segmental Activity Score (IBUS-SAS) and Simplified Magnetic Resonance Index of Activity (MARIAs).

METHODS

CD patients were retrospectively included from August 2018 to May 2021. We compared accuracy of B-mode intestinal ultrasound (B-IUS), computed tomography enterography (CTE), and magnetic resonance enterography (MRE) for the identification of disease location. Meanwhile, disease activity was compared on B-IUS, color Doppler imaging, CTE, and MRE. ROC analyses were used to validate MARIAs and IBUS-SAS. Spearman rank correlation was performed to evaluate the relationships between MARIAs/IBUS-SAS and CDAI, SES-CD, and inflammatory indicators.

RESULTS

A total of 115 CD patients were evaluated. The diagnostic accuracy of MRE in detecting small bowel disease was superior to that of B-IUS/CTE, showing sensitivity (89.3%), specificity (71.4%), and AUC (0.820). B-IUS had the highest sensitivity (81.2%), specificity (84.8%), and AUC (0.830) for detecting terminal ileal lesions. The diagnostic accuracy for colonic disease and disease activity was not significantly different among these techniques. In the validation of IBUS-SAS, the AUC was 0.860, with an optimal cutoff value to predict active disease of 46.7. MARIAs and IBUS-SAS showed no significant differences in the correlations of CDAI, SES-CD, and inflammatory indicators.

CONCLUSION

MRE and B-IUS are more sensitive for detecting small bowel CD and terminal ileal CD, respectively. IBUS-SAS has potential for precisely defining CD activity.

Dual energy computed tomography in Crohn's disease: a targeted review

INTRODUCTION

Crohn's disease (CD) is a common chronic inflammatory bowel disease characterized by transmural inflammation and extra-intestinal complications. The diagnosis of CD is made using a combination of clinical, biochemical, endoscopic, imaging and histological features. Among imaging methods, computed tomography enterography (CTE) is the most commonly used. Dual-energy CTE allows objective evaluation of patients with CD. Along with the findings seen in conventional CTE, dual-energy CTE can generate iodine density maps and quantify the iodine content in the involved segments of the bowel, thus providing a measure of the perfusion of the affected bowel. In addition, the virtual monochromatic images generated from dual-energy CTE allow better qualitative evaluation of the mural and extramural findings.

AREAS COVERED

We performed a targeted systemic review of all the studies in the literature to understand the role of dual-energy CT in the diagnosis and assessment of the severity of CD.

EXPERT OPINION

Dual-energy CTE is superior to conventional CTE in the evaluation of CD. Besides quantifying iodine in the pathological segments, other quantitative parameters like the mural thickness of affected bowel segments, the number of segments involved, ulcerations, comb sign, lymphadenopathy, and the mural heterogeneity can also be assessed in dual-energy CTE.

International consensus to standardise histopathological scoring for small bowel strictures in Crohn's disease

OBJECTIVE

Effective medical therapy and validated trial outcomes are lacking for small bowel Crohn's disease (CD) strictures. Histopathology of surgically resected specimens is the gold standard for correlation with imaging techniques. However, no validated histopathological scoring systems are currently available for small bowel stricturing disease. We convened an expert panel to evaluate the appropriateness of histopathology scoring systems and items generated based on panel opinion.

DESIGN

Modified RAND/University of California Los Angeles methodology was used to determine the appropriateness of 313 candidate items related to assessment of CD small bowel strictures.

RESULTS

In this exercise, diagnosis of naïve and anastomotic strictures required increased bowel wall thickness, decreased luminal diameter or internal circumference, and fibrosis of the submucosa. Specific definitions for stricture features and technical sampling parameters were also identified. Histopathologically, a stricture was defined as increased thickness of all layers of the bowel wall, fibrosis of the submucosa and bowel wall, and muscularisation of the submucosa. Active mucosal inflammatory disease was defined as neutrophilic inflammation in the lamina propria and any crypt or intact surface epithelium, erosion, ulcer and fistula. Chronic mucosal inflammatory disease was defined as crypt architectural distortion and loss, pyloric gland metaplasia, Paneth cell hyperplasia, basal lymphoplasmacytosis, plasmacytosis and fibrosis, or prominent lymphoid aggregates at the mucosa/submucosa interface. None of the scoring systems used to assess CD strictures were considered appropriate for clinical trials.

CONCLUSION

Standardised assessment of gross pathology and histopathology of CD small bowel strictures will improve clinical trial efficiency and aid drug development.

Systematic review with meta-analysis: The prevalence, risk factors and outcomes of upper gastrointestinal tract Crohn's disease

AIMS

Upper gastrointestinal Crohn's disease (UGI-CD) is an important subclassification of Crohn's Disease (CD). We performed a systematic review and meta-analysis to evaluate the prevalence, risk factors, and clinical outcomes associated with UGI-CD.

METHODS

We searched Embase and Medline for articles reporting the clinical information of UGI-CD in CD patients, through 27 October 2020. Disease location and phenotype were coded according to the Montreal classification, and results were pooled with random effects by DerSimonian and Laird model.

RESULTS

26 articles were included. The prevalence of UGI-CD was 13%. UGI-CD was most commonly found in the stomach (56%) and was associated with concurrent ileocolonic involvement (54%). Non-stricturing, non-penetrating UGI-CD was the most common behavioral phenotype (61%). L4-jejunal disease was associated with the highest rates of surgery. Region of origin did not significantly influence the location and phenotype of UGI-CD. Young, male patients presenting with erythema nodosum, aphthous ulcers and stricturing-phenotype are more likely to have UGI-CD, which in turn is linked to increased risk of hospitalization and surgery.

CONCLUSION

UGI-CD is present in 13% of patients with CD, and patients with L4-jejunal disease are more likely to require surgery. Further studies examining the effect of ethnicity and region on UGI-CD are needed.

Luminal Narrowing Alone Allows an Accurate Diagnosis of Crohn's Disease Small Bowel Strictures at Cross-Sectional Imaging

BACKGROUND AND AIMS

Current consensus recommendations define small bowel strictures [SBS] in Crohn's disease [CD] on imaging as luminal narrowing with unequivocal upstream bowel dilation. The aim of this study was to [1] evaluate the performance of cross-sectional imaging for SBS diagnosis in CD using luminal narrowing with upstream SB dilation and luminal narrowing with or without upstream dilation, and [2] compare the diagnostic performance of computed tomography [CT] and magnetic resonance enterography [MRE] for SBS diagnosis.

METHODS

In total, 111 CD patients [81 with pathologically confirmed SBS, 30 controls] who underwent CT and/or MRE were assessed. Two radiologists [R1, R2] blinded to pathology findings independently assessed the presence of luminal narrowing and upstream SB dilation. Statistical analysis was performed for [1] luminal narrowing with or without SB upstream dilation ['possible SBS'], and [2] luminal narrowing with upstream SB dilation ≥3 cm ['definite SBS'].

