MRI reveals different Crohn's disease phenotypes in children and adults. Eur Radiol. 2019;29:5082-5092. [PMID: 30729332 DOI: 10.1007/s00330-019-6006-5]

Magnetic Resonance Imaging of the Gastrointestinal Tract: Current Role, Recent Advancements and Future Prospectives

This review focuses on the role of magnetic resonance imaging (MRI) in the evaluation of the gastrointestinal tract (GI MRI), analyzing the major technical advances achieved in this field, such as diffusion-weighted imaging, molecular imaging, motility studies, and artificial intelligence. Today, MRI performed with the more advanced imaging techniques allows accurate assessment of many bowel diseases, particularly inflammatory bowel disease and rectal cancer; in most of these diseases, MRI is invaluable for diagnosis, staging, and disease monitoring under treatment. Several MRI parameters are currently considered activity biomarkers for inflammation and neoplastic disease. Furthermore, in younger patients with acute or chronic GI disease, MRI can be safely used for short-term follow-up studies in many critical clinical situations because it is radiation-free. MRI assessment of functional gastro-esophageal and small bowel disorders is still in its infancy but very promising, while it is well established and widely used for dynamic assessment of anorectal and pelvic floor dysfunction; MRI motility biomarkers have also been described. There are still some limitations to GI MRI related to high cost and limited accessibility. However, technical advances are expected, such as faster sequences, more specific intestinal contrast agents, AI analysis of MRI data, and possibly increased accessibility to GI MRI studies. Clinical interest in the evaluation of bowel disease using MRI is already very high, but is expected to increase significantly in the coming years.

MR Enterography Scores Correlate with Degree of Mucosal Healing in Pediatric Crohn's Disease: A Pilot Study

Objectives

MR enterography (MRE) Index of Activity (MaRIA) and Clermont are validated scores that correlate with Crohn's disease (CD) activity; however, the Clermont score has not been validated to correlate with the degree of change in mucosal inflammation post induction treatment in children. This pilot study evaluated if MaRIA and Clermont scores can serve as surrogates to ileocolonoscopy for assessing interval change in mucosal inflammation in pediatric CD post-induction treatment.

Methods

Children with known or newly diagnosed ileocolonic CD starting or changing therapy underwent ileocolonoscopy, scored with simple endoscopic score for Crohn's disease (SES-CD), and MRE on the same day at two time points (Week 0 and 12). Accuracy of global MaRIA and Clermont indices relative to ileocolonoscopy in detecting degree of post-treatment interval change in mucosal inflammation was assessed through correlational coefficients (r). Inter-reader agreement was calculated for imaging scores through intraclass correlation (ICC).

Results

Sixteen children (mean age 11.5 ± 2.8) were evaluated. Global MaRIA/Clermont correlated with SES-CD in detecting the degree of change in mucosal inflammation (r = 0.676 and r = 0.677, P < 0.005, respectively). Correlation for pooled timepoint assessments between SES-CD and global MaRIA/Clermont was moderate (r = 0.546, P < 0.001 and r = 0.582, P < 0.001, respectively). Inter-rater reliability for global MaRIA and Clermont was good (ICC = 0.809 and ICC = 0.768, respectively, P < 0.001).

Conclusions

MRE-based global scores correlate with endoscopic indices and may be used to monitor disease changes in children with CD undergoing induction treatment, which can advise the physician if treatment changes should be made.

Perianal Imaging in Crohn Disease: Current Status With a Focus on MRI, From the AJR Special Series on Imaging of Inflammation

Fistulizing perianal disease, a frequent, chronic, and often debilitating manifestation of Crohn disease (CD) in adults and children, has been relatively refractory to treatment in the past. The advent of biologic agents such as anti-tumor necrosis factor-α and cellular therapies, used in conjunction with a range of surgical interventions, has greatly improved disease outcomes, although complete remission can still be elusive. This Special Series review considers current perianal imaging options, specifically pelvic MRI and endoanal and transperineal ultrasound, as well as their roles in the diagnosis, management, and assessment of treatment response. Pelvic MRI is the first-line modality for imaging perianal CD, given the complexity of fistulas encountered in CD. MRI technical acquisition parameters for adults and children and an approach to MRI interpretation and reporting are provided. Anatomic classification systems for fistulizing peri-anal disease are presented. We also explore the history, current landscape, and future developments of MRI features of perianal disease as imaging biomarkers, to quantify activity and severity and to consider CD MRI-based inflammatory activity scores. We discuss the reliability and validation of a number of indexes (including the pediatric MRI-based perianal CD [PEMPAC] index, the MR novel index for fistula imaging in CD [MAGNIFI-CD], the Van Assche index, and the modified Van Assche index), their potential to quantify treatment response, and possible prognostic capabilities.

