MRI characteristics of proctitis in Crohn's disease on perianal MRI

Typical MR features and interpretation of perianal fistulas in patients with Crohn's disease

Perianal fistulas in Crohn's disease (CD) are a poor prognostic phenotype requiring a combination of medical and surgical management. Perianal fistulas in CD are characterized by more complex and multi-branched fistulas, association with skin tags, and frequent presence of proctitis. A comprehensive approach with clinical examination, endoscopic and MR assessment is required, and in particular, MR interpretation provides detailed information on the type of fistula with its internal component and activity, secondary tracts and extension, internal, external openings, associated abscess, and presence of proctitis. Structured reporting of these items would be recommended for further discussion and management planning both at initial diagnosis and for disease monitoring during treatment follow-up. Management strategy would be individualized for each patient, and control of luminal disease activity could be an important determinant in the selection of treatment options. In this review, we provide an overview of the MRI evaluation of perianal fistulas in CD with a proposed structured MR report.

Association between body fat composition and disease duration, clinical activity, and intravenous corticosteroid-induced response in inflammatory bowel disease

BACKGROUND

Body fat composition is believed to be associated with the progression, medical response, and prognosis of inflammatory bowel disease (IBD). Hence, we conducted this study to explore if fat metrics were associated with the disease activity of severe IBD and the response to intravenous corticosteroids (IVCS).

METHODS

We included 69 patients with ulcerative colitis (UC) and 72 patients with Crohn's disease (CD) who had previously received IVCS during hospitalization. We quantified individual fat distribution using abdominal computed tomography slices. The correlations between fat parameters and disease activity were available with Spearman correlation analysis. The prediction model was developed using independent risk factors derived from multivariable logistic regression analysis. Model discrimination was evaluated leveraging the receiver operating characteristic curve. 1000 bootstrap resamples internally validated the model's prediction performance.

RESULTS

Notable differences in age, nutritional status, serum cytomegalovirus replication, stool condition, and extraintestinal involvement between UC and CD patients were observed. UC subjects who responded to IVCS had higher subcutaneous adipose tissue index (SATI), visceral adipose tissue index (VATI), and mesorectal adipose tissue index (MATI) than non-responders. IVCS-responding CD individuals had lower VATI and mesenteric fat index (MFI) than non-responders. CD patients with a prolonged disease duration had a decreased SATI and an elevated MFI. VATI and MATI were reduced as UC clinically progressed, while more prominent clinical activity in CD correlated with increased VATI, MATI, and MFI. A high SATI indicated that patients with UC were more prone to be IVCS responders. For patients with CD, levels of VATI and MFI were negatively associated with effective IVCS treatment. The established models showed a discriminative accuracy of 0.834 [95% confidence interval (CI) 0.740-0.928] in the UC cohort and 0.871 (95% CI 0.793-0.949) in the CD cohort. Repeated samples supported the reliability of the developed models (AUC_UC = 0.836, 95% CI 0.735-0.919; AUC_CD = 0.876, 95% CI 0.785-0.946).

CONCLUSION

Human fat indexes represent novel imaging biomarkers for identifying IBD patients who respond to IVCS, thus building accelerated therapy regimens and avoiding the adverse effects of ineffective IVCS.

Anorectal pathology in the HIV population: a guide for radiologists

Patients with human immunodeficiency virus (HIV) can present with a wide range of different acute and chronic pathologies. Anorectal conditions are particularly common in this unique patient population, including pathologies, such as proctitis, anorectal abscess, anorectal fistula, and anal squamous cell carcinoma. The radiologist plays a critical role in the assessment of these common forms of anorectal disease, as these conditions can present with various findings on imaging assessment. Pelvic CT, MRI, and FDG-PET/CT are among the most common modalities used for assessment of anorectal disease in the HIV patient population. Knowledge of the fundamental clinical and imaging findings associated with these pathologies in HIV patients is critical for radiologists.

ACR Appropriateness Criteria® Anorectal Disease

This review summarizes the relevant literature for the selection of the initial imaging in 4 clinical scenarios in patients with suspected inflammatory disease or postoperative complication of the anorectum. These clinical scenarios include suspected perianal fistula or abscess; rectovesicular or rectovaginal fistula; proctitis or pouchitis; and suspected complication following proctectomy, coloproctectomy, or colectomy with a pouch or other anastomosis. The appropriateness of imaging modalities as they apply to each clinical scenario is rated as usually appropriate, may be appropriate, and usually not appropriate to assist the selection of the most appropriate imaging modality in the corresponding clinical scenarios of anorectal disease. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Magnetic resonance enterography and bowel ultrasonography in Saudi Arabian patients with Crohn's disease: A correlation study

BACKGROUND

Crohn's disease (CD) is a complex autoimmune disease that results in chronic inflammation of the gastrointestinal tract. CD activity is determined through clinical, laboratory, endoscopic, and radiological evaluations. Studies that examine the data of radiological modalities of evaluation are lacking, particularly in Saudi Arabia. This study compares magnetic resonance enterography (MRE) and ultrasonography (US) findings among patients diagnosed with CD, to uncover a possible correlation between these techniques.

