Utility of the diffusion-weighted imaging for activity evaluation in Crohn's disease patients underwent magnetic resonance enterography

Diffusion-weighted imaging in Crohn's disease

BACKGROUND

Diffusion-weighted MRI (DWI) is routinely used in abdominal imaging. In addition to neoplastic diseases, inflammatory changes can be delineated and diagnosed based on diffusion restriction in DWI. DWI is also increasingly used in the context of MRI of the small and large intestine.

OBJECTIVE

This article focuses on the technical aspects of DWI and its role in the diagnosis of Crohn's disease (CD) as well as in the grading of disease severity and in treatment monitoring.

MATERIALS AND METHODS

Guidelines, basic research papers, and review articles were analyzed.

RESULTS

Diffusion-weighted MRI is a specialized MRI technique that visualizes the diffusion of water molecules in biological tissues. In the context of MRI of the small and large intestine, DWI facilitates the diagnosis of inflammatory bowel disease and assessment of treatment response. DWI enables detection of not only intra- and transmural changes, but also extramural pathologies and complications. However, DWI also has its limitations and challenges.

CONCLUSION

This article provides a comprehensive overview of the use of DWI for diagnostic evaluation of bowel wall changes and extramural complications in the setting of CD. It also summarizes the relevant evidence available in the literature.

Small Bowel Imaging from Stepchild of Roentgenology to MR Enterography: Part I: Guidance in Performing and Observing Normal and Abnormal Imaging Findings

MRE has become a standard imaging test for evaluating patients with small bowel pathology, but the indications, interpretation of imaging findings, methodology, and appropriate use must be standardized and widely known. Several signs of small bowel damage in inflammatory and non-inflammatory small bowel pathology include strictures, abscess, inflammatory activity, sinus tract, wall edema, fistula, mucosal lesions, and mesentery fat hypertrophy, all of which are widely and accurately explained by MRE. MRE is a non-invasive modality that accurately assesses the intra-luminal, parietal, and extra-luminal small bowel. The differential MRE appearance allows us to distinguish between different small bowel pathologies, such as neoplastic and non-neoplastic small bowel diseases. The purpose of this paper is to present the MRE technique, as well as the interpretation of imaging findings, through the approach of a rigorous stepwise methodology.

Oesophageal cancer cases recorded in the Zambia National Cancer Registry: a cross-sectional study

Introduction

the aim of this study was to determine what proportion of patients with confirmed esophageal cancer at the largest hospital in the country were recorded in the Zambia National Cancer Registry (ZNCR).

Methods

we reviewed esophageal cancer records at the University Teaching Hospital (UTH) and ZNCR, between 2015 and 2017. Using Stata version 15, data were summarised and the Kruskal-Wallis was used to compute comparisons, Kaplan-Meier curves for survival estimates and Cox regression for associated factors.

Results

included in the final analysis were records for 222 patients with confirmed esophageal cancer and of these 51/222 (41%) were appearing in the ZNCR. The mean age of the patients was 56.2 years (SD, 13.0) and only 2/222 (1%) were confirmed alive at the time of data analysis. The median time from endoscopic diagnosis to histological confirmation was 12.5 days (IQR 7.5 - 21.5) and arrival at the Cancer Diseases Hospital (CDH) for treatment was 20 days (IQR 10 - 34). The overall median survival time in the study was 259 days (CI 95%; 151 - 501). Age, sex, time to diagnosis, histological classification and grade of tumour did not show any evidence of predicting survival in both the univariate and multivariable cox regression model (p>0.05).

Conclusion

a significant proportion of esophageal cancer cases seen at UTH were not included in the national registry suggesting that official figures for the prevalence of esophageal cancer in Zambia are underestimated. There is an urgent need to improve the collection of data on esophageal cancer in Zambia.

Diagnostic Performance of Diffusion-weighted Imaging for Evaluation of Bowel Inflammation in Paediatric Inflammatory Bowel Disease: A Systematic Review and Meta-analysis

BACKGROUND AND AIMS

The diagnostic performance of diffusion-weighted imaging magnetic resonance enterography [DWI-MRE] has not been clearly established in a paediatric population. We systematically evaluated the diagnostic performance of DWI-MRE for the detection of bowel inflammation in paediatric patients with suspected or known inflammatory bowel disease [IBD].

METHODS

MEDLINE/PubMed, EMBASE, Web of science and the Cochrane library were searched for articles investigating the diagnostic performance of DWI-MRE for the detection of bowel inflammation in paediatric patients with suspected or known IBD up to December 31, 2020. Pooled sensitivity and specificity were calculated using a bivariate random-effects model. Pooled inter-reader agreement for the interpretation of DWI-MRE was also calculated. This study was registered as PROSPERO CRD42021228754.