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Perianal magnetic resonance imaging findings and their potential impact on outcome in children with perianal fistulizing Crohn disease

BACKGROUND

Children with perianal fistulizing Crohn disease require intensive medical management but also have a higher risk for subsequent surgical interventions.

OBJECTIVE

We performed a retrospective study to identify patient factors and perianal anatomical features by pelvic MR that are associated with surgical interventions in these children.

MATERIALS AND METHODS

We included children with Crohn disease and perianal fistula who underwent pelvic MR with available, archived images and collected demographic, clinical and laboratory data. Radiologists reviewed pelvic MR exams and identified Park classification and additional anatomical features of perianal fistulas, including fistula branching, horseshoe ramifications, abscess, inflammatory mass, supralevator extension, anal sphincter damage, proctitis and posterior anal space involvement. We performed univariate and subsequent multivariate analysis to determine features associated with subsequent surgical intervention.

RESULTS

Ninety-nine children with Crohn disease underwent pelvic MR. In this cohort, 69 children had no surgical interventions prior to baseline MRI, with subsequent median clinical follow-up of 5.5 years. Univariate analysis demonstrated that branching (P=0.009), supralevator extension (P=0.015) and anal sphincter damage (P=0.031) were significantly associated with subsequent surgical intervention. Age at baseline MRI was also associated with intervention (hazard ratio [HR] every 5 years: 2.13; 95% confidence interval [CI]: 1.18-3.83; P=0.012). A multivariable model identified only fistula branching (HR: 2.31; 95% CI: 1.28-4.15; P=0.005) and age (HR: 5.18; CI: 1.57-17.14; P=0.007) as independent predictors of subsequent surgery. No demographic, clinical or laboratory parameter predicted subsequent surgical intervention.

CONCLUSION

Age and anatomical MR features indicating fistula complexity (branching, supralevator extension) and sphincter damage confer a higher risk of subsequent surgical intervention in children with perianal Crohn disease.

Diagnostic Accuracy of Magnetic Resonance Enterography in the Evaluation of Colonic Abnormalities in Crohn's Disease: A Systematic Review and Meta-Analysis

OBJECTIVES

To Evaluate the diagnostic performance of magnetic resonance enterography (MRE) for detecting colonic involvement of Crohn's disease (CD).

MATERIALS AND METHODS

A systematic search of the electronic bibliographic databases was conducted. The inclusion criteria of published original articles were: (1) Utilized MRE to evaluate colon; (2) Patients with documented CD by colonoscopy; (3) Provided crude data of diagnostic performance in the large bowel; (4) Performed segmental evaluation. The colorectal segments were defined as the right colon, transverse colon, left colon, and rectum. A hierarchical bivariate method was used for analysis.

RESULTS

Eleven articles (12 populations and 987 patients) were included. The pooled sensitivity and specificity of the studies were 69% (95% CI: 0.52-0.82) and 95% (95% CI:0.92-0.97), respectively (AUC = 0.95). The pooled positive and negative likelihood ratios were 14 (95% CI:7.5-26.3) and 0.31 (95% CI:0.19-0.51), respectively. Regarding segments, the left colon had the highest sensitivity (60%) and lowest specificity (92%), while the transverse colon showed lowest sensitivity (49%) and highest specificity (95%). Comparing the age groups, MRE sensitivity and specificity was 80% and 95%, versus 62% and 94%, in pediatrics and adults respectively.

CONCLUSION

MRE has a high specificity to detect colon pathologies in CD, while the sensitivity is low. Therefore, the test has a high value to rule in CD, while negative results are not sufficient to rule it out. Meanwhile, considering the higher sensitivity rate of the test in pediatrics, it has the potential to be used as a first-line investigation.

Diagnostic Features of Perianal Fistula in Patients With Crohn's Disease: Analysis of a Japanese Claims Database

Background

Perianal fistula (PAF) is a disabling complication of Crohn's disease (CD) which greatly impacts the quality of life. To address a scarcity of data in Asian populations, we determined the prevalence of CD-associated PAF in Japan, the order of diagnosis, and medical history of patients.

