Imaging indexes of activity and severity for Crohn's disease: current status and future trends

Correlation between magnetic resonance enterography and ileo-colonoscopy for assessment of disease activity in terminal ileal Crohn's disease

BACKGROUND

Magnetic resonance enterography (MRE) has emerged as a novel tool for the assessment of disease activity in Crohn's disease (CD). Real world data from Indian subcontinent on performance of MRE in terminal ileal CD are lacking.

METHODS

Retrospective analysis of patients with terminal ileal CD who underwent both ileo-colonoscopy and MRE was performed. Ileo-colonoscopy was considered the gold standard for assessment of disease activity. On ileo-colonoscopy, a simple endoscopic score for Crohn's disease (SES-CD) ≥2 was considered active disease; presence of ulcers indicated severe disease. MRE scoring of the disease activity was performed using magnetic resonance index of activity (MARIA) and simplified MARIA (MARIAs). The measure of agreement between ileo-colonoscopy and MRE and comparison of MARIA and MARIAs for assessment of disease activity and sensitivity of MRE to detect mucosal ulcerations were calculated.

RESULTS

Seventy patients with terminal ileal CD (mean age 40.74±15.56 years; 71.4% males [n=50]) were evaluated. The sensitivities of MARIA and MARIAs scores to detect active disease were 0.76 and 0.84, respectively. The area under the receiver operating characteristic curve (AUROC) for detecting severe disease was 0.836 (p<0.0001) for MARIA and 0.861 (p<0.0001) for MARIAs. For mild active disease, there was no agreement between SES-CD and MARIA or MARIAs; however, for severe disease, the agreement was fair and moderate for MARIA and MARIAs, respectively. MARIA and MARIAs were comparable for identification of active and severe disease (κ 0.759, p<0.0001 and κ 0.840, p<0.0001, respectively). MRE was 68.18% sensitive to detect mucosal ulcers.

CONCLUSION

MRE is a reliable and sensitive tool for detection of endoscopically severe, but not mild, terminal ileal CD.

Ultrasonographic Evaluation of Intestinal Fibrosis and Inflammation in Crohn's Disease. The State of the Art

The evaluation of the degree of inflammation and fibrosis, intrinsic elements in intestinal wall damage of Crohn’s disease, is essential to individuate the extent of the lesions and the presence of strictures. This information will contribute to the choice of the appropriate therapeutic approach, the prediction of the response to therapy and the course of the disease. The accurate evaluation of the extent and severity of inflammation and/or fibrosis in Crohn’s disease currently requires histopathological analysis of the intestinal wall. However, in clinical practice and research, transmural assessment of the intestinal wall with cross sectional imaging is increasingly used for this purpose. The B-mode ultrasonograhic characteristics of the intestinal wall, the assessment of its vascularization by color Doppler and I.V. contrast agents, and the evaluation of the mechanical and elastic properties by sonoelastography, may provide useful and accurate information on the severity and extent of inflammation and intestinal fibrosis in Crohn’s disease. The purpose of this review is to provide an update on current sonographic methods to discriminate inflammation and fibrosis in Crohn’s disease.

Quantitative Inflammation Assessment for Crohn Disease Using Ultrasensitive Ultrasound Microvessel Imaging: A Pilot Study

OBJECTIVES

Crohn disease (CD) is a chronic inflammation in the digestive tract that affects millions of Americans. Bowel vascularity has important diagnostic information because inflammation is associated with blood flow changes. We recently developed an ultrasensitive ultrasound microvessel imaging (UMI) technique with high vessel sensitivity. This study aimed to evaluate the feasibility of UMI to assist CD detection and staging.

METHODS

Ultrasound microvessel imaging was performed on 76 bowel wall segments from 48 symptomatic patients with CD. Clinically indicated computed tomographic/magnetic resonance enterography was used as the reference standard. The vessel-length ratio (VLR, the number of vessel pixels in the bowel wall segment normalized to the segment length) was derived in both conventional color flow imaging (CFI) and UMI to quantitatively stage disease activity. Receiver operating characteristic curves were then analyzed between different disease groups.

RESULTS

The VLR-CFI and VLR-UMI detected similar correlations between vascularization and disease activity: severe inflammation had a higher VLR than normal/mildly inflamed bowels (P < .05). No significant difference was found between quiescent and mild CD due to the small sample size. The VLR-CFI had more difficulties in distinguishing quiescent versus mild CD compared to the VLR-UMI. After combining the VLR-UMI with thickness, in the receiver operating characteristic curve analysis, the areas under the curves (AUCs) improved to AUC₁ = 0.996 for active versus quiescent CD, AUC₂ = 0.978 for quiescent versus mild CD, and AUC₃ = 0.931 for mild versus severe CD, respectively, compared to those using thickness alone (AUC₁ = 0.968; P = .04; AUC₂ = 0.919; P = .16; AUC₃ = 0.857; P = .01).

CONCLUSIONS

Ultrasound microvessel imaging offers a safe and cost-effective tool for CD diagnosis and staging, which may potentially assist disease activity classification and therapy efficacy evaluation.

