Developing role of magnetic resonance imaging in Crohn's disease

Emergency Medicine Evaluation and Management of Small Bowel Obstruction: Evidence-Based Recommendations

BACKGROUND

Small bowel obstruction (SBO) is a commonly diagnosed disease in the emergency department (ED). Recent literature has evaluated the ED investigation and management of SBO.

OBJECTIVE

This review evaluates the ED investigation and management of adult SBO based on the current literature.

DISCUSSION

SBO is most commonly due to occlusion of the small intestine, resulting in fluid and gas accumulation. This may progress to mucosal ischemia, necrosis, and perforation. A variety of etiologies are present, but in adults, adhesions are the most common cause. Several classification systems are present. However, the most important distinction is complete vs. partial and complicated vs. simple obstruction, as complete complicated SBO more commonly requires surgical intervention. History and physical examination can vary, but the most reliable findings include prior abdominal surgery, history of constipation, abdominal distension, and abnormal bowel sounds. Signs of strangulation include fever, hypotension, diffuse abdominal pain, peritonitis, and several others. Diagnosis typically requires imaging, and though plain radiographs are often ordered, they cannot exclude the diagnosis. Computed tomography and ultrasound are reliable diagnostic methods. Management includes intravenous fluid resuscitation, analgesia, and determining need for operative vs. nonoperative therapy. Nasogastric tube is useful for patients with significant distension and vomiting by removing contents proximal to the site of obstruction. Surgery is needed for strangulation and those that fail nonoperative therapy. Surgical service evaluation and admission are recommended.

CONCLUSION

SBO is a common reason for admission from the ED. Knowledge of recent literature can optimize diagnosis and management.

Detection of Crohn disease lesions of the small and large bowel in pediatric patients: diagnostic value of MR enterography versus reference examinations

OBJECTIVE

The purpose of this article is to prospectively determine the accuracy of MR enterography in detecting Crohn disease lesions from the jejunum to the anorectal region in pediatric patients, in comparison with main reference investigations.

SUBJECTS AND METHODS

Fifty consecutive children with known Crohn disease underwent MR enterography with oral contrast agent and gadolinium-chelate intravenous injection. Two radiologists detected and localized lesions by dividing the bowel into nine segments (450 analyzed segments in 50 patients). Ileocolonoscopy, barium studies, intestinal ultrasound, and capsule endoscopy were considered as first- and second-level reference examinations and were performed within 15 days of MR enterography.

RESULTS

MR enterography detected lesions in 164 of 450 segments, with 155 true-positive and nine false-positive findings; overall sensitivity, specificity, and positive and negative predictive values for small- and large-bowel lesions were 94.5%, 97%, 94.5%, and 97%, respectively (ĸ = 0.93; 95% CI, 0.89-0.97). Sensitivity and specificity values were 88% and 97%, respectively, for the jejunum, 100% and 97% for the proximal-to-mid ileum, 100% and 100% for the distal ileum, 93% and 100% for the cecum, 70% and 97% for the ascending colon, 80% and 100% for the transverse colon, 100% and 92% for the descending colon, 96% and 90% for the sigmoid colon, and 96% and 88% for the rectum. From jejunum to rectum, the AUC value ranged between 0.916 (jejunum) and 1.00 (distal ileum). Perianal fistulas were diagnosed in 15 patients, and other complications were found in 13 patients.

CONCLUSION

MR enterography showed an accuracy comparable to that of reference investigations, for both small- and large-bowel lesions. Because MR enterography is safer and more comprehensive than the reference examinations, it should be considered the primary examination for detecting Crohn disease lesions in children.

Magnetic resonance imaging of the gut: a primer for the luminal gastroenterologist

Magnetic resonance imaging (MRI) is well established for imaging the solid organs of the abdomen and pelvis. In recent years it has been having an increasingly important role in the evaluation of the gastrointestinal (GI) tract. Fluoroscopy and abdominal computed tomography, the traditional mainstays of bowel imaging, remain valuable; however, the contemporary emphasis on decreasing patient radiation exposure is driving practice toward non-ionizing modalities such as MRI. The inherent dynamic properties of MRI, its superior tissue contrast, and cross-sectional capabilities offer additional advantages. Here we review, from esophagus to anus, techniques and indications for MRI of the GI lumen with an emphasis on the normal MRI appearance of the GI tract and commonly encountered pathology.