RESULTS

Nine studies covering 400 paediatric patients were included. The pooled sensitivity and specificity of DWI-MRE for the detection of bowel inflammation were 0.93 (95% confidence interval [CI], 0.88-0.96) and 0.96 [95% CI, 0.87-0.99], respectively. Substantial heterogeneity was noted in both sensitivity [I2 = 66%; p < 0.01] and specificity [I2 = 94%; p < 0.01]. Meta-regression analysis identified that the use of spasmolytics contributed to higher specificity [0.89-0.99] and that quantitative assessment with an apparent diffusion coefficient cut-off value contributed to lower sensitivity [0.93-0.85] and specificity [0.98-0.72]. The pooled coefficient of inter-reader agreement, including four studies using visual assessment, was 0.97 [95% CI, 0.78-1.00].

CONCLUSIONS

DWI-MRE, especially when used with spasmolytics, is accurate for the detection of bowel inflammation in paediatric patients with suspected or known IBD. Quantitative measurement of ADC is not practical for this purpose.

High b-value computed diffusion-weighted imaging for differentiating bowel inflammation in Crohn's disease

Purpose This study evaluated whether high b-value computed diffusion-weighted imaging (cDWI) can improve detection and differentiation of bowel inflammation in patients with Crohn's disease (CD). Methods Fifty-four consecutive CD patients who had undergone magnetic resonance enterography (MRE) and ileocolonoscopy (ICS) or balloon-assisted enteroscopy (BAE) were retrospectively studied; cDWI with a b-value = 1500s/mm² (cDWI1500) was generated using DWI acquired with b-values of 0 and 800 s/mm² (aDWI800). Overall, 366 bowel segments were evaluated. The signal intensities (SIs) of the bowel lumina were visually assessed on DWI. Bowel wall-to-iliopsoas muscle SI ratios on aDWI800 and cDWI1500 images and apparent diffusion coefficient (ADC) values were measured; visual assessments for lesion detection were performed using a 5-point Likert-like scale on plain MRE with aDWI800, plain MRE with cDWI1500, and contrast-enhanced (CE)-MRE without DWI. The area under the receiver-operating characteristic curve (AUC) was calculated to compare quantitative and qualitative assessments. Results SIs of the intraluminal fluid were shown as comparable to, or lower than background SIs on 157 (44.7 %) and 345 (98.3 %) of 351 segments on aDWI800 and cDWI1500, respectively. AUCs of SI ratios on cDWI1500 images (82.0 %, [95 % confidence interval: 76.6-87.3 %]) were greater than on aDWI800 (75.2 %, [68.2-82.3 %]; p < 0.001), and were close to the ADC values (81.5 % [76.3-86.7 %]; p = 0.76). The AUCs of CE-MRE images were largest, followed by plain MRE with cDWI1500, and plain MRE with aDWI800. Conclusions As it suppresses the SIs of intraluminal fluid and improves contrast between severe and non-severe inflammation, cDWI1500 helps with CD evaluation.

Potential MR Enterography Features to Differentiate Primary Small Intestinal Lymphoma From Crohn Disease

OBJECTIVE. The purpose of this study was to assess the MR enterographic features of primary small intestinal lymphoma (PSIL) and compare them with active Crohn disease (CD) presenting with severe (≥ 10 mm) mural thickening of the small bowel. MATERIALS AND METHODS. This retrospective study included 15 patients with pathologically proven PSIL and 15 patients with active inflammatory CD with severe mural thickening. Various morphologic, enhancement, and diffusion parameters were compared between the two groups at MR enterography. The ratios of the upstream to involved luminal diameter and mural thickness to luminal diameter in the involved segment were calculated. An attempt was made to define a predictive model (morphologic score) for discriminating PSIL from CD with severe mural thickening. RESULTS. Patients with PSIL were more likely than those with CD to have unifocal disease (66.7% vs 20.0%, p = 0.025), circumferential involvement (86.7% vs 26.7%, p < 0.001), luminal dilatation (60.0% vs 7.0%, p = 0.005), and an attenuated fold pattern (53.3% vs none, p < 0.001). They were less likely to have serosal surface involvement (40.0% vs 100%, p = 0.001) and mesenteric fat infiltration (33.3% vs 100%, p < 0.001). Median upstream to involved luminal diameter ratio (1.5 vs 9.6, p < 0.001) and mural thickness to involved luminal diameter ratio (1.1 vs 4.3, p = 0.044) were significantly lower in patients with PSIL than in those with CD with severe mural thickening. No significant difference was observed in enhancement and diffusion measures. Morphologic score was based on the presence of luminal dilatation, unifocal involvement, mesenteric fat infiltration, and luminal stricture, yielding accuracy of 98% for differentiation between PSIL and CD with severe mural thickening. CONCLUSION. Morphologic features seen at MR enterography rather than enhancement or diffusion parameters may be valuable for differentiation of PSIL from active CD with severe mural thickening with significantly lower ratios of upstream to involved luminal diameter and mural thickness to involved luminal diameter in PSIL.

Can diffusion weighted imaging be used as an alternative to contrast-enhanced imaging on magnetic resonance enterography for the assessment of active inflammation in Crohn disease?