RESULTS

Sensitivity for detecting SBS was significantly higher using 'possible SBS' [R1, 82.1%; R2, 77.9%] compared to 'definite SBS' [R1, 62.1%; R2, 65.3%; p < 0.0001] with equivalent specificity [R1, 96.7%; R2, 93.3%; p > 0.9]. Using the criterion 'possible SBS', sensitivity/specificity were equivalent between CT [R1, 87.3%/93.3%; R2, 83.6%/86.7%] and MRE [R1, 75.0%/100%; R2: 70.0%/100%]. Using the criterion 'definite SBS', CT showed significantly higher sensitivity [78.2%] compared to MRE [40.0%] for R1 but not R2 with similar specificities [CT, 86.7-93.3%; MRE, 100%].

CONCLUSION

SBS can be diagnosed using luminal narrowing alone without the need for upstream dilation. CT and MRE show similar diagnostic performance for SBS diagnosis using luminal narrowing with or without upstream dilation.

Imaging Modalities for Evaluation of Intestinal Obstruction

It is essential for the colon and rectal surgeon to understand the evaluation and management of patients with both small and large bowel obstructions. Computed tomography is usually the most appropriate and accurate diagnostic imaging modality for most suspected bowel obstructions. Additional commonly used imaging modalities include plain radiographs and contrast imaging/fluoroscopy, while less commonly utilized imaging modalities include ultrasonography and magnetic resonance imaging. Regardless of the imaging modality used, interpretation of imaging should involve a systematic, methodological approach to ensure diagnostic accuracy.

Impact of Magnetic Resonance Imaging in Management of Pediatric Crohn's Disease

Crohn's disease (CD) is a chronic illness and radiographic evaluation is frequently used. Consequently, pediatric patients with CD who are diagnosed in childhood are at risk for high levels of radiation exposure during their lifetimes. We sought to evaluate the impact of magnetic resonance enterography (MRE) in management of pediatric patients with known or suspected Crohn's disease. A retrospective review of patients with known or suspected CD who underwent MRE for new onset of symptoms was conducted. All demographic data, clinical history, and results of all radiographic, endoscopic, and pathology studies were recorded. Twenty-eight patients with known or suspected CD underwent 31 MRE examinations. MRE showed active disease in 16 (52%), fistula or abscess in seven (22%), and no evidence of active disease in eight (26%). Sixty-five per cent of patients underwent MRE with no other radiation-based imaging used. Surgical intervention was deemed necessary after the MRE in 16 per cent. In all cases, surgical findings were consistent with MRE results. Nearly 60 per cent of patients with CD are managed based on the findings of MRE without additional radiographic evaluation. Based on the results of this retrospective study, we propose a clinical pathway for use of MRE in patients with known or suspected CD with new onset of symptoms.

ACR Appropriateness Criteria® Crohn Disease

Three common clinical scenarios involving use of imaging in Crohn disease are covered. These include the initial evaluation of Crohn disease when the diagnosis has not been previously established, the evaluation for anticipated exacerbation of known disease, and the evaluation of disease activity during therapy monitoring. The appropriateness of a given imaging modality for each scenario is rated as one of three categories (usually appropriate, may be appropriate, usually not appropriate) to help guide evaluation. Pediatric presentation of Crohn disease and the appropriateness of imaging are not covered in this document. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Usefulness of magnetic resonance enterography in the clinical decision-making process for patients with inflammatory bowel disease

OBJECTIVE

To evaluate the impact of magnetic resonance enterography (MRE) diagnosis on clinical decision-making regarding treatment choice and maintenance of treatment over time in patients with inflammatory bowel disease (IBD).

METHODS

A cohort of patients who underwent MRE for IBD assessment between 2011 and 2014 was analyzed. From clinical records, we retrospectively retrieved their demographic data and clinical data on their IBD at the time of MRE, the results of MRE and the patient's clinical course. Medical management decisions made during the three months following MRE and at the 15-month follow-up were assessed.

RESULTS

In total, 474 MREs were reviewed. In the first three-month period, MRE results led to changes in the medical management of 266 patients (56.1%). Of those, maintenance therapy was altered in 140 patients (68.3%) (90.7% step-up and 9.3% top-down strategy), 65 (24.4%) were prescribed a course of steroids and 61 (22.9%) underwent surgery. MRE confirmed a CD diagnosis in 14/41 patients (34.1%) previously diagnosed with indeterminate colitis or ulcerative colitis and in 4/18 patients (22.2%) with suspected IBD. At the 15-month follow-up, treatment remained unchanged in 289 patients (65.8%).

CONCLUSIONS

These results suggest that MRE is a diagnostic tool that provides valid information for the clinical-decision making process for patients with CD.

Safety and effectiveness of MRE in comparison with CTE in diagnosis of adult Crohn's disease

Background: Crohn's disease (CD) is a chronic inflammatory disease of the gastrointestinal tract that is characterized by recurrent attacks and frequent recovery. The lifelong course of this disease requires frequent assessment of the disease activity. The aim of this study was to compare the effectiveness and safety of computed tomography enterography (CTE) to magnetic resonance enterography (MRE) in adults with CD.

Methods: A systematic review of the literatures was performed to evaluate the effectiveness and safety of CTE in comparison with MRE. PubMed, Cochrane Library, Scopus, Web of Science, and Embase were searched. Effectiveness outcomes included were sensitivity, specificity, diagnosis difference, diagnostic odds ratio, and positive and negative likelihood. Quality assessment of the studies was conducted using the QADAS score. Meta-analysis was done by RevMan 5.3 for selected outcomes.

Results: Five studies had eligibility for analyzing effectiveness. The meta-analysis results showed that diagnosis difference of MRE and CTE, for diagnosing active CD (0.03 CI 95% -0.07–0.13), fistula (-0.01 CI 95% -0.09–0.07), and cramping (-0.02 CI 95% -0.1– 0.06) were not statistically significant. Six studies were finally selected for safety assessment. The results showed that people who are examined with CTE frequently are at increased risk of developing cancer significantly, as they receive more than 50 msv of radiation per year.

Conclusion: There was no significant difference between MRE and CTE in diagnosis of Crohn’s activity, detection of bowel obstruction, and detection of fistula and stenosis of the alimentary canal. However, the assessment of the safety profile of MRE and CTE showed that MRE is meaningfully safer than CTE for evaluating the recurrence of CD.

Imaging in discriminating intestinal tuberculosis and Crohn's disease: past, present and the future

Introduction: Intestinal tuberculosis (ITB) and Crohn's disease (CD) have similar clinical presentation, but require different treatment approaches. Despite advances in various endoscopic, imaging, microbiological, and histological techniques, the differentiation of these two entities is often difficult. Newer radiological and image acquisition modalities have now become indispensable tools for evaluation of these two diseases.Areas covered: This review summarizes the currently available literature on various radiological investigations to differentiate ITB from CD. This review also enumerates the newer modalities in image acquisition techniques and their potential role for differentiating these two diseases. At present abdominal computed tomography (CT) scan is used as a first line investigation for differentiating ITB from CD. Magnetic resonance imaging (MRI) is preferred in pediatric patients and for follow-up studies.Expert opinion: Role of newer modalities like contrast enhanced abdominal ultrasound, perfusion CT, advanced MRI and positron emission tomography (PET) is evolving and requires further exploration. Till further robust studies are available, differentiation between ITB and CD requires use of a combination of clinical, endoscopic, serological, histological, and radiological parameters rather than relying on a single test.

