The Role of Magnetic Resonance Enterography in Crohn’s Disease: A Review of Recent Literature

Combined [18F]-Fluorodeoxyglucose Positron Emission Tomography-MR Imaging: A Promising Tool for Diagnostics of Small Bowel Crohn's Disease

INTRODUCTION

Diagnostics of small bowel Crohn's disease (CD) can be difficult. Combined positron emission tomography-magnetic resonance enterography (PET-MRE) can be used to evaluate intestinal metabolism, but clinical use has been limited due to accessibility, costs, absence of standardized methods, and diagnostic thresholds. Our aim was to show that combined PET-MRE can be used to diagnose active small bowel CD.

METHODS

We performed a fusion PET-MRE scan with [18F]-FDG tracer to 30 patients with suspected small bowel CD in colonoscopy. Standardized uptake values (SUVs) were measured from small bowel. The diagnosis was confirmed with small bowel capsule endoscopy. Clinicians chose appropriate medication to each patient blinded from SUV results. Endoscopic, laboratory, and MRE findings were investigated in relation to SUV.

RESULTS

Fusion PET-MRE outperformed MRE in diagnostic accuracy. Patients diagnosed with CD (N = 24) had higher SUV than patients not diagnosed with CD (N = 6) (3.34 vs. 1.84, p = 0.022). A diagnostic cut-off at SUV at 2.5 could be used (AUROC = 0.81). A higher SUV predicts need for immunosuppressive medication (p = 0.0026) and biologics (p = 0.0005). SUV correlates positively with Simple Endoscopic Score for Crohn's Disease (SES-CD), fecal calprotectin, and CRP and negatively with Hb and serum albumin.

CONCLUSION

In future, [18F]-FDG PET-MRE can be used in diagnostics of small bowel CD as a safe alternative for capsule endoscopy. High SUV can predict a more progressive disease course and need for more advanced therapies.

INTRODUCTION

Diagnostics of small bowel Crohn's disease (CD) can be difficult. Combined positron emission tomography-magnetic resonance enterography (PET-MRE) can be used to evaluate intestinal metabolism, but clinical use has been limited due to accessibility, costs, absence of standardized methods, and diagnostic thresholds. Our aim was to show that combined PET-MRE can be used to diagnose active small bowel CD.

METHODS

We performed a fusion PET-MRE scan with [18F]-FDG tracer to 30 patients with suspected small bowel CD in colonoscopy. Standardized uptake values (SUVs) were measured from small bowel. The diagnosis was confirmed with small bowel capsule endoscopy. Clinicians chose appropriate medication to each patient blinded from SUV results. Endoscopic, laboratory, and MRE findings were investigated in relation to SUV.

RESULTS

Fusion PET-MRE outperformed MRE in diagnostic accuracy. Patients diagnosed with CD (N = 24) had higher SUV than patients not diagnosed with CD (N = 6) (3.34 vs. 1.84, p = 0.022). A diagnostic cut-off at SUV at 2.5 could be used (AUROC = 0.81). A higher SUV predicts need for immunosuppressive medication (p = 0.0026) and biologics (p = 0.0005). SUV correlates positively with Simple Endoscopic Score for Crohn's Disease (SES-CD), fecal calprotectin, and CRP and negatively with Hb and serum albumin.

CONCLUSION

In future, [18F]-FDG PET-MRE can be used in diagnostics of small bowel CD as a safe alternative for capsule endoscopy. High SUV can predict a more progressive disease course and need for more advanced therapies.

The Current Role of Imaging in the Diagnosis of Inflammatory Bowel Disease and Detection of Its Complications: A Systematic Review