Correlation between ultrasound consolidated score and simple endoscopic score for determining the activity of Crohn's disease

OBJECTIVES

The aim of this study was to develop an ultrasound consolidated score (UCS) in determining the activity of Crohn's disease (CD) and evaluate it with reference to simple endoscopic score (SES).

METHODS

From June 2014 to June 2017, 66 patients with CD were retrospectively enrolled in this study. Each patient underwent endoscopy and transabdominal ultrasound (US) examination. The morphological symmetry, echogenicity of bowel wall, bowel wall layer structure, echogenicity of peri-bowel fat, bowel wall thickness (BWT), and Limberg type on power Doppler US were assessed with transabdominal US, and an UCS scoring system was developed based on these characteristics. Endoscopic results were used as the reference standard and SES was calculated to determine the CD activity. Receiver operating characteristic curve analysis was performed to assess the diagnostic performance for determining CD activity and the correlation between UCS and SES was assessed using Spearman correlation analysis.

RESULTS

330 intestinal segments in 66 patients were included. The UCS of the segments in the remission phase ranged from 3.0 to 9.0 (mean, 3.6 ± 0.9) whereas in the active phase from 3.0 to 20.0 (mean, 10.6 ± 4.0) (p < 0.001). The cut-off value of UCS was 6. The associated area under ROC curve, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 0.980, 88.3%, 95.5%, 93.8%, 91.3%, and 92.3%, respectively. The correlation coefficient between UCS and SES was 0.90, which was higher than the correlation coefficient of 0.83 between BWT and SES.

CONCLUSIONS

The newly developed UCS with transabdominal US has a good performance and potentially provides an effective alternative for evaluating the activity of CD.

ADVANCES IN KNOWLEDGE

UCS is an effective method to evaluate the activity of CD because it provides comprehensive information of the disease. Therefore, it could be employed as an alternative for diagnosis of CD.

Relevance of dynamic studies with magnetic resonance enterography in Crohn's disease

INTRODUCTION

A proper quantification of the inflammatory activity in Crohn's disease (CD) lesions is needed to establish the appropriate management for each patient. The aim of this study is to evaluate the inflammatory activity of affected segments in small bowel lesions using dynamic studies of magnetic resonance enterography (MRE) in patients undergoing surgery, and their correlation with the level of inflammation and histological fibrosis of the surgical piece.

METHODS

A prospective, consecutive, observational, clinical study was conducted that included all the patients with small bowel CD that underwent surgery in this center between March 2011 and September 2013. Diagnosis was established according to Lennard-Jones criteria and the Montreal classification. All the patients underwent MRE within three months before surgery, using a routine protocol involving Liver Acquisition with Volume Acceleration-Extended Volume (LAVA-XV) sequence for the dynamic studies before intravenous administering of gadolinium and 30, 70, 120, and 420s after administering this. The results allowed the designing of graphics with different uptake patterns. The Chiorean classification was used in the histological analysis, as well as a modified version published previously by this study group.

RESULTS

A total of 28 patients with 47 lesions were analyzed. There was a significant correlation between both curve patterns, including the modified Chiorean classification (P<0.0001) as well as the level of inflammation (P<0.0001) and fibrosis (P<0.002). Inflammatory patterns of dynamic studies are related to histological findings with 80.9% accuracy (sensitivity=75.7%; specificity=100%).

CONCLUSION

There is a high correlation between dynamic enhancement studies and the level of inflammatory activity. MRE is a suitable tool to differentiate between inflammatory and fibrotic lesions, making it useful to decide the appropriate management of each patient.

Use of magnetic resonance index of activity (MaRIA) in the preoperative assessment of small bowel Crohn's disease

BACKGROUND

Accurate quantification of the inflammatory activity in Crohn's Disease is essential to determine adequate treatment for each patient. The aim of the present study is to assess the correlation between the pre-operative Magnetic Resonance Index of Activity (MaRIA) and the histologic degree of inflammation from surgically resected intestinal Crohn's Disease lesions.

METHODS

This is a prospective study including a consecutive case series of patients with small bowel Crohn's Disease, who underwent surgical resection. Magnetic resonance enterography was performed in the 3months prior to surgery, applying a pre-established protocol. Relative contrast enhancements, wall thickness, presence of edema or ulcerations were the parameters used to calculate the MaRIA Index. All patients underwent surgery and every specimen was analyzed. The modified Chiorean classification was applied for the histological analysis and an ordinal regression analysis was used to correlate MaRIA and the grade of inflammation for each lesion.

RESULTS

59 lesions from 35 different patients were analyzed. The degree of inflammation of the lesions was statistically correlated to the MaRIA values (P=.002). The MaRIA index was significantly different (P<.001) between the different histological types of the Crohn's Disease lesions (inflammatory/ fibrotic). The best cut-off for detecting severe inflammation using MaRIA was 20 (AUC: 0.741; 74.1% sensitivity and 78.1% specificity).

CONCLUSION

MaRIA is a reliable tool to distinguish inflammatory from fibrotic lesions. Therefore, it could be considered essential for determining the most appropriate Crohn's Disease treatment for each patient.