METHODS

All patients were assessed for disease activity using MRE and US.

RESULTS

A total of 376 patients with CD were recruited. The mean age was 14.9 ± 4.3 years (range, 8-27 years), and males constituted 64% (n = 239) of the cohort. Overall, a strong positive correlation was found between US and MRE evaluations of disease activity (r = 0.83, P < 0.001). US activity correlated positively with MRE findings of enlarged lymph nodes (P < 0.001), bowel wall enhancement (P < 0.001), distal jejunal thickness (P < 0.001), and distal ileal thickness (P < 0.001). The mean difference in wall thickness was significant based on gender (P < 0.001), age in proximal jejunal thickness (P < 0.001), and distal ileal thickness (P = 0.011).

CONCLUSIONS

MRE and US correlate significantly as imaging techniques for the assessment of CD activity.

Optimized timing of using infliximab in perianal fistulizing Crohn's disease

Infliximab (IFX), as a drug of first-line therapy, can alter the natural progression of Crohn’s disease (CD), promote mucosal healing and reduce complications, hospitalizations, and the incidence of surgery. Perianal fistulas are responsible for the refractoriness of CD and represent a more aggressive disease. IFX has been demonstrated as the most effective drug for the treatment of perianal fistulizing CD. Unfortunately, a significant proportion of patients only partially respond to IFX, and optimization of the therapeutic strategy may increase clinical remission. There is a significant association between serum drug concentrations and the rates of fistula healing. Higher IFX levels during induction are associated with a complete fistula response in these patients. Given the apparent relapse of perianal fistulizing CD, maintenance therapy with IFX over a longer period seems to be more beneficial. It appears that patients without deep remission are at an increased risk of relapse after stopping anti-tumor necrosis factor agents. Thus, only patients in prolonged clinical remission should be considered for withdrawal of IFX treatment when biomarker and endoscopic remission is demonstrated, especially when the hyperintense signals of fistulas on T2-weighed images have disappeared on magnetic resonance imaging. Fundamentally, the optimal timing of IFX use is highly individualized and should be determined by a multidisciplinary team.

Development and Validation of a Magnetic Resonance Index for Assessing Fistulas in Patients With Crohn's Disease

BACKGROUND & AIMS

There is no validated magnetic resonance imaging (MRI) index for assessment of perianal fistulas in patients with Crohn's disease (CD). We developed and internally validated a new instrument.

METHODS

We used paired baseline and week-24 MRI scans from 160 participants in a randomized placebo-controlled trial of stem cell therapy for patients with perianal fistulizing CD. Four radiologists scored disease activity using index items identified during previous studies and exploratory items. Reliability was assessed using intraclass correlation coefficients. We developed an index using backward elimination linear regression analysis, in which potential independent variables were items having intraclass correlation coefficients of at least 0.4 and the dependent variable was perianal fistulizing disease activity, measured on a 100-mm visual analogue scale. The final model was internally validated using the .632 bootstrap method to correct model optimism and quantify calibration accuracy. We evaluated responsiveness of the index by assessing longitudinal validity and estimating standardized effect sizes.

RESULTS

We developed the magnetic resonance novel index for fistula imaging in CD (MAGNIFI-CD) using 6 items. The optimism-corrected R² of the model was 0.71, which was comparable to R² for the original sample (0.74). The calibration slope for the model was 0.98. Compared with the original and modified versions of the Van Assche Index, the MAGNIFI-CD had improved operating characteristics. Estimates of intraclass correlation coefficients for MAGNIFI-CD, the modified Van Assche Index, and Van Assche Index were 0.85 (95% confidence interval [CI], 0.77-0.90), 0.81 (95% CI, 0.74-0.86), and 0.81 (95% CI, 0.71-0.86) for intra-rater reliability, and 0.74 (95% CI, 0.63-0.80), 0.67 (95% CI, 0.55-0.75) and 0.68 (95% CI, 0.56-0.77) for inter-rater reliability. Corresponding standardized effect size estimates were 1.02 (95% CI, 0.65-1.39), 0.84 (95% CI, 0.48-1.21), and 0.68 (95% CI, 0.33-1.03).

CONCLUSIONS

We developed an index called the MAGNIFI-CD, which is based on 6 items. It assesses MRI data and determines perianal fistulizing CD activity with improved operating characteristics compared to previous indices. This index may be used as an outcome measure in clinical trials comparing treatment effects in patients with perianal fistulizing CD. Although the performance of the MAGNIFI-CD indicates its stability and reasonable external validity, external validation is needed.

Structured versus narrative reporting of pelvic MRI in perianal fistulizing disease: impact on clarity, completeness, and surgical planning

OBJECTIVE

To evaluate clarity, completeness, and impact on surgical planning of MRI reporting of perianal fistulizing disease using a structured disease-specific template versus narrative reporting for planning of disease treatment by colorectal surgeons.

