Abdominal MRI after enteroclysis or with oral contrast in patients with suspected or proven Crohn's disease

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.

The Spectrum of Magnetic Resonance Enterography Findings and the Role of Diffusion-Weighted Imaging in Patients with Active Crohn's Disease

Background

The goal of this study was to evaluate magnetic resonance enterography (MRE) findings and assess the role of diffusion-weighted imaging (DWI) in patients suffering from active Crohn's disease.

Methods

This retrospective study included a total number of 76 patients diagnosed with active Crohn's disease, as established by the Crohn's Disease Activity Index (CDAI). The study consisted of 30 women and 46 men, ranging in age from 13 to 72 years. All participants underwent MRE with DWI sequences. The study was conducted at Imam Khomeini hospital in Tehran between 2013 and 2018. The imaging modality utilized for the study included a 3-T SIGNA Excite MRE machine and a Siemens Magnetom 3-T magnetic resonance imaging (MRI) machine.

Results

Bowel wall restriction was observed in less than half of the patients, and no significant correlation was found with extramural findings such as mesenteric edema. The study did not reveal any meaningful association between diffusion restriction and specific mural enhancement patterns, mesenteric lymphadenopathy with or without enhancement, or the length of the affected segments (P>0.05). The most common findings observed in MRI were ileum thickness in 72.4% of patients, mesenteric lymphadenopathy without enhancement in 46.1%, ileocecal thickness in 42.1%, DWI findings in 42.1%, the presence of a comb sign in 36.8%, and jejunum thickness in 30.3% of patients.

Conclusion

MRE findings are useful in the evaluation of Crohn's disease activity.

Imaging of Gastrointestinal Tract Ailments

Gastrointestinal (GI) disorders comprise a diverse range of conditions that can significantly reduce the quality of life and can even be life-threatening in serious cases. The development of accurate and rapid detection approaches is of essential importance for early diagnosis and timely management of GI diseases. This review mainly focuses on the imaging of several representative gastrointestinal ailments, such as inflammatory bowel disease, tumors, appendicitis, Meckel's diverticulum, and others. Various imaging modalities commonly used for the gastrointestinal tract, including magnetic resonance imaging (MRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT), and photoacoustic tomography (PAT) and multimodal imaging with mode overlap are summarized. These achievements in single and multimodal imaging provide useful guidance for improved diagnosis, staging, and treatment of the corresponding gastrointestinal diseases. The review evaluates the strengths and weaknesses of different imaging techniques and summarizes the development of imaging techniques used for diagnosing gastrointestinal ailments.

Challenges and Strategies to Optimising the Quality of Small Bowel Magnetic Resonance Imaging in Crohn’s Disease

Magnetic resonance enterography (MRE) is one of the most highly utilised tools in the assessment of patients with small bowel Crohn’s disease (CD). As a non-invasive modality, it has both patient and procedure-related advantages over ileocolonoscopy which is the current gold standard for Crohn’s disease activity assessment. MRE relies upon high-quality images to ensure accurate disease activity assessment; however, few studies have explored the impact of image quality on the accuracy of small bowel CD activity assessment. Bowel distension and motion artifacts are two key imaging parameters that impact the quality of images obtained through MRE. Multiple strategies have been employed to both minimise the effects of motion artifacts and improve bowel distension. This review discusses the definitions of bowel distension and motion artifacts within the literature with a particular focus on current strategies to improve bowel distension and limit motion artifacts in MRE.

ACR Appropriateness Criteria® Crohn Disease-Child

Crohn disease is an inflammatory condition of the gastrointestinal tract with episodes of exacerbation and remission occurring in children, adolescents, and adults. Crohn disease diagnosis and treatment depend upon a combination of clinical, laboratory, endoscopic, histological, and imaging findings. Appropriate use of imaging provides critical information in the settings of diagnosis, assessment of acute symptoms, disease surveillance, and therapy monitoring. Four variants are discussed. The first variant discusses the initial imaging for suspected Crohn disease before established diagnosis. The second variant pertains to appropriateness of imaging modalities during suspected acute exacerbation. The third variant is a substantial discussion of recommendations related to disease surveillance and monitoring of Crohn disease. Finally, panel recommendations and discussion of perianal fistulizing disease imaging completes the document. 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.

Analysis of core processes of the MRI workflow for improved capacity utilization

PURPOSE

To analyze core processes of the MRI workflow and to evaluate efficiency for improved patient throughput and capacity utilization.

METHOD

Prospective data collection was conducted during a four-week time period and a total sum of 160 working hours for each of the two 1.5 T MRI scanners. Three core processes defined the value stream of patient handling before, during and after the MRI examination: i) Scheduling & Registration, ii) Organization & Preparation, and iii) MR scan. Quantitative data was collected for six essential time intervals of the MRI workflow.

RESULTS

A total of 302 MRI examinations were assessed. The workflow analysis revealed that effective utilization of scan capacity during operating hours varied by scanner (Scanner 1: 77 % / Scanner 2: 85 %). Mean process times for were: patient preparation time 18.9 min (±15.1) p = 0.11, scan preparation time 5.7 min (±4.0) p = 0,015, effective scan time 39.6 min (±18.0) p < 0.0001, scan room occupation time 50.9 min (±21.0) p < 0.0001, clean-up time 5.6 min (±3.2) p = 0.001, total patient handling time 69.7 min (±26.3) p < 0.0001, turnover time 13.4 min (±21.4) p = 0.65.

CONCLUSIONS

This study demonstrates the utility and applicability of a standardized core processes analyses for MRI scanning, which identified underutilization of scanning capacities, related to multiple factors, such as punctuality of patients, the number of same day cancellations, the process of placing an IV access and patient transport contribute to underutilization of MRI scanners. Furthermore, proactive patient management and effective communication with patients and referring physicians might have relevant time saving potential in the scan room.