Inflammatory bowel disease (IBD) encompasses complex gastrointestinal (GI) conditions, primarily Crohn's disease (CD) and ulcerative colitis (UC), requiring precise imaging for effective diagnosis and management of complications. This systematic review aimed to evaluate the current role of imaging modalities in diagnosing IBD and detecting related complications. The review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We performed a literature search using text words and controlled vocabulary applying Boolean operators "AND," "OR," with various combinations on databases such as PubMed, Embase, and Cochrane Library. The search targeted open-access articles involving humans, with full-text available, and published in the English Language from 2005 to 2024. The quality of the included studies was assessed using the Cochrane Risk-of-Bias (RoB) checklist. Our search process identified 127 records from Cochrane (39), Embase (29), and PubMed (59). After removing 98 irrelevant records, 29 underwent further screening. Five were excluded as they involved irrelevant problems or outcomes, leaving us with 24 reports with full text, all of which were accessible. Following the eligibility assessment, two more reports were excluded due to inaccessibility, and 22 studies were included in the final analysis. The risk of bias and methodological quality assessment revealed that out of 22 studies analyzed, five (23%) had a high risk of bias, while 13 (59%) were classified as moderate risk, and four (18%) showed low risk. This distribution highlights a predominance of moderate-risk studies in research on imaging in IBD, emphasizing the need for enhanced study designs in future investigations. Our findings revealed the varying effectiveness of imaging modalities in diagnosing complications of CD and UC. Magnetic resonance enterography (MRE) stands out as the preferred method for CD due to its high sensitivity and noninvasive nature. In contrast, colonoscopy remains the gold standard for UC, providing direct visualization of mucosal lesions. While techniques like ultrasound and capsule endoscopy offer valuable insights, they have limitations that may affect their utility in certain cases.

18F-FDG-PET and other imaging modalities in the diagnosis and management of inflammatory bowel disease

Inflammatory bowel disease (IBD), which encompasses ulcerative colitis (UC) and Crohn's disease (CD), is a chronic inflammatory condition of the gastrointestinal (GI) tract that presents complex diagnostic and management challenges. Early detection and treatment of IBD is paramount, as IBD can present with serious complications, including bowel perforation, arthritis, and colorectal cancer. Most forms of diagnosis and therapeutic management, like ileocolonoscopy and upper endoscopy are highly invasive and require extensive preparation at great discomfort to patients. 18F-fluorodeoxyglucose-positron emission tomography (18F-FDG-PET) imaging can be a potential solution to the current limitations in imaging for IBD. This review explores the utility and limitations of various imaging modalities used to detect and manage IBD including ileocolonoscopy, magnetic resonance enterography (MRE), gastrointestinal ultrasound (IUS), and 18F-FDG-PET/computed tomography (18F-FDG-PET/CT) and magnetic resonance imaging (18F-FDG-PET/MR). This review has an emphasis on PET imaging and highlights its benefits in detection, management, and monitoring therapeutic response of UC and CD.

Imaging of Ulcerative Colitis: The Role of Diffusion-Weighted Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) has emerged as a promising and appealing alternative to endoscopy in the objective assessment of patients with inflammatory bowel disease (IBD). Diffusion-weighted imaging (DWI) is a specialized imaging technique that enables the mapping of water molecule diffusion within biological tissues, eliminating the need for intravenous gadolinium contrast injection. It is expanding the capability of traditional MRI sequences in Ulcerative Colitis (UC). Recently, there has been growing interest in the application of intravoxel incoherent motion (IVIM) imaging in the field of IBD. This technique combines diffusion and perfusion information, making it a valuable tool for assessing IBD treatment response. Previous studies have extensively studied the use of DWI techniques for evaluating the severity of activity in IBD. However, the majority of these studies have primarily focused on Crohn's disease (CD), with only a limited number of reports specifically examining UC. Therefore, this review briefly introduces the basics of DWI and IVIM imaging and conducts a review of relevant studies that have investigated its application in UC to show whether these techniques are useful techniques for evaluating patients with UC in terms of detection, characterization, and quantification of disease activity. Through the extensive literature survey, most of these studies indicate that DWI proves valuable in the differential diagnosis of UC and could be used as an effective modality for staging UC.

An applicability study of rapid artificial intelligence-assisted compressed sensing (ACS) in anal fistula magnetic resonance imaging

Objective

To evaluate the applicability of artificial intelligence-assisted compressed sensing (ACS) to anal fistula magnetic resonance imaging (MRI).

Methods

51 patients were included in this study and underwent T2-weighted sequence of MRI examinations both with ACS and without ACS technology in a 3.0 T MR scanner. Subjective image quality scores, and objective image quality-related metrics including scanning time, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR), were evaluated and statistically compared between the images collected with and without ACS.

Results

No significant difference in the subjective image quality of lesion conspicuity was observed between the two groups. However, ACS MRI decreased the acquisition time with regard to control group (74.00 s vs. 156.00 s). Besides, SNR of perianal and muscle in the ACS group was significantly higher than that of the control group (164.07 ± 33.35 vs 130.81 ± 29.10, p < 0.001; 109.87 ± 22.01 vs 87.61 ± 17.95, p < 0.001; respectively). The CNR was significantly higher in the ACS group than in the control group (54.02 ± 23.98 vs 43.20 ± 21.00; p < 0.001). Moreover, the accuracy rate of the ACS groups in evaluating the direction and internal opening of the fistula was 88.89 %, exactly the same as that of the control group.