Diagnostic accuracy of intestinal ultrasound and magnetic resonance enterography for the detection of endoscopy-based disease activity in ileocolonic Crohn's disease

BACKGROUND

Crohn's disease (CD) is characterised by chronic gastrointestinal inflammation with relapsing-remitting behaviour and often requires endoscopic and/or radiologic assessment.

OBJECTIVE

The objective of this study was to compare the diagnostic accuracy of intestinal ultrasound (IUS) and magnetic resonance enterography (MRE) for the assessment of disease activity in CD using a simple endoscopic score for CD as a reference standard.

PATIENTS AND METHODS

A prospective observational study was carried out in 71 consecutive adult patients with known CD, attending our tertiary inflammatory bowel disease clinic, between November 2014 and July 2016. Ileocolonoscopy, IUS and MRE were performed within 1 month prospectively. The simple endoscopic score-CD 0-2 was accepted as remission.

RESULTS

The sensitivity of IUS and MRE for detecting endoscopic activity was found similar with regard to bowel wall thickening and mesenteric fibrofatty proliferation (P>0.05). The overall accuracy for detecting mural lesions was similar between IUS and MRE. When mural lesions were analysed, the sensitivity of MRE in detecting the loss of wall stratification and stenosis was significantly higher than IUS (P<0.001 for both). IUS showed higher specificity for bowel wall thickening, loss of wall stratification and stenosis (P=0.009, P<0.001 and P<0.001, respectively). Sensitivity and accuracy of IUS were higher in detecting ascites in active disease (P=0.002).

DISCUSSION

Our results showed that IUS and MRE were equally accurate in detecting endoscopic activity. IUS may be the preferred technique for the evaluation of disease activity and for the follow-up of CD.

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.

Ultrasound for Assessing Disease Activity in IBD Patients: A Systematic Review of Activity Scores

BACKGROUND AND AIMS

Ultrasound [US] indices for assessing disease activity in IBD patients have never been critically reviewed. We aimed to systematically review the quality and reliability of available ultrasound [US] indices compared with reference standards for grading disease activity in IBD patients.

METHODS

Pubmed, Embase and Medline were searched for relevant literature published within the period 1990 to June 2017. Relevant publications were identified through full text review after initial screening by two investigators. Data on methodology and index characteristics were collected. Study quality was assessed using a modified version of the Quadas-2 tool for risk of bias assessment.

RESULTS

Of 20 studies with an US index, 11 studies met the inclusion criteria. Out of these 11 studies, 7 and 4 studied Crohn's disease [CD] and ulcerative colitis [UC0 activity indices, respectively. Parameters that were used in these indices included bowel wall thickness [BWT], Doppler signal [DS], wall layer stratification [WLS], compressibility, peristalsis, haustrations, fatty wrapping, contrast enhancement [CE], and strain pattern. Study quality was graded high in 5 studies, moderate in 3 studies and low in 3 studies. Ileocolonoscopy was used as the reference standard in 9 studies. In 1 study a combined index of ileocolonoscopy and barium contrast radiography and in 1 study histology was used as the reference standard. Only 5 studies used an established endoscopic index for comparison with US.

CONCLUSIONS

Several US indices for assessing disease activity in IBD are available; however, the methodology for development was suboptimal in most studies. For the development of future indices, stringent methodological design is required.

Magnetic Resonance Enterography for Inflammatory and Noninflammatory Conditions of the Small Bowel

Magnetic resonance enterography (MRE) is an effective noninvasive tool for evaluation of inflammatory and noninflammatory conditions of the small bowel. MRE allows for repeated evaluation of patients with Crohn disease without exposure to ionizing radiation, and can be used to assess disease status and direct management. MRE also allows evaluation of neoplastic and other nonneoplastic conditions of the small bowel. Adequate patient preparation and acquisition techniques are required for optimal image quality.

Reliability of Measuring Ileo-Colonic Disease Activity in Crohn's Disease by Magnetic Resonance Enterography

BACKGROUND

Magnetic resonance enterography is increasingly utilized for assessment of luminal Crohn's disease activity. The Magnetic Resonance Index of Activity and the London Index are the most commonly used outcome measures in clinical trials. We assessed the reliability of these indices and several additional items.

METHODS

A consensus process clarified scoring conventions and identified additional items based on face validity. Four experienced radiologists evaluated 50 images in triplicate, in random order, at least 1 month apart, using a central image management system. Intra- and interrater reliability were assessed by calculating and comparing intraclass correlation coefficients.

RESULTS

Intrarater intraclass correlation coefficients (95% confidence intervals) for the Magnetic Resonance Index of Activity, London, and London "extended" indices and a visual analogue scale were 0.89 (0.84 to 0.91), 0.87 (0.83 to 0.90), 0.89 (0.85 to 0.92), and 0.86 (0.81 to 0.90). Corresponding interrater intraclass correlation coefficients were 0.71 (0.61 to 0.77), 0.67 (0.55 to 0.75), 0.70 (0.61 to 0.76), and 0.71 (0.62 to 0.77). Reliability for each index was greatest in the terminal ileum and poorest in the rectum. All 3 indices were highly correlated with the visual analogue scale; 0.79 (0.71 to 0.85), 0.78 (0.71 to 0.84), and 0.79 (0.72 to 0.85) for the Magnetic Resonance Index of Activity, London, and the London "extended" indices, respectively.