Artificial intelligence in radiotherapy: a technological review

Radiation therapy (RT) is widely used to treat cancer. Technological advances in RT have occurred in the past 30 years. These advances, such as three-dimensional image guidance, intensity modulation, and robotics, created challenges and opportunities for the next breakthrough, in which artificial intelligence (AI) will possibly play important roles. AI will replace certain repetitive and labor-intensive tasks and improve the accuracy and consistency of others, particularly those with increased complexity because of technological advances. The improvement in efficiency and consistency is important to manage the increasing cancer patient burden to the society. Furthermore, AI may provide new functionalities that facilitate satisfactory RT. The functionalities include superior images for real-time intervention and adaptive and personalized RT. AI may effectively synthesize and analyze big data for such purposes. This review describes the RT workflow and identifies areas, including imaging, treatment planning, quality assurance, and outcome prediction, that benefit from AI. This review primarily focuses on deep-learning techniques, although conventional machine-learning techniques are also mentioned.

Evaluating inflammatory activity in Crohn's disease by cross-sectional imaging techniques

The evaluation of inflammatory bowel activity in patients with Crohn’s disease has traditionally been a challenge, mainly because of the difficulty in gaining endoscopic access to the small bowel. Historically, barium-based contrast studies were the only option for the evaluation of inflammatory activity in Crohn’s disease. They were gradually replaced by cross-sectional imaging techniques, computed tomography enterography (CTE) and magnetic resonance enterography (MRE) now being the modalities of choice for such evaluations. Those two imaging methods have provided important information regarding intestinal wall involvement and extra-intestinal manifestations of Crohn’s disease, not only assessing lesion characteristics and complications but also quantifying inflammatory bowel activity. The objective of this article is to review the main technical aspects of CTE and MRE, together with their indications, contraindications, and limitations, as well as the CTE and MRE imaging characteristics of inflammatory activity in Crohn’s disease.

Indian guidelines on imaging of the small intestine in Crohn's disease: A joint Indian Society of Gastroenterology and Indian Radiology and Imaging Association consensus statement

The Indian Society of Gastroenterology (ISG) Task Force on Inflammatory Bowel Disease and the Indian Radiological and Imaging Association (IRIA) developed combined ISG-IRIA evidence-based best-practice guidelines for imaging of the small intestine in patients suspected to have or having Crohn's disease. The 29 consensus statements, developed through a modified Delphi process, are intended to serve as reference for teaching, clinical practice, and research.

The bowel preparation for magnetic resonance enterography in patients with Crohn's disease: study protocol for a randomized controlled trial

Background

Adequate bowel preparation is required for magnetic resonance enterography (MRE), which can be achieved by administering contrast solution after mid-gut tubing or taking contrast solution orally. We present the design of randomized controlled trial (RCT) to compare the efficacy and compliance of bowel preparation between mid-gut tubing and oral administering for MRE in patients with Crohn’s disease (CD).

Methods/design

This is an open-label, multicenter RCT. Ninety-six patients with CD in need of MRE examination and mid-gut tubing (prepared for fecal microbiota transplantation and/or enteral nutrition), aged ≥ 14 years, will be included. Patients will be randomized 1:1 into either bowel preparation by oral administering (oral group) or bowel preparation through mid-gut transendoscopic enteral tubing (TET) (tubing group). The primary outcome measures are: (1) degree of discomfort before/during/after bowel preparation for MRE using a visual 5-grade scale (1 = few, 5 = very severe); and (2) grade of bowel distention evaluated by a 5-grade scale (1 = 0–20% segmental distention, 2 = 20–40% distention, 3 = 40–60% distention, 4 = 60–80% distention, 5 = 80–100% distention). The secondary outcome measure is the accuracy of lesion detection through MRE confirmed by colonoscopy which is evaluated by a 5-point scale.

Discussion

The outcome of this study is expected to provide a novel effective clinical protocol of bowel preparation for MRE in patients with CD. We hope to highlight the concept of physician–patient satisfaction based on different methods of bowel preparation for MRE.

Trial registration

ClinicalTrials.gov, NCT03541733. Registered on 30 May 2018.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-3101-x) contains supplementary material, which is available to authorized users.

Imaging of the small intestine in Crohn's disease: Joint position statement of the Indian Society of Gastroenterology and Indian Radiological and Imaging Association

The Indian Society of Gastroenterology (ISG) Task Force on Inflammatory Bowel Disease and the Indian Radiological and Imaging Association (IRIA) developed combined ISG-IRIA evidence-based best-practice guidelines for imaging of the small intestine in patients with suspected or known Crohn's disease. These 29 position statements, developed through a modified Delphi process, are intended to serve as reference for teaching, clinical practice, and research.

Shortened oral contrast preparation for improved small bowel distension at MR enterography

Purpose

Adequate small bowel distension in MR enterography is important for the evaluation of disease activity in Crohn’s disease patients. While distension of the distal small bowel can be achieved using standard oral contrast preparation, proximal small bowel distension remains a common impediment. The aim of this study was to compare small bowel distension between a 60-min oral contrast preparation and a 45-min oral contrast preparation.

Methods

Fifty retrospectively included patients with a 60-min oral preparation protocol and 50 prospectively included patients with a 45-min three-portion oral preparation protocol were included in the study. Both groups gradually ingested a total of 1600 mL 2% Mannitol solution during the preparation time. Two observers independently graded distension of the stomach, duodenum, jejunum, ileum, and (neo-) terminal ileum. Total small bowel distension was calculated as the sum of all small bowel segment scores. Individual and averaged observer distension scores were compared between both groups of patients using χ² test for ordinal variables.

Results

Significant differences in distension for one of both observers in favor of the 45-min protocol were found for the stomach (p = 0.04), duodenum (p = 0.02), jejunum (p = 0.02), and total small bowel (p = 0.02). When distension scores were averaged between observers, the stomach, jejunum, and total small bowel showed a significant difference in favor of the 45-min protocol (p = 0.04, 0.02, and 0.02, respectively).

Conclusion

We advise to use a 45-min three-portion oral preparation protocol for MR enterography for improved overall small bowel distension, proximal small bowel distension, and especially jejunal distension.