Noninflammatory conditions of the small bowel

Magnetic resonance (MR) imaging has been playing an evolving role in evaluating noninflammatory small-bowel conditions, such as tumors and malabsorption syndrome. MR imaging has shown to be superior to other diagnostic methods in identifying tumors of the small bowel. MR enterography and MR enteroclysis are both valid for studying noninflammatory conditions of the small intestine, although MR enteroclysis may be considered the modality of choice because of its accuracy in the diagnosis of small-bowel neoplasms. Intraluminal and extraluminal MR findings, combined with contrast-agent enhancement and functional information, help to make an accurate diagnosis and consequently to characterize small-bowel diseases.

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.

Differences in the location and activity of intestinal Crohn's disease lesions between adult and paediatric patients detected with MRI

OBJECTIVES

To prospectively compare paediatric patients (PP) and adult patients (AP) affected by Crohn's disease (CD) in terms of the location and activity of intestinal lesions.

METHODS

Forty-three children (mean age 15 years) and 43 adults (mean age 48 years) with proven CD underwent magnetic resonance enterography (MRE) to localise lesions and detect their activity in 9 segments of the small and large bowel. The results were analysed on a per patient and per segment basis. Ileo-colonoscopy was performed in all patients. P values less than 0.05 were considered statistically significant.

RESULTS

Involvement of terminal ileum was significantly different in the two groups: observed in 100 % of AP (43/43) versus 58 % (23/43) of PP (P < 0.0001). Conversely, the colon was diseased in 84 % of PP versus 64 % of AP. In particular, left colonic segments were significantly more involved in PP (descending colon 53 % versus 21 %, P < 0.01; rectum 67 % versus 23 %, P < 0.0001; sigmoid colon 56 % versus 37 %, not significant), whereas caecal involvement was equal in both groups. In children the maximal disease activity was found in left colonic segments, whereas in adults it was in the terminal ileum.

CONCLUSIONS

MRE detected significant differences between the two populations, showing a more extensive and severe involvement of the left colon in children but the distal ileum in adults.

KEY POINTS

• MRI is useful for assessing Crohn's disease in adult and paediatric patients. • Adult and paediatric patients show different intestinal involvement on MRI. • The distal ileum is maximally involved in adults vs. the left colon in children. • The causes of the severe left colonic disease in children are unknown. • The extensive colonic involvement in children has clinical-diagnostic implications.

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.

Minimising medically unwarranted computed tomography scans

As computed tomography (CT) is such a superb diagnostic tool and individual CT risks are small, whenever a CT scan is clinically warranted, the CT benefit/risk balance is by far in the patient's favour. However, if a CT scan is not clinically warranted, this balance shifts dramatically. It is likely that at least 25% of CT scans fall into this latter category, in that they could either be replaced with alternative imaging modalities or could be avoided entirely. Use of clinical decision rules for CT usage represents a powerful approach for slowing down the increase in CT usage, because they have the potential to overcome some of the major factors that result in some CT scans being undertaken when they may not be clinically helpful.

Feasibility of using MR enterography for the assessment of terminal ileitis and inflammatory activity in children with Crohn disease

BACKGROUND AND OBJECTIVE

Radiation exposure increases cancer risk in children with Crohn disease (CD). Magnetic resonance enterography (MRE) can image the gastrointestinal tract without exposure to radiation. The aim of the present study was to determine whether our MRE protocol could diagnose terminal ileitis and the degree of inflammatory activity in children with CD.

METHODS

Retrospective review of patients 18 years of age or younger who underwent MRE for known or suspected CD from June 15, 2007 to April 1, 2010. MRE was performed with Volumen and water as oral contrast and gadolinium-based intravenous contrast. No antiperistaltic agent was used. Each MRE was compared with ileal biopsies obtained within 90 days. Severity of inflammation on MRE was scored and compared with the Pediatric Crohn Disease Activity Index (PCDAI).

RESULTS

Seventy-two patients underwent 80 MREs during the study period. Forty-two of the 72 patients (58.3%) underwent colonoscopy within 90 days of MRE, and the terminal ileum was intubated in 33. Compared with histology, MRE had a sensitivity of 71.4% and a specificity of 100% for terminal ileitis. The positive and negative predictive values were 100% and 70%, respectively. PCDAI was calculated in 39 of the 72 patients (54.2%) and had a statistically significant positive correlation with MRE score of 0.37 (P = 0.020426).

CONCLUSIONS

In children with known or suspected CD, our MRE protocol has a high specificity and positive predictive value for terminal ileitis. Severity of inflammation on MRE had a statistically significant positive correlation with PCDAI.