CONCLUSIONS

"Substantial" interrater reliability was observed for all 3 indices. Future studies should assess responsiveness to treatment in order to confirm their utility as evaluative indices in clinical trials and clinical practice.

A Simple Ultrasound Score for the Accurate Detection of Inflammatory Activity in Crohn's Disease

BACKGROUND

Ultrasound is accurate in the detection of Crohn's disease. Our aim was to identify ultrasound parameters contributing to inflammatory disease activity, develop a simple score, and validate this score prospectively.

METHODS

This study comprised 2 single-center investigations. The first was a retrospective study on a population that had received colonoscopies (as a gold-standard diagnostic) within 60 days of ultrasound. The second was a prospective study on 2 populations: patients requiring induction with adalimumab and patients on adalimumab maintenance therapy. Ultrasound and endoscopy were preformed within 14 days in both prospective groups. The endoscopy results were graded with the Simple Endoscopic Score and the Rutgeerts score and compared with 5 ultrasound parameters. We used a proportional odds model to determine which ultrasound parameters correlated significantly with the endoscopy results. We then developed a predictive ultrasound score for disease activity, plotted the receiver operating characteristic curves, and undertook prospective validation of the score.

RESULTS

We evaluated 160 patients retrospectively to compare ultrasound and colonoscopy. Two of 5 parameters were found to correlate significantly with disease activity: bowel wall thickness (P = <0.0001) and color Doppler signal (P = 0.0292). We developed a score that uses weighted variables. The area under the corresponding receiver operating characteristic curve was 0.8658.

CONCLUSIONS

A simple ultrasonographic score that accurately identifies Crohn's disease activity has been developed and validated. Ultrasound may be a surrogate for endoscopy to guide disease management, but future studies should be conducted to establish interrater variability.

Comparison of three magnetic resonance enterography indices for grading activity in Crohn's disease

BACKGROUND

Magnetic resonance enterography (MRE) is an accurate examination for assessing activity in Crohn's disease (CD). Various MRE indices have been developed for that purpose, but have not been directly compared. The aim of the study was to compare the diagnostic accuracy of three MRE indices for detecting and grading disease activity in CD, using endoscopy as gold standard.

METHODS

MRE and ileocolonoscopies performed within 1 month in 43 patients with CD were analyzed. The magnetic resonance index of activity (MaRIA), Clermont, and London indices for each colonic segment and the terminal ileum were calculated. Simplified endoscopy score for CD (SES-CD) was considered the gold standard.

RESULTS

Two hundred and twenty-four intestinal segments were included in the analysis. According to the established cut-off points for detecting active disease using MaRIA, Clermont, and London indices, the sensitivity of each index was 0.88, 0.89, and 0.71, and the specificity was 0.97, 0.78, and 0.99, respectively. The sensitivity for detecting ulcerations was 0.90 and 0.83 for the MaRIA and Clermont indices, respectively, with a specificity of 0.91 and 0.89. The AUROC curve for the MaRIA, Clermont, and London indices for detecting active disease was 0.92, 0.84, and 0.85, and for detecting ulcerations was 0.90 for the MaRIA, and 0.86 for Clermont index.

CONCLUSIONS

The three MRE-based indices evaluated in the current study have high diagnostic accuracy for assessment of disease activity. The MaRIA index has the best operational characteristics for detecting not only disease activity but also for grading severity, which supports its use in clinical studies and clinical practice.

MR Enterography Assessment of Bowel Inflammation Severity in Crohn Disease Using the MR Index of Activity Score: Modifying Roles of DWI and Effects of Contrast Phases

OBJECTIVE

The purpose of this article is to appraise the use of the MR index of activity (MaRIA) score in evaluating Crohn disease (CD) on present-day MR enterography images, with an emphasis on determining the modifying roles of DWI and the effects of different contrast enhancement phases.

SUBJECTS AND METHODS

Fifty patients prospectively underwent MR enterography, including DWI and enteric and portal phase scans, and ileocolonoscopy with segmental CD endoscopic index of severity (CDEIS) scoring within a week. Thirty-nine terminal ilea and 40 right-sided colons (mean [± SD] segmental CDEIS score, 14.3 ± 12.1) from 42 patients with CD (mean age, 27 ± 6.2 years) were finally analyzed by three independent readers. Original and modified (ulcer replaced with DWI grade) MaRIA scores were compared regarding their correlation with segmental CDEIS score, accuracy in diagnosing active (segmental CDEIS score ≥ 3) and severe (segmental CDEIS score ≥ 12) inflammation, and interobserver reproducibility. The primary analysis used portal phase data, and the agreement between portal and enteric phase scores was analyzed.

RESULTS

MaRIA and modified MaRIA scores correlated similarly with CDEIS scores (r = 0.737 and 0.742; p = 0.387) and did not significantly differ in terms of AUC values for the diagnosis of active (0.909 and 0.903; p = 0.571) or severe (0.907 and 0.892; p = 0.443) inflammation. The intraclass correlation coefficient was significantly higher for modified MaRIA than for MaRIA (0.845 and 0.701; p < 0.001). The mean difference between portal and enteric phase scores (i.e., portal minus enteric) was 0.33-0.36 score points for individual readers, and the Bland-Altman repeatability coefficient was 0.9-1.42 score points.