Methods

A retrospective, longitudinal, observational cohort study was conducted, using an employer-based health insurance claims database. The study included patients diagnosed with CD and/or PAF from October 2013 to September 2019.

Results

The age- and gender-adjusted prevalence rates of CD-associated PAF increased from 10.33 per 100 000 in 2014, to 13.68 per 100 000 in 2019. Among patients with CD-associated PAF, 15.7% were diagnosed with PAF after diagnosis of CD, 68.6% were diagnosed with PAF before diagnosis with CD, and 15.7% were diagnosed with CD and PAF within the same month. Of the patients diagnosed with CD after PAF, approximately 30% were diagnosed with PAF by the age of 20 years, whereas less than 10% of PAF patients without CD were diagnosed with PAF by the age of 20 years.

Conclusions

The study reveals the prevalence of CD-associated PAF in Japan and that most individuals were diagnosed with CD after the diagnosis of PAF. Crohn's disease may be underdiagnosed in patients with PAF; patients diagnosed with PAF at a young age should be monitored to allow timely diagnosis of CD.

Accuracy of Ultrasound for Evaluation of Colorectal Segments in Patients With Inflammatory Bowel Diseases: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

The accuracy of ultrasound for evaluation of individual colorectal segments in patients with inflammatory bowel diseases (IBD) has not been evaluated in a systematic review. We evaluated the diagnostic accuracy of ultrasound in different colorectal segments of patients with IBD.

METHODS

We searched publication databases from inception through March 2019 for studies that assessed the accuracy of ultrasound in detection of inflammation in right, transverse, and left colon and in rectum in patients with IBD, using findings from colonoscopy as the reference standard. Subgroup analyses were performed including IBD type, patient age, body mass index, and study design. The risk of bias was assessed with the Quality Assessment of Diagnostic Accuracy Studies-2 tool.

RESULTS

Nineteen studies (1101 patients) were included in the qualitative synthesis. After we assessed the risk of bias, 7 studies (comprising 84 patients with Crohn's disease and 420 patients with ulcerative colitis) were included in the meta-analysis. Bowel wall thickness ≥ 3 mm identified colorectal segments with inflammation with 86.4% pooled sensitivity (95% CI, 76.1%-92.7%) and 88.3% pooled specificity (95% CI, 58.1%-97.6%). In rectum only, bowel wall thickness ≥ 3 mm identified inflammation with 74.5% sensitivity (95% CI, 53.0%-88.3%) and 69.5% specificity (95% CI, 33.6%-91.1%). Diagnostic accuracy was comparable among subgroups. Increased bowel wall flow and loss of stratification had higher true-positive odds ratios.

CONCLUSIONS

Based on meta-analysis of patient-level data, ultrasound has higher diagnostic accuracy for detecting inflammation in colon than rectum in patients with IBD. Studies are needed to increase the accuracy of ultrasound detection of inflammation in rectum.

Early Infliximab in Crohn's is associated with decreased intestinal surgery and similar health care costs

BACKGROUND

Using Infliximab early in Crohn's disease can provide a window of opportunity in children for restoration of growth and achievement of puberty. We aimed to compare clinical outcomes and costs of a retrospective pediatric Crohn's disease (pCD) cohort treated with early use Infliximab (EUI) within 12 months compared with later use Infliximab (LUI).

METHODS

Retrospective review of all children with pCD commenced on Infliximab was undertaken in a tertiary Australian pediatric center.

RESULTS

pCD progressing to Infliximab was identified in 70 children: 38 (54%) in the EUI cohort versus 32 (46%) in the LUI cohort. Intestinal surgery had a higher risk of occurring in EUI when compared with LUI (2 (5%) versus 9 (28%), HR 5.67 (95% CI 1.21-26.38); p = .027). No patients in EUI underwent intestinal surgery post Infliximab commencement compared with 3 (9%) in LUI (p = .09). Escalation of Infliximab in luminal Crohn's disease was not significantly different in EUI when compared with LUI (3 (10.3%) versus 9 (39.1%) (p = .1)). EUI was more frequently used than LUI in 2015-2018 (27 (71%) versus 14 (44%)) p = .029, with the inverse occurring in 2010-2014 (11 (29%) versus 18 (56%)). Hospital admissions per person per year in EUI and LUI were 43 (0.23 visits/person/year) versus 84 (0.67 visits/person/year); IRR 2.51 (95% CI 0.9-7.01); p = .078). Health costs were not significantly different between cohorts.

