Diagnosis of postoperative recurrence of Crohn disease with MR-enterography: Value of diffusion-weighted imaging

Small bowel imaging in Crohn’s disease with a special focus on obesity, pregnancy and postsurgical assessment

Crohn’s disease (CD) is an immune-mediated, multisystem inflammatory disorder characterised by discontinuous transmural, sometimes granulomatous, inflammation of the gastrointestinal tract. Although it can occur anywhere in the gastrointestinal tract, it has a 70% predilection for the terminal ileum. Ileocolonoscopy with biopsy remains the gold standard for initial diagnosis and assessment of CD activity but has several limitations, including invasiveness, risk of complications and cost. With a shifting focus towards treatment targets including transmural healing, non-invasive imaging modalities are being used increasingly to assess the small bowel, particularly the terminal ileum. CT enterography, magnetic resonance enterography and gastrointestinal ultrasound are widely used for small bowel imaging in clinical practice and have relatively good sensitivity and specificity. Obesity is a growing problem for patients with CD and is associated with limitations in medical imaging. Equally, cross-sectional imaging in pregnant and postsurgical patients with CD has its own challenges. In this article, we review small bowel imaging in CD with a special focus on obesity, pregnancy and postsurgical assessment.

Diagnostic value of MR and CT enterography in post-operative recurrence of Crohn's disease: a systematic review and meta-analysis

Post-operative recurrence is a critical issue in the surveillance of Crohn's disease after ileocecal resection. This meta-analysis aims to assess the diagnostic yield of enterography techniques in post-operative recurrence of Crohn's disease. A systematic electronic bibliographic databases search was conducted. The inclusion criteria of original articles were: Utilized MR enterography or CT enterography after ileocolonic resection; Documented recurrence by ileo-colonoscopy (Rutgeerts' score ≥ i2); Provided crude data of diagnostic performance. A random-effect method was used for analysis. Relative risk and diagnostic value of each imaging feature were calculated. Eleven studies (11 populations and 589 patients) were included (4 CTE and 7 MRE with 248 and 341 patients, respectively). The pooled sensitivity and specificity of the enterography were 91% (95% CI: 0.85-0.95) and 75% (95% CI: 0.56-0.87), respectively. The pooled sensitivity and specificity of CTE were 93% (95% CI: 0.87-0.96) and 67% (95% CI: 0.35-0.90), respectively. MRE revealed pooled sensitivity and specificity of 90% (95% CI: 0.78-0.96) and 78% (95% CI: 0.57-0.90), respectively. The inter-study heterogeneity was low for sensitivity (I2 = 29%, p-value = 0.17) and high for specificity (I2 = 85%, p-value < 0.01). Wall enhancement, anastomosis wall thickening, anastomosis stenosis, pre-anastomotic dilatation, penetrating lesion, comb sign, and perivisceral edema were significantly higher in POR patients. Wall thickening and penetrating lesion were the most sensitive (81%) and specific (97%) findings, respectively. MRE and CTE exhibit high sensitivity and acceptable specificity (especially MRE) for detection of recurrence in Crohn's disease which makes them an effective initial screening tool and reserves ileo-colonoscopy for those patients with inconclusive enterography results.

Imaging findings of thoracic manifestations of Crohn's disease and ulcerative colitis

Thoracic manifestations of inflammatory bowel disease (IBD) are rare, occurring in less than 1% of patients. Unlike most other extra-intestinal manifestations, they predominate in patients with ulcerative colitis rather than in Crohn's disease. In most patients, thoracic involvement follows the onset of IBD by several years. However, thoracic involvement may also occur synchronously or even precede the onset of digestive symptoms. The thoracic manifestations of IBD include airway involvement and parenchymal lung abnormalities. Airways are the most frequent anatomical site for thoracic involvement in IBD. Airway manifestations usually develop several years after the onset of intestinal manifestations, preferentially when the latter are stable or in remission. Airway manifestations include bronchial wall thickening, bronchiectasis, small airway disease, and tracheal wall thickening. Parenchymal lung abnormalities are less prevalent in IBD and include organizing pneumonia, necrobiotic nodules, noncaseating granulomatous nodules, drug-induced pneumonia, and rarely interstitial lung diseases. The differential diagnosis between organizing pneumonia, necrobiotic nodules, and noncaseating granulomatous nodules is difficult and usually requires histopathological analysis for a definite diagnosis. Radiologists play a key role in the detection of thoracic manifestations of Crohn's disease and ulcerative colitis and, therefore, need to be familiar with their imaging findings. This article aims to offer an overview of the imaging findings of thoracic manifestations in patients with Crohn's disease or ulcerative colitis. CRITICAL RELEVANCE STATEMENT: Thoracic manifestations of Crohn's disease and ulcerative colitis include tracheal involvement, bronchiectasis, small airway disease, and parenchymal lung abnormalities such as organizing pneumonia and necrobiotic nodules. These rare manifestations (< 1% of patients) more often affect patients with ulcerative colitis. KEY POINTS: Thoracic manifestations of inflammatory bowel disease are rare, occurring in less than 1% of patients. Thoracic manifestations are more frequent in patients with ulcerative colitis than Crohn's disease. Bronchial disease is the most frequent thoracic manifestation of Crohn's disease and ulcerative colitis.