MATERIALS AND METHODS

In this HIPAA-compliant, IRB-approved study with waiver of informed consent, a structured reporting template for perianal fistulizing disease MRIs was developed based on collaboration between colorectal surgeons and abdominal radiologists. The study population included 45 consecutive patients who underwent pelvic MRI for perianal fistulizing disease prior to implementation of structured reporting, and 60 consecutive patients who underwent pelvic MRI for perianal fistulizing disease after implementation of structured reporting. Objective evaluation of the reports for the presence of 12 key features was performed, as also subjective evaluation regarding the clarity and completeness of reports, and impact on surgical planning.

RESULTS

Significantly more key features were absent in narrative reports [mean: 6.3 ± 1.8 (range 3-11)] than in structured reports [mean: 0.3 ± 0.9 (range 1-5)] (p ≤ 0.001). The use of structured reporting also increased the percentage of completeness (72.5-88.3% for surgeon 1, and 61.2-81.3% for surgeon 2; p = 0.05 and 0.03, respectively), helpfulness in surgical planning (7.1 ± 1.5-7.6 ± 1.5 for surgeon 1, and 5.8 ± 1.4-7.1 ± 1.1 for surgeon 2; p = 0.05 and p < 0.001, respectively), and clarity (7.6 ± 1.3-8.3 ± 1.1 for surgeon 1, and 5.2 ± 1.4-7.1 ± 1.3 for surgeon 2; p = 0.006 and p < 0.001, respectively) of the reports.

CONCLUSION

Structured MRI reports in patients with perianal fistulizing disease miss fewer key features than narrative reports. Moreover, structured reports were described as more complete and clear, and more helpful for treatment planning.

The development of a magnetic resonance imaging index for fistulising Crohn's disease

BACKGROUND

Magnetic resonance imaging (MRI) is the gold standard for assessment of perianal fistulising Crohn's disease (CD). The Van Assche index is the most commonly used MRI fistula index.

AIMS

To assess the reliability of the Van Assche index, and to modify the instrument to improve reliability and create a novel index for fistulising CD.

METHODS

A consensus process developed scoring conventions for existing Van Assche index component items and new items. Four experienced radiologists evaluated 50 MRI images in random order on three occasions. Reliability was assessed by estimates of intraclass correlation coefficients (ICCs). Common sources of disagreement were identified and recommendations made to minimise disagreement. A mixed effects model used a 100 mm visual anologue scale (VAS) for global severity as outcome and component items as predictors to create a modified Van Assche index.

RESULTS

Intraclass correlation coefficients (95% confidence intervals) for intra-rater reliability of the original and modified Van Assche indices and the VAS were 0.86 (0.81-0.90), 0.90 (0.86-0.93) and 0.86 (0.82-0.89). Corresponding ICCs for inter-rater reliability were 0.66 (0.52-0.76), 0.67 (0.55-0.75) and 0.58 (0.47-0.66). Sources of disagreement included number, location, and extension of fistula tracts, and rectal wall involvement. A modified Van Assche index (range 0-24) was created that included seven component items.

CONCLUSIONS

Although "almost perfect" intra-rater reliability was observed for the assessment of MRI images for fistulising CD using the Van Assche index, inter-rater reliability was considerably lower. Our modification of this index should result in a more optimal instrument.

Magnetic resonance imaging may predict deep remission in patients with perianal fistulizing Crohn's disease

AIM

To evaluate the imaging course of Crohn’s disease (CD) patients with perianal fistulas on long-term maintenance anti-tumor necrosis factor (TNF)-α therapy and identify predictors of deep remission.

METHODS

All patients with perianal CD treated with anti-TNF-α therapy at our tertiary care center were evaluated by magnetic resonance imaging (MRI) and clinical assessment. Two MR examinations were performed: at initiation of anti-TNF-α treatment and then at least 2 years after. Clinical assessment (remission, response and non-response) was based on Present’s criteria. Rectoscopic patterns, MRI Van Assche score, and MRI fistula activity signs (T2 signal and contrast enhancement) were collected for the two MR examinations. Fistula healing was defined as the absence of T2 hyperintensity and contrast enhancement on MRI. Deep remission was defined as the association of both clinical remission, absence of anal canal ulcers and healing on MRI. Characteristics and imaging patterns of patients with and without deep remission were compared by univariate and multivariate analyses.

RESULTS

Forty-nine consecutive patients (31 females and 18 males) were included. They ranged in age from 14-70 years (mean, 33 years). MRI and clinical assessment were performed after a mean period of exposure to anti-TNF-α therapy of 40 ± 3.7 mo. Clinical remission, response and non-response were observed in 53.1%, 20.4%, and 26.5% of patients, respectively. Deep remission was observed in 32.7% of patients. Among the 26 patients in clinical remission, 10 had persisting inflammation of fistulas on MRI (T2 hyperintensity, n = 7; contrast enhancement, n = 10). Univariate analysis showed that deep remission was associated with the absence of rectal involvement and the absence of switch of anti-TNF-α treatment or surgery requirement. Multivariate analysis demonstrated that only the absence of rectal involvement (OR = 4.6; 95%CI: 1.03-20.5) was associated with deep remission.

CONCLUSION

Deep remission is achieved in approximately one third of patients on maintenance anti-TNF-α therapy. Absence of rectal involvement is predictive of deep remission.