MRI evaluation of inflammatory activity in Crohn's disease

Contrast agents for MR enterography

Magnetic resonance enterography is primarily indicated for inflammatory bowel diseases. The study of the gastrointestinal tract using MRI has become feasible due to the emergence of ultrafast sequences with higher spatial resolution and phased-array coils enabling wider fields of view. However, to ensure the quality of the examination, it is essential to have prior preparation with oral or rectal contrast to distend the lumen and improve the definition of the intestinal wall. These contrast agents can be positive, negative or biphasic, depending on the signal intensity they induce in the intestinal lumen. Most commonly used biphasic contrasts agents behave as hyperintense in T2 and hypointense in T1. Achieving a "black" intestinal lumen in 3D T1-weighted sequences with intravenous contrast injection is crucial for mucosal assessment and parietal enhancement. Although more cost-effective and accessible, biphasic agents like PEG and mannitol are relatively discomforting for patients. While negative agents are preferred, they are currently unavailable. The purpose of this article is to review the different types of contrast agents mentioned in the literature and their application in intestinal resonance, analyzing the effects they generate on the image, their possible indications and associated limitations.

Evaluation of 3D MRI for early detection of bone edema associated with apical periodontitis

OBJECTIVES

To detect and evaluate early signs of apical periodontitis using MRI based on a 3D short-tau-inversion-recovery (STIR) sequence compared to conventional panoramic radiography (OPT) and periapical radiographs in patients with apical periodontitis.

MATERIALS AND METHODS

Patients with clinical evidence of periodontal disease were enrolled prospectively and received OPT as well as MRI of the viscerocranium including a 3D-STIR sequence. The MRI sequences were assessed for the occurrence and extent of bone changes associated with apical periodontitis including bone edema, periradicular cysts, and dental granulomas. OPTs and intraoral periapical radiographs, if available, were assessed for corresponding periapical radiolucencies using the periapical index (PAI).

RESULTS

In total, 232 teeth of 37 patients (mean age 62±13.9 years, 18 women) were assessed. In 69 cases reactive bone edema was detected on MRI with corresponding radiolucency according to OPT. In 105 cases edema was detected without corresponding radiolucency on OPT. The overall extent of edema measured on MRI was significantly larger compared to the radiolucency on OPT (mean: STIR 2.4±1.4 mm, dental radiograph 1.3±1.2 mm, OPT 0.8±1.1 mm, P=0.01). The overall PAI score was significantly higher on MRI compared to OPT (mean PAI: STIR 1.9±0.7, dental radiograph 1.3±0.5, OPT 1.2±0.7, P=0.02).

CONCLUSION

Early detection and assessment of bone changes of apical periodontitis using MRI was feasible while the extent of bone edema measured on MRI exceeded the radiolucencies measured on OPT.

CLINICAL RELEVANCE

In clinical routine, dental MRI might be useful for early detection and assessment of apical periodontitis before irreversible bone loss is detected on conventional panoramic and intraoral periapical radiographs.

Role of MR enterography versus ileo-colonoscopy in the assessment of inflammatory bowel diseases

Background

Inflammatory bowel disease (IBD) is widespread and rapidly rising in developing countries. It remains a significant issue in Western culture with a prevalence of more than 0.3%. Symptom control has been the only focus of treatment before the discovery that many individuals with IBD continue to have disease activity even in the absence of clinical symptoms. Therefore, treatment goals now include establishing clinical remission, steroid-free remission, and mucosal healing, which may eventually be complemented by transmural healing in cross-sectional imaging modalities. Magnetic resonance enterography (MRE), computed tomography enterography, and small-bowel ultrasound are now reliable methods for staging intramural lesions and extramural consequences in CD and for determining disease activity and severity. Recently literature suggests the incorporation of (MRE) for periodic reevaluation of IBD patients, as it offers small-bowel, colonic, and extra-enteric assessment as well as monitors the response to the anti-inflammatory therapy. The purpose of the current study was to compare MRE with ileo-colonoscopy findings in the diagnosis of IBD features, specifically Crohn's disease, and ulcerative colitis, as well as in the detection of disease exacerbation (Activity).

Results

This study used MRE and ileo-colonoscopy to assess chronic inflammatory bowel disease patients; the patient population (n = 30) was made up of (14/30, 46.7%) females and (16/30, 53.3%) males, with a mean age of 32 ± SD 13 years. MRE alone detected lymphadenopathy in 73.3% of patients, and mural thickening with a mean of 4.1 ± SD 5.1 mm. It has detected mucosal enhancement with 80% sensitivity and 60% specificity. However, it was unable to detect mucosal erosions or ulceration.

Conclusions

MRE is sensitive, inexpensive, noninvasive, and radiation-free for inflammatory bowel disease detection, with 86.7% diagnostic accuracy for affected areas. Unlike ileo-colonoscopy, it could examine the entire small intestine, precisely measure the affected loop, and detect activity signs such as mural thickening and lymphadenopathy. Only ileo-colonoscopy could detect mucosal degradation and superficial ulcers. IBD treatment protocols should incorporate MRE for small-bowel, colonic, and extra-enteric assessment, monitoring of disease activity, and anti-inflammatory therapy response.

Comparison of Magnetic Resonance Enterography Global Score (MEGS) with indices of Crohn's disease activity in South Asian population

PURPOSE

Assessment of disease activity in Crohn's helps predict important clinical outcomes. Among the various modalities available to assess disease activity, magnetic resonance enterography (MRE) is considered a safe and reliable imaging option. Various MRE-based scoring systems have been developed to measure disease activity, one of which being the MRE global score (MEGS). We aimed to correlate MEGS with some of the important indices of Crohn's disease activity.

METHODOLOGY

Crohn's disease patients referred for MRE were included in the study. Along with demographic profile and relevant investigations, MRE parameters related to MEGS were also assessed.

RESULT

A total of 47 patients were recruited for the study. Their median age was 34 years (range 18-68 years), and male:female ratio was 16:31. There was modest positive correlation between MEGS and faecal calprotectin (r = 0.3, p = 0.04), CRP level (r = 0.34, p = 0.02) and Harvey Bradshaw index (r = 0.3, p = 0.043), respectively. However, there was strong correlation between segmental MEGS and Simple Endoscopic Score in those with terminal ileal disease (r = 0.81, p < 0.001). Mural thickness was the only MRE parameter that correlated with active disease (OR - 1.35, 95% CI 1.01, 1.81, p = 0.041) on multivariate analysis. There was moderate inter-observer agreement (Lin's r = 0.78, p < 0.001).