The present study aimed to investigate the potential use of T2-weighted sequences with diffusion weighted imaging (DWI) in magnetic resonance (MR) enterography instead of conventional contrast-enhanced MR imaging (MRI) sequences for the evaluation of active inflammation in Crohn disease.Two-hundred thirteen intestinal segments of 43 patients, who underwent colonoscopy within 2 weeks before or after MR enterography were evaluated in this retrospective study. DWI sequences, T2-weighted sequences, and contrast-enhanced T1-weighted sequences were acquired in the MR enterography scan after cleaning of the bowel and using an oral contrast agent. First, the intestinal segments that had active inflammation in MR enterography were qualitatively evaluated in T2-weighted and contrast-enhanced T1-weighted sequences and then MR activity index (MRAI 1) and MRAI 2 were formed with and without contrast-enhanced sequences in 2 separate sessions.The correlation coefficient between contrast enhanced and DWI MR enterography scores (MRAI 1 and MRAI 2) of intestinal inflammation was 0.97 for all segments. In addition, separate correlation coefficients were calculated for terminal ileum, right colon, transverse colon, left colon, and rectum, and there was a strong correlation between the MRAI 1 and MRAI 2 scores of each segment (r = 0.86-0.97, P < .001). On the other hand, MR enterography had 88.7% sensitivity, 97.9% specificity, 95.5% positive predictive value, 94.6% negative predictive value, and 94.8% accuracy for detection of active inflammation in all intestinal segments in Crohn disease.DWI and T2-weighted sequences acquired with cleaning of the bowel can be used instead of contrast-enhanced MRI sequences for the evaluation of active inflammation in Crohn disease.

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.

Can ADC be used as a surrogate marker of response to therapy in intestinal tuberculosis?

PURPOSE

To evaluate the utility of Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) in assessing treatment response in patients of intestinal tuberculosis (ITB).

METHOD AND MATERIALS

MR Enterography (MRE) was done for patients with suspicion of ITB and 19 patients with pre- and post-treatment imaging were included in the analysis. MRE included T1W, T2W, post-contrast T1W, and DWI sequences. DWI was done using b values-0, 400 and 800 s/mm², and ADC maps were generated. The trace DW images and ADC values were compared before and after therapy. Composite gold standard (clinical, colonoscopic criteria, and biopsy) was used to assess treatment response and to classify into no response, partial response, and complete response.

RESULTS

Thirty-one bowel segments were evaluated at baseline and after treatment in 19 patients. Prior to therapy, restricted diffusion was seen in 29/31 (93.5%) segments. After treatment, patients with either complete or partial response (27/31 segments, 15 patients) showed significant rise in mean ADC values from 1.1 ± 0.37 × 10^-3 to 2.1 ± 0.64 × 10^-3 mm²/s (p value < 0.05), whereas no significant change was found in mean ADC values of non-responders (4/29 segments in 4 patients) which increased from 1.0 ± 0.1 × 10^-3 mm²/s on baseline scan to 1.32 ± 0.2 × 10^-3 mm²/s on post-treatment scan (p value = 0.318). An increase in ADC value was found to be a reliable and objective marker of improvement with response to therapy.

CONCLUSION

ADC values show good correlation with treatment response in ITB and can be used for objectively quantifying it.

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.

Evaluating the inflammatory activity in Crohn's disease using magnetic resonance diffusion kurtosis imaging

OBJECTIVES

To explore the feasibility of diffusion kurtosis imaging (DKI) for evaluating inflammatory activity in Crohn's disease (CD).

MATERIALS AND METHODS

In all, 51 CD patients were included, who were performed with consecutive enteroscopy, MR and DKI (b values = 0-2000 mm²/s). The lesions of bowel segments were graded as inactive (0-2), mild (3-6), and moderate-severe group (> 6) based on simplified endoscopic activity score for Crohn's disease (SES-CD), The abilities of the parameters of DKI and DWI in grading different activity lesions were compared.

RESULTS

One hundred and twenty-seven bowel segments including inactive (15), mild (45) and moderate-severe (67) were analyzed. ADC (r = - 0.627, p < 0.001), D_app (r = - 0.381, p < 0.001) and K_app (r = 0.641, p < 0.001) were correlated with SES-CD. These parameters were significantly different among the three groups (all p < 0.001). ROC analysis found ADC had the highest accuracy (AUC = 0.884, p < 0.001) to differentiate inactive from active group with the threshold at 0.865 × 10^-3 mm²/s, which was slightly higher than K_app (AUC = 0.867, p < 0.001) with the threshold at 0.645, and was obviously higher than D_app (AUC = 0.726, p = 0.005). Similarly, ADC also had the highest accuracy (AUC = 0.846, p < 0.001) to differentiate inactive-mild from moderate-severe group with the threshold at 0.825 × 10^-3 mm²/s, and minimally higher than K_app (AUC = 0.843, p < 0.001) with the threshold at 0.695, and obviously higher than D_app (AUC = 0.690, p < 0.001).

CONCLUSION

DKI is feasible and comparable to conventional DWI for the evaluation of inflammatory activity in CD.