Selection of symptomatic patients with Crohn's disease for abdominopelvic computed tomography: role of serum C-reactive protein

BACKGROUND

Results of previous studies have shown that repeated abdominopelvic computed tomography (CT) examinations can lead to substantial cumulative diagnostic radiation exposure in patients with Crohn's disease (CD). Improved selection of patients referred for CT will reduce unnecessary radiation exposure. This study examines if serum C-reactive protein (CRP) concentration predicts which symptomatic patients with CD are likely to have significant disease activity or disease complications (such as abscess) detected on abdominopelvic CT.

METHODS

All abdominopelvic CTs performed on patients with CD at a tertiary referral centre during the period June 2003 to June 2008 were identified. CT findings were coded by a pair of independent blinded senior radiologists for (i) small bowel luminal disease, (ii) large bowel luminal disease, (iii) mesenteric inflammatory changes, (iv) penetrating disease (fistulas, abscess, or phlegmon), (v) acute disease complications (obstruction or perforation), and (vi) acute non-CD findings. Imaging findings were correlated with serum CRP checked within 14 days before imaging. The reference range for CRP was defined as 0-5 mg/L.

RESULTS

A total of 147 patients with symptomatic CD had a CRP assay performed within 14 days before undergoing abdominopelvic CT. The median time from CRP assay to imaging was 2 days (interquartile range, 0-6 days). Median CRP before imaging was 24 mg/L (interquartile range, 6-88 mg/L). CT was normal in 34 of 147 case (23.1%). Patients with normal CRP (n = 36) were significantly less likely to have penetrating disease (odds ratio [OR], 0.04 [95% confidence interval {CI}, 0.01-0.7]; P < .001) or large bowel luminal disease (OR, 0.3 [95% CI, 0.1-0.8]; P < .05). Normal CRP excluded penetrating disease with a sensitivity of 1.0 (95% CI, 0.87-1.0). CRP levels did not correlate with the presence of small bowel luminal disease (n = 82), mesenteric inflammatory changes (n = 68), or acute disease complications (n = 10).

CONCLUSION

Symptomatic patients with CD and normal serum CRP are unlikely to have evidence of abscess, fistulating disease, or large bowel luminal disease detected on abdominopelvic CT. However, abdominopelvic CT may demonstrate evidence of clinically significant non-penetrating CD or complications, including perforation and acute obstruction, regardless of serum CRP concentration.

MR enterography to evaluate sub-clinical intestinal inflammation in children with spondyloarthritis

BACKGROUND

Magnetic resonance enterography (MRE) is an established tool to evaluate for changes associated with inflammatory bowel disease (IBD), but has not been studied in sub-clinical IBD. We sought to evaluate the use of MRE in children with spondyloarthritis (SpA), who are at risk of having sub-clinical gut inflammation.

METHODS

Children with juvenile idiopathic arthritis (JIA) with evidence of intestinal inflammation as evidence by an abnormal fecal calprotectin assay were offered MRE of their intestines. Flavored sports drink containing polyethylene glycol 3350 was used as oral contrast. Glucagon was used to arrest peristalsis. Patients were imaged in the prone position on a 1.5 T scanner. Heavily T2-weighted fat-suppressed coronal and axial images using breath-hold technique were obtained, followed by post-gadolinium fat-suppressed T1-weighted gradient echo images.

RESULTS

We recruited five children with juvenile idiopathic arthritis (JIA); four had SpA, and one had poly-articular JIA. All five had evidence of intestinal inflammation based upon a positive fecal calprotectin assay and successfully completed the MRE. Three of the studies showed findings suggestive of IBD, including thickening and contrast uptake at the terminal ileum (TI) in one child, contrast uptake of the distal ileum in another, and prominent vasa recta and mesenteric lymph nodes in the third. The child with evidence of inflammatory changes at the TI underwent colonoscopy, which revealed inflammatory bowel disease limited to the TI.

CONCLUSIONS

MRE can be used to evaluate for subclinical IBD in children with JIA. This protocol was safe and well-tolerated, and identified mild changes in three of the subjects.

Magnetic resonance enterography: safe and effective imaging for stricturing Crohn's disease

BACKGROUND

Symptomatic Crohn's disease (CD) patients often undergo diagnostic imaging studies for evaluation of disease activity or complications including bowel strictures and obstruction. Magnetic resonance enterography (MRE) provides information regarding disease activity, chronicity, and stricture formation without using ionizing radiation.