CONCLUSION

MEGS showed modest correlation with indices of Crohn's disease activity which corroborates the complementary role of MRE in management of such patients.

Magnetic resonance imaging (MRI) for diagnosis of acute appendicitis

BACKGROUND

Appendicitis remains a difficult disease to diagnose, and imaging adjuncts are commonly employed. Magnetic resonance imaging (MRI) is an imaging test that can be used to diagnose appendicitis. It is not commonly regarded as a first-line imaging test for appendicitis, but the reported diagnostic accuracy in some studies is equivalent to computed tomography (CT) scans. As it does not expose patients to radiation, it is an attractive imaging modality, particularly in women and children.

OBJECTIVES

The primary objective was to determine the diagnostic accuracy of MRI for detecting appendicitis in all patients. Secondary objectives: To investigate the accuracy of MRI in subgroups of pregnant women, children, and adults. To investigate the potential influence of MRI scanning variables such as sequences, slice thickness, or field of view.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase until February 2021. We searched the references of included studies and other systematic reviews to identify further studies. We did not exclude studies that were unpublished, published in another language, or retrospective.

SELECTION CRITERIA

We included studies that compared the outcome of an MRI scan for suspected appendicitis with a reference standard of histology, intraoperative findings, or clinical follow-up. Three study team members independently filtered search results for eligible studies.

DATA COLLECTION AND ANALYSIS

We independently extracted study data and assessed study quality using the Quality Assessment of Studies of Diagnostic Accuracy - Revised (QUADAS-2) tool. We used the bivariate model to calculate pooled estimates of sensitivity and specificity.

MAIN RESULTS

We identified 58 studies with sufficient data for meta-analysis including a total of 7462 participants (1980 with and 5482 without acute appendicitis). Estimates of sensitivity ranged from 0.18 to 1.0; estimates of specificity ranged from 0.4 to 1.0. Summary sensitivity was 0.95 (95% confidence interval (CI) 0.94 to 0.97); summary specificity was 0.96 (95% CI 0.95 to 0.97). Sensitivity and specificity remained high on subgroup analysis for pregnant women (sensitivity 0.96 (95% CI 0.88 to 0.99); specificity 0.97 (95% CI 0.95 to 0.98); 21 studies, 2282 women); children (sensitivity 0.96 (95% CI 0.95 to 0.97); specificity 0.96 (95% CI 0.92 to 0.98); 17 studies, 2794 children); and adults (sensitivity 0.96 (95% CI 0.93 to 0.97); specificity 0.93 (95% CI 0.80 to 0.98); 9 studies, 1088 participants), as well as different scanning techniques. In a hypothetical cohort of 1000 patients, there would be 12 false-positive results and 30 false-negative results. Methodological quality of the included studies was poor, and the risk of bias was high or unclear in 53% to 83% of the QUADAS-2 domains.

AUTHORS' CONCLUSIONS

MRI appears to be highly accurate in confirming and excluding acute appendicitis in adults, children, and pregnant women regardless of protocol. The methodological quality of the included studies was generally low due to incomplete and low standards of follow-up, so summary estimates of sensitivity and specificity may be biased. We could not assess the impact and direction of potential bias given the very low number of high-quality studies. Studies comparing MRI protocols were few, and although we found no influence of MRI protocol variables on the summary estimates of accuracy, our results do not rule out that some MRI protocols are more accurate than others.

Magnetic resonance imaging as a diagnostic tool for periodontal disease: A prospective study with correlation to standard clinical findings-Is there added value?

AIM

To evaluate the correlation between standard clinical findings, radiographic (OPT) and magnetic resonance imaging (MRI) as well as to assess whether MRI is capable of providing additional information related to the severity and extent of periodontal disease.

METHODS

42 patients with generalized periodontitis received pre-interventional MRI scans. These were compared to MR images of a periodontal healthy control group (n = 34). The extent of the osseous oedema, detected by MRI, was set in correlation with clinical periodontitis-associated findings.

RESULTS

A highly significant correlation between bone oedema and clinical testings such as probing depth (p < 0.0001) and bleeding on probing (p < 0.0001) was revealed. The oedema exceeded the extent of demineralized bone. Patients with a positive BOP test showed a 2.51-fold increase in risk of already having a bone oedema around the respective tooth even if probing depth was ≤3 mm (logistic binary regression analysis, OR 2.51; 95% CI: 1.54-4.11; p < 0.0001).

CONCLUSION

MRI findings correlated with standard clinical findings, and MRI was able to depict intraosseous changes before any osseous defect had occurred.

State of the Art MR Enterography Technique

ABSTRACT

Magnetic resonance enterography (MRE) is a well-established imaging technique that is commonly used for evaluating a variety of bowel diseases, most commonly inflammatory bowel disease which is increasing in prevalence. Inflammatory bowel disease is composed of 2 related, but distinct disease entities: Crohn disease (CD) and ulcerative colitis. In ulcerative colitis, inflammation is generally limited to the mucosa and invariably involves the rectum, and often the more proximal colon. CD is typified by transmural inflammation with skip lesions occurring anywhere from the mouth to anus, but characteristically involves the terminal ileum. The transmural involvement of CD may lead to debilitating ulceration and, ultimately, development of sinus tracts, which can be associated with abscesses and fistulae as extraenteric manifestations of the disease. Because much of the small bowel and extraenteric disease cannot be adequately assessed with conventional endoscopy, imaging plays a crucial role in initial diagnosis and follow-up. MRE does not use ionizing radiation which is important for these patients, many of which present earlier in life and may require multiple imaging examinations. In this article, we review the clinical indications, patient preparation, and optimal technique for MRE. We also discuss the role and proper selection of intravenous gadolinium-based contrast material, oral contrast material, and antiperistaltic agents, including pediatric considerations. Finally, we review the recommended and optional pulse sequence selection, including discussion of a "time-efficient" protocol, reviewing their utility, advantages, and limitations. Our hope is to aid the radiologist seeking to develop a robust MRE imaging program for the evaluation of bowel disease.