The role of diffusion-weighted MRI in assessment of inflammatory bowel disease

AIM

To evaluate the role of diffusion-weighted MRI (DW-MRI) in detecting and differentiating acute from chronic bowel inflammation in patients with Crohn's disease (CD).

MATERIALS AND METHODS

MR-enteroclysis examinations with DW-MRI were reviewed from 24 patients with histologically proven CD. Segments of bowel were evaluated for acute and chronic inflammation in three different reviews of the MRI images: T2w alone, T2w + DWI, and T2w + CET1w. Mean ADC values of normal bowel segments, as well as bowel segments with acute and chronic inflammation were calculated and compared. Analyses of receiver-operating characteristic (ROC) curve were performed.

RESULTS

Hundred and forty four bowel segments in total were reviewed. Inflammation was present in 45 segments. Acute inflammation was present in 31 segments, chronic inflammation in 14. 98 bowel segments showed no inflammatory activity. Sensitivity and specificity for differentiation between normal and inflamed bowel segments was 0.6, 0.67, and 0.80 on T2w, T2w + DWI, and T2w + CET1w datasets, respectively. Specificities for differentiation between normal and inflamed bowel segments were 0.96, 0.96, and 0.98. Sensitivities for differentiation between acute and chronically inflamed bowel segments were 0.85, 0.91, and 0.96, and specificities were 0.88, 0.89, and 1.0, respectively. The mean ADC value of normal bowel (2.18 ± 0.37 × 10(-3) mm(2)/s) was statistically significantly greater than the mean value of inflamed bowel segments (p < 0.001). The mean ADC value of acutely inflamed bowel segments was statistically significantly lower than that of chronically inflamed bowel segments (1.09 ± 0.18 × 10(-3) vs. 1.55 ± 0.21 × 10(-3) mm(2)/s) (p < 0.001). Estimated area under the ROC curve for the diagnosis of acute vs. chronic inflammation was 0.950. A threshold of ADC value of 1.41 × 10(-3) mm(2)/s was optimal for calculation of sensitivity and specificity.

CONCLUSION

DW-MRI improves detection and differentiation of acute vs. chronic inflammatory changes of the bowel in patients with CD compared to T2w-images alone.

The role of small bowel capsule endoscopy and ileocolonoscopy in patients with nonspecific but suggestive symptoms of Crohn's disease

OBJECTIVES

Ileocolonoscopy (IC) and small bowel capsule endoscopy (SBCE) are essential tools in the investigation of suspected small bowel Crohn's disease (CD). Overutilization of SBCE should be avoided as it leads to unwanted healthcare expenses; thus, it is recommended when IC is normal and CD is still highly suspected. Our aim was to compare the role of SBCE and IC in the investigation of suspected CD irrespective of its location and assess the additional diagnostic benefit of SBCE over IC.

METHODS

This was a retrospective study of 91 patients with chronic abdominal pain and/or diarrhea. All patients were evaluated with both colonoscopy (with terminal ileum intubation where possible) and SBCE. The severity of inflammation on SBCE was assessed using the Lewis Score. Endoscopic findings were analyzed toward CD diagnosis.

RESULTS

The sensitivity of IC and SBCE in the diagnosis of either small bowel or colonic CD was 81.82 and 63.64%, whereas the specificity was 77.50 and 92.50%, respectively. Positive and negative predictive value was 33.33 and 96.88% for IC, as well as 53.85 and 94.87% for SBCE. Area under receiver operating characteristic curve was 0.797 for IC and 0.781 for SBCE. IC was superior to SBCE in diagnosing small and large bowel CD. SBCE showed the true extent of CD in one patient missed by IC. It identified lesions suggestive of CD in three patients with normal IC, one of whom was finally diagnosed with CD.

CONCLUSION

IC should be the initial diagnostic test in patients with nonspecific, but suggestive symptoms of CD. SBCE offers additional information on small bowel mucosa and disease extent.

Magnetic resonance enterography: A stepwise interpretation approach and role of imaging in management of adult Crohn's disease

Crohn's disease (CD) is a chronic inflammatory bowel disease that often requires frequent imaging of patients in order to detect active disease and other complications related to disease activity. While endoscopy is the gold standard for diagnosis, it may be contraindicated in some patients and has a limited role in detecting deep submucosal/mesenteric diseases and intra abdominal complications. In recent years, magnetic resonance enterography (MRE) has evolved as a noninvasive, radiation free imaging modality in the evaluation of patients with CD. This review article will focus on role of MRE in imaging patients with CD with emphasis on technical considerations, systematic image interpretation, differential diagnoses, and the role of imaging in deciding treatment options for patients.

ACR Appropriateness Criteria Crohn Disease

Crohn disease is a chronic inflammatory disorder involving the gastrointestinal tract, characterized by episodic flares and times of remission. Underlying structural damage occurs progressively, with recurrent bouts of inflammation. The diagnosis and management of this disease process is dependent on several clinical, laboratory, imaging, endoscopic, and histologic factors. In recent years, with the maturation of CT enterography, and MR enterography, imaging has played an increasingly important role in relation to Crohn Disease. In addition to these specialized examination modalities, ultrasound and routine CT have potential uses. Fluoroscopy, radiography, and nuclear medicine may be less beneficial depending on the clinical scenario. The imaging modality best suited to evaluating this disease may change, depending on the target population, severity of presentation, and specific clinical situation. This document presents seven clinical scenarios (variants) in both the adult and pediatric populations and rates the appropriateness of the available imaging options. They are summarized in a consolidated table, and the underlying rationale and supporting literature are presented in the accompanying narrative. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Magnetic resonance enterography for the evaluation of the deep small intestine in Crohn's disease

For the control of Crohn's disease (CD) a thorough assessment of the small intestine is essential; several modalities may be utilized, with cross-sectional imaging being important. Magnetic resonance (MR) enterography, i.e., MRE is recommended as a modality with the highest accuracy for CD lesions. MRE and MR enteroclysis are the two methods performed following distension of the small intestine. MRE has sensitivity and specificity comparable to computed tomography enterography (CTE); although images obtained using MRE are less clear compared with CTE, MRE does not expose the patient to radiation and is superior for soft-tissue contrast. Furthermore, it can assess not only static but also dynamic and functional imaging and reveals signs of CD, such as abscess, comb sign, fat edema, fistula, lymph node enhancement, less motility, mucosal lesions, stricture, and wall enhancement. Several indices of inflammatory changes and intestinal damage have been proposed for objective evaluation. Recently, diffusion-weighted imaging has been proposed, which does not need bowel preparation and contrast enhancement. Comprehension of the characteristics of MRE and other modalities is important for better management of CD.