AIM

Examine the use of MRE among CD patients presenting with symptoms suggesting obstruction in a tertiary care practice setting.

METHODS

We performed a retrospective study of all CD patients undergoing MRE at a tertiary IBD referral center over a 3-year study period including a subgroup analysis of patients presenting obstructive symptoms. Positive and negative findings from MRE were correlated with medical and surgical decision outcomes over the subsequent 90-day period.

RESULTS

In the study, 119 CD patients underwent 133 MRE scans, including 40 scans on individuals presenting with obstructive symptoms. Positive findings of CD including active inflammation, stricturing, and penetrating disease were more frequent in MREs ordered to evaluate obstructive symptoms (87.5%) compared other indications (58.1%, p = 0.001). In patients presenting with obstructive symptoms, MRE findings assisted in directing a change of clinical management towards escalation of medical therapy in 55% and surgery in 32.5%. Review of surgical resection specimens corroborated MRE findings of disease activity and fibrosis in 92% of cases going to surgery.

CONCLUSIONS

In practice-based use at a tertiary IBD referral center, MRE provided an effective, radiation-free alternative to computed tomography by providing valuable diagnostic information for evaluating and directing care in Crohn's disease, particularly for patients presenting with obstructive symptoms.

Prospective evaluation of MR enterography as the primary imaging modality for pediatric Crohn disease assessment

OBJECTIVE

The objectives of this study were prospective evaluation of MR enterographic accuracy for detecting Crohn disease imaging features in pediatric patients, compared with a CT reference standard, as well as determination of MR enterographic accuracy for detecting active bowel inflammation and fibrosis using a histologic reference standard.

SUBJECTS AND METHODS

The study group for this blinded prospective study included 21 pediatric subjects with known Crohn disease scheduled for clinical CT and histologic bowel sampling for symptomatic exacerbation. All subjects and their parents gave informed consent to also undergo MR enterography. CT and MR enterography examinations were independently reviewed by two radiologists and were scored for Crohn disease features. All bowel histology specimens were reviewed by a single pathologist for the presence of active mucosal inflammation and mural fibrosis, followed by correlation of imaging and histologic findings.

RESULTS

All 21 subjects underwent MR enterography and histologic sampling, 18 of whom also underwent CT. MR enterography had high sensitivity for detecting Crohn disease imaging features (e.g., bowel wall thickening, mesenteric inflammation, lymphadenopathy, fistula, and abscess) compared with CT, with individual sensitivity values ranging from 85.1% to 100%. Of a total of 53 abnormal bowel segments with correlation of MRI and histologic findings, MR enterography showed 86.7% accuracy (90.0% sensitivity and 82.6% specificity) for detecting active inflammation (p < 0.001). The accuracy of MR enterography for detecting mural fibrosis overall was 64.9%, compared with histology, but increased to 83.3% (p < 0.05) for detecting fibrosis without superimposed active inflammation.

CONCLUSION

MR enterography can substitute for CT as the first-line imaging modality in pediatric patients with Crohn disease, on the basis of its ability to detect intestinal pathologic abnormalities in both small and large bowel as well as extraintestinal disease manifestations. Additionally, MR enterography provides an accurate noninvasive assessment of Crohn disease activity and mural fibrosis and can aid in formulating treatment strategies for symptomatic patients and assessing therapy response.

Relative efficacy of different MRI signs in diagnosing active Crohn's disease, compared against a histological gold standard

INTRODUCTION

There has been growing interest in the use of MRI in assessing Crohn's disease because of its lack of ionising radiation. Many MRI signs have been described in the literature, but their relative utility is unknown.

METHODS

The MRIs of the bowel performed at 1.5 Tesla were blindly reviewed on 26 patients with recent histology (surgery and/or colonoscopy and their associated reports) according to a dedicated pro forma. Each patient's bowel was divided into nine segments. Each segment was assessed as to the presence or absence of 15 MRI signs described in the literature: abnormal gadolinium enhancement (both subjective and objective), wall oedema, fat oedema, fat proliferation, nodal enlargement, free fluid, wall nodularity, serosal blurring, mural thickening >4 mm, stricture, multi-segmental disease, fistula, abscess and layered contrast enhancement. The results were compared against a histological gold standard with a six-point scale of disease severity.