ACR Appropriateness Criteria® Crohn Disease

Three common clinical scenarios involving use of imaging in Crohn disease are covered. These include the initial evaluation of Crohn disease when the diagnosis has not been previously established, the evaluation for anticipated exacerbation of known disease, and the evaluation of disease activity during therapy monitoring. The appropriateness of a given imaging modality for each scenario is rated as one of three categories (usually appropriate, may be appropriate, usually not appropriate) to help guide evaluation. Pediatric presentation of Crohn disease and the appropriateness of imaging are not covered in this 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.

Can diffusion weighted imaging be used as an alternative to contrast-enhanced imaging on magnetic resonance enterography for the assessment of active inflammation in Crohn disease?

The present study aimed to investigate the potential use of T2-weighted sequences with diffusion weighted imaging (DWI) in magnetic resonance (MR) enterography instead of conventional contrast-enhanced MR imaging (MRI) sequences for the evaluation of active inflammation in Crohn disease.Two-hundred thirteen intestinal segments of 43 patients, who underwent colonoscopy within 2 weeks before or after MR enterography were evaluated in this retrospective study. DWI sequences, T2-weighted sequences, and contrast-enhanced T1-weighted sequences were acquired in the MR enterography scan after cleaning of the bowel and using an oral contrast agent. First, the intestinal segments that had active inflammation in MR enterography were qualitatively evaluated in T2-weighted and contrast-enhanced T1-weighted sequences and then MR activity index (MRAI 1) and MRAI 2 were formed with and without contrast-enhanced sequences in 2 separate sessions.The correlation coefficient between contrast enhanced and DWI MR enterography scores (MRAI 1 and MRAI 2) of intestinal inflammation was 0.97 for all segments. In addition, separate correlation coefficients were calculated for terminal ileum, right colon, transverse colon, left colon, and rectum, and there was a strong correlation between the MRAI 1 and MRAI 2 scores of each segment (r = 0.86-0.97, P < .001). On the other hand, MR enterography had 88.7% sensitivity, 97.9% specificity, 95.5% positive predictive value, 94.6% negative predictive value, and 94.8% accuracy for detection of active inflammation in all intestinal segments in Crohn disease.DWI and T2-weighted sequences acquired with cleaning of the bowel can be used instead of contrast-enhanced MRI sequences for the evaluation of active inflammation in Crohn disease.

Crohn's disease activity before and after medical therapy evaluated by MaRIA score and others parameters in MR Enterography

AIM

Aim of this retrospective study is to evaluate the response to therapy in Crohn's disease (CD) patients studied by MR Enterography (MRE) in comparison with Harvey Bradshaw Index (HBI).

METHODS

One hundred and sixty patients with histological proved CD have undergone MRE in the last years. Forty-six patients who repeated MRE after medical therapy within six months were selected for the study. Magnetic Resonance Index of Activity (MaRIA) was evaluated for each patient and used to define the MR judgment. In MRE we also evaluated wall thickening, longitudinal extension of wall thickening, presence of stratified mural hyperenhancement and extraintestinal signs. The clinical response to therapy was judged based on HBI and classified as improved, worsened or stable disease. Clinical judgment was correlated with MRE findings and the agreement was analysed using the Cohen Kappa test.

RESULTS

Among 46 enrolled patients, 18 (39%) improved clinically, 4 (10%) worsened, 24 (51%) remained stable. MR judgment was in agreement with clinical assessment in 33 patients (72%), showing moderate significant concordance (Kappa = 0.49; p < 0.01). No agreement was observed in 13 (28%) patients. Moreover, clinical improvement was significantly correlated to reduction of wall thickening, reduction of longitudinal extension of the disease and reduction of engorged vasa recta (p < 0.05). Worsening conditions were significantly correlated to increased wall thickening (p = 0.05).

CONCLUSIONS

MRE is useful in evaluating the response to therapy in CD patients.

Imaging Inflammation and Infection in the Gastrointestinal Tract

A variety of seemingly non-specific symptoms manifest within the gastrointestinal (GI) tract, particularly in the colon, in response to inflammation, infection, or a combination thereof. Differentiation between symptom sources can often be achieved using various radiologic studies. Although it is not possible to provide a comprehensive survey of imaging gastrointestinal GI tract infections in a single article, the purpose of this review is to survey several topics on imaging of GI tract inflammation and infections. The review discusses such modalities as computed tomography, positron emission tomography, ultrasound, endoscopy, and magnetic resonance imaging while looking at up-an-coming technologies that could improve diagnoses and patient comfort. The discussion is accomplished through examining a combination of organ-based and organism-based approaches, with accompanying selected case examples. Specific focus is placed on the bacterial infections caused by Shigella spp., Escherichia coli, Clostridium difficile, Salmonella, and inflammatory conditions of diverticulitis and irritable bowel disease. These infectious and inflammatory diseases and their detection via molecular imaging will be compared including the appropriate differential diagnostic considerations.

Magnetic resonance enterography

Crohn's disease is a condition of chronic inflammation that may involve any part of the gastrointestinal tract, although it more frequently affects the terminal ileum. Longstanding inflammation may lead to several bowel complications including obstruction, stricture, fistula and abscesses which often necessitate surgery. Cross-sectional imaging methods such as computed tomography and magnetic resonance imaging are being utilized more frequently to assess mural and extramural inflammatory bowel disease manifestations. Magnetic resonance enterography (MRE) for assessment of small bowel is optimal because of absence of ionizing radiation, better soft tissue contrast, development of motion-free sequences and high resolution images. A typical protocol includes pre and postcontrast sequences utilizing an enteric contrast agent for adequate bowel distention and an antiperistaltic agent. Overall, MRE allows the evaluation of disease activity, extraenteric complication and response to therapy with a great impact on patient management. In this review we discuss the features of MRE from patient's preparation and exam protocol to pathological findings.

Early Predictors of the Long-term Response to Therapy in Patients With Crohn Disease Derived From a Time-Intensity Curve Analysis After Microbubble Contrast Agent Injection

OBJECTIVES

The aim of this study was to identify early predictors of the long-term response to therapy in patients with Crohn disease (CD) from time-intensity curves obtained after microbubble injection.

METHODS

One hundred fifteen consecutive patients with a proven diagnosis of CD involving the terminal ileal loop who were scheduled to begin pharmacologic therapy with biologics (infliximab or adalimumab) were scanned after sulfur hexafluoride-filled microbubble injection before the beginning and at the end of the sixth week of treatment. The absolute value and percentage change of each semiquantitative kinetic parameter (peak enhancement, time to peak enhancement, rise time, mean transit time, wash-in and wash-out rates, area under the curve [AUC] for the whole time-intensity curve, AUC during wash-in, AUC during wash-out, and wash-in perfusion index) as measured on the terminal ileal tract and adjacent reactive mesenteric fat were calculated from time-intensity curves. Patients were followed for at least 24 months with redetermination of the Crohn Disease Activity Index and with at least 1 endoscopy within 18 weeks after the beginning of pharmacologic treatment. The absolute values and percentage changes of kinetic parameters were assessed as potential predictors of the therapeutic outcome by a logistic regression analysis.