The Influence of Bowel Preparation on ADC Measurements: Comparison between Conventional DWI and DWIBS Sequences

Background and objectives: The aim of the study was to assess whether there were differences between apparent diffusion coefficient (ADC) values of diffusion-weighted imaging (DWI) and diffusion-weighted imaging with background body signal suppression (DWIBS) sequences in non-prepared and prepared bowels before and after preparation with an enteric hyperosmolar agent, to assess whether ADC measurements have the potential to avoid bowel preparation and whether ADC-DWIBS has advantages over ADC-DWI. Materials and Methods: 106 adult patients without evidence of inflammatory bowel disease (IBD) underwent magnetic resonance (MR) enterography before and after bowel preparation. ADC-DWI and ADC-DWIBS values were measured in the intestinal and colonic walls demonstrating high signal intensity (SI) at DWI tracking images of b = 800 s/mm² before and after preparation. Results: There were significant difference (p < 0.0001) in both ADC-DWI and ADC-DWIBS results between non-prepared and prepared jejunum for DWI being 1.09 × 10⁻³ mm²/s and 1.76 × 10⁻³ mm²/s, respectively, and for DWIBS being 0.91 × 10⁻³ mm²/s and 1.75 × 10⁻³ mm²/s, respectively. Both ADC-DWI and DWIBS also showed significant difference between non-prepared and prepared colon (p < 0.0001), with DWI values 1.41 × 10⁻³ mm²/s and 2.13 × 10⁻³ mm²/s, and DWIBS—1.01 × 10⁻³ mm²/s and 2.04 × 10⁻³ mm²/s, respectively. No significant difference between ADC-DWI and ADC-DWIBS was found in prepared jejunum (p = 0.84) and prepared colon (p = 0.58), whereas a significant difference was found in non-prepared jejunum and non-prepared colon (p = 0.0001 in both samples). Conclusions: ADC between DWI and DWIBS does not differ in prepared bowel walls but demonstrates a difference in non-prepared bowel. ADC in non-prepared bowel is lower than in prepared bowel and possible overlap with the ADC range of IBD is possible in non-prepared bowel. ADC-DWIBS has no advantage over ADC-DWI in regard to IBD assessment.

Comparison of contrast-enhanced and diffusion-weighted MRI in assessment of the terminal ileum in Crohn's disease patients

PURPOSE

The purpose of the study was to compare the performance of contrast-enhanced (CE)-MRI and diffusion-weighted imaging (DW)-MRI in grading Crohn's disease activity of the terminal ileum.

METHODS

Three readers evaluated CE-MRI, DW-MRI, and their combinations (CE/DW-MRI and DW/CE-MRI, depending on which protocol was used at the start of evaluation). Disease severity grading scores were correlated to the Crohn's Disease Endoscopic Index of Severity (CDEIS). Diagnostic accuracy, severity grading, and levels of confidence were compared between imaging protocols and interobserver agreement was calculated.

RESULTS

Sixty-one patients were included (30 female, median age 36). Diagnostic accuracy for active disease for CE-MRI, DW-MRI, CE/DW-MRI, and DW/CE-MRI ranged between 0.82 and 0.85, 0.75 and 0.83, 0.79 and 0.84, and 0.74 and 0.82, respectively. Severity grading correlation to CDEIS ranged between 0.70 and 0.74, 0.66 and 0.70, 0.69 and 0.75, and 0.67 and 0.74, respectively. For each reader, CE-MRI values were consistently higher than DW-MRI, albeit not significantly. Confidence levels for all readers were significantly higher for CE-MRI compared to DW-MRI (P < 0.001). Further increased confidence was seen when using combined imaging protocols.

CONCLUSIONS

There was no significant difference of CE-MRI and DW-MRI in determining disease activity, but the higher confidence levels may favor CE-MRI. DW-MRI is a good alternative in cases with relative contraindications for the use of intravenous contrast medium.

Can MR Enterography and Diffusion-Weighted Imaging Predict Disease Activity Assessed by Simple Endoscopic Score for Crohn's Disease?

Purpose:

Monitoring Crohn’s disease (CD) activity has a crucial importance, especially for evaluating treatment efficacy. Magnetic resonance enterography (MRE) and diffusion-weighted imaging (DWI) or their combination may represent potential non-invasive tools for this purpose. This study aimed to examine DWI and MRE for their potential to differentiate between different grades of ileocolonic CD activity.

Materials and Methods:

This retrospective study included 54 adult patients with a diagnosis of CD who underwent ileocolonoscopy and MRE including the DWI sequence. The severity of CD inflammation was categorized by Simple Endoscopic Score for Crohn’s Disease (SES-CD) as inactive, mild, moderate and severe. In addition, following conventional MRE and DWI parameters were examined: bowel wall thickness, mural T2 hyperintensity, contrast enhancement, DWI signal intensity, and apparent diffusion coefficient (ADC) values.