Magnetic Resonance Enterography in Crohn׳s Disease

Over the past decade, magnetic resonance (MR) enterography has become established as the first-line imaging test for patients with Crohn׳s disease. This article reviews the role of MR enterography in assessing the extent and activity of Crohn׳s disease at baseline and on treatment follow-up. It discusses the role of diffusion-weighted imaging, and the recent introduction of MR scoring systems to facilitate noninvasive objective assessment of disease activity and cumulative bowel damage.

Magnetic resonance enterography or video capsule endoscopy - what do Crohn's disease patients prefer?

BACKGROUND

Despite differences in the information obtained by capsule endoscopy (CE) and magnetic resonance enterography (MRE), one of these modalities is usually needed when evaluating disease activity. There are no data on patients' preference that would help guide the choice between these two modalities in these instances.

AIM

To compare patients' tolerance and preference to MRE versus CE.

PATIENTS AND METHODS

Patients with known small bowel Crohn's disease (CD) in clinical remission (Crohn's disease activity index [CDAI] <150) or with mild symptoms (CDAI <220) were prospectively recruited. All patients underwent MRE followed by CE. Patients were asked to fill out a questionnaire addressing specific points regarding inconvenience during the preparation for the procedures, the procedures, and postprocedures. Side effects and procedure preference were addressed. Questionnaires were included for analysis only when more than 95% of the items were addressed.

RESULTS

Fifty-six patients fulfilled inclusion criteria. Pre-exam discomfort, during-exam discomfort, nausea, vomiting, bloating, and abdominal pain were all significantly more prominent in MRE as compared to CE (P<0.0001, P<0.0001, P<0.0001, P=0.009, P=0.0002, P<0.0001, respectively). MRE was perceived as a more difficult procedure (P<0.0001). Furthermore, MRE was associated with a specific adverse event - claustrophobia. Seventy-eight percent of patients (44 patients) preferred to repeat CE as compared to 22% (P<0.0001) who preferred MRE.

CONCLUSION

CE was better tolerated by CD patients compared to MRE and was preferred by 78% of patients. The superior tolerability of CE should be considered along with the diagnostic features, and more data sought when choosing between these two modalities for CD patients for long-term follow-up.

Impact of Small Bowel MRI in Routine Clinical Practice on Staging of Crohn's Disease

BACKGROUND AND AIMS

Small bowel visualisation is a complex diagnostic approach, but mandatory for risk stratification and stage-adjusted therapy in Crohn's disease. Current guidelines favour transabdominal ultrasound and small bowel MRI as methods of choice, although their clinical impact in daily practice remains controversial. The aim of this study was to evaluate the diagnostic benefit of small bowel MRI in Crohn's disease according to Montreal Classification, in routine practice.

METHODS

Patients who underwent MR-enterography [MRE] or MR-enteroclysis [MRY] were included in a retrospective single-centre study. MRI findings were correlated with results from clinical work-up and evaluated in terms of [1] diagnostic yield, [2] significant additional information, and [3] alterations in the assessment of disease behaviour and location according to Montreal Classification.

RESULTS

A total of 347 small bowel MRI examinations were analysed [MRE: 49 / MRY: 298]. MRI had an average sensitivity/specificity of 82.5% and 99.9% [positive predictive value: 99.8% / negative predictive value: 91.1%] respectively. In every second patient, new relevant diagnostic information was provided. Incorporation of the MRI results caused significant shifts in Montreal Classification, specifically higher L-levels [+21.2%; p < 0.05] and higher B-levels: [+24.6%; p < 0.05].

CONCLUSIONS

Even in routine practice, small bowel MRI is a powerful and reliable technique in small bowel work-up. Since MRE and MRY presented high diagnostic yields, often detected significant additional information, and significantly caused shifts in Montreal Classification, both techniques are confirmed to be excellent tools in diagnosing and monitoring Crohn's disease in its daily course.

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.

Monitoring disease activity and progression in Crohn's disease. A Swiss perspective on the IBD ahead 'optimised monitoring' recommendations

BACKGROUND AND AIMS

The structured IBD Ahead 'Optimised Monitoring' programme was designed to obtain the opinion, insight and advice of gastroenterologists on optimising the monitoring of Crohn's disease activity in four settings: (1) assessment at diagnosis, (2) monitoring in symptomatic patients, (3) monitoring in asymptomatic patients, and (4) the postoperative follow-up. For each of these settings, four monitoring methods were discussed: (a) symptom assessment, (b) endoscopy, (c) laboratory markers, and (d) imaging. Based on literature search and expert opinion compiled during an international consensus meeting, recommendations were given to answer the question 'which diagnostic method, when, and how often'. The International IBD Ahead Expert Panel advised to tailor this guidance to the healthcare system and the special prerequisites of each country. The IBD Ahead Swiss National Steering Committee proposes best-practice recommendations adapted for Switzerland.

METHODS

The IBD Ahead Steering Committee identified key questions and provided the Swiss Expert Panel with a structured literature research. The expert panel agreed on a set of statements. During an international expert meeting the consolidated outcome of the national meetings was merged into final statements agreed by the participating International and National Steering Committee members - the IBD Ahead 'Optimized Monitoring' Consensus.