RESULTS

The study group included 66 male and 49 female patients (mean age ± SD, 45.76 ± 11 years). The pretreatment values and percentage changes of the peak enhancement, AUC, AUC during wash-in, and AUC during wash-out were found to be predictors (P < .05) of the long-term therapeutic outcome.

CONCLUSIONS

The analysis of time-intensity curves obtained after microbubble contrast agent injection provides early predictors of the long-term therapeutic outcome in patients with CD.

Advances in Imaging Specific Mediators of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is characterized by chronic remitting and relapsing inflammation of the lower gastrointestinal tract. The etiology underlying IBD remains unknown, but it is thought to involve a hypersensitive immune response to environmental antigens, including the microbiota. Diagnosis and monitoring of IBD is heavily reliant on endoscopy, which is invasive and does not provide information regarding specific mediators. This review describes recent developments in imaging of IBD with a focus on positron emission tomography (PET) and single-photon emission computed tomography (SPECT) of inflammatory mediators, and how these developments may be applied to the microbiota.

Magnetic Resonance Enterography for Inflammatory and Noninflammatory Conditions of the Small Bowel

Magnetic resonance enterography (MRE) is an effective noninvasive tool for evaluation of inflammatory and noninflammatory conditions of the small bowel. MRE allows for repeated evaluation of patients with Crohn disease without exposure to ionizing radiation, and can be used to assess disease status and direct management. MRE also allows evaluation of neoplastic and other nonneoplastic conditions of the small bowel. Adequate patient preparation and acquisition techniques are required for optimal image quality.

Role of contrast-enhanced ultrasound in evaluation of the bowel

Contrast-enhanced ultrasound (CEUS) of the gastrointestinal tract provides vascular information helpful for characterizing masses and other pathologies in and around the bowel, similar to contrast applications in other solid organs. However, the use of microbubble contrast agents for the bowel provides additional unique contributions as it gives both subjective and objective information about mural and mesenteric blood flow, invaluable for the determination of disease activity in those many patients affected by inflammatory bowel disease (IBD). IBD is a lifelong chronic disease and has its peak age of onset in adolescence or young adult life. Today, we have moved away from treating patient’s symptoms and strive instead to alter the course of disease by obtaining mucosal healing. Expensive and aggressive biologic therapies and lack of agreement of patient’s symptoms with their disease activity and complications necessitate frequent imaging surveillance, which must be safe, readily available, inexpensive, and effective. Ultrasound with the benefit of contrast enhancement meets these requirements and is shown in meta-analysis to be equivalent to CT and MRI scans for these indications.

Differentiation of Inflammatory from Fibrotic Ileal Strictures among Patients with Crohn's Disease through Analysis of Time-Intensity Curves Obtained after Microbubble Contrast Agent Injection

The aim of the study described here was to assess whether the analysis of time-intensity curves obtained after microbubble contrast agent injection could differentiate inflammatory from fibrotic ileal strictures among patients with Crohn's disease. Sixty-five consecutive patients (40 male and 25 female; mean age ± SD, 42.2 ± 12.22 y) with stricture of the terminal ileal loop from Crohn's disease were scanned after microbubble injection. Time-intensity curves were obtained from quantitative analysis, and peak enhancement, rise time, time to peak, area under the time-intensity curve (AUC), AUC during wash-in (AUCWI) and AUC during wash-out (AUCWO) were compared between patients with inflammatory strictures and patients with fibrotic strictures. Inflammatory (n = 40) and fibrotic (n = 25) strictures differed (p < 0.05) in peak enhancement, wash-in rate, wash-in perfusion index, AUC, AUCWI and AUCWO. The quantitative analysis of small bowel wall contrast enhancement after microbubble contrast agent injection may differentiate inflammatory from fibrotic ileal strictures in patients with Crohn's disease.

Quantification of inflammatory activity in patients with Crohn's disease using diffusion weighted imaging (DWI) in MR enteroclysis and MR enterography

Background Individual studies have demonstrated the potential of diffusion-weighted magnetic resonance imaging (DWI-MRI) for identifying inflamed bowel segments. However, these studies were conducted with rather small patient cohorts and in most cases by means of MR enterography only. Purpose To demonstrate the feasibility of detecting inflamed bowel segments in a large collective of patients with Crohn's disease using DWI in MR enteroclysis and MR enterography and to compare the results of both techniques, also considering clinical parameters by means of the Harvey-Bradshaw Index (HBI). Material and Methods Ninety-six patients underwent MRI enteroclysis and 35 patients MR enterography, both with additional DWI. The HBI as well as apparent diffusion coefficients (ADC) in areas of inflamed and normal bowel wall were determined. Thus resulting in 208 bowel segments that were visualized and subsequently statistically analyzed. Results There were no significant differences in ADC values in MR enteroclysis and MR enterography ( P = 0.383 in inflammation, P = 0.223 in normal wall). Areas of inflammation showed statistically highly significant lower ADC values than areas of normal bowel wall ( P < 0.001). An ADC threshold of 1.56 × 10^-3mm²/s can distinguish between normal and inflamed bowel segments with a sensitivity of 97.4% and a specificity of 99.2%. A highly significant correlation could be shown between ADC and HBI values ( P = 0.001). Conclusion DWI-MRI facilitates recognition of inflamed bowel segments in patients with Crohn's disease and the ADC values show an excellent correlation to the HBI. There were no significant differences in ADC values in MR enteroclysis and MR enterography. An ADC threshold of 1.56 × 10^-3mm²/s differentiates between normal and inflamed bowel wall.