CONCLUSION

EUI in pCD is associated with an increased likelihood of being diagnosed in more recent years, less intestinal surgery and a trend toward decreased hospital admissions than LUI.

Assessment of pediatric Crohn's disease activity: validation of the magnetic resonance enterography global score (MEGS) against endoscopic activity score (SES-CD)

OBJECTIVE

The aim of this study is to evaluate the ability of magnetic resonance enterography global score (MEGS) to diagnose the activity of pediatric Crohn's disease (CD) and its correlation with endoscopic activity score.

MATERIALS AND METHODS

70 pediatric CD patients (between the ages of 6 and 17) were enrolled who underwent ileocolonoscopy and magnetic resonance enterography (MRE) within 7 days. The simplified endoscopic activity score for Crohn's disease (SES-CD) and MEGS were acquired in the terminal ileum. Sensitivity and specificity of MEGS for detection disease activity against SES-CD was compared using the McNemar test. The correlation between MEGS and SES-CD was assessed by Spearman's rank estimation. The diagnostic accuracy of MEGS for active disease defined by SES-CD was calculated. Receiver operating characteristic curves (ROC) were constructed.

RESULTS

Fifty-two pediatric CD patients (median age, 12 years old; 28 girls, 24 boys) were included. The incidence of upper gastrointestinal (GI) tract (23%) involvement and perianal lesions (42%) is high in pediatric Crohn's patients, and most of them suffer from internal hemorrhoids (86.5%). MEGS showed strong correlation to SES-CD (r = 0.70, P < 0.001). With endoscopic as the standard of reference, the MEGS had a high accuracy for the detection of inflammation (area under the ROC curve (AUC) of 0.89, sensitivity 0.95 and specificity 0.82) and for disease activity (AUC of 0.81, sensitivity 0.88 and specificity 0.75) in the terminal ileum.

CONCLUSION

Pediatric Crohn's disease is unique. Our study has shown a good correlation between MEGS and endoscopy activity score with equal diagnostic efficacy. MEGS is a promising method to assess disease activity and perhaps be a valuable tool in following therapeutic changes.

Dynamic contrast-enhanced magnetic resonance imaging and diffusion-weighted imaging in the activity staging of terminal ileum Crohn's disease

BACKGROUND

The activity staging of Crohn’s disease (CD) in the terminal ileum is critical in developing an accurate clinical treatment plan. The activity of terminal ileum CD is associated with the microcirculation of involved bowel walls. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) can reflect perfusion and permeability of bowel walls by providing microcirculation information. As such, we hypothesize that DCE-MRI and DWI parameters can assess terminal ileum CD, thereby providing an opportunity to stage CD activity.

AIM

To evaluate the value of DCE-MRI and DWI in assessing activity of terminal ileum CD.

METHODS

Forty-eight patients with CD who underwent DCE-MRI and DWI were enrolled. The patients’ activity was graded as remission, mild and moderate-severe. The transfer constant (K^trans), wash-out constant (K_ep), and extravascular extracellular volume fraction (V_e) were calculated from DCE-MRI and the apparent diffusion coefficient (ADC) was obtained from DWI. Magnetic Resonance Index of Activity (MaRIA) was calculated from magnetic resonance enterography. Differences in these quantitative parameters were compared between normal ileal loop (NIL) and inflamed terminal ileum (ITI) and among different activity grades. The correlations between these parameters, MaRIA, the Crohn’s Disease Activity Index (CDAI), and Crohn’s Disease Endoscopic Index of Severity (CDEIS) were examined. Receiver operating characteristic curve analyses were used to determine the diagnostic performance of these parameters in differentiating between CD activity levels.

RESULTS

Higher K^trans (0.07 ± 0.04 vs 0.01 ± 0.01), K_ep (0.24 ± 0.11 vs 0.15 ± 0.05) and V_e (0.27 ± 0.07 vs 0.08 ± 0.03), but lower ADC (1.41 ± 0.26 vs 2.41 ± 0.30) values were found in ITI than in NIL (all P < 0.001). The K^trans, K_ep, V_e and MaRIA increased with disease activity, whereas the ADC decreased (all P < 0.001). The K^trans, K_ep, V_e and MaRIA showed positive correlations with the CDAI (r = 0.866 for K^trans, 0.870 for K_ep, 0.858 for V_e, 0.890 for MaRIA, all P < 0.001) and CDEIS (r = 0.563 for K^trans, 0.567 for K_ep, 0.571 for V_e, 0.842 for MaRIA, all P < 0.001), while the ADC showed negative correlations with the CDAI (r = -0.857, P < 0.001) and CDEIS (r = -0.536, P < 0.001). The areas under the curve (AUC) for the K^trans, K_ep, V_e, ADC and MaRIA values ranged from 0.68 to 0.91 for differentiating inactive CD (CD remission) from active CD (mild to severe CD). The AUC when combining the K^trans, K_ep and V_e was 0.80, while combining DCE-MRI parameters and ADC values yielded the highest AUC of 0.95.