CONCLUSION

Interobserver reproducibility in evaluating the severity of bowel inflammation in CD using the MaRIA score can be improved by modification with DWI. MaRIA scoring provides steady results across enteric and portal phases.

The influence of anti-TNF therapy on the magnetic resonance enterographic parameters of Crohn's disease activity

Purpose

Magnetic resonance enterography (MRE) is a useful tool in assessing the transmural and extraintestinal lesions in Crohn’s disease (CD). However, the influence of anti-tumor necrosis factor (anti-TNF) therapy on MRE features of CD severity remains unknown. The purpose of the study was to assess the short- and long-term changes in MRE features of CD activity in relation to CD clinical course in patients treated with anti-TNF antibodies.

Methods

The influence on the most important parameters of CD activity seen in MRE was assessed retrospectively using a validated score. Patients were treated with anti-TNF agents and the clinical, laboratory, and MRE CD activity was estimated at baseline, after the induction therapy and after 1 year of treatment.

Results

71 patients were enrolled in a study. The change in CD clinical activity correlated significantly with fluctuations in MRE activity score (P < 0.0001, r = 0.5 for induction; P = 0.004, r = 0.7 for maintenance anti-TNF therapy, respectively). Bowel wall thickening, mesenteric lymphadenopathy, and fat wrapping with vascular proliferation were MRE parameters which changed significantly both after the induction and maintenance treatment in patients responding to the therapy. The change in MRE activity score was mostly pronounced during the first 3 months of treatment, when compared to the continuation of the therapy till week 52–54 (−6 points vs. −2 points, respectively; P = 0.0008).

Conclusions

Transmural and extraintestinal healing seen in MRE correlates with changes in CD clinical activity during anti-TNF therapy, thus MRE seems to be a useful tool in monitoring the efficacy of biological agents.

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.

Assessment of stricturing Crohn's disease: Current clinical practice and future avenues

Crohn’s disease (CD) is a chronic remittent idiopathic disease. Although the early phase of the disease is commonly characterized by inflammation-driven symptoms, such as diarrhea, the frequency of fibrostenotic complications in patients with CD increases over the long-term course of the disease. This review presents the current diagnostic options for assessing CD-associated strictures. In addition to the endoscopic evaluation of CD strictures, this review summarizes the currently available imaging modalities, including ultrasound and cross-sectional imaging techniques. In addition to stricture detection, differentiating between the primarily inflammatory strictures and the predominantly fibrotic ones is essential for selecting the appropriate treatment strategy (anti-inflammatory medical treatment vs endoscopical or surgical approaches). Therefore, recent imaging advances, such as contrast-enhanced ultrasound and ultrasound elastography, contribute to the development of non-invasive non-radiating imaging of CD-associated strictures. Finally, novel magnetic resonance imaging techniques, such as diffusion-weighted, motility and magnetization transfer imaging, as well as ¹⁸F-FDG PET/CT, molecular imaging approaches and biomarkers, are critically reviewed with regard to their potential role in assessing stricturing CD.

Inflammatory bowel disease imaging: Current practice and future directions

The purpose of this paper is to evaluate the role of imaging in inflammatory bowel disease (IBD), including detection of extraluminal complications and extraintestinal manifestations of IBD, assessment of disease activity and treatment response, and discrimination of inflammatory from fibrotic strictures. IBD is a chronic idiopathic disease affecting the gastrointestinal tract that is comprised of two separate, but related intestinal disorders; Crohn’s disease and ulcerative colitis. The paper discusses, in detail the pros and cons of the different IBD imaging modalities that need to be considered in order to optimize the imaging and clinical evaluation of patients with IBD. Historically, IBD evaluation of the bowel has included imaging to assess the portions of the small bowel that are inaccessible to optical endoscopic visualization. This traditionally was performed using barium fluoroscopic techniques; however, cross-sectional imaging techniques (computed tomography and magnetic resonance imaging) are being increasingly utilized for IBD evaluation because they can simultaneously assess mural and extramural IBD manifestations. Recent advances in imaging technology, that continue to improve the ability of imaging to noninvasively follow disease activity and treatment response, are also discussed. This review article summarizes the current imaging approach in inflammatory bowel disease as well as the role of emerging imaging modalities.

[Modern MRI of the small bowell]

CLINICAL METHODOLOGICAL ISSUES

The radiological diagnostics of diseases of the small intestine have undergone a great change in the last two decades. Through rapid progress with new treatments and an increasing therapeutic focus on transmural healing, a complete evaluation of the gastrointestinal tract is now crucial.

STANDARD RADIOLOGICAL METHODS

With the introduction of endoscopy, gastrointestinal imaging with a relatively high radiation exposure had only limited applications. The development of cross-sectional imaging allowed a much broader radiological evaluation of abdominal diseases. Due to rapid investigation techniques, excellent soft tissue contrast and the distinct advantage of eliminating exposure to radiation, magnetic resonance imaging (MRI) of the gastrointestinal tract has gained increasing importance. With sufficient filling of the intestinal lumen, simultaneous imaging of all the intestinal wall layers, the perienteric structures and associated abdominal pathologies is now possible.