Magnetic resonance enterography in Crohn’s disease: How we do it and common imaging findings

Crohn’s disease (CD) is a chronic inflammatory disease of the gastrointestinal tract, with unpredictable clinical course by phases of relapses alternating with other of quiescence. The etiology is multifactorial and is still not completely known; globally the westernization of lifestyle is causing an increasing incidence of CD, with peak age of 20-30 years. The diagnostic workup begins with the evaluation of the clinical history, physical examination and laboratory tests. However, the clinical assessment is subjected interobserver variability and, occasionally, the symptoms of acute and chronic inflammation may be indistinguishable. In this regards, the role of magnetic resonance (MR) enterography is crucial to determine the extension, the disease activity and the presence of any complications without ionizing radiations, making this method very suitable for young population affected by CD. The purpose of this review article is to illustrate the MR enterography technique and the most relevant imaging findings of CD, allowing the detection of small bowel involvement and the assessment of disease activity.

T2 relaxation mapping MRI of healthy and inflamed gingival tissue

OBJECTIVES

To investigate the use and reproducibility of MRI transverse relaxation time (T₂) mapping in healthy and inflamed gingivae.

METHODS

21 subjects were recruited into 2 groups: those without evidence of gingivitis ("healthy"; n = 11, age 24.0 ± 3.66 years) by visual assessment and those with moderate to severe gingivitis ("gingivitis"; n = 10, age 28.9 ± 6.03 years) exhibited across the second mandibular premolar and first mandibular molar buccal gingivae. Subjects were imaged by MRI twice in a single day. Three T₂ weighted turbo spin-echo volumes with 0.25 × 0.25 × 0.8-mm³ resolution were acquired at echo times of 16, 32 and 48 ms for T₂ decay fitting. Image analysis was fully blinded; the two imaging sessions were not identifiable as coming from the same subject. Each imaging session had independent regions of interest drawn on the first echo image and applied to the calculated T₂ decay maps.

RESULTS

The coefficient of variation was low and similar in healthy and gingivitis populations: 6.10 and 5.25% populations, respectively, with 5.65% populations across both groups. Bland-Altman analysis revealed no bias (mean -2.93%; 95% confidence intervals -22.20 to 16.34%) between sessions. The intersession agreement was good (r = 0.744, ρ = 0.568, intraclass correlation coefficient = 0.68). T₂ mapping did not differentiate healthy from gingivitis groups. The mean T₂ value in the healthy group (63.7 ms) was similar to that of the gingivitis group (65.23 ms) (p = 0.30).

CONCLUSIONS

Mapping of the T₂ decay in the gingivae was a repeatable process; however, T₂ value alone did not differentiate those with clinical examination-determined gingivitis from those without signs of gingivitis.

Inter- and intraobserver agreement in computed tomography enterography in inflammatory bowel disease

AIM

To evaluate intra- and interobserver agreement in imaging features in inflammatory bowel disease and comparison with fecal calprotectin (FC) levels.

METHODS

Our institutional computed tomography enterography (CTE) database was retrospectively queried to identify patients who underwent CTE from January 2014 to June 2015. Patient inclusion criteria were confirmed inflammatory bowel disease (IBD) and FC collected < 4 mo after CTE without any change in clinical treatment or surgical treatment during this interval. The exclusion criterion was poor image quality. Two blinded abdominal radiologists, with 12 and 3 years of experience analyzed the CTE regarding localization (small bowel, colonic, both, or no disease detected); type of IBD (inflammatory, stenosing, fistulizing, > 1 pattern, or normal); and signs of active disease (present or absent). In 42 of 44 patients evaluated, routine CTE reports were made by one of the readers who re-evaluated the CTEs ≥ 6 mo later, to determine the intraobserver agreement. FC was considered a sign of disease activity when it was higher than 250 μg/g.

RESULTS

Forty-four patients with IBD (38 with Crohn’s disease and 6 with ulcerative colitis) were included. There was a moderate interobserver agreement regarding localization of IBD (κ = 0.540), type of disease (κ = 0.410) and the presence of active signs in CTE (κ = 0.419). There was almost perfect intraobserver agreement regarding localization, type and signs of active disease in IBD. The κ values were 0.902, 0.937 and 0.830, respectively. After a consensus between both radiologists regarding inflammatory activity in CTE, we found that 24 (85.7%) of 28 patients who were classified with active disease had elevated FC, and six (37.5%) of 16 patients without inflammatory activity in CTE had elevated FC (P = 0.003). The correlation between elevated FC and the presence of active disease in CTE was significant (κ = 0.495, P = 0.001).

CONCLUSION

We found almost perfect intraobserver and moderate interobserver agreement in the signs of active disease in CTE with concurrence of high FC levels.

In Vivo 19F MR Imaging Cell Tracking of Inflammatory Macrophages and Site-specific Development of Colitis-associated Dysplasia

Purpose To investigate whether the magnitude of in vivo fluorine 19 (¹⁹F) magnetic resonance (MR) imaging signal is associated with subsequent development of colitis-associated dysplasia after in situ fluorination of inflammatory macrophages in a mouse model of inflammatory bowel disease (IBD). Materials and Methods Experiments were approved by the institutional animal care and use committee. Mice in the experimental group (n = 10) were administered azoxymethane and dextran sulfate sodium to induce colitis-associated dysplasia. Five mice were in the noninduced control group. Animals were injected with a commercially available perfluorocarbon and were examined in vivo with an 11.7-T MR imager for up to 110 days. Colons were then harvested followed by high-spatial-resolution ex vivo MR imaging. Multiple colon segments with or without ¹⁹F signal were histologically graded and were correlated with ¹⁹F signal intensity by using a Spearman correlation test. The signal intensity in mice with colitis-associated dysplasia was compared with that in control mice with a two-tailed Mann-Whitney U test. Results Patchy distributions of ¹⁹F signal intensity in the colon wall were seen on in vivo and ex vivo images, representing chronic inflammation as shown by immunohistochemistry. Histologic scores of inflammation and site-specific development of colitis-associated dysplasia in the descending colon showed good correlation with normalized ¹⁹F signal intensity (r = 0.88, P = .033 for the ascending colon; r = 0.82, P = .006 for the descending colon). A significantly (P = .002) higher normalized ¹⁹F signal-to-noise ratio was found at sites that developed dysplasia (mean, 0.58 ± 0.09 [standard deviation]) as compared with sites that did not (mean, 0.17 ± 0.22). Conclusion ¹⁹F MR imaging cell tracking of macrophages can be used to assess local inflammation in a mouse model of IBD. The resulting local ¹⁹F signal intensity, representing the magnitude of inflammation, has a positive correlation with the development of colitis-associated dysplasia. ^© RSNA, 2016 Online supplemental material is available for this article.

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.