Conclusion

We demonstrated the applicability of using ACS to accelerate MR of anal fistulas with improved SNR and CNR. Meanwhile, the accuracy rates of the ACS group and the control were equivalent in evaluating the direction and internal opening of the fistula, based on the results of surgical exploration.

The role of intestinal ultrasound with colour Doppler in predicting the response to biologic therapy in inflammatory bowel disease patients

Introduction

Inflammatory bowel disease patients are exposed to frequent procedures and hospital admissions as well as recurrent need for radiological examinations with a high risk of exposure to radiation and contrast.

Aim

Our objective was to evaluate the role of a combination of both intestinal ultrasound (IUS) and colour Doppler with different parameters for monitoring changes in inflammation over time and to reveal their potential role in the assessment of response to biologic therapy in inflammatory bowel disease (IBD) patients.

Material and methods

Before the induction of biological therapy, IUS together with colour Doppler of the intestine was conducted. Response to therapy was defined following the international guidelines.

Results

A total of 45 patients with histopathological diagnosis of IBD were enrolled in the study. All patients received biological therapy and were assessed for response after 3 months. Out of those patients, 34 (75.6%) had good response while 11 (24.4%) failed to respond to the treatment. Our findings point to a strong association between bowel wall thickening (BWT) and serum albumin, erythrocyte sedimentation rate (ESR), and c-reactive protein (CRP). The overall sensitivity of IUS varied from 54 to 93% when evaluating bowel affection, with a specificity of 97-100%, in comparison to our results, which showed a sensitivity of 64-74% and specificity of 79-82%. Doppler parameters could predict the response to the biologic therapy in IBD patients.

Conclusions

Intestinal ultrasound and colour Doppler provide a safe, non-invasive way to monitor changes in inflammation and blood flow in the digestive tract.

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.

Comparison of Diagnostic Performance of Ultrasonography and Magnetic Resonance Enterography in the Assessment of Active Bowel Lesions in Patients with Crohn’s Disease: A Systematic Review and Meta-Analysis

We aimed to evaluate and compare the diagnostic performances of ultrasonography (US) and magnetic resonance enterography (MRE) in assessing active bowel lesions in patients with Crohn’s disease (CD). Materials and Methods: We searched PubMed and EMBASE for studies in which US and MRE were used to assess active bowel lesions in CD patients. Bivariate random effect meta-analytic methods were used to estimate pooled sensitivity, specificity, and hierarchical summary receiver operating characteristic (HSROC) curves. We performed a meta-regression analysis to explore the source of study heterogeneity. Results: Eleven studies involving 752 patients were included. US exhibited a pooled sensitivity of 86% (95% confidence interval (CI) 72–94), pooled specificity of 88% (95% CI 78–94), and HSROC of 0.93 in 10 studies. MRE exhibited a pooled sensitivity of 88% (95% CI 76–95), pooled specificity of 87% (95% CI 73–95), and an HSROC of 0.94 in eight studies. In seven studies comparing the diagnostic performances of US and MRE, the summary sensitivity of US and MRE were 86% (95% CI 65–96, I² = 92.1) and 86% (95% CI 72–93, I² = 88.1) (p = 0.841), respectively. The summary specificity of US and MRE were 87% (95% CI 78–93, I² = 79.8%) and 84% (72–90, I² = 72.5%) (p = 0.431), respectively, which showed no statistical differences. On meta-regression analysis, studies from Europe (p = 0.002), those that used linear US probes (p = 0.012), those on small bowel lesions (p = 0.01), and those with outcomes as combined features (active inflammation) reported higher US sensitivity than those from other regions, those that used both linear and convex US probes, those on small and large bowels, and those with outcome as one feature (bowel wall thickening or ulcer). Studies with pediatric patients (p = 0.001), those with reference standards including US (p = 0.001), and outcomes as combined features (p = 0.01) reported higher MRE specificity than those with adult populations, reference standards other than the US, and outcomes as one feature. Conclusions: In spite of considerable heterogeneity in the included studies, both US and MRE can diagnose active bowel lesions with comparable diagnostic accuracy in patients with CD. The study region, type of US probe, lesion location, investigated outcome for US sensitivity and study population, reference standards, and investigated outcomes for MRE specificity were potential sources of heterogeneity.