METHODOLOGICAL INNOVATIONS

New MR sequences, such as diffusion-weighted sequences, dynamic contrast-enhanced sequences and MR fluoroscopy, enable the detection of morphological changes, with additional characterization of affected bowel loops as well as the assessment of functional pathologies with dynamic information about intestinal motility disturbances.

ACHIEVEMENTS

Recent guidelines of European radiological and gastroenterological organizations have confirmed the importance of cross-sectional imaging and particularly of MRI for diagnostics and follow-up in patients with Crohn's disease. Due to the possibility of assessment of all the layers of the intestinal wall and the presence of extramural complications, MRI has a significant impact on further therapeutic treatment in patients with inflammatory bowel disease.

PRACTICAL RECOMMENDATIONS

Especially in patients with inflammatory bowel disease, MR enterography and MR enteroclysis should be the methods of choice for the evaluation of small bowel pathologies because of radiation issues and the great diagnostic value they provide. A variety of MR sequences has enabled not only the detection but also the characterization of pathological changes of the small intestine, which are vital for further treatment of these patients.

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.

Systematic Review of the Clinical Disease Severity Indices for Inflammatory Bowel Disease

BACKGROUND

Clinical disease severity indices are increasingly being used in choosing treatment and monitoring the response of patients with inflammatory bowel disease (IBD). The aim of this study was to systematically review the clinical disease severity indices in IBD and to appraise their measurement properties and methodological quality.

METHODS

We searched the MEDLINE, Embase, and PsycINFO databases for original articles describing the development and/or evaluation of one or more of the measurement properties of clinical disease severity indices used in IBD. We assessed these properties (e.g., internal consistency, reliability, validity, responsiveness) using a standardized checklist.

RESULTS

We examined the full text of 142 articles that we deemed potentially eligible and identified 22 clinical disease severity indices in IBD. No clinical disease index has met all the required measurement properties. All of the validation studies were not descriptive enough to allow assessment of their methodology.

CONCLUSIONS

Although commonly used in multiple clinical trials, none of the clinical disease severity indices in IBD had all the required measurement properties. Further validation studies are required.

Development and validation of a new disease severity index: the Inflammatory Bowel Disease Index (IBDEX)

OBJECTIVE

To develop, validate and apply a generic clinical severity index applicable to all adult patients with inflammatory bowel disease (IBD).

DESIGN

A review of the literature and an expert focus group consultation were carried out in order to draw out relevant items from existing literature. The new index was called the IBD Index (IBDEX). Standard psychometric analysis was carried out. The construct validity was assessed against biochemical markers, clinical and endoscopic indices. The new index was completed again within 6 weeks to check responsiveness and reproducibility.

RESULTS

IBDEX was used to assess 255 adult patients with IBD (125 with Crohn's disease and 130 with ulcerative colitis), and 64 patients were re-evaluated within 6 weeks. It had good internal consistency (Cronbach's α=0.79) and correlated very well with the Harvey Bradshaw Index (r=0.94), the Simple Clinical Colitis Activity Index (r=0.92), the Mayo Clinic Index (r=0.87) and the Simple Endoscopic Score (r=0.76), all with p values <0.05. IBDEX had a moderate but positive correlation with C reactive protein (r=0.51) and erythrocyte sedimentation rate (r=0.36) p values both <0.05. The test-retest reliability was good (intraclass correlation coefficient 0.97) and responsiveness ratio was 2.27.

CONCLUSIONS

IBDEX is the first properly validated Clinical Disease Severity Index in IBD. Our results showed that it is valid, reliable and reproducible and has the potential to be used in clinical practice.

Magnetic resonance enterographic predictors of one-year outcome in ileal and ileocolonic Crohn's disease treated with anti-tumor necrosis factor antibodies

The aim of the study was to assess the role of magnetic resonance enterography (MRE) in predicting one-year efficacy of anti-tumor necrosis factor antibodies - infliximab (IFX), adalimumab (ADA) in Crohn’s disease (CD) patients primarily responding to therapy. We performed retrospective analysis among 61 CD patients who had undergone a successful IFX/ADA induction therapy and were treated with maintenance doses. All patients underwent MRE at week 0. We assessed which MRE features were predictive for steroid-free remission at week 52, and which were associated with a secondary loss of response. 44 patients were in steroid-free remission at week 52, 17 - were secondary non-responders. The ROC curve showed that bowel thickening with contrast enhancement analyzed together at week 0 were associated with steroid-free remission at week 52 (p = 0.01; AUC 0.67). Bowel stenosis with or without prestenotic dilatation [OR 5.8 (95% CI 1.4 – 25) and 2.4 (95% CI 1.2 – 5) respectively; p = 0.01] and the presence of intra-abdominal fistulas [OR 1.4 (95% CI 1.1 – 2); p = 0.004] were related to secondary non-response. A high baseline inflammatory activity detected by MRE predicts one-year response in CD after IFX/ADA. In case of bowel stenosis, intra-abdominal fistulas, other therapeutic options should be considered.

Diffusion-weighted MR enterography for evaluating Crohn's disease: how does it add diagnostically to conventional MR enterography?