RESULTS

A systematic assessment of symptoms, endoscopy findings, and laboratory markers with special emphasis on faecal calprotectin is deemed necessary even in symptom-free patients. The choice of recommended imaging methods is adapted to the specific situation in Switzerland and highlights the importance of ultrasonography and magnetic resonance imaging besides endoscopy.

CONCLUSION

The recommendations stress the importance of monitoring disease activity on a regular basis and by objective parameters, such as faecal calprotectin and endoscopy with detailed documentation of findings. Physicians should not rely on symptoms only and adapt the monitoring schedule and choice of options to individual situations.

Plain magnetic resonance imaging as an alternative in evaluating inflammation and bowel damage in inflammatory bowel disease--a prospective comparison with conventional magnetic resonance follow-through

OBJECTIVE

To compare prospectively the diagnostic accuracy of magnetic resonance imaging (MRI) without use of contrast medium orally or intravenously (plain MRI) with magnetic resonance follow-through (MRFT) in patients with inflammatory bowel disease (IBD).

MATERIAL AND METHODS

Plain MRI was carried out in addition to MRFT, to which the patients were referred. All patients underwent both examinations on the same day. For the evaluation, the bowel was divided into nine segments. Two radiologists, blinded to clinical findings, evaluated bowel wall thickness, diffusion weighted imaging (DWI), and other inflammatory changes in each bowel segments. Further, hyperenhancement of the bowel was also evaluated in MRFT.

RESULTS

A total of 100 patients (40 males and 60 females; median age: 38.5; range: 19-90) were enrolled; 44 with Crohn's disease (CD), 25 with ulcerative colitis (UC), 24 with IBD unclassified (IBD-U), and 7 had other diagnosis. Sensitivity, specificity, and accuracy in CD ranged 50-86%, 93-94%, and 91-92% for wall thickening and 49-82%, 85-93%, and 84-89% for DWI, respectively. Sensitivity, specificity, and accuracy in UC range 0-40%, 87-100%, and 80-100% for wall thickening and 0-52%, 83-94% and 76-92% for DWI, respectively. The κ values for bowel wall thickening, DWI, and mural hyperenhancement were detected with fair agreement (κ = 0.26-0.39) at both MRI examinations, whereas only bowel wall thickening in MRFT were detected with moderate agreement (κ = 0.47) Conclusion. Plain MRI cannot currently replace MRFT in the workup of patients with IBD. Further research on plain MRI is needed to improve the protocol.

Magnetic resonance enterography of Crohn's disease

Magnetic resonance enterography (MRE) has been reported to be a useful modality for the evaluation of luminal inflammation and extraintestinal complications in Crohn's disease (CD). A recent study indicated that the diagnostic ability of MRE was comparable to the diagnostic ability of other devices, such as ileocolonoscopy. MRE can be performed repeatedly because there is no radiation exposure. Therefore, MRE is useful as a method of follow-up for younger patients with established CD. It is useful for evaluating the efficacy of medical treatments, such as biologics. MRE can detect small intestinal lesions even if the endoscope does not pass through the stenosis. The concerns of availability of expertise and the costs associated with MRE should be addressed so MRE can be widely used for CD patients in the near future.

Magnetic resonance enterography in Crohn's disease: a comparison with the findings at surgery

AIM

Magnetic resonance (MR) enterography is a radiation-free small bowel investigation which identifies luminal and extra-luminal pathology in patients with Crohn's disease. Most studies have validated MR against conventional radiology. We evaluated the results of MR enterography by comparison with findings at elective surgery for patients with Crohn's disease, including complex pathology.

METHOD

Between January 2007 and March 2012 the results of preoperative MR enterography for Crohn's disease in consecutive patients in one unit were compared with the detailed findings at surgery.

RESULTS

Fifty-one patients underwent 55 laparotomies during the study period. MR enterography identified the presence of Crohn's disease in the distal ileum in 33/34 patients, in the proximal ileum in 7/12 patients, in the jejunum in 7/8 patients, in the large bowel in 10/11 patients and in the duodenum in one of two patients. MR enterography identified ileo-enteric fistula in 10/12 patients, ileosigmoid fistula in all of seven patients and other fistulae in 10/11 patients. An abscess was identified on MR enterography in eight of nine patients. Within abnormal distal ileal segments, the mean contrast enhancement ratio of acute inflammation was 2.39 ± 0.59 compared with 1.82 ± 0.63 (P < 0.05) in segments with fibrosis only.

CONCLUSION

Magnetic resonance enterography identifies small bowel Crohn's disease with an accuracy similar to or better than those of previously published series. Fistulation, abscess formation and large bowel disease can be reliably identified and disease activity assessed. Normal, uninvolved small bowel length can also be measured. Discrete proximal small bowel lesions may not always be detected. In our practice, MR enterography has replaced conventional radiology in the assessment of symptomatic patients with Crohn's disease.

ESPGHAN revised porto criteria for the diagnosis of inflammatory bowel disease in children and adolescents

BACKGROUND

The diagnosis of pediatric-onset inflammatory bowel disease (PIBD) can be challenging in choosing the most informative diagnostic tests and correctly classifying PIBD into its different subtypes. Recent advances in our understanding of the natural history and phenotype of PIBD, increasing availability of serological and fecal biomarkers, and the emergence of novel endoscopic and imaging technologies taken together have made the previous Porto criteria for the diagnosis of PIBD obsolete.

METHODS

We aimed to revise the original Porto criteria using an evidence-based approach and consensus process to yield specific practice recommendations for the diagnosis of PIBD. These revised criteria are based on the Paris classification of PIBD and the original Porto criteria while incorporating novel data, such as for serum and fecal biomarkers. A consensus of at least 80% of participants was achieved for all recommendations and the summary algorithm.