Value of Computerized Tomography Enterography in Predicting Crohn's Disease Activity: Correlation with Crohn's Disease Activity Index and C-Reactive Protein

Background

The accurate evaluation of Crohn’s disease activity is important for the treatment of the disease and for monitoring the response. Computerized tomography (CT) enterography is a useful imaging modality that reflects enteric inflammation, as well as extramural complications.

Objectives

The aim of this study was to evaluate the correlation between CT enterographic (CTE) findings of active Crohn’s disease and the Crohn’s disease activity index (CDAI) and C-reactive protein (CRP).

Patients and Methods

Fifty CT enterographies of 39 patients with Crohn’s disease in the small bowel were used in our study. The CDAI was assessed through clinical and laboratory variables. Multiple CT parameters, including mural hyperenhancement, mural thickness, mural stratification, comb sign, and mesenteric fat attenuation, were evaluated with a four-point scale. The presence or absence of enhanced lymph nodes, fibrofatty proliferation, sinus or fistula, abscess, and stricture were also assessed. Two gastrointestinal radiologists independently reviewed all CT images, and inter-observer agreement was examined. Correlations between CT findings, CRP, and CDAI were assessed using Spearman’s rank correlation and logistic regression analysis. To assess the predictive accuracy of the model, a receiver-operating characteristic curve analysis for the sum of CT enterographic scores was used.

Results

Mural hyperenhancement, mural thickness, comb sign, mesenteric fat density, and fibrofatty proliferation were significantly correlated with CDAI and CRP (P < 0.05). The binary logistic regression model demonstrated that mesenteric fat density, mural stratification, and the presence of enhanced lymph nodes (P < 0.05) had an influence on CDAI severity. The area under the receiver operating characteristic curve (AUROC) of the CTE index for predicting disease activity was 0.85. Using a cut-off value of 8, the sensitivity and negative predictive values were 95% and 94%, respectively.

Conclusion

Most CTE findings correlated with CDAI and CRP in patients with active Crohn’s disease.

Quantitative Contrast-Enhanced Ultrasound Parameters in Crohn Disease: Their Role in Disease Activity Determination With Ultrasound

OBJECTIVE

The primary objective of our study was to examine the association between contrast-enhanced ultrasound (CEUS) parameters and established gray-scale ultrasound with color Doppler imaging (CDI) for the determination of disease activity in patients with Crohn disease. Our secondary objective was to develop quantitative time-signal intensity curve thresholds for disease activity.

MATERIALS AND METHODS

One hundred twenty-seven patients with Crohn disease underwent ultrasound with CDI and CEUS. Reviewers graded wall thickness, inflammatory fat, and mural blood flow as showing remission or inflammation (mild, moderate, or severe). If both gray-scale ultrasound and CDI predicted equal levels of disease activity, the studies were considered concordant. If ultrasound images suggested active disease not supported by CDI findings, the ultrasound results for disease activity were indeterminate. Time-signal intensity curves from CEUS were acquired with calculation of peak enhancement (PE), and AUCs. Interobserver variation and associations between PE and ultrasound parameters were examined. Multiclass ROC analysis was used to develop CEUS thresholds for activity.

RESULTS

Ninety-six (76%) studies were concordant, 19 of which showed severe disease, and 31 (24%) studies were indeterminate. Kappa analyses revealed good interobserver agreement on grades for CDI (κ = 0.76) and ultrasound (κ = 0.80) assessments. PE values on CEUS and wall thickness showed good association with the Spearman rank correlation coefficient for the entire population (ρ = 0.62, p < 0.01) and for the concordant group (ρ = 0.70, p < 0.01). Multiclass ROC analyses of the concordant group using wall thickness alone as the reference standard showed cutoff points of 18.2 dB for differentiating mild versus moderate activity (sensitivity, 89.0% and specificity, 87.0%) and 23.0 dB for differentiating moderate versus severe (sensitivity, 90% and specificity, 86.8%). Almost identical cutoff points were observed when using ultrasound global assessment as the reference standard: using 18.2 dB to differentiate mild versus moderate activity yielded sensitivity of 89.2% and specificity of 90.9% and using 22.9 dB to differentiate moderate versus severe activity yielded sensitivity of 89.5% and specificity of 83.1%.

CONCLUSION

Quantitative CEUS parameters integrated into inflammatory assessments with ultrasound reduce indeterminate results and improve disease activity level determinations.

Detecting inflammation in the unprepared pediatric colon - how reliable is magnetic resonance enterography?

BACKGROUND

Pediatric inflammatory bowel disease frequently affects the colon. MR enterography is used to assess the small bowel but it also depicts the colon.

OBJECTIVE

To compare the accuracy of MR enterography and direct visualization at endoscopy in assessing the colon in pediatric inflammatory bowel disease.

MATERIALS AND METHODS

We included children with inflammatory bowel disease who had undergone both MR enterography and endoscopy, and we restrospectively assessed the imaging and endoscopic findings. We scored the colonic appearance at MR using a total colon score. We then compared scores for the whole colon and for its individual segments with endoscopy and histology.

RESULTS

We included 15 children. An elevated MR colonic segmental score predicted the presence of active inflammation on biopsy with a specificity of 90% (95% confidence interval [CI] 79.5-96.2%) and sensitivity of 60% (CI 40.6-77.3%); this compares reasonably with the predictive values for findings at colonoscopy - specificity 85% (CI 73.4-92.9%) and sensitivity 53.3% (CI 34.3%-71.6%). Accuracy did not change significantly with increasing bowel distension.

CONCLUSION

MR-derived scores had comparable accuracy to those derived during visualization at colonoscopy for detecting biopsy-proven inflammation in our patient group. MR enterography might prove useful in guiding biopsy or monitoring treatment response. Collapse of a colonic segment did not impair assessment of inflammation.

Identifying decreased peristalsis of abnormal small bowel segments in Crohn's disease using cine MR enterography: the frozen bowel sign

PURPOSE

The purpose of this study was to evaluate whether affected bowel in Crohn's disease patients can be identified by observing decreased peristalsis (frozen bowel sign) using cine balanced steady-state free precession (cine BSSFP) images.

MATERIALS AND METHODS

5 radiologists independently reviewed cine BSSFP sequences from randomized MR Enterography (MRE) exams for 30 normal and 30 Crohn's disease patients, graded overall small bowel peristalsis from slowest to fastest, and graded peristalsis for the most abnormal small bowel segment. Sensitivity and specificity of the frozen bowel sign for diagnosing Crohn's disease were calculated. T tests of the peristalsis difference between abnormal segments and overall small bowel were conducted.