Indian guidelines on imaging of the small intestine in Crohn's disease: A joint Indian Society of Gastroenterology and Indian Radiology and Imaging Association consensus statement

The Indian Society of Gastroenterology (ISG) Task Force on Inflammatory Bowel Disease and the Indian Radiological and Imaging Association (IRIA) developed combined ISG-IRIA evidence-based best-practice guidelines for imaging of the small intestine in patients suspected to have or having Crohn's disease. The 29 consensus statements, developed through a modified Delphi process, are intended to serve as reference for teaching, clinical practice, and research.

Feasibility study using iodine quantification on dual-energy CT enterography to distinguish normal small bowel from active inflammatory Crohn's disease

BACKGROUND

Assessment of Crohn's disease (CD) activity is important to identify patients with active inflammation for therapy management. Quantitative analysis can provide objective measurement of disease presence.

PURPOSE

To evaluate the feasibility of quantitative analysis of contrast-enhanced dual-energy computed tomography (DECT) data in detection of small bowel inflammation in patients with CD with an emphasis on iodine quantification.

MATERIAL AND METHODS

DECT enterography was prospectively performed in 20 patients with active CD and in 20 healthy individuals, as the control group. Iodine overlay images were created. Wall thickness, attenuation, absolute iodine density, relative iodine density, and fat fraction were measured in the terminal ileum of all patients by two radiologists. Intraclass correlation coefficients were calculated to assess inter-rater agreement. Parameters were compared between patient groups using mixed model analysis. Receiver operating characteristic (ROC) analysis was performed.

RESULTS

Both absolute and relative iodine density were significantly higher in active disease than in normal small bowel (all P < 0.001). In contrast, measurement of fat fraction was not significantly different in affected terminal ileal loops compared to normal terminal ileum ( P = 0.075). ROC analysis demonstrated a similar excellent diagnostic accuracy of wall thickness, attenuation, and absolute and relative iodine density with area under the ROC curve (AUC) values in the range of 0.96 for attenuation to 1 for relative iodine density.

CONCLUSION

DECT with iodine quantification can be used in distinguishing normal small bowel from active inflammatory CD. Further research should investigate the value of iodine quantification in grading CD activity and in monitoring therapeutic response.

"Can Magnetic Resonance Enterography (MRE) replace ileo-colonoscopy for evaluating disease activity in Crohn's disease?"

Crohn's disease is a form of chronic inflammatory bowel disease that can lead to structural bowel damage due to transmural inflammation. Ileo-colonosocopy is currently essential for initial diagnosis. Reassessment of disease burden is frequently needed during episodes of active disease and when evaluating treatment efficacy. This review compares the role of Magnetic Resonance Enterography (MRE) and ileocolonoscopy in Crohn's disease management and whether cross-sectional imaging can replace invasive endoscopic tests. MRE can give information on the small bowel not visible at ileo-colonoscopy, and on extra-luminal complications. Evaluation of the bowel by MRE allows assessment of the submucosa and serosa, and thus transmural healing. MRE offers a well tolerated investigation and additional information on disease activity to better manage patients with Crohn's disease. Increasingly, there are a range of newer techniques such as diffusion weighted imaging, magnetisation transfer and motility MRI which provide greater information on fibrosis and predictors to treatment response which has been lacking despite the use of ileo-colonoscopy for several decades.

The Management of Intestinal Penetrating Crohn's Disease

Crohn's disease (CD) leads to the development of complications through progressive uncontrolled inflammation and the transmural involvement of the bowel wall. Most of the available literature on penetrating CD focuses on the perianal phenotype. The management of nonperianal penetrating complications poses its own set of challenges and can result in significant morbidity and an increased risk of mortality. Few controlled trials have been published evaluating this subgroup of patients for clinicians to use for guidance. Utilizing the available evidence, we review the epidemiology, presentation, and modalities used to diagnosis and assess intestinal fistulas, phlegmons, and abscesses. The literature regarding the medical, endoscopic, and surgical management options are reviewed providing physicians with a therapeutic framework to comprehensively treat these nonperianal penetrating complications. Through a multidisciplinary evidence-based approach to the complex sequela of CD outcomes can be improved and patient's quality of life enhanced.10.1093/ibd/izx108_video1izx108_Video5754037501001.

Capsule Endoscopy Validation of the Magnetic Enterography Global Score in Patients with Established Crohn's Disease

BACKGROUND AND AIMS

Capsule endoscopy [CE] and magnetic resonance enterography [MRE] are prime modalities for evaluation of the small bowel in Crohn's disease [CD]. Detection of proximal small bowel [SB] inflammation in CD by MRE is challenging. Currently available quantitative MRE scores do not incorporate proximal SB data. The MRE global score [MEGS] was designed for quantitative evaluation of the entire digestive tract; its accuracy in the proximal SB has not previously been evaluated. This study compared the evaluation of the small bowel inflammation by MEGS and CE-derived quantitative score (the Lewis score[LS]).

METHODS

CD patients in stable clinical remission were prospectively recruited and underwent MRE and CE; faecal calprotectin [FC] levels were obtained. MEGS was calculated for each SB segment and the entire SB [SBMEGS]. SB inflammation on CE was quantified using LS. A cumulative Lewis score [C-LS] was calculated based on summation of three tertiles scores.

RESULTS

Fifty patients were included. There was a significant correlation of SBMEGS with LS and C-LS [r = 0.61 and 0.71, both p = 0.001]. The correlation with FC was stronger for MEGS than for LS or C-LS [r = 0.68 vs r = 0.46 vs r = 0.53, all p = 0.001]. The correlation between the proximal LS and MEGS was significant [r = 0.55, p = 0.001]; median MEGS was significantly different in patients, with LS values consistent with mucosal healing, mild and moderate-to-severe inflammation.

CONCLUSIONS

MEGS provides accurate evaluation of the SB and strongly correlates with FC; the main advantage of MEGS is the accurate quantification of proximal SB inflammation unavailable for alternative MRE scores.

Prospective Comparison of Standard- Versus Low-Radiation-Dose CT Enterography for the Quantitative Assessment of Crohn Disease

OBJECTIVE

CT enterography (CTE) is sensitive and specific for active inflammatory changes of Crohn disease (CD), but its use has been limited by exposure to ionizing radiation. The objective of this study is to show the noninferiority of a model-based iterative reconstruction (MBIR) technique using lower radiation doses compared with standard-dose CTE in the assessment of CD.

SUBJECTS AND METHODS

Patients referred to a hospital radiology department for CTE for the evaluation of CD underwent both a standard examination (used to generate filtered back-projection and adaptive statistical iterative reconstruction [ASIR] images) and low-dose MBIR CTE performed in a random sequence on the same day. Images were reviewed by two radiologists for signs of small-bowel CD. Radiologic findings obtained using ASIR and clinical assessments of disease activity served as the reference standard for comparison with low-dose CTE findings.

RESULTS

A total of 163 patients, 92 (56.4%) of whom had active disease, underwent CTE. MBIR was found to be noninferior to the two standard-dose techniques, with no significant differences noted between the three types of images when compared with the clinical reference standard. As compared with the radiologic standard of ASIR, the very-low-dose scans had a high degree of accuracy, with sensitivity ranging from 0.85 to 0.94 and specificity ranging from 0.84 to 0.97 depending on the reader. A significant reduction in radiation exposure was noted with MBIR (mean [± SD] reduction, 3.30 ± 3.17 mSv) versus standard-dose imaging (7.16 ± 4.61 mSv; p < 0.001).