RESULTS

The revised criteria depart from existing criteria by defining 2 categories of ulcerative colitis (UC, typical and atypical); atypical phenotypes of UC should be treated as UC. A novel approach based on multiple criteria for diagnosing IBD-unclassified (IBD-U) is proposed. Specifically, these revised criteria recommend upper gastrointestinal endoscopy and ileocolonscopy for all suspected patients with PIBD, with small bowel imaging (unless typical UC after endoscopy and histology) by magnetic resonance enterography or wireless capsule endoscopy.

CONCLUSIONS

These revised Porto criteria for the diagnosis of PIBD have been developed to meet present challenges and developments in PIBD and provide up-to-date guidelines for the definition and diagnosis of the IBD spectrum.

Imaging Crohn disease: MR enterography

Magnetic resonance enterography in Crohn disease management has been rapidly growing in importance during recent years. Being familiar to this technique is essential for radiologists and also, to some extent, for gastroenterologists. Our aim is to study and describe the imaging findings in magnetic resonance enterography in Crohn disease to develop a comprehensive and useful review article and imaging atlas.

Outcomes of computed tomography and magnetic resonance enterography in clinical practice of inflammatory bowel disease

BACKGROUND

Computed tomography (CT) and magnetic resonance (MR) enterography are now widely used to diagnose and monitor Crohn's disease.

AIM

We sought to assess the use of enterography for management of inflammatory bowel disease (IBD) in our medical center.

METHODS

We performed a retrospective review of all patients diagnosed with IBD who underwent MR or CT enterography from November 1, 2010 to October 25, 2012 at our institution. We assessed disease complications identified by enterography, agreement between disease activity determined by endoscopy and enterography, association between inflammatory markers and enterography-determined disease activity and recommended changes in medical and surgical management following enterography.

RESULTS

A total of 311 enterography studies (291 MR and 20 CT enterographies) were performed on 270 patients, including 258 (83.0 %) on patients with presumed Crohn's disease and 53 (17.0 %) with presumed ulcerative colitis. Active small bowel (SB) disease was noted in 73/311 (23.5 %) studies. Complications including strictures, perianal fistulas, abscesses and SB fistulas were noted in 108/311 (34.7 %) studies. Endoscopic and enterography defined active disease had an agreement of κ = 0.36 in the ileum (n = 179). A total of 142/311 (45.7 %) enterographies were associated with recommended medication changes within 90 days while surgery or endoscopic dilation of stricture was recommended following 41/311 (13.2 %) enterographies. Enterography resulted in a change in diagnosis from ulcerative colitis to Crohn's in 5/311 (1.6 %) studies.

CONCLUSION

Enterography reveals active disease and complications not evident on endoscopy and should be considered in the initial diagnosis, assessment of disease activity, and monitoring of therapy in patients with IBD.

Advances in the diagnosis and management of inflammatory bowel disease: challenges and uncertainties

Over the past two decades, several advances have been made in the management of patients with inflammatory bowel disease (IBD) from both evaluative and therapeutic perspectives. This review discusses the medical advancements that have recently been made as the standard of care for managing patients with ulcerative colitis (UC) and Crohn's Disease (CD) and to identify the challenges associated with implementing their use in clinical practice. A comprehensive literature search of the major databases (PubMed and Embase) was conducted for all recent scientific papers (1990-2013) giving the recent updates on the management of IBD and the data were extracted. The reported advancements in managing IBD range from diagnostic and evaluative tools, such as genetic tests, biochemical surrogate markers of activity, endoscopic techniques, and radiological modalities, to therapeutic advances, which encompass medical, endoscopic, and surgical interventions. There are limited studies addressing the cost-effectiveness and the impact that these advances have had on medical practice. The majority of the advances developed for managing IBD, while considered instrumental by some IBD experts in improving patient care, have questionable applications due to constraints of cost, lack of availability, and most importantly, insufficient evidence that supports their role in improving important long-term health-related outcomes.

Imaging the small bowel

PURPOSE OF REVIEW

Radiologic investigations continue to play a pivotal role in the diagnosis of pathologic conditions of the small intestine despite enhancement of capsule endoscopy and double-balloon endoscopy. Imaging techniques continue to evolve and new techniques in MRI in particular, are being developed.

RECENT FINDINGS

Continued advances in computed tomography (CT) and MRI techniques have reinforced the importance of these imaging modalities in small bowel assessment. The more invasive enteroclysis technique yields better small bowel distension for both CT and MRI when compared with peroral enterography, but no clinically significant difference is seen in terms of diagnostic accuracy. Recent concern regarding radiation exposure means that MRI is gaining in popularity. Fluoroscopic studies such as barium follow through and small bowel enteroclysis are being replaced by the cross-sectional alternatives. Contrast-enhanced ultrasound is showing results comparable with CT and MRI, but concern remains regarding reproducibility, especially outside centres that specialize in advanced sonographic techniques.

SUMMARY

CT and MRI enterography are comparable first-line modalities for patients with suspected small bowel disease, but magnetic resonance enterography is favoured given the absence of ionizing radiation. Capsule endoscopy is a reasonable alternative investigation in exploration of chronic gastrointestinal blood loss, but is best kept as a second-line test in patients with other symptoms.

Evolving role of MRI in Crohn's disease

MR enterography is playing an evolving role in the evaluation of small bowel Crohn's disease (CD). Standard MR enterography includes a combination of rapidly acquired T2 sequence, balanced steady-state acquisition, and contrast enhanced T1-weighted gradient echo sequence. The diagnostic performance of these sequences has been shown to be comparable, and in some respects superior, to other small bowel imaging modalities. The findings of CD on MR enterography have been well described in the literature. New and emerging techniques such as diffusion-weighted imaging (DWI), dynamic contrast enhanced MRI (DCE-MRI), cinematography, and magnetization transfer, may lead to improved accuracy in characterizing the disease. These advanced techniques can provide quantitative parameters that may prove to be useful in assessing disease activity, severity, and response to treatment. In the future, MR enterography may play an increasing role in management decisions for patients with small bowel CD; however, larger studies are needed to validate these emerging MRI parameters as imaging biomarkers.

