Advancing magnetic resonance imaging in Crohn's disease

Recent Trends in Non-Invasive Methods of Diagnosis and Evaluation of Inflammatory Bowel Disease: A Short Review

Inflammatory bowel diseases are a conglomerate of disorders causing inflammation of the gastrointestinal tract, which have gained a significant increase in prevalence in the 21st century. As they present a challenge in the terms of diagnosis as well as treatment, IBDs can present an overwhelming impact on the individual and can take a toll on healthcare costs. Thus, a quick and precise diagnosis is required in order to prevent the high number of complications that can arise from a late diagnosis as well as a misdiagnosis. Although endoscopy remains the primary method of evaluation for IBD, recent trends have highlighted various non-invasive methods of diagnosis as well as reevaluating previous ones. This review focused on the current non-invasive methods in the diagnosis of IBD, exploring their possible implementation in the near future, with the goal of achieving earlier, feasible, and cheap methods of diagnosis as well as prognosis in IBD.

Ultrasound findings of Crohn's disease: correlation with MR enterography

Crohn's disease is a chronic inflammatory bowel disease characterized by periods of relative inactivity alternating with acute flare-ups. Imaging techniques play a fundamental role in the diagnosis and follow-up of Crohn's disease, providing information on the extent of disease, disease activity, and the presence of extramural complications. Because of the frequent re-evaluation required by the relapsing nature of Crohn's disease and the relative young age at which most patients are diagnosed, techniques that use ionizing radiation are best avoided in monitoring this population. Thus, magnetic resonance enterography (MRE) and ultrasonography (US) are the preferable techniques. Various studies have demonstrated that US is accurate in assessing the gut. Despite some clear advantages over MRE, US has long been underused in the evaluation of intestinal disease. This review presents an overview of the main imaging findings in Crohn's disease, correlating representative US images with MRE and surgical pathology specimens. We conclude that US reliably depicts both bowel-related and mesenteric features of Crohn's disease and US findings correlate strongly with MRE findings.

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.

Prevalence and clinical significance of incidental extra-intestinal findings in MR enterography: experience of a single University Centre

PURPOSE

To determine the incidence and clinical relevance of extra-intestinal incidental findings (IF) in a cohort of patients with proven or suspected Crohn disease (CD) examined with magnetic resonance enterography (MR-E) in a single University Centre.

METHODS

Between January 2018 and June 2019, 182 patients with proven or suspected CD with a planned first MR-E examination, were retrospectively included in this study. Incidental findings were considered as any abnormality identified in the absence of previous clinically suspected or known disease. IF were categorized as unremarkable, benign or potentially relevant findings requiring further imaging or specific treatment.

RESULTS

Of the 182 revised MR-E, extra-intestinal IF were recorded in 70 cases (38.5%); 35 (50%) incidental lesions were recognized as non-significant, 24 (34%) as benign and 11 (16%) as clinically relevant. Moreover, there was a positive correlation between IF and patients' age (p < 0.0001).

CONCLUSIONS

In our experience, a high number of IF (38.5%) was found, with a prevalence that increases with patients' age. Clinically relevant findings were found in 16% of MR-E. This means that MR-E is a useful tool to detect IF, therefore, the presence of a radiologist during the image acquisition is crucial in adding sequences to the examination.

MR enterocolonography in patients with Crohn's disease and healthy volunteers - Do we achieve diagnostic bowel distension?

PURPOSE

The aim of our prospective randomized study was to assess diagnostic quality and stability of bowel distension in patients with Crohn's disease (CD) and healthy volunteers subjected to synchronous magnetic resonance enterography and colonography (MREC), as well as to test the role of water enema and intravenous spasmolytics. The influence of gastric content, age, gender, and body mass on bowel distension was also evaluated.

METHOD

Study groups included 164 CD patients and 53 healthy volunteers. After bowel preparation, randomized subgroups started ingestion ≥1000 mL of hyperosmolar solution within 30, 45, 60, 75, and 90 min before admission to MRI, respectively. Patients were examined in prone position and water enema was applied. Spasmolytics were administered prior to I.V. gadolinium. Distension of five bowel segments was independently assessed by two experienced radiologists.