CONCLUSION

Low-dose CTE using MBIR is sensitive and specific for the detection of active inflammatory changes of CD while utilizing radiation doses substantially lower than those associated with standard techniques.

Imaging of the small intestine in Crohn's disease: Joint position statement of the Indian Society of Gastroenterology and Indian Radiological and Imaging Association

The Indian Society of Gastroenterology (ISG) Task Force on Inflammatory Bowel Disease and the Indian Radiological and Imaging Association (IRIA) developed combined ISG-IRIA evidence-based best-practice guidelines for imaging of the small intestine in patients with suspected or known Crohn's disease. These 29 position statements, developed through a modified Delphi process, are intended to serve as reference for teaching, clinical practice, and research.

Faecal biomarkers for screening small bowel inflammation in patients with Crohn's disease: a prospective study

BACKGROUND

The value of faecal biomarkers for screening small bowel inflammation in patients with Crohn's disease (CD) remains to be elucidated. This prospective study was to evaluate the utility of faecal biomarkers for detecting small intestinal inflammation.

METHODS

A total of 122 consecutive patients with a diagnosis of CD in the small intestine were screened for eligibility. Computed tomography enterography (CTE) was undertaken to evaluate small bowel inflammation followed by colonoscopy to confirm no large bowel involvement. Seventy eligible patients with inflammation confined to the small intestine were included. Faecal samples were collected for assaying calprotectin, lactoferrin and haemoglobin. For assessing the degree of small bowel inflammation, a semi-quantitative scoring system (CTE0, normal; CTE1, mild; CTE2, moderate; CTE3, severe) was applied.

RESULTS

The median calprotectin, lactoferrin and haemoglobin levels were significantly higher in patients with small bowel inflammation, CTE scores 1-3 (n = 42) versus 0 (n = 28): calprotectin, 330 versus 40 ng/ml, p < 0.0001; lactoferrin, 14 versus 3 ng/ml, p < 0.0001; haemoglobin, 29.5 versus 6.5 ng/ml, p = 0.005. There was a strong positive relationship between the faecal biomarkers and CTE score: calprotectin, p < 0.0001; lactoferrin, p < 0.0001; haemoglobin, p = 0.0004. A cutoff value of 140 ng/ml for calprotectin had a sensitivity of 69% and a specificity of 82% with an area under the receiver operating characteristic curve (AUC) of 0.82 to detect small bowel inflammation (CTE scores 1-3), while lactoferrin 6 ng/ml had a sensitivity of 69% and a specificity of 79% with an AUC of 0.83, and haemoglobin 9 ng/ml showed a sensitivity of 71% and a specificity of 39% with an AUC of 0.70.

CONCLUSIONS

Faecal calprotectin, lactoferrin, and to a lesser degree haemoglobin are relevant biomarkers for screening small bowel inflammation in CD patients without large bowel involvement. Further well-designed large-scale studies in this clinical setting should strengthen our findings.

Crohn's Strictures-Moving Away from the Knife

Crohn's disease (CD) is a lifelong inflammatory bowel disease with a rapidly rising incidence in the pediatric population. A common complication of CD is the development of fibrotic strictures, which may be present at initial diagnosis or develop many years later. Clinical presentation depends on stricture location and degree of obstruction, and strictures frequently contain a mixture of inflammatory and fibrotic tissue. Histological examination of Crohn's strictures shows thickening of the muscular layers and the submucosa, where increased collagen deposition by activated myofibroblasts is concentrated around islands of smooth muscle cells and at the superficial margin of the muscularis propria. No antifibrotic therapies for Crohn's strictures exist. Profibrotic transforming growth factor-β (TGFβ)/bone morphogenetic protein signaling stimulates myofibroblast differentiation and extracellular matrix deposition. Understanding and targeting TGFβ1 downstream signaling is the main focus of current research, raising the possibility of specific antifibrotic therapy in CD becoming available in the future.

Intraoperative Enteroscopy: Is There Still a Role?

Intraoperative enteroscopy (IOE) to explore obscure gastrointestinal bleeding is now rarely indicated. IOE allows complete small bowel exploration in 57% to 100% of cases, finds a bleeding source in 80% of cases, allows the recurrence-free management of gastrointestinal bleeding in 76% of cases, but carries a high morbidity and mortality. IOE only remains indicated to guide the intraoperative treatment of preoperatively identified small bowel lesions when nonoperative treatments are unavailable and/or when intraoperative localization by external examination is impossible.

Findings of ulceration and severe stricture on MRE can predict prognosis of Crohn's disease in patients treated with anti-TNF treatment

BACKGROUND

MR enterography (MRE) is useful for evaluating transmural lesions and extra-intestinal complications of Crohn's disease (CD). The aim of this study was to prospectively evaluate whether MRE could detect severe strictures and inflammatory lesions in patients who lost the responsiveness to anti-TNF treatment and whether MRE could predict prognosis of CD patients with clinical remission.

PATIENTS AND METHODS

MRE were conducted in 50 patients who were treated with infliximab or adalimumab. The main aims of this study were as follows; (1) to compare the rates of CD lesions of the patients with clinical remission and active disease at the baseline and (2) to assess the MRE findings that were predictors of clinical recurrence among patients with clinical remission at the baseline.

RESULTS

The MRE detection rates of markedly increased contrast uptake, severe strictures, and the presence of ulcers were significantly higher in patients with Crohn Disease Activity Index ≥150 than in patients with clinical remission. Over a mean follow-up of 18.2 months, the absence of ulceration (p = 0.001) or severe stricture (p = 0.01) prolonged clinical recurrence among patients with clinical remission at baseline. Expected duration of recurrence significantly prolonged in patients with total magnetic resonance index of activity (MaRIA) <36.3 [29.8 months (95% CI 23.7-35.9)] than in patients with total MaRIA ≥36.3 (13.9 months (95% CI 7.7-20.1). A cut-off value of total MaRIA score of 36.3 had a sensitivity of 75% and specificity of 70% for predicting recurrence.

CONCLUSION

Findings of ulceration and severe stricture on MRE predict prognosis of CD patients who were treated with anti-TNF treatment. MRE might be useful for making treatment decisions in patients who lost the effectiveness of medical treatments.

Inter- and intraobserver agreement in computed tomography enterography in inflammatory bowel disease

AIM

To evaluate intra- and interobserver agreement in imaging features in inflammatory bowel disease and comparison with fecal calprotectin (FC) levels.

METHODS

Our institutional computed tomography enterography (CTE) database was retrospectively queried to identify patients who underwent CTE from January 2014 to June 2015. Patient inclusion criteria were confirmed inflammatory bowel disease (IBD) and FC collected < 4 mo after CTE without any change in clinical treatment or surgical treatment during this interval. The exclusion criterion was poor image quality. Two blinded abdominal radiologists, with 12 and 3 years of experience analyzed the CTE regarding localization (small bowel, colonic, both, or no disease detected); type of IBD (inflammatory, stenosing, fistulizing, > 1 pattern, or normal); and signs of active disease (present or absent). In 42 of 44 patients evaluated, routine CTE reports were made by one of the readers who re-evaluated the CTEs ≥ 6 mo later, to determine the intraobserver agreement. FC was considered a sign of disease activity when it was higher than 250 μg/g.