RESULTS

For 5 readers, the sensitivity and specificity of cine BSSFP of the frozen bowel sign for diagnosing Crohn's disease ranged from 70% to 100% and 87% to 100%, respectively. There were significant differences in peristalsis between abnormal small bowel segments and the overall small bowel for Crohn's patients, but not in the overall small bowel between normal-MRE patients and Crohn's disease patients.

CONCLUSION

Abnormal Crohn's small bowel segments have significantly decreased peristalsis compared to normal small bowel, which can be identified using cine BSSFP sequences as the frozen bowel sign.

Value of diffusion-weighted imaging when added to magnetic resonance enterographic evaluation of Crohn disease in children

BACKGROUND

MR enterography is increasingly utilized for noninvasive evaluation of disease activity in young patients with Crohn disease and has great impact on clinical management. Diffusion-weighted imaging (DWI) is a rapid MR imaging technique that measures molecular diffusion of water and is sensitive to the inflammatory process; however, its value to MR enterography has not been rigorously evaluated.

OBJECTIVE

To determine whether the addition of DWI to MR enterography is helpful in evaluating Crohn disease activity in young patients when compared to a histological reference.

MATERIALS AND METHODS

In this single-institution retrospective study, we searched an imaging database for the period January 2010 to December 2012 to identify patients age 19 years and younger who had MR enterography with diffusion-weighted imaging (DWI). We used an electronic medical record search to identify those who had MR enterography and colonoscopy performed within 28 days of each other. All MR enterography scans were performed on a 1.5-T or 3-T clinical MR scanner with phased-array torso coil configuration using standard pulse sequences as well as axial DWI with b values of 50, 400 and 800. Bowel segments were evaluated for disease activity based on standard MR enterography sequences; in addition, segmental apparent diffusion coefficient (ADC) values were calculated based on DWI. Histological reference for disease activity was based on assessment for mucosal inflammatory changes on endoscopic biopsy. MR enterography and DWI evaluation were performed in a blinded fashion with respect to histological results.

RESULTS

We included imaging of 78 bowel segments from 27 patients (mean age 14.5 ± 3.02 years) with known Crohn disease in the study. The mean ADC for bowel segments with active disease was 1.56 ± 0.7 × 10(3) mm(2)/s compared with 2.58 ± 1.4 × 10(3) mm(2)/s for segments without active disease, a difference that was statistically significant (P < 0.01, Student's t-test). Using a threshold value of 2.0 × 10(3) mm(2)/s, DWI demonstrated lower accuracy (64.1%) but higher sensitivity (78.8%) for detecting active disease compared with standard MR enterography (69.2% and 54.6%, respectively). Combining DWI with MR enterography, using DWI as the initial screen and MR enterography afterward to reduce false negativity, led to a significant increase in accuracy (76.9%; P = 0.03, McNemar's test) compared with either imaging technique alone.

CONCLUSION

Although DWI does not perform as well as standard MR enterography for detection of active Crohn disease, the combination of DWI and MR enterography increases imaging accuracy for determining disease activity compared with either technique alone. These results indicate that DWI adds value to MR enterography and supports the incorporation of DWI into MR enterography protocols for evaluation of Crohn disease in young patients.

[Modern MRI of the small bowell]

CLINICAL METHODOLOGICAL ISSUES

The radiological diagnostics of diseases of the small intestine have undergone a great change in the last two decades. Through rapid progress with new treatments and an increasing therapeutic focus on transmural healing, a complete evaluation of the gastrointestinal tract is now crucial.

STANDARD RADIOLOGICAL METHODS

With the introduction of endoscopy, gastrointestinal imaging with a relatively high radiation exposure had only limited applications. The development of cross-sectional imaging allowed a much broader radiological evaluation of abdominal diseases. Due to rapid investigation techniques, excellent soft tissue contrast and the distinct advantage of eliminating exposure to radiation, magnetic resonance imaging (MRI) of the gastrointestinal tract has gained increasing importance. With sufficient filling of the intestinal lumen, simultaneous imaging of all the intestinal wall layers, the perienteric structures and associated abdominal pathologies is now possible.

METHODOLOGICAL INNOVATIONS

New MR sequences, such as diffusion-weighted sequences, dynamic contrast-enhanced sequences and MR fluoroscopy, enable the detection of morphological changes, with additional characterization of affected bowel loops as well as the assessment of functional pathologies with dynamic information about intestinal motility disturbances.

ACHIEVEMENTS

Recent guidelines of European radiological and gastroenterological organizations have confirmed the importance of cross-sectional imaging and particularly of MRI for diagnostics and follow-up in patients with Crohn's disease. Due to the possibility of assessment of all the layers of the intestinal wall and the presence of extramural complications, MRI has a significant impact on further therapeutic treatment in patients with inflammatory bowel disease.

PRACTICAL RECOMMENDATIONS

Especially in patients with inflammatory bowel disease, MR enterography and MR enteroclysis should be the methods of choice for the evaluation of small bowel pathologies because of radiation issues and the great diagnostic value they provide. A variety of MR sequences has enabled not only the detection but also the characterization of pathological changes of the small intestine, which are vital for further treatment of these patients.

Abdominal MRI without Enteral Contrast Accurately Detects Intestinal Fibrostenosis in Patients with Inflammatory Bowel Disease

Patients with inflammatory bowel disease (IBD) presenting for surgical evaluation require thorough small bowel surveillance as it improves accuracy of diagnosis (ulcerative colitis versus Crohn's) and differentiates those who may respond to nonoperative therapy, preserving bowel length. MRI has not been validated conclusively against histopathology in IBD. Most protocols require enteral contrast. This study aimed to 1) evaluate the accuracy of MRI for inflammation, fibrosis, and extraluminal complications and 2) compare MRI without enteral contrast to standard magnetic resonance enterography. Adults with Crohn's disease or ulcerative colitis who underwent abdominal MRI and surgery were retrospectively reviewed. Of 65 patients evaluated, 55 met inclusion criteria. Overall sensitivity and specificity of MRI for disease involvement localized by segment were 93 per cent (95% confidence interval = 89.4–95.0) and 95 per cent (95% confidence interval = 92.3–97.0), respectively (positive predictive value was 86%, negative predictive value was 98%). Sensitivity and specificity between MRI with and without oral and rectal contrast were similar (96% vs 91% and 99% vs 94%, P > 0.10). As were positive predictive value and negative predictive value (85% vs 96%, P = 0.16; 97% vs 99%, P = 0.42). Magnetic resonance is highly sensitive and specific for localized disease involvement and extraluminal abdominal sequelae of IBD. It accurately differentiates patients who have chronic transmural (fibrotic) disease and thus may require an operation from those with acute inflammation, whose symptoms may improve with aggressive medical therapy alone. MRI without contrast had comparable diagnostic yield to standard magnetic resonance enterography.