BACKGROUND

Diffusion-weighted imaging (DWI) is a novel technique to evaluate bowel inflammation in Crohn's disease (CD). It is unknown whether and how DWI adds to the accuracy of conventional magnetic resonance enterography (MRE).

METHODS

Fifty consecutive adults suspected of CD prospectively underwent clinical assessment, conventional MRE and DWI at b = 900 sec/mm without water enema, and ileocolonoscopy within 1 week. MRE images were interpreted with proper blinding. Forty-four patients finally diagnosed with CD (male:female, 34:10; 26.9 ± 6.1 yr) were analyzed. The per-segment accuracy of MRE for diagnosing active CD was assessed in the terminal ileum, right colon, and rectum using location-by-location matching with endoscopy as the reference standard.

RESULTS

The study evaluated 58 bowel segments with deep or superficial ulcers, 34 with aphthae, erythema, or edema only, and 35 without inflammation. Conventional MRE + DWI was more sensitive for bowel inflammation than conventional MRE alone (83% [76/92] versus 62% [57/92]; P = 0.001) largely because of additional detection of aphthae, erythema, or edema. The sensitivities for deep and overt ulcers were similar regardless of DWI, ranging from 88% to 97%. Conventional MRE + DWI was less specific than conventional MRE alone (60% [21/35] versus 94% [33/35]; P < 0.001), mostly because of many false positives in the colorectum. Positive DWI findings in the bowel showing active inflammation on conventional MRE were associated with higher Crohn's disease endoscopic index of severity score (P = 0.021) and deep ulcers (P = 0.01; diagnostic odds ratio, 12).

CONCLUSIONS

DWI performed without water enema is not useful for incremental detection of bowel inflammation. DWI may help identify more severe inflammation among bowel segments showing active inflammation on conventional MRE.

Small bowel Crohn's disease: an emerging disease phenotype?

An increasing understanding of the pathogenesis of Crohn's disease (CD), coupled with improvements in therapeutic options, has promoted the concept of stratifying patients with CD into distinct disease phenotypes according to risk. Small bowel CD, due to the numerous non-specific potential symptoms and the anatomical location of the disease, is a particularly difficult phenotype to identify. The fact that the majority of de novo strictures occur in the ileum/ileo-colonic region ensures that recognition of small bowel involvement is essential. Certainly, it is becoming increasingly recognised due to improvements in imaging and endoscopic techniques. Both CT and MR enterography appear capable of accurately diagnosing small bowel CD. Furthermore, the development of capsule endoscopy and balloon-assisted enteroscopy allow direct visualisation of the small bowel. Limited data to date would suggest that small bowel CD is a difficult entity to treat even in the current era of the ever-expanding field of biological therapies. Further long-term follow-up studies are necessary using both small bowel capsule endoscopy and cross-sectional imaging to truly assess, firstly, whether small bowel CD is more resistant to treatment and, secondly, whether it has an effect over time in terms of complications. In the future, serological and genetic tests, coupled with the aforementioned investigations, will permit early diagnosis and early treatment of small bowel CD.

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

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

Gastrointestinal imaging-practical magnetic resonance imaging approach

Over the past two decades, advances in cross-sectional imaging such as computed tomography and magnetic resonance imaging (MRI) have dramatically changed the concept of gastrointestinal imaging. MR is playing an increasing role in the evaluation of gastrointestinal disorders. MRI combines the advantages of excellent soft-tissue contrast, noninvasiveness, functional information and lack of ionizing radiation. Furthermore, recent developments of MRI have led to improved spatial and temporal resolution as well as decreased motion artifacts. In this article we describe the technical aspects of gastrointestinal MRI and present a practical approach for a well-known spectrum of gastrointestinal disease processes.

Measuring disease activity in Crohn's disease: what is currently available to the clinician

Crohn’s disease (CD) is a chronic inflammatory bowel disease characterized by a relapsing-remitting clinical behavior and dominated by intestinal inflammation. Being a chronic disorder that with time develops into a disabling disease, it is important to monitor the severity of inflammation to assess the efficacy of medication, rule out complications, and prevent progression. This is particularly true now that the goals of treatment are mucosal healing and deep remission. Endoscopy has always been the gold standard for assessing mucosal activity in CD, but its use is limited by its invasiveness and its inability to examine the small intestine, proximal to the terminal ileum. Enteroscopy and the less invasive small bowel capsule endoscopy enable the small bowel to be thoroughly explored and scores are emerging for classifying small bowel disease activity. Cross-sectional imaging techniques (ultrasound, magnetic resonance, computed tomography) are emerging as valid tools for monitoring CD patients, assessing inflammatory activity in the mucosa and the transmucosal extent of the disease, and for excluding extra-intestinal complications. Neither endoscopy nor imaging are suitable for assessing patients frequently, however. Noninvasive markers such as C-reactive protein, and fecal biomarkers such as calprotectin and lactoferrin, are therefore useful to confirm the inflammatory burden of the disease and to identify patients requiring further investigations.