Crohn's Disease: Radiological Answers to Clinical Questions and Review of the Literature

Background: Crohn's disease (CD) is a chronic, progressive inflammatory condition, involving primarily the bowel, characterized by a typical remitting-relapsing pattern. Despite endoscopy representing the reference standard for the diagnosis and assessment of disease activity, radiological imaging has a key role, providing information about mural and extra-visceral involvement. Methods: Computed Tomography and Magnetic Resonance Imaging are the most frequently used radiological techniques in clinical practice for both the diagnosis and staging of CD involving the small bowel in non-urgent settings. The contribution of imaging in the management of CD is reported on by answering the following practical questions: (1) What is the best technique for the assessment of small bowel CD? (2) Is imaging a good option to assess colonic disease? (3) Which disease pattern is present: inflammatory, fibrotic or fistulizing? (4) Is it possible to identify the presence of strictures and to discriminate inflammatory from fibrotic ones? (5) How does imaging help in defining disease extension and localization? (6) Can imaging assess disease activity? (7) Is it possible to evaluate post-operative recurrence? Results: Imaging is suitable for assessing disease activity, extension and characterizing disease patterns. CT and MRI can both answer the abovementioned questions, but MRI has a greater sensitivity and specificity for assessing disease activity and does not use ionizing radiation. Conclusions: Radiologists are essential healthcare professionals to be involved in multidisciplinary teams for the management of CD patients to obtain the necessary answers for clinically relevant questions.

How Reliable Is Endoscopic Scoring of Postoperative Recurrence in Crohn Disease?: A Systematic Review and Meta-Analysis

Objective

Guidelines advise to perform endoscopic surveillance following ileocolic resection (ICR) in Crohn disease (CD) for timely diagnosis of recurrence. This study aims to assess the variation in endoscopic recurrence (ER) rates in patients after ICR for CD using the most commonly used classification systems, the Rutgeerts score (RS) and modified Rutgeerts score (mRS) classifications.

Methods

A systematic literature search using MEDLINE, Embase, and the Cochrane Library was performed. Randomized controlled trials and cohort studies describing ER < 12 months after an ICR for CD were included. Animal studies, reviews, case reports (<30 included patients), pediatric studies, and letters were excluded. The Newcastle-Ottawa Quality Assessment Scale and Cochrane Collaboration's tool were used to assess risk of bias. Main outcome was the range of ER rates within 12 months postoperatively, defined as RS ≥ i2 and/or mRS ≥ i2b. A proportional meta-analysis was performed. The final search was performed on January 4, 2022. The study was registered at PROSPERO, CRD42022363208.

Results

Seventy-six studies comprising 7751 patients were included. The weighted mean of ER rates in all included studies was 44.0% (95% confidence interval, 43.56-44.43). The overall range was 5.0% to 93.0% [interquartile range (IQR), 29.2-59.0]. The weighted means for RS and mRS were 44.0% and 41.1%, respectively. The variation in ER rates for RS and mRS were 5.0% to 93.0% (IQR, 29.0-59.5) and 19.8% to 62.9% (IQR, 37.3-46.5), respectively. Within studies reporting both RS and mRS, the weighted means for ER were 61.3% and 40.6%, respectively.

Conclusions

This study demonstrates a major variation in ER rates after ICR for CD, suggesting a high likelihood of inadequate diagnosis of disease recurrence, with potentially impact on quality of life and health care consumption. Therefore, there is an important need to improve endoscopic scoring of recurrent disease.