RESULTS

Forty-four patients with IBD (38 with Crohn’s disease and 6 with ulcerative colitis) were included. There was a moderate interobserver agreement regarding localization of IBD (κ = 0.540), type of disease (κ = 0.410) and the presence of active signs in CTE (κ = 0.419). There was almost perfect intraobserver agreement regarding localization, type and signs of active disease in IBD. The κ values were 0.902, 0.937 and 0.830, respectively. After a consensus between both radiologists regarding inflammatory activity in CTE, we found that 24 (85.7%) of 28 patients who were classified with active disease had elevated FC, and six (37.5%) of 16 patients without inflammatory activity in CTE had elevated FC (P = 0.003). The correlation between elevated FC and the presence of active disease in CTE was significant (κ = 0.495, P = 0.001).

CONCLUSION

We found almost perfect intraobserver and moderate interobserver agreement in the signs of active disease in CTE with concurrence of high FC levels.

Testing for Chronic Diarrhea

Chronic diarrhea is a frequently encountered symptom in clinical practice. The etiologies for chronic diarrhea are diverse and broad with varying clinical implications. A useful method of categorizing chronic diarrhea to guide a diagnostic work-up is a pathophysiology-based framework. Chronic diarrhea may be categorized as malabsorptive, secretory, osmotic, and inflammatory or motility related. Frequently, overlap between categories may exist for any given diarrhea etiology and diagnostic testing must occur with an understanding of the differential diagnosis. Investigations to achieve a diagnosis for chronic diarrhea range from screening blood and stool tests to more directed testing such as diagnostic imaging, and endoscopic and histological evaluation. The pathophysiology-based framework proposed in this chapter will allow the clinician to select screening tests followed by targeted tests to minimize cost and complications to the patient, while providing a highly effective method to achieve an accurate diagnosis.

Systematic review: Safety of balloon assisted enteroscopy in Crohn's disease

AIM

To determine the overall and comparative risk of procedure related perforation of balloon assisted enteroscopy (BAE) in Crohn's disease (CD).

METHODS

Systematic review (PROSPERO #CRD42015016381) of studies reporting on CD patients undergoing BAE. Seventy-three studies reporting on 1812 patients undergoing 2340 BAEs were included. Primary outcome of interest was the overall and comparative risk of procedure related perforation of diagnostic BAE in CD. Secondary outcomes of interest were risk of procedure related perforation of diagnostic double balloon enteroscopy (DBE), risk of procedure related perforation of therapeutic BAE, efficacy of stricture dilation, and clinical utility of endoscopically assessing small bowel disease activity.

RESULTS

Per procedure perforation rate of diagnostic BAE in CD was 0.15% (95%CI: 0.05-0.45), which was similar to diagnostic BAE for all indications (0.11%; IRR = 1.41, 95%CI: 0.28-4.50). Per procedure perforation rate of diagnostic DBE in CD was 0.12% (95%CI: 0.03-0.44), which was similar to diagnostic DBE for all indications (0.22%; IRR = 0.54, 95%CI: 0.06-0.24). Per procedure perforation rate of therapeutic BAE in CD was 1.74% (95%CI: 0.85-3.55). Eighty-six percent of therapeutic perforations were secondary to stricture dilation. Dilation was attempted in 207 patients and 30% required surgery during median follow-up of 18 months. When diagnostic BAE assessed small bowel disease activity, changes in medical therapy resulted in endoscopic improvement in 77% of patients.

CONCLUSION

Diagnostic BAE in CD has a similar rate of perforation as diagnostic BAE for all indications and can be safely performed in assessment of mucosal healing.

Capsule Endoscopy and Deep Enteroscopy in Irritable Bowel Disease

In approximately one-third of Crohn's disease patients, the disease is confined to the small bowel, inaccessible to the reach of standard endoscopy. Thorough and complete evaluation of the small bowel is crucial in such patients for the initial diagnosis, prognostication, and disease monitoring. Video capsule endoscopy and device-assisted enteroscopy have revolutionized the ability to visualize the small-bowel mucosa. This article reviews the literature pertaining to the use of capsule endoscopy and deep enteroscopy in established Crohn's disease, including the major indications, applications, and safety issues.

Magnetic resonance enterography versus capsule endoscopy activity indices for quantification of small bowel inflammation in Crohn's disease

BACKGROUND

Video capsule endoscopy (VCE) and magnetic resonance enterography (MRE) are the prime modalities for the evaluation of small bowel (SB) Crohn's disease (CD). Mucosal inflammation on VCE is quantified using the Lewis score (LS). Diffusion-weighted (DW) magnetic resonance imaging (MRI) allows for accurate assessment of SB inflammation without administration of intravenous contrast material. The Magnetic Resonance Index of Activity (MaRiA) and the Clermont index are quantitative activity indices validated for contrast-enhanced MRE and DW-MRE, respectively. The aim of this study was to compare the quantification of distal SB inflammation by VCE and MR-related activity indices.

METHODS

Patients with known quiescent SB CD were prospectively recruited and underwent MRE and VCE. LS, MaRIA and Clermont scores were calculated for the distal SB.

RESULTS

Both MRI-based indices significantly correlated with the LS and the Clermont index (r = 0.50, p = 0.001 and r = 0.53, p = 0.001, respectively). Both MaRIA and Clermont scores were significantly lower in patients with mucosal healing (LS < 135). The area under the curve (AUC) with both MR scores was moderate for prediction of any mucosal inflammation (LS ⩾ 135) and excellent for prediction of moderate-to-severe inflammation (LS ⩾ 790) (0.71 and 0.74 versus 0.93 and 0.91 for MaRIA and Clermont score, respectively).

CONCLUSIONS

Modest correlation between VCE- and MRE-based quantitative indices of inflammation in patients with quiescent SB CD was observed. Between-modality correlation was higher in patients with endoscopically severe disease. DW-MRE gauged by Clermont score was at least as accurate as contrast-enhanced MRE for quantification of SB inflammation.

Diagnostic value of capsule endoscopy combined with computed tomography enterography for small intestinal diseases

AIM: To assess diagnostic value of capsule endoscopy (CE) combined with computed tomography enterography (CTE) for small bowel diseases.

METHODS: One hundred and fourteen patients with suspected small bowel diseases underwent CE and CTE examinations (interval time 2-7 d). The diagnostic accuracy for small bowel diseases was compared between CE and CTE, based on pathological or follow-up results. The diagnostic accuracy of combined CE and CTE was also estimated.

RESULTS: The symptoms of enrolled patients included obscure gastrointestinal bleeding (OGIB, 35 cases), unexplained abdominal pain (32 cases), suspected Crohn's disease (29 cases) and unexplained weight loss (18 cases). For OGIB, CE had a higher diagnostic accuracy than CTE (51.4% vs 40.0%, P < 0.05). The diagnostic accuracy reached 57.1% when the two methods were combined. For unexplained abdominal pain, diagnostic accuracy was comparable between CE and CTE (46.9% vs 40.6%, P > 0.05). The diagnostic accuracy reached 59.3% when the two methods were combined, which was higher than that of CE or CTE alone. For suspected Crohn's disease, CE had a higher diagnostic accuracy than CTE (86.2% vs 65.5%, P < 0.05). The diagnostic accuracy reached 93.1% when the two methods were combined, which was higher than that of CTE alone.