RESULTS

MREC yields diagnostic distension of the jejunum in 81.1 % and 79.2 % patients in the CD group and controls, respectively. For the terminal ileum it was >94 % in both groups. Good and excellent distension was achieved in other bowel segments. Distension was maintained up to 75 min from the start of oral ingestion. Water enema and spasmolytics significantly and independently improved distension of the small bowel. Distension of the cecum after spasmolytics was decreased. Gastric content, age, gender and body mass had no significant influence of bowel distension.

CONCLUSIONS

MREC enables diagnostic distension of the colon and ileum (including terminal segment) in CD patients and healthy volunteers and diagnostically acceptable distension of the jejunum.

Objective evaluation for treat to target in Crohn's disease

BACKGROUND

Crohn's disease (CD) is a chronic and destructive bowel disease; continued disease activity can lead to penetrating complications. With the recent advent of effective medications, the importance of using a treat-to-target approach to guide therapy is becoming important.

METHODS

In this review, we reviewed the previous evidence for evaluating CD lesions.

RESULTS

We describe ileocolonoscopy's role in assessing disease activity, as well as recent progress in modalities, such as balloon-assisted endoscopy, capsule endoscopy, magnetic resonance enterography, computed tomography enterography, and ultrasonography. Advances in modalities have changed CD assessment, with small-bowel involvement becoming more important.

CONCLUSIONS

Proper optimization is necessary in clinical practice.

Abdominal ultrasonography with color Doppler analysis in the assessment of ileal Crohn's disease: comparison with magnetic resonance enterography

Background/Aims

Consistently defining disease activity remains a critical challenge in the follow-up of patients with Crohn’s disease (CD). We investigated the potential applicability of abdominal ultrasonography with color Doppler (USCD) analysis for the detection of morphological alterations and inflammatory activity in CD.

Methods

Forty-three patients with CD ileitis/ileocolitis were evaluated using USCD analysis with measurements obtained on the terminal ileum and right colon. Sonographic parameters included wall thickening, stricture, hyperemia, presence of intra-abdominal mass, and fistulas. Patients were evaluated for the clinical activity (Harvey-Bradshaw Index [HBI]), fecal calprotectin (FC) and C-reactive protein (CRP). The USCD performance was assessed using magnetic resonance enterography (MRE) as a criterion standard.

Results

Most measurements obtained with USCD matched the data generated with MRE; however, the agreement improved in clinically active patients where sensitivity, positive predictive value, and accuracy were >80%, considering wall thickening and hyperemia. Complications such as intestinal wall thickening, stricture formation, and hyperemia, were detected in the USCD analysis with moderate agreement with MRE. The best agreement with the USCD analysis was obtained in regard to FC, where the sensitivity, positive predictive value, and accuracy were >70%. The overall performance of USCD was superior to that of HBI, FC and CRP levels, particularly when considering thickening, stricture, and hyperemia parameters.

Conclusions

USCD represents a practical noninvasive and low-cost tool for evaluating patients with ileal or ileocolonic disease, particularly in clinically active CD. Therefore, USCD might become a useful asset in the follow-up of patients with CD.

Evaluation by MR Enterocolonography of Lansoprazole-induced Collagenous Colitis Accompanied with Protein-losing Enteropathy

We herein describe a 69-year-old man suffering from chronic diarrhea caused by lansoprazole (LPZ)-induced collagenous colitis (CC) accompanied with protein-losing enteropathy (PLE), diagnosed by increased fecal alpha-1 antitrypsin clearance and the findings of leakage from the descending colon to the sigmoid colon on scintigraphy. MR enterocolonography (MREC) was also performed for differentiating digestive diseases, and inflamed findings were observed around the same portion as those on scintigraphy, suggesting that this region was responsible for protein loss in this case. The MREC findings improved after the cessation of LPZ, and hypoalbuminemia also improved simultaneously. This case suggests that MREC may be a new and useful diagnostic tool for CC with PLE.