Role of abbreviated non-contrast-enhanced MR-enterography in the evaluation of Crohn's disease activity and complications as an alternative for full protocol contrast-enhanced study: A systematic review and meta-analysis

Background

Crohn's disease (CD) is a chronic disorder that often starts at a young age and involves periods of remission and relapse. Prompt diagnosis of relapses through screening is crucial due to the potential morbid complications of untreated active inflammation. Magnetic resonance enterography (MRE) is a noninvasive technique to screen for active inflammation. The standard protocol involves intravenous injection of contrast agents with potential side effects. Some abbreviated non-contrast-enhanced MRE protocols are proposed as alternatives for conventional MRE to identify active inflammation. Currently, there is controversy regarding the applicability and accuracy of these protocols. This study aims to describe and compare these protocols and evaluate their accuracy in detecting active inflammation and CD complications.

Methods

Results from a systematic search of three databases in August 2022 were queried and screened by abstract and full text. Eligible studies were qualitatively and quantitatively analyzed by diagnostic test accuracy meta-analysis.

Results

59 studies entered the systematic review, and 37 were eligible for meta-analysis. Diffusion-weighted imaging (DWI) and fast T2-weighted (T2w) sequences were most frequently used in abbreviated protocols and showed non-inferior accuracy compared to the full protocol in detecting active inflammation. ADC and qualitative DWI had pooled sensitivity of 90% (CI: 82-95%) and 89% (CI:82-93%) and pooled specificity of 94% (CI: 88-97%) and 89% (CI: 79-94%), respectively for detecting active inflammation. Moreover, T2w and combined T2w+DWI sequences had pooled sensitivity of 80% (CI: 64-90%) and 76% (CI: 61-86%) and pooled specificity of 90% (CI: 80-95%) and 87% (CI: 74 - 94%), respectively. Unenhanced protocols show relatively poor diagnostic accuracy in detecting penetrating complications of CD. Magnetization transfer imaging (MTI) has demonstrated excellent accuracy in detecting fibrosis. High heterogeneity was observed in all subgroups, and accuracy was reported to be highly operator dependent in most studies.

Conclusion

An abbreviated protocol consisting of DWI and fast T2w imaging can potentially replace the full protocol MRE. Full protocol MRE will still have its role in identifying penetrating complications. MTI should be indicated in case of suspected fibrostenotic disease.

Preoperative computed tomography enterography-based radiomics signature: A potential predictor of postoperative anastomotic recurrence in patients with Crohn's disease

BACKGROUND

More than half of patients with Crohn's disease (CD) require at least one surgery for symptom management; however, approximately half of the patients may experience postoperative anastomotic recurrence (PAR).

OBJECTIVES

This study aims to develop and validate a preoperative computed tomography enterography (CTE)-based radiomics signature to predict early PAR in CD.

DESIGN

A total of 186 patients with CD (training cohort, n = 134; test cohort, n = 52) who underwent preoperative CTE and surgery between January 2014 and June 2020 were included in this retrospective multi-centre study.

METHODS

106 radiomic features were initially extracted from intestinal lesions and peri-intestinal mesenteric fat, respectively; significant radiomic features were selected from them and then used to develop intestinal or mesenteric radiomics signatures, using the least absolute shrinkage and selection operator and a Cox regression model. A radiomics-based nomogram incorporating these signatures with clinical-radiological factors was created for comparison with a model based on clinical-radiological features alone.

RESULTS

68 of 134 patients in training cohort and 16 of 52 patients in test cohort suffered from PAR. The intestinal radiomic signature (hazard ratio [HR]: 2.17; 95% confidence interval [CI]: 1.32-3.58; P = 0.002) and mesenteric radiomic signature (HR: 2.19; 95% CI: 1.14-4.19; P = 0.018) were independent risk factors for PAR in the training cohort as per a multivariate analysis. The radiomics-based nomogram (C-index: 0.710; 95% CI: 0.672-0.748) yielded superior predictive performance than the clinical-radiological model (C-index, 0.607; 95% CI: 0.582-0.632) in the test cohort. Decision curve analysis demonstrated that the radiomics-based nomogram outperformed the clinical-radiological model in terms of clinical usefulness.

CONCLUSIONS

Preoperative mesenteric and intestinal CTE radiomics signatures are potential non-invasive predictors of PAR in postoperative patients with CD.