CONCLUSION: Both CE and CTE prove to be effective procedures for patients with suspected small bowel disease, but the diagnostic value of CE is higher than that of CTE for OGIB and suspected Crohn's disease. The combination of CE and CTE may be a better strategy.

ACR Appropriateness Criteria Crohn Disease

Crohn disease is a chronic inflammatory disorder involving the gastrointestinal tract, characterized by episodic flares and times of remission. Underlying structural damage occurs progressively, with recurrent bouts of inflammation. The diagnosis and management of this disease process is dependent on several clinical, laboratory, imaging, endoscopic, and histologic factors. In recent years, with the maturation of CT enterography, and MR enterography, imaging has played an increasingly important role in relation to Crohn Disease. In addition to these specialized examination modalities, ultrasound and routine CT have potential uses. Fluoroscopy, radiography, and nuclear medicine may be less beneficial depending on the clinical scenario. The imaging modality best suited to evaluating this disease may change, depending on the target population, severity of presentation, and specific clinical situation. This document presents seven clinical scenarios (variants) in both the adult and pediatric populations and rates the appropriateness of the available imaging options. They are summarized in a consolidated table, and the underlying rationale and supporting literature are presented in the accompanying narrative. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Endoscopy and cross-sectional imaging for assessing Crohn׳s disease activity

Crohn's disease (CD) is principally characterized by chronic and recurrent inflammation of the gastrointestinal tract, most commonly found in the ileo-colonic region. The chronicity and severity of intestinal inflammation together contribute to progressive, cumulative, deep, transmural intestinal damage, including stricturing, obstruction, abscesses, and fistulae. Both intestinal inflammation and its chronic complications result in a range of symptoms subsequently leading to patient presentations with diarrhea, abdominal pain, and anemia related to intestinal blood loss. Measuring disease activity and severity are essential for decision of treatment intensity early in the disease course and longitudinal monitoring of therapeutic efficacy. This review will summarize the transition from subjective symptoms driving disease activity indices, into increasingly objective and quantitative measures of intestinal injury by direct mucosal assessment (endoscopy), cross-sectional imaging, and surrogate biomarkers. Specific commentary on intestinal stricture and perianal fistula assessment and management are presented in accompanying sections of this series.

MR Enterographic Findings as Biomarkers of Mucosal Healing in Young Patients With Crohn Disease

OBJECTIVE

The purpose of this study was to investigate the MR enterographic findings that best correlate with mucosal healing assessed with ileocolonoscopy.

MATERIALS AND METHODS

Patients with Crohn disease who underwent two ileocolonoscopic examinations and also underwent MR enterography close in time to the second endoscopic examination were included in a retrospective study. Two pediatric gastroenterologists blinded to the imaging findings reviewed the endoscopic examinations to assess for mucosal healing, defined as resolution of inflammation within a bowel segment at subsequent ileocolonoscopy. Two radiologists blinded to endoscopic and clinical data interpreted the MR enterographic images. Sensitivity, specificity, and accuracy for mucosal healing were calculated for several imaging features.

RESULTS

A total of 30 patients (15 female patients, 15 male patients; age range, 8-24 years; mean, 17.2 ± 3.2 years) with pediatric-onset Crohn disease were examined. The average time between MR enterography and the second ileocolonoscopic examination was 12.7 ± 7.9 days. A total of 202 bowel segments from the terminal ileum to rectum were evaluated in the 60 ileocolonoscopic examinations. Forty-four bowel segments exhibited mucosal healing, and 37 segments exhibited persistent inflammation. At imaging, the MR index of activity score in mucosal healing segments was 6.6 ± 3.4, compared with 13.7 ± 9.7 in segments without mucosal healing (p = 0.0001). The average bowel wall thickness in healing segments was 2.7 ± 0.9 mm compared with 4.7 ± 3.1 mm in persistently inflamed segments (p = 0.0004). An MR index of activity score less than 8 had the highest accuracy for mucosal healing (accuracy, 74%; sensitivity, 84%; specificity, 62%; p < 0.0001). Mucosal hyperenhancement (72%, 98%, 41%), mesenteric hypervascularity (72%, 98%, 41%), bowel wall edema (72%, 93%, 46%), and bowel wall thickness less than 4 mm (72%, 84%, 57%) were also strongly associated with mucosal healing (p < 0.0003).

CONCLUSION

In this study MR enterography was accurate for assessing mucosal healing, an important therapeutic endpoint in pediatric patients with Crohn disease.

The Diagnostic Role of Magnetic Resonance Enterography as a Complementary Test to Colonoscopy in Active Crohn's Disease

BACKGROUND

According to recent studies comparing magnetic resonance enterography (MRE) with ileocolonoscopy for assessing inflammation of small bowel and colonic segments in adults with active Crohn’s disease (CD), we aimed to compare the accuracy of these two diagnostic methods in Iranian population.

METHODS

During 2013-2014 a follow-up study was done on 30 patients with active CD in a gastroenterology clinic affiliated to Tehran University of Medical Sciences. MRE and ileocolonoscopy were performed for all the patients. All statistical analyses were performed using SPSS (version 18) and p-value<0.05 was considered as statistically significant.

RESULTS

Of the 30 patients with active CD, 11(36.7%) were men and 19 (63.3%) were women with mean age of 37.30±13.66 years (range: 19-67 years). MRE had sensitivity and specificity of 50% and 90% with positive predictive value (PPV) and negative predictive value (NPV) of 71.43 and 78.26, respectively for localizing sigmoid lesions and ileum had sensitivity and specificity of 84.21 and 45.45 with PPV and NPV of 72.73 and 62.50, respectively.

CONCLUSION

While moderate sensitivity and high specificity of MRE in localizing colonic lesions makes it an appropriate confirmatory test after colonoscopy, the reported high sensitivity and moderate specificity of MRE versus colonoscopy in detecting ileal lesions makes it a suitable screening test for ileal lesions. Finally we can conclude that MRE can be an important complementary test to colonoscopy in detecting active disease.

Medical Imaging in Small Bowel Crohn's Disease-Computer Tomography Enterography, Magnetic Resonance Enterography, and Ultrasound: "Which One Is the Best for What?"

BACKGROUND

Small bowel imaging in Crohn's disease (CD) is an important adjunct to endoscopy for the diagnosis, assessment of postoperative recurrence, and detection of complications. The best imaging modality for such indications though remains unclear. This systematic review aims to identify the imaging modality of choice considering the use of ultrasound (US), computed tomography enterography (CTE), and magnetic resonance enterography (MRE).

METHODS

Databases were systematically searched for studies pertaining to the performance of US, CTE, and MRE, as compared with a predefined reference standard in the assessment of small bowel CD.

RESULTS

Thirty-three studies, from a total of 1427 studies, were included in the final analysis. A comparable performance was demonstrated for MRE, CTE, and US for the diagnosis of small CD. Ultrasound was found to have the highest accuracy in the differentiation of inflammation and fibrosis. Postoperative recurrence detection was feasible with the use of MRE and US. All 3 modalities were shown to have a role in the detection of small bowel CD complications. The radiation exposure associated with CTE can be minimized by using lower radiation protocols.