Imaging in Patients with Crohn's Disease: Trends in Abdominal CT/MRI Utilization and Radiation Exposure Considerations over a 10-Year Period

PURPOSE

To study the trends in utilization of computed tomography (CT) and magnetic resonance imaging (MRI) in patients with Crohn's disease and to evaluate changes in CT radiation exposure over a 10-year period.

METHODS

In this institutional review board-approved single-institution retrospective study, we included patients who underwent CT and MRIs for evaluation of Crohn's disease between 2006 and 2015. A total of 3196 CTs and 1924 MR scans were performed in 2156 patients (mean age: 34.8 ± 17.71 yr; range: 3-91 yr) for initial diagnosis or follow-up of Crohn's disease between 2006 and 2015. Trends in CT/MR utilization was assessed by comparing the volume of CT/MRI studies performed each year. The changes in CT radiation exposure over the study period were estimated and compared.

RESULTS

The annual combined CT/MR utilization demonstrated a 1.9-fold rise over the last decade (2006: n = 358, 2015: n = 681, P < 0.001, r = 0.96). It was predominantly because of a substantial growth (9.2-fold increase) in the MR scan volume (2006: n = 37, 2015: n = 341, P < 0.001, r = 0.93), whereas CT volume did not show significant change (2006: n = 321, 2015: n = 340, P = 0.6). Over this same period, there was a 59.4% reduction in mean radiation exposure (2006: CT dose indexvol 16.9 ± 7.1 mGy, 2015: CT dose indexvol 6.87 ± 4.62 mGy, P < 0.001).

CONCLUSIONS

A 9-fold growth in annual MR scan volume contributed to a nearly 2-fold rise in yearly cross-sectional imaging utilization in Crohn's patients between 2006 and 2015. Rising trend in imaging utilization paralleled a 60% reduction of CT radiation exposure.

Is there a role of magnetic resonance imaging in deciding to stop anti-tumor necrosis factor treatment in ileal Crohn's disease?

PURPOSE

This study was performed to assess the ability of magnetic resonance enterography to predict the evolution of patients in whom anti-tumor necrosis factor-α therapy was suspended.

METHODS

A prospective study of patients with ileal Crohn's disease was performed.

RESULTS

Twenty-nine patients were included. Patients who later relapsed showed higher magnetic resonance scores than those who did not relapse (4.2 vs. 2.5, respectively; p<0.02). The area under the receiving-operating characteristics curve was 0.755 when discriminating patients who relapsed.

CONCLUSIONS

Magnetic resonance enterography should be taken into account when deciding the withdrawal of anti-tumor necrosis factor-α in patients with Crohn's disease.

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.

The Diagnostic Role of Magnetic Resonance Enterography as a Complementary Test to Colonoscopy in Active Crohn's Disease

BACKGROUND

According to recent studies comparing magnetic resonance enterography (MRE) with ileocolonoscopy for assessing inflammation of small bowel and colonic segments in adults with active Crohn’s disease (CD), we aimed to compare the accuracy of these two diagnostic methods in Iranian population.

METHODS

During 2013-2014 a follow-up study was done on 30 patients with active CD in a gastroenterology clinic affiliated to Tehran University of Medical Sciences. MRE and ileocolonoscopy were performed for all the patients. All statistical analyses were performed using SPSS (version 18) and p-value<0.05 was considered as statistically significant.

RESULTS

Of the 30 patients with active CD, 11(36.7%) were men and 19 (63.3%) were women with mean age of 37.30±13.66 years (range: 19-67 years). MRE had sensitivity and specificity of 50% and 90% with positive predictive value (PPV) and negative predictive value (NPV) of 71.43 and 78.26, respectively for localizing sigmoid lesions and ileum had sensitivity and specificity of 84.21 and 45.45 with PPV and NPV of 72.73 and 62.50, respectively.

CONCLUSION

While moderate sensitivity and high specificity of MRE in localizing colonic lesions makes it an appropriate confirmatory test after colonoscopy, the reported high sensitivity and moderate specificity of MRE versus colonoscopy in detecting ileal lesions makes it a suitable screening test for ileal lesions. Finally we can conclude that MRE can be an important complementary test to colonoscopy in detecting active disease.