Results:

In patients with moderate to severe disease based on SES-CD, T2 hyperintensity score [1.68 ± 0.77 (1–3) vs. 2.19 ± 0.69 (1–3); p = 0.013] and mean DWI score [2.42 ± 0.58 (1–3) vs. 2.04 ± 0.69 (1–3); p = 0.037 ] were higher and mean ADC values [1.5 ± 0.4 (0.9–2.5) vs. 1.2 ± 0.3 (0.6–1.8)] were lower compared to patients with inactive to mild CD. ADC had a moderate diagnostic accuracy in predicting moderate to severe disease (AUC = 0.729, 95% CI = 0.591–0.841, p = 0.001), with a cut-off value of ≤1.47 × 10^–3 mm²/sec yielded 88.5% (23/26) sensitivity, 57.1% (16/28) specificity.

Conclusion:

DWI, ADC and T2 signal appear to differentiate moderate to severe CD from inactive to mildly active CD, based on SES-CD evaluation and may be useful in monitoring disease activity, particularly when evaluating treatment response.

Assessment of normal jejunum with diffusion-weighted imaging on MRE in children

BACKGROUND

Diffusion restriction has been utilized as a marker for bowel inflammation on magnetic resonance enterography (MRE). However, diffusion restriction has been seen in otherwise normal appearing small bowel in patients without active inflammation, with little published data on this subject.

OBJECTIVE

Assess diffusion restriction in normal loops of jejunum and to determine if there is a correlation to luminal distention, age, magnet field strength, slice thickness, and bowel segment location.

MATERIALS AND METHODS

A retrospective analysis of subjects with a normal MRE and clinical work-up was performed. The abdomen was divided into four quadrants. If available, two loops of jejunum were randomly chosen in each quadrant. Two radiologists evaluated the loops of jejunum for distension, wall thickness, enhancement and diffusion restriction. Disagreement was resolved by consensus. Presence of diffusion restriction was correlated with luminal distension, age, magnet field strength, slice thickness and abdominal quadrant.

RESULTS

One hundred ninety-seven loops of jejunum were evaluated in 39 subjects. Fifteen subjects (38.5%) had jejunal loops with diffusion restriction for a total of 28 loops. There was no correlation between diffusion restriction and luminal distension, age, magnet field strength or quadrant location (P>0.05, Pearson chi-squared test or Student's t-tests). Of the 15 subjects with a loop demonstrating diffusion restriction, additional loops with diffusion restriction were found in 40%. There was a very weak trend observed for greater slice thickness in patients with jejunal diffusion restriction (Student's t-test, P=0.10).

CONCLUSION

Jejunal diffusion restriction is a common finding in children with no clinical evidence of bowel pathology, irrespective of patient age, luminal distension, location of bowel loop and magnetic field strength. Further studies may be valuable in assessing the impact of slice thickness on subjective diffusion restriction in the jejunum.

Diagnostic Value of Diffusion-Weighted Imaging and Apparent Diffusion Coefficient in Assessment of the Activity of Crohn Disease: 1.5 or 3 T

Objective

The objective of this study is to evaluate the role of diffusion-weighted imaging (DWI) in assessment of the activity of Crohn disease (CD) and to explore differences between DWI in 3 T and 1.5 T.

Methods

Postcontrast magnetic resonance enterography with DWI of 72 patients with pathological proof of CD was retrospectively evaluated for restricted diffusion qualitatively and quantitavely in 3 T (n = 40) and 1.5 T (n = 32). Magnetic resonance activity score of 7 or higher was used as reference of activity.

Results

Fifty-five patients had active lesions. Diffusion-weighted imaging hyperintensity showed sensitivity (100%, 100%) and specificity (88.89%, 100%) in 1.5/3 T for activity assessment. Mean ± SD apparent diffusion coefficient for active lesions was 1.21 ± 0.42 and 1.28 ± 0.59 × 10⁻³ mm²/s in 1.5 and 3 T, respectively. The proposed cutoff values of 1.35 and 1.38 × 10⁻³ mm²/s in 1.5 and 3 T, respectively, had sensitivity (80%, 93%), specificity (100%, 90%), accuracy (88%, 93%), and no significant difference in accuracy between 1.5/3 T (P = 0.48).

Conclusions

Diffusion-weighted imaging hypersensitivity and apparent diffusion coefficient values accurately assessed the activity of CD. No significant statistical difference in diagnostic accuracy was detected between 1.5 and 3 T.

New cross-sectional imaging in IBD

PURPOSE OF REVIEW

Cross-sectional imaging, namely ultrasound, CT and MR enterography, complements clinical and endoscopic monitoring of activity and complications in IBD, and emerging new radiological technologies may have clinical applications in the near future. This review offers an update on the potential role of these new imaging methods in the management of IBD.

RECENT FINDINGS

Specific MR techniques [diffusion-weighted imaging (DWI), diffusion kurtosis imaging (DKI) and magnetization transfer] allow accurate detection of inflammation (DWI and maybe DKI) and fibrosis (magnetization transfer) in Crohn's disease, without the need of intravenous gadolinium administration. ultrasonography developments (elastography, contrast-enhanced ultrasonography, small intestine contrast ultrasonography and multispectral optoacoustic tomography) are promising techniques for evaluation of fibrosis (elastography) and inflammation (contrast ultrasonography). Dose-reduction techniques in CT allow similar quality imaging and diagnostic accuracy with lower radiation exposure. Hybrid imaging (PET/MR and PET/CT) hold promise for grading inflammation in Crohn's disease.