Update imaging in inflammatory bowel diseases

Imaging is a central component of the diagnostic process in inflammatory bowel diseases. This review summarizes the recent progress of various most commonly used imaging modalities including computed tomography enterography, magnetic resonance enterography and capsule endoscopy. Advantages and disadvantages of each imaging protocol in suspected and established inflammatory bowel diseases are reviewed and brought into context in proposed diagnostic algorithms.

CT and MR enterography in evaluating small bowel diseases: when to use which modality?

MR and CT techniques optimized for small bowel imaging are playing an increasing role in the evaluation of small bowel disorders. Several studies have shown the advantages of these techniques over traditional barium fluoroscopic examinations due to improvements in spatial and temporal resolution combined with improved bowel distending agents. The preference of MR vs. CT has been geographical and based on expertise and public policy. With the increasing awareness of radiation exposure, there has been a more global interest in implementing techniques that either reduce or eliminate radiation exposure. This is especially important in patients with chronic diseases such as inflammatory bowel disease who may require multiple studies over a lifetime or in studies that require sequential imaging time points such as in assessment of gastrointestinal motility. MRI has many properties that make it well suited to imaging of the small bowel: the lack of ionizing radiation, the improved tissue contrast that can be obtained by using a variety of pulse sequences, and the ability to perform real time functional imaging. Moreover, MR modalities allow visualization of the entire bowel, without overlapping bowel loops, as well as the detection of both intra- and extraluminal abnormalities.The intra- and extraluminal MR findings, combined with contrast enhancement and functional information, help to make an accurate diagnosis and consequently characterize small bowel diseases.

Sensitivity and specificity of magnetic resonance enterography in the clinical management of fistulizing Crohn's disease

BACKGROUND

High diagnostic accuracy is reported for magnetic resonance enterography (MRE) in Crohn's disease (CD), but few studies have evaluated its role in abdominal fistulae. The primary aim of this study was to assess the reliability of MRE in the identification of internal fistulae in CD.

METHODS

One hundred and eighty-six patients with moderate CD (CD Activity Index : 250-400) were prospectively selected from the inflammatory bowel disease clinic of Parma University Hospital. Eligible patients had already undergone nutritional screening, pancolonoscopy, and computed tomography enterography (CTE) in the month before enrollment. MRE was performed according to the study protocol. Additional fluoroscopic contrast-enhanced studies or surgical evaluation were used for discordance between CTE and MRE results. A consensus committee resolved equivocal findings. Surgical findings and/or fluoroscopic contrast-enhanced studies together with the clinical data were considered the composite "reference standard" to which the results of MRE were compared.

RESULTS

MRE identified 22 internal fistulae in 21 patients (11%), of whom 4 (19%) also had perianal fistulae and found 7 abscesses (33%). Forty-one (22%) additional patients with perianal fistulae were identified. Thirteen patients (57%) with internal fistulae required enteral nutrition support. No statistically significant differences were found between MRE and CTE in fistula detection. There was also no significant difference between MRE and the composite diagnosis in those who underwent surgery (n = 8) and/or contrast-enhanced studies (n = 7).

CONCLUSIONS

CTE and MRE accurately detect internal fistulae in CD. MRE is preferable because it avoids radiation. Reliable identification of internal fistulae by MRE should permit earlier and improved treatment.

Small Bowel Imaging: Clinical Applications of the Different Imaging Modalities—A Comprehensive Review

In the last years, MR and CT techniques have been optimized for small bowel imaging and are playing an increasing role in the evaluation of small bowel disorders. In comparison to traditional barium fluoroscopic examinations, spatial and temporal resolution is now much more improved partially thanks to modern bowel distending agents. However, there is a global interest in implementing techniques that either reduce or eliminate radiation exposure. This is especially important in patients with chronic diseases such as inflammatory bowel disease who may require multiple studies over a lifetime. Owing to the excellent soft tissue contrast, direct multiplanar imaging capabilities, new ultrafast breath-holding pulse sequences, lack of ionizing radiation, and availability of a variety of oral contrast agents, MR is well suited to play a critical role in the imaging of small bowel disorders.

Impact of magnetic resonance enterography in the management of small bowel Crohn's disease

INTRODUCTION

Magnetic resonance enterography (MRE) is a relatively new imaging modality that involves small bowel distension with orally administered fluid. Few studies have assessed its impact on patient management.

AIM

The aim of this study was to determine whether MRE influenced the management of patients with established small bowel Crohn's disease (CD).

MATERIALS AND METHODS

From a prospectively maintained database of patients with inflammatory bowel disease, we identified patients with small bowel CD who underwent MRE between January 2007 and December 2010. The results of the MRE and subsequent changes in patient management within 1 month were evaluated.

RESULTS

Thirty women and 27 men with CD were included. Seven patients (12%) had a normal MRE. Forty-two of 57 (74%) patients had a change in management, and 41/50 (82%) patients with an abnormal MRE had changes in management (P<0.0008). After MRE, 20/42 (47%) patients had surgery and 22/42 (53%) had changes in medical treatment. Patients with stricturing disease had more surgical intervention (P=0.02), and patients with active disease on MRE had more medical intervention (P=0.0001). Patients with two or more abnormalities on MRE had more surgery compared with medical therapy (P=0.02).

CONCLUSION

The majority of patients with small bowel CD had a change in management as a result of the MRE. Because of its high clinical impact on patient management, MRE should become one of the preferred methods of small bowel evaluation in CD. Specific MRE findings may help to stratify treatment options, however, further work is required to validate this.

Assessment of disease behavior in patients with Crohn's disease by MR enterography

BACKGROUND

Magnetic resonance imaging (MRI) of the bowel is an increasingly used modality to evaluate patients with Crohn's disease. The Montreal classification of the disease behavior is considered as an excellent prognostic and therapeutic parameter for these patients. In our study, we correlated the behavior assessment performed by a radiologist based on MRI with the surgeons' clinical assessment based on the assessment during abdominal surgery.