CONCLUSIONS

Ultrasound, CTE, and MRE all play an important role in the diagnosis and management of small bowel CD, with preference for a particular modality being influenced by specific indication, institution resources, and patient preference.

Model-Based Iterative Reconstruction in CT Enterography

OBJECTIVE

The purpose of this study was to analyze the performance of pure model-based iterative reconstruction (MBIR) in low-dose CT enterography.

SUBJECTS AND METHODS

Forty-four patients with Crohn disease referred for CT enterography were included. Low-dose modified-protocol and conventional-protocol CT datasets were contemporaneously acquired. Conventional-protocol image formation was performed with 40% adaptive statistical iterative reconstruction (ASIR). Modified-protocol data were reconstructed with 100% MBIR and 40% ASIR. Image quality was assessed subjectively and objectively at six levels. Independent clinical interpretations by two fully blinded radiologists were compared with reference standard consensus reviews by two nonblinded readers who had access to clinical information, previous imaging studies, and medical records.

RESULTS

A 74.7% average radiation dose reduction was seen: low-dose modified-protocol effective dose, 1.61 ± 1.18 mSv (size-specific-dose-estimate, 2.47 ± 1.21 mGy); conventional-protocol effective dose, 6.05 ± 2.84 mSv (size-specific-dose-estimate, 9.25 ± 2.9 mGy). Image quality assessment yielded 9372 data points. Objective noise on modified-protocol MBIR images was superior (p < 0.05) to that with the conventional protocol at three of six levels and comparable at the other three levels. Modified-protocol images were superior to conventional-protocol ASIR images (p < 0.05 in all cases) for subjective noise, spatial resolution, contrast resolution, streak artifact, and diagnostic acceptability on coronal reconstructions. Axial diagnostic acceptability was superior for conventional-protocol ASIR (p = 0.76). For both readers, modified-protocol MBIR clinical readings agreed more closely with reference standard readings than did conventional-protocol ASIR readings with regard to bowel wall disease assessment (κ = 0.589 and 0.700 vs 0.583 and 0.564). Overall Crohn disease activity grade (κ = 0.549 and 0.441 vs 0.315 and 0.596) and detection of acute complications (κ = 1.0 and 0.689 vs 0.896 and 0.896) were comparable when evaluated on conventional-protocol ASIR and modified-protocol MBIR images.

CONCLUSION

Low-dose CT enterography with MBIR yields images that are comparable to or superior to conventional images.

Diagnostic imaging and radiation exposure in inflammatory bowel disease

Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease (IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentially harmful cumulative levels of ionising radiation in their lifetime, increasing malignant potential in a population already at risk. In this review we explore the proportion of IBD patients exposed to high cumulative radiation doses, the risk factors associated with higher radiation exposures, and we compare conventional diagnostic imaging with newer radiation-free imaging techniques used in the evaluation of patients with IBD. While computed tomography (CT) performs well as an imaging modality for IBD, the effective radiation dose is considerably higher than other abdominal imaging modalities. It is increasingly recognised that CT imaging remains responsible for the majority of diagnostic medical radiation to which IBD patients are exposed. Magnetic resonance imaging (MRI) and small intestine contrast enhanced ultrasonography (SICUS) have now emerged as suitable radiation-free alternatives to CT imaging, with comparable diagnostic accuracy. The routine use of MRI and SICUS for the clinical evaluation of patients with known or suspected small bowel Crohn’s disease is to be encouraged wherever possible. More provision is needed for out-of-hours radiation-free imaging modalities to reduce the need for CT.

Magnetic Resonance Imaging of the Small Bowel in Crohn's Disease: A Systematic Review and Meta-Analysis

Introduction. Crohn's disease is most commonly found in the terminal ileum and colonic region. Magnetic resonance has become a useful modality for assessing small bowel activity. In this study, we performed a systematic review and meta-analysis on the use of MR in detecting small bowel activity as well as extramural complications in Crohn's patients. Methods. Two independent reviewers sorted through articles until October 2, 2014. We included both studies providing raw data for pooling and studies without raw data. Sensitivity, specificity, likelihood ratios, and 95% confidence intervals were calculated for each study. Results. There were 27 included studies, of which 19 were included in the pooled analysis. Pooled analysis of the 19 studies (1020 patients) with raw data revealed a sensitivity of 0.88 (95% CI 0.86 to 0.91) and specificity was 0.88 (95% CI 0.84 to 0.91). In regard to detecting stenosis, pooled sensitivity was 0.65 (95% CI 0.53 to 0.76) and specificity was 0.93 (95% CI 0.89 to 0.96). Conclusion. MR imaging provides a reliable alternative in detecting small bowel activity in patients with Crohn's disease. Its advantages include high diagnostic accuracy and no radiation exposure while its disadvantages include high cost and limited availability.

Grading of Crohn's disease activity using CT, MRI, US and scintigraphy: a meta-analysis

PURPOSE

To assess the grading of Crohn's disease activity using CT, MRI, US and scintigraphy.

MATERIALS AND METHODS

MEDLINE, EMBASE and Cochrane databases were searched (January 1983-March 2014) for studies evaluating CT, MRI, US and scintigraphy in grading Crohn's disease activity compared to endoscopy, biopsies or intraoperative findings. Two independent reviewers assessed the data. Three-by-three tables (none, mild, frank disease) were constructed for all studies, and estimates of accurate, over- and under-grading were calculated/summarized by fixed or random effects models.

RESULTS

Our search yielded 9356 articles, 19 of which were included. Per-patient data showed accurate grading values for CT, MRI, US and scintigraphy of 86% (95% CI: 75-93%), 84% (95% CI: 67-93%), 44% (95% CI: 28-61%) and 40% (95% CI: 16-70%), respectively. In the per-patient analysis, CT and MRI showed similar accurate grading estimates (P = 0.8). Per-segment data showed accurate grading values for CT and scintigraphy of 87% (95% CI: 77-93%) and 86% (95% CI: 80-91%), respectively. MRI and US showed grading accuracies of 67-82% and 56-75%, respectively.

CONCLUSIONS

CT and MRI showed comparable high accurate grading estimates in the per-patient analysis. Results for US and scintigraphy were inconsistent, and limited data were available.

KEY POINTS

• CT and MRI have comparable high accuracy in grading Crohn's disease. • Data on US and scintigraphy is inconsistent and limited. • MRI is preferable over CT as it lacks ionizing radiation exposure.

Circulating microRNAs as biomarkers of adult Crohn's disease

OBJECTIVE

Previous studies have found a differential expression of microRNAs (miRNAs) in the blood of patients with Crohn's disease (CD) compared with healthy controls. The aim of this study was to identify circulating miRNAs expressed in CD and assess their performance as biomarkers in patients with clinically suspected or known CD.

METHODS

The study consisted of two parts: (a) miRNA profiling: The miRNA expression pattern was examined in six patients with CD and six controls using OpenArray miRNA profiling, and the best miRNAs were selected according to their P-value. (b) Validation cohort: In a well-characterized cohort of 102 patients with suspected or known CD, miRNAs identified by miRNA profiling or selected from previously published studies (hsa-miR-16, hsa-miR-21, hsa-miR-106a, and hsa-miR-140-3p) were measured in plasma using reverse transcription PCR.