SUMMARY

The potential benefits of new cross-sectional imaging techniques in IBD include better inflammation grading, such as identification of mild degree of activity, which may be relevant whenever assessing response to treatment and, of uttermost importance, accurate preoperative detection and grading of fibrosis in stricturing Crohn's disease, facilitating surgical vs. medical therapeutic decisions.

A review of magnetic resonance enterography-based indices for quantification of Crohn's disease inflammation

Magnetic resonance enterography (MRE) is a leading radiological modality in Crohn's disease (CD) and is used together with laboratory findings and endoscopic examinations for the evaluation of patients during initial diagnosis and follow up. Over the years, there has been great progress in the understanding of CD and there is a continuous strive to achieve better monitoring of patients and to develop new modalities which will predict disease course and thus help in clinical decisions making. An objective evaluation of CD using a quantification score is not a new concept and there are different clinical, endoscopies, radiological and combined indices which are used in clinical practice. Such scores are a necessity in clinical trials on CD for evaluation of disease response, however, there is no consensus of the preferred MRE score and they are not routinely used. This review presents MRE-based indices in use in the last decade: the Magnetic Resonance Index of Activity (MaRIA), the Clermont score, the Crohn's Disease Magnetic Resonance Imaging (MRI) Index (CDMI), the Magnetic Resonance Enterography Global Score (MEGS) and the Lemann index. We compare the different indices and evaluate the clinical research that utilized them. The aim of this review is to provide a reference guide for researchers and clinicians who incorporate MRE indices in their work. When devising future indices, accumulated data of the existing indices must be taken into account, as each of the current indices has its own strengths and weakness.

Capsule Endoscopy Crohn's Disease Activity Index (CECDAIic or Niv Score) for the Small Bowel and Colon

BACKGROUND AND THE STUDY AIM

Crohn's disease (CD) is a chronic inflammatory disorder defined as a transmural inflammation of the bowel wall, affecting the small and large intestine. The Capsule Endoscopy Crohn's Disease Activity Index (CECDAI or Niv score) was devised to measure mucosal disease activity. We extended the Niv score to the colon and have a comprehensive view of the whole intestine.

METHODS

We evaluated 3 parameters of intestinal pathology: A, Inflammation; B, Extent of disease; C, Presence of strictures. The scoring formula is as follows: CEDCAIic=(A1×B1+C1)+(A2×B2+C2)+(A3×B3+C3)+(A4×B4+C4) (1=proximal small bowel, 2=distal small bowel, 3=right colon, 4=left colon).

RESULTS

The median CECDAIic score was 15.5 (range, 0 to 42), and the mean±SD score was 17.2±11.5. The CECDAIic scores per patient were similar among the 5 observers. Kendall's coefficient of concordance was high and significant for almost all the parameters examined except for strictures in the proximal small bowel and distal colon. Nevertheless, the coefficients for the small bowel and for the whole intestine were high, 0.85 and 0.77, P<0.0001, respectively.

CONCLUSIONS

We established a new score, the CECDAIic of the small-bowel and colonic CD. We offer this easy, user-friendly score for use in randomized controlled trials and in the clinical follow-up of CD patients.

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.

Small-bowel mucosal healing assessment by capsule endoscopy as a predictor of long-term clinical remission in patients with Crohn's disease: a systematic review and meta-analysis

Capsule endoscopy (CE) may be used for the evaluation and follow-up of patients with Crohn's disease. CE scores correspond to the degree of mucosal inflammation, a major therapeutic target. The aim of this meta-analysis and systematic review was to determine whether mucosal healing assessment by CE may serve as a predictor of clinical remission in patients with Crohn's disease. To identify observational or controlled English-language full-text studies assessing mucosal healing by CE in patients with Crohn's disease up to 30 September 2016, we searched PubMed, Embase, Central, Medline, and Scopus using the key words 'mucosal healing' and 'capsule endoscopy'. A meta-analysis was carried out using 'Comprehensive meta-analysis' software. Pooled odds ratios and 95% confidence intervals were calculated. Five observational studies including 142 patients from five countries fulfilled the inclusion criteria. No publication bias was found by funnel plot. The mucosal healing CE score was found to be significantly associated with improved outcome after a follow-up of 12 weeks to 24 months, with an odds ratio of 11.06 (95% confidence interval: 3.74-32.73, P<0.001). The degree of heterogeneity among the studies was small (Q=2.014, d.f.[Q]=3, P=0.569 and I=0). Endoscopy scores may play a role in the long-term prognostic evaluation of patients with Crohn's disease. Our results may be accepted as proof of concept, but larger studies are needed to corroborate these findings.

Diffusion-weighted imaging in quiescent Crohn's disease: correlation with inflammatory biomarkers and video capsule endoscopy

AIM

To investigate the role of restricted diffusion in quiescent Crohn's disease (CD) patients and its association with inflammatory biomarkers and endoscopic disease.