METHODS

We evaluated 76 patients with Crohn's disease, who underwent bowel resection and had an MRI within 4 weeks before surgery. Radiological behavior assessment was performed by 2 radiologists based on MRI. Behavior was classified into B1 (nonstricturing and nonpenetrating), B2, and B3 (penetrating) disease. Surgical assessment was done by the same surgeon, who performed all bowel resections, based on intraoperative findings and histologic results.

RESULTS

The surgical assessment identified 4 patients (5%) as B1, 16 patients (21%) as B2, and 56 patients (74%) as B3. In 97% (n = 74) of all patients, the intraoperative and radiological assessment were identical with interobserver agreement of 0.937. In one case, B2 was radiological considered as B1, and in another case, B3 was diagnosed as B2. The diagnosis of a stricture had the highest sensitivity of 96%, whereas the detection of inflammatory mass showed the lowest sensitivity of 81%. Abscesses had the lowest positive predictive value of 68% with a specificity of 88%. Best correlation was found for fistulae (0.895).

CONCLUSIONS

MRI represents an excellent imaging modality to correctly assess the Montreal classification-based disease behavior in patients scheduled for bowel resection with Crohn's disease.

Is magnetic resonance imaging a reliable diagnostic tool in the evaluation of active Crohn's disease in the small bowel?

GOALS

To evaluate the overall diagnostic accuracy of magnetic resonance imaging (MRI) in assessing the activity of Crohn's disease (CD) in the small bowel.

BACKGROUND

Cross-sectional imaging techniques are playing an increasing role in the evaluation of suspected CD. Advantages of MRI include a lack of ionizing radiation, the ability to provide dynamic information regarding bowel distention and motility, improved soft-tissue contrast, and a relatively safe intravenous contrast agent profile.

STUDY

Two reviewers searched MEDLINE, EMBASE, and other electronic databases to identify studies in which MRI imaging was evaluated for assessing the activity of CD in the small bowel from January 2001 to September 2011. Bivariate random-effects meta-analytic methods were used to estimate summary, sensitivity, specificity, and receiver operating characteristic curves.

RESULTS

MRI had a pooled sensitivity of 0.87 [95% confidence interval (CI): 0.77, 0.93] and a pooled specificity of 0.91 (95% CI: 0.81, 0.96). Overall, likelihood ratio (LR)+ was 9.5 (95% CI: 4.4, 20.6) and LR- was 0.14 (95% CI: 0.08, 0.26). In patients with high pretest probabilities, MRI enabled confirmation of active CD; in patients with low pretest probabilities, MRI enabled exclusion of active CD. Worst-case-scenario (pretest probability, 50%) posttest probabilities were 90% and 13% for positive and negative MRI results, respectively.

CONCLUSIONS

A limited number of small studies suggest that MRI has high sensitivity and specificity for diagnosis of active CD in the small bowel; MRI will likely also prove to be suitable as the primary modality for active CD imaging surveillance.

Imaging of pediatric patients with inflammatory bowel disease

OBJECTIVE

The goal of this review is to examine the current imaging literature and develop basic imaging guidelines for evaluation of children with inflammatory bowel disease (IBD). The three following typical clinical scenarios in the imaging evaluation of IBD are considered: patient with an initial diagnosis of suspected IBD, the goals being to determine disease extent and severity and to differentiate Crohn disease from ulcerative colitis; patient with known IBD presenting with new acute symptoms (fever, peritonitis, leukocytosis) requiring urgent evaluation; and patient with known IBD presenting with nonacute symptomatic recurrence (abdominal pain, diarrhea), the goals being to assess the efficacy of the current treatment and to evaluate the possible need for additional medical or surgical intervention.

CONCLUSION

Imaging of pediatric patients with IBD must balance considerations of diagnostic accuracy against concerns about patient exposure to ionizing radiation and tolerance of the imaging technique. The imaging modality chosen depends on the clinical presentation and expected pathologic finding.

Small bowel imaging with MRI

Magnetic resonance imaging (MRI) has evolved as a powerful tool for the assessment of the small bowel. Strengths of MRI include the superb soft-tissue contrast, lack of radiation exposure, and the implementation of fast scanning techniques. Clinically relevant findings such as inflammation and tumor disease can be well-depicted. We describe in this article current techniques of small bowel MRI including its implementation and clinical outcome in comparison to other radiological and endoscopic procedures.

MR imaging of the small bowel

Small-bowel radiology has undergone dramatic changes in the past 2 decades. Despite important recent advances in small-bowel endoscopy, radiologic imaging remains important for patients suspected of having or with established small-bowel disease. Cross-sectional imaging techniques (computed tomography and magnetic resonance [MR] imaging), used to investigate both extraluminal abnormalities and intraluminal changes, have gradually replaced barium contrast examinations, which are, however, still used to examine early mucosal disease. MR imaging techniques clearly highlight endoluminal, mural and extramural enteric details and provide vascular and functional information, thereby enhancing the diagnostic value of these techniques in small-bowel diseases. Two MR imaging based techniques are currently utilized: MR enteroclysis and MR enterography. In enteroclysis, enteric contrast material is administered through a nasoenteric tube, whereas in enterography, large volumes of enteric contrast material are administered orally. MR enteroclysis ensures consistently better luminal distention than does MR enterography in both the jejunum and the ileum and more accurately depicts endoluminal abnormalities and early disease, particularly at the level of the jejunal loops. Moreover, MR enteroclysis provides a high level of accuracy in the diagnosis and exclusion of small-bowel inflammatory and neoplastic diseases and can be used for the first radiologic evaluation, while MR enterography may effectively be used to follow up both Crohn disease patients without jejunal disease and in pediatric patients where nasogastric intubation might be a problem. MR enteroclysis may also reveal subtle transition points or an obstruction in the lower small bowel, which may escape detection when more routine methods, including enterography, are used. MR imaging offers detailed morphologic information and functional data of small-bowel diseases and provides reliable evidence of normalcy, thereby allowing the diagnosis of early or subtle structural abnormalities and guiding treatment and decisions in patient care.