Non-enhanced magnetic resonance imaging of the small bowel at 7 Tesla in comparison to 1.5 Tesla: First steps towards clinical application

OBJECTIVE

To perform non-enhanced (NE) magnetic resonance imaging (MRI) of the small bowel at 7 Tesla (7T) and to compare it with 1.5 Tesla (1.5T).

MATERIAL AND METHODS

Twelve healthy subjects were prospectively examined using a 1.5T and 7T MRI system. Coronal and axial true fast imaging with steady-state precession (TrueFISP) imaging and a coronal T2-weighted (T2w) half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequence were acquired. Image analysis was performed by 1) visual evaluation of tissue contrast and detail detectability, 2) measurement and calculation of contrast ratios and 3) assessment of artifacts.

RESULTS

NE MRI of the small bowel at 7T was technically feasible. In the vast majority of the cases, tissue contrast and image details were equivalent at both field strengths. At 7T, two cases revealed better detail detectability in the TrueFISP, and better contrast in the HASTE. Susceptibility artifacts and B1 inhomogeneities were significantly increased at 7T.

CONCLUSION

This study provides first insights into NE ultra-high field MRI of the small bowel and may be considered an important step towards high quality T2w abdominal imaging at 7T MRI.

Assessment of Disease Activity in Small Bowel Crohn's Disease: Comparison between Endoscopy and Magnetic Resonance Enterography Using MRIA and Modified MRIA Score

Objectives. To retrospectively compare the results of the MRIA (magnetic resonance index of activity) with a modified MRIA (mMRIA), which was calculated excluding from MRIA formula the data of relative contrast enhancement (RCE). Materials and Methods. MR-E and corresponding endoscopic records of 100 patients were reviewed. MRIA, mMRIA, and SES endoscopic index were calculated for all the patients. Namely, MRIA was calculated as follows: (1.5 × wall thickening + 0.02 × RCE + 5 × intramural edema + 10 × ulcers), while mMRIA was calculated with the modified formula (1.5 × wall thickening + 5 × intramural edema + 10 × ulcers). Results. Mean MRIA and mMRIA values were 19.3 and 17.68, respectively (p < 0.0001). A significant correlation (p < 0.0001) was observed between MRIA and mMRIA scores and between both MR indexes and SES (p < 0.0001). Conclusions. mMRIA was comparable to MRIA in the evaluation of disease activity in Crohn's disease.

MRI for Crohn's Disease: Present and Future

Crohn's disease (CD) is a chronic inflammatory condition with relapsing-remitting behavior, often causing strictures or penetrating bowel damage. Its lifelong clinical course necessitates frequent assessment of disease activity and complications. Computed tomography (CT) enterography has been used as primary imaging modality; however, the concern for radiation hazard limits its use especially in younger population. Magnetic resonance (MR) imaging has advantages of avoiding radiation exposure, lower incidence of adverse events, ability to obtain dynamic information, and good soft-tissue resolution. MR enterography (MRE) with oral contrast agent has been used as primary MR imaging modality of CD with high sensitivity, specificity, and interobserver agreement. The extent of inflammation as well as transmural ulcers and fibrostenotic diseases can be detected with MRE. Novel MR techniques such as diffusion-weighted MRI (DWI), motility study, PET-MRI, and molecular imaging are currently investigated for further improvement of diagnosis and management of CD. MR spectroscopy is a remarkable molecular imaging tool to analyze metabolic profile of CD with human samples such as plasma, urine, or feces, as well as colonic mucosa itself.

Diagnostic accuracy of three different MRI protocols in patients with inflammatory bowel disease

BACKGROUND

Magnetic resonance imaging (MRI) is used for workup and control of inflammatory bowel disease (IBD); however, disagreement remains as to how the MRI should be performed.

PURPOSE

To compare prospectively the diagnostic accuracy of MRI with neither oral nor intravenous contrast medium (plain MRI), magnetic resonance follow-through (MRFT) and MR enteroclysis (MRE) using MRE as the reference standard in patients with inflammatory bowel disease.