MATERIAL AND METHODS

Fifty-two quiescent CD patients prospectively underwent magnetic resonance enterography (MRE) and video capsule endoscopy (VCE) and were tested for the inflammatory biomarkers, faecal calprotectin (FCP) and C-reactive protein (CRP). Restricted diffusion in the distal ileum was qualitatively (absence/presence) and quantitatively (apparent diffusion coefficient [ADC]) assessed by two readers. The VCE-based Lewis score was calculated for the distal ileum. Restricted diffusion sensitivity and specificity for VCE ulcerations were assessed for patients with elevated (>100 μg/g) or normal (<100 μg/g) FCP. Receiver operating characteristic (ROC) curve was used to assess the ability of ADC to identify patients with concurrent VCE ulceration and elevated FCP.

RESULTS

The sensitivity and specificity of restricted diffusion for patients with VCE ulceration were higher in patients with elevated FCP (reader 1: 71.4%, 80%, reader 2: 76.2%, 100%, respectively) compared to patients with normal FCP (reader 1: 46.2%, 61.5%; reader 2: 15.4%, 76.9%, respectively). The ADC had a high diagnostic accuracy for identifying patients that had concurrent VCE ulceration and elevated FCP (reader 1: AUC=0.819, reader 2: AUC=0.832).

CONCLUSION

In quiescent CD patients, the presence of restricted diffusion is suggestive of an active inflammation, associated with elevated FCP. Thus, DWI may serve as a clinical tool in the follow-up of these patients, implying subclinical inflammatory flares.

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.

Utility of MR enterography and ultrasound for the investigation of small bowel Crohn's disease

Cross sectional Imaging plays an increasingly important role the diagnosis and management of Crohn's disease. Particular emphasis is placed on MRI and Ultrasound as they do not impart ionising radiation. Both modalities have reported high sensitivity for disease detection, activity assessment and evaluation of extra-luminal complications, and have positive effects on clinical decision making. International Guidelines now recommend MRI and Ultrasound in the routine management of Crohn's disease patients. This article reviews the current evidence base supporting both modalities with an emphasis on the key clinical questions. We describe current protocols, basic imaging findings and highlight areas in need of further research.

LEVEL OF EVIDENCE

5 Technical Efficacy: Stage 4 J. MAGN. RESON. IMAGING 2017;45:1573-1588.

Patient optimization for surgery relating to Crohn's disease

The majority of patients with Crohn's disease require abdominal surgery during their lifetime, some of whom will require multiple operations. Postoperative complications are seen more frequently in patients requiring abdominal surgery for Crohn's disease than in patients requiring abdominal surgery for other conditions. In this article, we review the evidence supporting preoperative optimization, discussing strategies that potentially improve surgical outcomes and reduce perioperative morbidity and mortality. We discuss the roles of adequate cross-sectional imaging, nutritional optimization, appropriate adjustments of medical therapy, management of preoperative abscesses and phlegmons, smoking cessation and thromboembolic prophylaxis. We also review operation-related factors, and discuss their potential implications with respect to postoperative complications. Overall, the literature suggests that preoperative management has a major effect on postoperative outcomes.

Diffusion weighted imaging: Technique and applications

Diffusion weighted imaging (DWI) is a method of signal contrast generation based on the differences in Brownian motion. DWI is a method to evaluate the molecular function and micro-architecture of the human body. DWI signal contrast can be quantified by apparent diffusion coefficient maps and it acts as a tool for treatment response evaluation and assessment of disease progression. Ability to detect and quantify the anisotropy of diffusion leads to a new paradigm called diffusion tensor imaging (DTI). DTI is a tool for assessment of the organs with highly organised fibre structure. DWI forms an integral part of modern state-of-art magnetic resonance imaging and is indispensable in neuroimaging and oncology. DWI is a field that has been undergoing rapid technical evolution and its applications are increasing every day. This review article provides insights in to the evolution of DWI as a new imaging paradigm and provides a summary of current role of DWI in various disease processes.

DWI in Pediatric Small-Bowel Crohn Disease: Are Apparent Diffusion Coefficients Surrogates for Disease Activity in Patients Receiving Infliximab Therapy?

OBJECTIVE

The purpose of this study was to determine prospectively whether bowel wall apparent diffusion coefficient (ADC) measurements can be used to monitor treatment response to infliximab therapy in the setting of pediatric small-bowel Crohn disease.

SUBJECTS AND METHODS

Twenty-eight pediatric subjects with newly diagnosed biopsy-proven Crohn disease of the distal or terminal ileum treated with infliximab were enrolled. Subjects underwent MR enterography at baseline, 1 month after therapy, and 6 months after therapy. Imaging features were documented, including bowel wall ADC and arterial or enteric phase contrast-enhanced signal intensity normalized to that of unenhanced imaging. A linear mixed model assessed the relationship between ADC and time; patient age and sex and azathioprine combination therapy were covariates. The diagnostic performance (with 95% CIs) of an increase in bowel wall ADC of 20% or more for identifying response to infliximab was calculated using a decrease in normalized contrast-enhanced bowel wall signal intensity of 20% or more as the reference standard.