Contrast-enhanced ultrasound of the small bowel in Crohn's disease

Crohn's disease (CD) is a chronic transmural inflammatory disease of the gastrointestinal tract characterized by episodes of inflammation alternating with periods of remission. Unenhanced grey-scale ultrasound may evaluate the localisation and the length of the affected intestinal segments and may detect transmural complications, including fistulas, abscesses and phlegmons, but it is less accurate to assess the CD activity. Contrast-enhanced ultrasound has become an important imaging modality in patients with CD for the grading of disease activity, the differentiation between small bowel stricture due to inflammation or mural fibrosis, and for the assessment of the response to specific therapy. New dedicated software packages allow the accurate quantification of the enhancement within the small bowel wall after microbubble contrast agent injection to obtain different kinetic semi-quantitative parameters-the percentage of the maximal enhancement, the time-to-the peak enhancement, and the area under the time-intensity curve-which are very useful to differentiate the inflammatory oedema from fibrosis and to differentiate responders from non-responders to the specific therapy among patients with CD.

Endoluminal ultrasound biomicroscopy as a reliable tool for in vivo assessment of colonic inflammation in rats

PURPOSE

Endoscopic ultrasound (EUS) imaging of the colon is an important diagnostic tool for early neoplasia, although usually restricted to the rectum in inflammatory bowel disease (IBD). This study aimed to evaluate the ability of an endoluminal ultrasound biomicroscopic (eUBM) system to detect and characterize lesions simulating Crohn's disease in the colon of rats in vivo.

METHODS

Colitis was induced with trinitrobenzene sulfonic acid instillated in the distal colon. Eighteen Wistar rats were submitted to eUBM in three time points: week 1 group (18 animals examined on day 3 after colitis induction), week 2 group (12 animals on days 3 and 10), and week 3 group (7 animals on days 3, 10, and 17). This design yielded distinct inflammation intensities. Three untreated rats were used for acquisition of control images. Scores were used for comparison with histology.

RESULTS

Scores for eUBM and histology in the different moments of examination achieved a Spearman's rank correlation coefficient of 0.87 (p < 0.001). Findings of wall thickening presented positive predictive value (PPV) and sensitivity of 94 and of 100 %, respectively. Superficial and deep ulcers presented a PPV of 89 and 80 %, respectively, and negative predictive values of 100 and 85 %, respectively.

CONCLUSION

Accurate detection and analysis of the lesions was achieved. The model is essential for the clinical development of the technique and a reproducible method for the evaluation of experimental colitis. eUBM might be applicable in different segments of the gut, developing into a novel adjunct method for IBD evaluation.

Update imaging in inflammatory bowel diseases

Imaging is a central component of the diagnostic process in inflammatory bowel diseases. This review summarizes the recent progress of various most commonly used imaging modalities including computed tomography enterography, magnetic resonance enterography and capsule endoscopy. Advantages and disadvantages of each imaging protocol in suspected and established inflammatory bowel diseases are reviewed and brought into context in proposed diagnostic algorithms.

MR imaging techniques of the bowel

Due to advances in technology, magnetic resonance is an increasingly popular method for evaluating the small bowel and colon because of the lack of radiation, wealth of information provided by the images, and growing demand from gastroenterologists, surgeons, and oncologists. Careful attention to proper technique, however, is necessary to obtain high-quality images. Factors that need to be considered for successful magnetic resonance of the bowel include method for administration of oral or rectal contrast, patient positioning, need for antiperistaltic medication, and imaging sequences and planes.

The value of time-intensity curves obtained after microbubble contrast agent injection to discriminate responders from non-responders to anti-inflammatory medication among patients with Crohn's disease

OBJECTIVE

To assess the value of time-intensity curves obtained after sulphur hefluoride-filled microbubble contrast agent injection to discriminate responders from non-responders among patients with Crohn's disease (CD).

METHODS

Forty-three patients (29 male and 14 female; mean age ± SD, 48.5 ± 17.17 years) with initial diagnosis of active CD were recruited. In each patient, the therapeutic outcome was assessed after 12 weeks from the beginning of pharmacologic treatment. The terminal ileal loop was scanned after sulphur hexafluoride-filled microbubble injection, and the digital cine-clip registered during the first-pass dynamic enhancement was quantified in gray-scale levels. The percentage of maximal enhancement, time to peak enhancement, and area under the time-intensity curve in responders vs. non-responders were compared by Mann-Whitney U non-parametric test.

RESULTS

Responders (n = 25 patients) vs. non-responders (n = 18) differed in the area under the time-intensity curve (621.58 ± 374.53 vs. 1,199.64 ± 386.39 P < 0.05), while they did not differ in percentage of maximal enhancement (41.26 ± 15.22 vs. 43.17 ± 4.41, P = 0.25) and time to peak enhancement (11.31 ± 3.06 vs. 10.12 ± 3.47, P = 0.15).

CONCLUSIONS

The area under the time-intensity curve obtained after microbubble injection was the only parameter to discriminate responders from non-responders among patients with CD during pharmacologic treatment.

KEY POINTS

• Dynamic ultrasound using microbubble contrast agents can help assess inflammatory bowel disease • Time-intensity curves can assess therapeutic outcome in Crohn's disease (CD) • The area under the time-intensity curve differentiates responders from non-responders during pharmacological treatment.