RESULTS

miRNA profiling: hsa-miR-369-3p, hsa-miR-376a, hsa-miR-376, hsa-miR-411#, hsa-miR-411, and mmu-miR-379 were downregulated in CD patients compared with the controls; hsa-miR-200c, hsa-miR-181-2#, and hsa-miR-125a-5p were upregulated (P<0.05). Validation cohort: Only hsa-miR-16 was significantly downregulated in patients with CD compared with patients without CD (fold change 0.83, P=0.02). Receiver operating characteristic analyses showed an area under the curve of 0.65. miRNAs could not discriminate inflammatory from stricturing CD or small bowel CD from CD involving the colon.

CONCLUSION

In a clinically relevant cohort of patients, miRNAs in plasma identified in the present and previous studies were inadequate biomarkers for the diagnosis of CD.

Recent trends in diagnostic techniques for inflammatory bowel disease

Although ileocolonoscopy is the gold standard for diagnosis of inflammatory bowel disease and is useful for assessing the disease severity in the colon and terminal ileum, several alternative diagnostic techniques have been developed recently. For ulcerative colitis (UC), magnification colonoscopy, endocytoscopy, and confocal laser endomicroscopy enable assessment of histological inflammation without the need for biopsy. Capsule endoscopy is useful for detection of small intestinal and colonic lesions in both female and male patients. For UC, capsule endoscopy may be useful for evaluating colonic inflammation in patients with a previous poor colonoscopy experience, while it should be used only in Crohn's disease (CD) patients with unexplained symptoms when other examinations are negative. Magnetic resonance enterography (MRE) is particularly useful for detecting transmural inflammation, stenosis, and extraintestinal lesions, including abscesses and fistulas. MRE is also useful when evaluating small and large intestinal lesions, even in cases with severe strictures in which full evaluation of the small bowel would be virtually impossible using other devices. Therefore, the appropriate diagnostic devices for detecting CD lesions in the small and large intestine should be used.

Computed tomography enterography and magnetic resonance enterography in the diagnosis of Crohn's disease

Imaging of the small bowel is complicated by its length and its overlapping loops. Recently, however, the development of crosssectional imaging techniques, such as computed tomography enterography (CTE) and magnetic resonance enterography (MRE) has shifted fundamental paradigms in the diagnosis and management of patients with suspected or known Crohn's disease (CD). CTE and MRE are noninvasive imaging tests that involve the use of intraluminal oral and intravenous contrast agents to evaluate the small bowel. Here, we review recent advances in each cross-sectional imaging modality, their advantages and disadvantages, and their diagnostic performances in the evaluation of small bowel lesions in CD.

Magnetic resonance enterography of Crohn's disease

Magnetic resonance enterography (MRE) has been reported to be a useful modality for the evaluation of luminal inflammation and extraintestinal complications in Crohn's disease (CD). A recent study indicated that the diagnostic ability of MRE was comparable to the diagnostic ability of other devices, such as ileocolonoscopy. MRE can be performed repeatedly because there is no radiation exposure. Therefore, MRE is useful as a method of follow-up for younger patients with established CD. It is useful for evaluating the efficacy of medical treatments, such as biologics. MRE can detect small intestinal lesions even if the endoscope does not pass through the stenosis. The concerns of availability of expertise and the costs associated with MRE should be addressed so MRE can be widely used for CD patients in the near future.

Magnetic resonance enterography: state of the art

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

Systematic review with meta-analysis: magnetic resonance enterography signs for the detection of inflammation and intestinal damage in Crohn's disease

BACKGROUND

In the treatment of Crohn's disease (CD), mucosal healing has become a major goal, with the hope of avoiding intestinal damage from chronic inflammation. Magnetic resonance enterography (MRE) has emerged as a non-invasive means of monitoring inflammation and damage.

AIMS

As part of the development of MRE-based multi-item measures of inflammation and damage for paediatric studies, we carried out a systematic review and meta-analysis to identify MRE variables used to describe these two distinct concepts.

METHODS

2501 studies of MRI and CD were identified. Studies written in any language reporting individual MRE signs for patients diagnosed with CD were included. Two-hundred-and-forty-four studies were fully reviewed and 62 were included (inflammation, n = 51; damage, n = 24). Sensitivity, specificity and associated confidence intervals were calculated, and hierarchical summary ROC curves were constructed for each MRE sign.

RESULTS

A total of 22 MRE signs were used to reflect inflammation, and 9 to reflect damage. Diagnostic accuracy of MRE signs of inflammation and damage was heterogeneous; however, wall enhancement, mucosal lesions and wall T2 hyperintensity were the most consistently useful for inflammation (most sensitivities >80% and specificities >90%), and detection of abscess and fistula were most consistently useful for damage (most sensitivities >90%, specificities >95%).

CONCLUSIONS

Identifying the best MRE variables to reflect inflammation and damage will maximise the utility of this rapidly emerging technique and is the first stage of constructing MRE-based indices for evaluating inflammation and intestinal damage.

Accuracy of CT enterography and magnetic resonance enterography imaging to detect lesions preoperatively in patients undergoing surgery for Crohn's disease

BACKGROUND

CT enterography and magnetic resonance enterography have emerged as first-line imaging technologies for the evaluation of the gastrointestinal tract in Crohn's disease.

OBJECTIVE

The purpose of this work was to evaluate the accuracy of these imaging modalities to identify Crohn's disease lesions preoperatively.

DESIGN

This was a retrospective chart review.

SETTINGS

The study was conducted at a single institution.

PATIENTS

Seventy-six patients with Crohn's disease with preoperative CT enterography and/or magnetic resonance enterography were included in the study.

MAIN OUTCOME MEASURES

The number of stenoses, fistulas, and abscesses on CT enterography and/or magnetic resonance enterography before surgery were compared with operative findings.

RESULTS

Forty patients (53%) were women, 46 (60%) underwent surgery for recurrent Crohn's disease, and 46 (57%) had previous abdominal surgery. Thirty-six (47%) had a preoperative CT enterography and 43 (57%) had a preoperative magnetic resonance enterography. CT enterography sensitivity was 75% for stenosis and 50% for fistula. MRE sensitivity was 68% for stenosis and 60% for fistula. The negative predictive values of CT enterography and magnetic resonance enterography for stenosis were very low (54% and 65%) and were 85% and 81% for fistula. CT enterography had 76% accuracy for stenosis and 79% for fistula; magnetic resonance enterography had 78% accuracy for stenosis and 85% for fistula. Both were accurate for abscess. False-negative rates for CT enterography were 50% for fistula and 25% for stenosis. False-negative rates for magnetic resonance enterography were 40% for fistula and 32% for stenosis. Unexpected intraoperative findings led to modification of the planned surgical procedure in 20 patients (26%).

LIMITATIONS

This study was limited by its small sample size, its retrospective nature, and that some studies were performed at outside institutions.

CONCLUSIONS

CT enterography and magnetic resonance enterography in patients with Crohn's disease were accurate for the identification of abscesses but not for fistulas or stenoses. Surgeons should search for additional lesions intraoperatively. Patients should be appropriately counseled regarding the need for unexpected interventions (see Video, Supplemental Digital Content 1, http://links.lww.com/DCR/A162).