RESULTS

Bowel wall ADC increased over time (mean [± SD], 1180 ± 200 × 10^-6 mm²/s at baseline, 1420 ± 420 × 10^-6 mm²/s at 1 month, and 1450 ± 450 × 10^-6 mm²/s at 6 months; p = 0.0003); azathioprine therapy modulated this rate of change (p = 0.003). There was a statistically significant negative correlation between change in ADC and change in normalized contrast-enhanced signal intensity over time (ρ = -0.36; p < 0.001). The diagnostic performance of change in ADC for identifying response to infliximab therapy was sensitivity of 0.58 (95% CI, 0.34-0.80), specificity of 0.52 (95% CI, 0.31-0.72), positive predictive value of 0.48 (95% CI, 0.27-0.69), and negative predictive value of 0.62 (95% CI, 0.38-0.82).

CONCLUSION

Bowel wall ADC increases over time in pediatric subjects receiving infliximab, but the diagnostic performance of ADC is likely insufficient for reliable treatment monitoring.

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

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

DWI at MR Enterography for Evaluating Bowel Inflammation in Crohn Disease

OBJECTIVE

The purpose of this article is to provide a comprehensive review regarding DWI enterography used for evaluating Crohn disease and to summarize the relevant evidence.

CONCLUSION

Active bowel inflammation in Crohn disease causes restricted diffusion on MR enterography with DWI. Enterographic DWI to evaluate Crohn disease is increasingly drawing attention for both academic research and clinical practice and has shown potential as a quantitative tool for assessing bowel inflammation. DWI enterography also has multiple unresolved issues and limitations.

Diffusion-weighted Magnetic Resonance Enterography for Evaluating Bowel Inflammation in Crohn's Disease: A Systematic Review and Meta-analysis

BACKGROUND

To systematically determine the performance of diffusion-weighted imaging magnetic resonance enterography (DWI-MRE) for evaluating bowel inflammation in Crohn's disease and sources of heterogeneity between reported results.

METHODS

We identified research studies that investigated DWI-MRE to diagnose bowel inflammation (present versus absent) or to assess bowel inflammatory severity in Crohn's disease by performing a systematic search of PubMed MEDLINE and EMBASE (until March 31, 2015). Study quality was assessed using QUADAS-2. For studies reporting dichotomous diagnosis of bowel inflammation, study heterogeneity and threshold effect were analyzed, summary sensitivity and specificity were estimated, and meta-regression analysis was performed to further explore study heterogeneity. For studies reporting assessment of inflammatory severity, a qualitative summary was performed.

RESULTS

Of 159 articles screened, we found 12 studies (1515 bowel segments) reporting a diagnosis of bowel inflammation and 6 studies (1066 bowel segments) reporting assessment of inflammatory severity. The summary sensitivity and specificity were 92.9% (95% CI, 85.8%-96.6%; I = 87.9%) and 91% (95% CI, 79.7%-96.3%; I = 95.1%), respectively. Sensitivity and false-positive rate were inversely correlated (r = -0.650; P = 0.022). Lack of blinding to contrast-enhanced MRE when interpreting DWI-MRE (P = 0.01) and use of contrast-enhanced MRE as a reference standard (P < 0.01) in some studies were significant factors for study heterogeneity and likely caused overestimation of DWI-MRE accuracy. There was rather clear correlation between diffusion-related parameters and bowel inflammation severity, although the strengths were heterogeneous (correlation coefficient, 0.39-0.98).

CONCLUSIONS

DWI-MRE accuracy was very heterogeneous between studies and was likely overestimated in some studies. Despite rather clear correlation between diffusion-related parameters and bowel inflammatory severity, its strength was variable.

New Imaging Techniques in the Diagnosis of Inflammatory Bowel Diseases

Background

Cross-sectional imaging modalities are fundamental in the management of patients with inflammatory bowel disease (IBD) from the first diagnosis and throughout the entire course of the disease. Over the past few years, the use of magnetic resonance (MR) imaging (MRI) has considerably increased, and no other imaging modality has experienced as advanced a development as MRI.

Methods

A comprehensive literature search (PubMed/Medline) using keywords such as ‘MR enterography’, ‘imaging modalities’, ‘IBD’, and ‘Crohn's disease’ was performed. 48 articles published between 1999 and 2015 were systematically reviewed. In this article, besides the current standard MRI techniques, we review novel and implementable for routine use MR techniques. The use of positron emission tomography/computed tomography (PET/CT) and hybrid imaging such as PET/MRI with enormous potential will also be briefly discussed.

Results

New imaging techniques such as diffusion-weighted imaging, dynamic contrast-enhanced MR perfusion, and MR motility imaging yield advanced findings about changes in the microenvironment and alterations in motility of the affected bowel segment, and are proven to improve the diagnostic accuracy in assessing the scale, activity level, and severity of the IBD. Novel magnetization transfer imaging allows direct visualization of fibrosis in the bowel wall.

Conclusion

Diffusion-weighted imaging can be easily implemented in standard MRI for routine use to further enhance the diagnostic accuracy in disease assessment. For validation of magnetization transfer imaging, larger studies are warranted.