Use of imaging modalities for decision-making in inflammatory bowel disease

Cross-sectional magnetic resonance enterography (MRE) and intestinal ultrasonography (IUS) provide valuable and noninvasive information to accurately assess disease activity, severity, and extent; detect complications; and monitor the response to treatment, as well as predict the postoperative recurrence of Crohn's disease and a negative disease course. Therefore, both imaging modalities are emerging as pivotal diagnostic tools to achieve the emerging therapeutic target of transmural healing associated with better disease outcomes. Despite its numerous potential advantages over endoscopy and even MRE and its good availability, IUS is still widely underused to monitor and manage inflammatory bowel disease (IBD) patients and help in making clinical decisions in routine practice. This situation is clearly due to the absence of validated, reliable, and responsive indices, as well as the lack of trained gastroenterologists and radiologists, as IUS is a component of radiologist expertise in several countries but not yet integrated into the training program of gastroenterologists. However, there is an increasing body of evidence in the literature that IUS and MRE are both becoming essential imaging resources to help clinicians in making reliable decisions. Here, we discuss the up-to-date evidence about the usefulness and performance of cross-sectional imaging, focusing on the ability of bowel US and MRE to aid clinical decision-making for the optimal management and monitoring of IBD.

New magnetic resonance imaging sequences for fibrosis assessment in Crohn's disease: a pilot study

BACKGROUND AND OBJECTIVE

Patients with Crohn's disease can develop intestinal strictures, containing various degrees of inflammation and fibrosis. Differentiation of the main component of a structuring lesion is the key for defining the therapeutic management. We evaluated new magnetic resonance imaging sequences (IVIM (Intravoxel Incoherent Motion imaging) and T1 mapping) for assessing fibrosis in Crohn's disease.

METHODS

This was a prospective, single-center study of adult patients with Crohn's disease and magnetic resonance imaging examination, including IVIM and T1 mapping sequences, between March 2021 and April 2021. The association between the perfusion fraction (IVIM), reduction of relaxation time between pre- and postcontrast enhancement (T1 mapping), and the degree of fibrosis assessed by a visual analog scale from 0 to 10 was evaluated.

RESULTS

A total of 33 patients were included. The perfusion fraction was significantly correlated with fibrosis, with lower perfusion fraction in severe fibrosis (p = .002). T1 mapping sequence was also correlated with the degree of fibrosis, reduction of relaxation time was higher in patients with severe fibrosis than in patients with mild fibrosis (p = .05).

CONCLUSION

In Crohn's disease, these new tools could improve the performance of magnetic resonance imaging for transmural fibrosis quantification, and may be useful for improving care.

Reproducibility of apparent diffusion coefficient measurement in normal prostate peripheral zone at 1.5T MRI

PURPOSE

The purpose of this study was to quantify the influence of factors of variability on apparent diffusion coefficient (ADC) estimation in the normal prostate peripheral zone (PZ).

MATERIALS AND METHODS

Fifty healthy volunteers underwent in 2017 (n = 17) or 2020 (n = 33) two-point (0, 800 s/mm²) prostate diffusion-weighted imaging in the morning on 1.5 T scanners A and B from different manufacturers. Additional five-point (50, 150, 300, 500, 800 s/mm²) acquisitions were performed on scanner B in the morning and evening. ADC was measured in PZ at midgland using ADC maps reconstructed with various b-value combinations. ADC distributions from 2017 and 2020 were compared using Wilcoxon rank sum test. ADC obtained in the same volunteers were compared using Bland Altman methodology. The 95% confidence interval upper limit of the repeatability/reproducibility coefficient defined the lowest detectable ADC difference.

RESULTS

Forty-nine participants with a mean age of 24.6 ± 3.8 [SD] years (range: 21-37 years) were finally included. ADC distributions from 2017 and 2020 were not significantly different and were combined. Despite high individual variability, there was no significant bias (10 × 10^-6 mm²/s, P = 0.58) between ADC measurements made on both scanners. On scanner B, differences in lowest b-values chosen within the 0-500 s/mm² range for two-point ADC computation induced significant biases (56-109 × 10^-6 mm²/s, P < 0.0001). ADC was significantly lower in the morning (bias: 33 × 10^-6 mm²/s, P = 0.006). The number of b-values had little influence on ADC values. The lowest detectable ADC difference varied from 85 × 10^-6 to 311 × 10^-6 mm²/s across scanners, b-value combinations and periods of the day.

CONCLUSIONS

The MRI scanner, the lowest b-value used and the period of the day induce substantial variability in ADC computation.