CONCLUSION

DCE-MRI and DWI parameters all serve as measures to stage CD activity. When they are combined, the assessment performance is improved and better than MaRIA.

Magnetic resonance imaging findings in patients with initial manifestations of perianal fistulas

BACKGROUND

Crohn's disease (CD) is a serious cause of perianal disease and the incidence is increasing in Saudi Arabia. MR imaging may document specific features that may help to foresee Crohn's disease in patients making an initial presentation.

OBJECTIVE

Present MR imaging findings of perianal fistulas in patients making an initial presentation.

DESIGN

Retrospective, observational.

SETTING

Radiology clinic in in Dhahran.

PATIENTS AND METHODS

All previously undiagnosed and untreated patients who presented for the first time to the outpatient clinics from September 2015-2018 with perianal fistulas were retrospectively evaluated. Previously diagnosed CD patients, post-surgical or intervention cases were excluded. Fistulas were categorized as low or high anal, simple or complex, and were graded per St. James University Hospital Classification. Imaging was interpreted by two experienced readers based on the Van Assche score.

MAIN OUTCOME MEASURES

Fistula features on MR imaging and diagnosis of CD.

SAMPLE SIZE

171 patients.

RESULTS

Of 171 patients, 139 (81.3%) were males with mean age of 37.2 (12.7) years; the 32 females had a mean age of 35.8 (10.6) years. Twenty-one patients (12.3%) had CD. Fourteen (40.4%) patients with complex fistulas had CD in comparison to only 5 (4.8%) simple fistula patients ( P=.0005). More than half of patients with complex and high anal fistulas had CD ( P=.0005). Females were more affected than males ( P=.0005).

CONCLUSION

Complex or high anal fistula on MR imaging may be the initial presentation of CD and warrant further work up to establish the diagnosis.

LIMITATIONS

Retrospective, small sample, single center, and short duration study.

CONFLICT OF INTEREST

None.

Diagnostic Accuracy of Short Tau Inversion Recovery as a Limited Protocol for Diagnosing Perianal Fistula

Introduction

Perianal fistula refers to abnormal communication between perianal skin and anal canal. Magnetic resonance imaging (MRI) and endoanal ultrasound have been used in the evaluation of perianal fistula. Endoanal ultrasound is a cost-effective but operator-dependent technique. MRI provides accurate details regarding anal canal anatomy and effectively identifies the fistulae. For evidence-based care, a cost-effective and an accurate imaging modality is required in a developing country. Therefore, the aim of this study was to determine the diagnostic accuracy of short tau inversion recovery (STIR) as a limited protocol MRI pelvis in diagnosing perianal fistula taking surgical findings as the gold standard.

Materials and methods

A retrospective review of MRI pelvis from 1^st February 2018 to 1^st July 2018 was undertaken. Patients of any age or gender suspected to have perianal fistula were included. One radiologist interpreted the complete MRI pelvis and the other radiologist only viewed axial and coronal STIR sequences as a limited protocol. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of axial and coronal STIR sequence were calculated taking surgical findings as the gold standard.

Results

In total, 150 patients were included in this study. The mean age of the patients was 43.20 ± 13.75 years. In total, 122 (81.3%) were males and 28 (18.7%) were females. Using STIR as a limited protocol, fistulae were found in 125 (83.3%) patients, whereas on surgery, the fistulae were found in 119 (79.3%) patients. Sensitivity, specificity, PPV, NPV, and diagnostic accuracy of STIR as limited protocol MRI pelvis in diagnosing perianal fistulae was found to be 96.6%, 67.7%, 92.0%, 84.0%, and 90.6%, respectively, taking surgical findings as the gold standard.

Conclusion

STIR has high sensitivity and diagnostic accuracy in diagnosing in the perianal fistula. Using STIR as a limited protocol in a developing country can help improving patient care by accurately diagnosing perianal fistulae. Moreover, it is recommended that further studies for identifying internal opening on STIR should also be carried out to improve patient care.