Pediatric Magnetic Resonance Enterography: Focused on Crohn's Disease

Crohn's disease is a chronic idiopathic inflammatory disease of the intestines characterized by frequent relapse and remission. It often develops in children and adolescents, who are vulnerable to repeated exposure to ionizing radiations. Magnetic resonance enterography (MRE) is an increasingly important radiation-free imaging modality that is used to evaluate pediatric patients with Crohn's disease. MRE can evaluate extraluminal and extraintestinal abnormalities as well as the status of the bowel wall. In addition, MRE has an advantage in the evaluation of the small bowel involvement. MRE can be used for the initial diagnosis of Crohn's disease, and can aid in the assessment of disease activity and complications such as penetrating and fibrostenotic diseases. The aims of this article are to review the MRE technique for obtaining diagnostic and high-quality images and to discuss interpretations of imaging findings in patients with 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.

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.

Systematic review with meta-analysis: magnetic resonance enterography signs for the detection of inflammation and intestinal damage in Crohn's disease

BACKGROUND

In the treatment of Crohn's disease (CD), mucosal healing has become a major goal, with the hope of avoiding intestinal damage from chronic inflammation. Magnetic resonance enterography (MRE) has emerged as a non-invasive means of monitoring inflammation and damage.

AIMS

As part of the development of MRE-based multi-item measures of inflammation and damage for paediatric studies, we carried out a systematic review and meta-analysis to identify MRE variables used to describe these two distinct concepts.

METHODS

2501 studies of MRI and CD were identified. Studies written in any language reporting individual MRE signs for patients diagnosed with CD were included. Two-hundred-and-forty-four studies were fully reviewed and 62 were included (inflammation, n = 51; damage, n = 24). Sensitivity, specificity and associated confidence intervals were calculated, and hierarchical summary ROC curves were constructed for each MRE sign.

RESULTS

A total of 22 MRE signs were used to reflect inflammation, and 9 to reflect damage. Diagnostic accuracy of MRE signs of inflammation and damage was heterogeneous; however, wall enhancement, mucosal lesions and wall T2 hyperintensity were the most consistently useful for inflammation (most sensitivities >80% and specificities >90%), and detection of abscess and fistula were most consistently useful for damage (most sensitivities >90%, specificities >95%).

CONCLUSIONS

Identifying the best MRE variables to reflect inflammation and damage will maximise the utility of this rapidly emerging technique and is the first stage of constructing MRE-based indices for evaluating inflammation and intestinal damage.

Current radiological strategies for the assessment of right lower quadrant abdominal pain

Right lower quadrant abdominal pain is a common clinical entity. Imaging and the radiologistplay an integral role in achieving a diagnosis, so guiding prompt management of patients.This review discusses the spectrum of pathology and imaging findings, and highlights and contrasts the preferred imaging modalities in different subsets of patients.

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.

Biochemical markers and MR imaging findings as predictors of crohn disease activity in patients scanned by contrast-enhanced MR enterography

RATIONALE AND OBJECTIVES

To define the best independent predictors for active inflammation in patients with Crohn disease (CD) examined by contrast-enhanced magnetic resonance (MR) enterography.

MATERIALS AND METHODS

Ninety-one patients (47 men and 44 women; aged 39.58 ± 17.1 years) with a diagnosis of CD; CD activity index (CDAI) ≥ 150 (n = 19 patients) or <150 (n = 72) underwent MR enterography including T2-weighted half-Fourier acquisition single-shot turbo spin-echo, T2-weighted spectral fat presaturation with inversion recovery, T1-weighted balanced steady-state free precession, and T1-weighted breath-hold resolution isotropic high volume three-dimensional MR imaging sequences before and after administration of gadobenate dimeglumine during arterial (30 seconds), portal venous (70 seconds), and delayed phase (3 and 5 minutes from contrast injection). Two readers analyzed the MR images in consensus. Reference standard was the Crohn's Disease Endoscopic Index of Severity (CDEIS) with deep mucosal biopsy or the histologic analysis of the surgical specimen in those patients (n = 30) who underwent elective small-bowel resection. Univariate and multivariate logistic regression analyses were performed to assess CDAI, biochemical markers (C-reactive protein and fecal calprotectin levels) and MR imaging findings as potential predictors of inflammatory CD activity.

RESULTS

Patients revealed prevalently active (n = 47 patients) or quiescent CD with mural fibrosis (n = 44 patients). The bowel wall T2 hyperintensity (odds ratio [OR], 9.20; 95% confidence interval [CI], 2.71-31.19) and total length of disease (OR, 1.29; 95% CI, 1.11-1.49) were found as the best independent predictors of active CD. CDAI, C-reactive protein, and fecal calprotectin were not found independent predictors of active CD.

CONCLUSIONS

The bowel wall T2 hyperintensity and the length of the involved bowel tract were predictors of active inflammation in patients with CD examined by contrast-enhanced MR enterography.

Diagnostic imaging in Crohn's disease: what is the new gold standard?

Historically Barium and isotope studies been used for imaging of inflammatory bowel disease (IBD) but carry risk of radiation exposure. Use of Barium is declining resulting in fewer radiologists that have the necessary expertise. Isotopes studies lack anatomical definition but 18F - fludeoxyglucose (FDG) positron emission tomography (PET) shows promise in accurate assessment of disease compared to endoscopy. Computerised tomography (CT) is particularly useful in assessment of complications of Crohn's disease (CD) but radiation exposure is high. CT enterography (CTE) has improved visualisation of small bowel mucosal disease and allows assessment of disease activity. Ultrasound is increasingly used for preliminary assessment of patients with potential IBD. Although widely available and economically attractive, the expertise required is not widespread. Finally magnetic resonance imaging (MRI) is proving to be the most accurate tool for assessment of disease extent and distribution. MRI of the pelvis has superseded other techniques in assessment of peri-anal fistulation.