MATERIAL AND METHODS

Plain MRI and MRE were carried out in addition to MRFT. All patients underwent both plain MR and MRFT on the same day and MRE within seven days. For the evaluation, the bowel was divided into nine segments. One radiologist, blinded to clinical findings, evaluated bowel wall thickness, diffusion weighted imaging (DWI), mural hyperenhancement, and other inflammatory changes in each bowel segment.

RESULTS

Twenty patients (6 men, 14 women; median age, 43.5 years; age range, 26-76 years) underwent all three examinations; 10 with Crohn's disease (CD), three with ulcerative colitis (UC), and seven with IBD unclassified (IBD-U). Sensitivity, specificity, and accuracy were in the range of 0-75%, 81-96%, and 75-95% for wall thickening, and 0-37%, 59-89%, and 50-86% for DWI in plain MRI, respectively. Sensitivity, specificity, and accuracy were in the range of 0-50%, 96-100%, and 90-100% for wall thickening, 0-50%, 84-97%, and 82-95% for DWI, and 0-71%, 94-100%, and 85-100% for mural hyperenhancement in MRFT, respectively.

CONCLUSION

The use of oral and intravenous contrast agent improves detection of bowel lesions resulting in MRFT remaining the superior choice over plain MRI for diagnostic workup in patients with IBD.

Diagnosis and monitoring of postoperative recurrence in Crohn's disease

Despite advances in medical management, many patients with Crohn's disease (CD) require intestinal surgery throughout their lives. Surgery is not a cure, and postoperative recurrence is common in patients with CD. Ileocolonoscopy has been considered to be the gold standard in the diagnosis and monitoring of postoperative recurrence. However, the optimal monitoring strategy for postoperative recurrence has yet to be established. Capsule endoscopy and cross-sectional imaging techniques, including ultrasonography, computed tomography and MRI, have been used in the postoperative setting, and their usefulness in the monitoring of disease activity has been evaluated in recent clinical trials. The value of fecal markers, such as calprotectin and lactoferrin, has been also assessed in several studies. This review was to identify optimized methods for the diagnosis and monitoring of postoperative recurrence in CD.

Comparison of magnetic resonance and balloon enteroscopic examination of the small intestine in patients with Crohn's disease

BACKGROUND & AIMS

Magnetic resonance (MR) enterography is a recommended imaging technique for detecting intestinal involvement in Crohn's disease (CD). However, the diagnostic accuracy of MR enterography has not been compared directly what that of enteroscopy of the jejunum and proximal ileum. We evaluated the usefulness of MR enterocolonography (MREC) by comparing its findings with those from balloon-assisted enteroscopy.

METHODS

In a prospective study, MREC and enteroscopy were performed within 3 days of each other on 100 patients. Ulcerative lesions and all mucosal lesions were evaluated. Physicians and radiologists were blinded to results from other studies. Findings from MREC were compared directly with those from enteroscopy; the sensitivity and specificity with which MREC detected CD lesions were assessed.

RESULTS

MREC detected ulcerative lesions and all mucosal lesions in the small intestine with 82.4% sensitivity (95% confidence interval [CI], 75.4%-87.7%) and 67.5% sensitivity (95% CI, 63.1%-70.0%); specificity values were 87.6% (95% CI, 83.7%-90.6%) and 94.8% (95% CI, 90.1%-97.5%). MREC detected major stenosis with 58.8% sensitivity (95% CI, 37.6%-77.2%) and 90.0% specificity (95% CI, 88.4%-91.5%) and all stenoses with 40.8% sensitivity (95% CI, 30.8%-49.4%) and 93.7% specificity (95% CI, 91.1%-95.9%).

CONCLUSIONS

MREC is useful for detecting active lesions in the small intestine. However, MR imaging is less sensitive for detecting intestinal damage, such as stenoses. Enteroscopy is preferred for identifying intestinal damage. Suitable imaging approaches should be selected to assess CD lesions in deep small intestine.