RESULTS AND CONCLUSIONS

MRI correctly identified all 15 patients with at least established mucosal disease, and three of eight with only mild mucosal disease. Combining these results, a positive MRI correlated highly with at least early mucosal disease (positive predictive value 95%), while the presence of established mucosal disease was unlikely if MRI was negative (negative predictive value 100%). The MRI signs found to be the most sensitive for detecting active Crohn's disease were those related to the bowel wall, namely, wall thickening, nodularity, contrast enhancement and oedema. The most specific signs were the presence of multi-segmental disease, layered contrast enhancement and complications (fistula and abscess).

Role of Magnetic Resonance Enterography in Differentiating between Fibrotic and Active Inflammatory Small Bowel Stenosis in Patients with Crohn's Disease

Objective:

To assess the diagnostic accuracy of magnetic resonance imaging (MRI) in prospectively differentiating between fibrotic and active inflammatory small bowel stenosis in patients with Crohn's disease (CD).

Materials and Methods:

A total of 111 patients with histologically proven CD presenting with clinical and plain radiographic signs of small bowel obstruction underwent coronal and axial MRI scans after oral administration of polyethylene glycol solution. A stenosis was judged present if a small bowel segment had >80% lumen reduction as compared to an adjacent normal loop and mural thickening of >3 mm. At the level of the stenosis, both T2 signal intensity and post-gadolinium T1 enhancement were quantified using a 5-point scale (0: very low; 1: low; 2: moderate; 3: high; and 4: very high). A stenosis was considered fibrotic if the sum of the two values (activity score: AS) did not exceed 1.

Results:

A small bowel stenosis was identified in 48 out of 111 patients. Fibrosis was confirmed at histology in all of the 23 patients with AS of 0 or 1, who underwent surgery within 3 days of the MRI examination. In the remaining 25 patients (AS: 2–8), an active inflammatory stenosis was suspected and remission of the obstructive symptoms was obtained by means of medical treatment. One of these patients (AS: 2), however, underwent surgery after 14 days, due to recurrence. MRI had 95.8% sensitivity, 100% specificity, and 97.9% accuracy in the diagnosis of fibrotic stenosis.

Conclusion:

MRI is reliable in differentiating fibrotic from inflammatory small bowel stenosis in CD.

Assessment of appropriateness of indications for CT enterography in younger patients

BACKGROUND

The small potential risk of radiation-induced cancer is increased in younger patients undergoing serial imaging with computed tomography enterography (CTE). We sought to determine the appropriateness of CTEs based on clinical indication in patients < or =35 years old, and the potential impact of evolution of practice to alternative magnetic resonance enterography (MRE).

METHODS

Over a 7-year period, the medical records of all patients < or =35 years old undergoing CTE were reviewed to determine the clinical indications for each CTE exam. An interdisciplinary consensus panel evaluated the appropriateness of all CTE exams based on American College of Radiology appropriateness criteria and peer-reviewed literature, classifying indications into "appropriate" or "inappropriate." For repeat CTEs, an "alternative MRE suggested" pathway was created. Criteria for evolution of practice to "alternative MRE" were suspicion of obstruction and evaluation of disease activity/therapeutic response in the absence of new symptoms.

RESULTS

In all, 2022 patients < or =35 years old underwent 2295 CTEs. Ninety-nine percent (2008/2022) of first-time CTE exams were "appropriate" by the defined criteria. A total of 197 patients (9.7%) underwent multiple exams, with 73% of these patients having Crohn's disease. Repeat exams occurred in 9% (18/197) with obstructive symptoms and evaluation of disease activity/therapeutic response in the absence of new symptoms in 41% (80/197).

CONCLUSIONS

A multidisciplinary expert panel concluded that the vast majority of young patients underwent clinically appropriate first-time CTE exams. However, a shift in clinical practice to MRE appears warranted for approximately half of young patients undergoing repeat CTE examinations.

Progression and variability of TNBS colitis-associated inflammation in rats assessed by contrast-enhanced and T2-weighted MRI

BACKGROUND

A common feature of preclinical models of colitis is that the time-course, magnitude, and persistence of inflammation vary considerably within the experimental animal group. Accordingly, noninvasive, serial quantification of colonic inflammation could advantageously guide dosing regimens and assess drug efficacy, thus enhancing the value of colitis models in research. This investigation using magnetic resonance imaging (MRI) was therefore undertaken to objectively determine inflammatory progression, variability, and response to therapy associated with trinitrobenzene sulfonic acid (TNBS)-induced colitis in Wistar rats.

METHODS

Rats underwent TNBS treatment on Day 0 and received sulfasalazine or vehicle (methylcellulose) orally, daily, from Day -1 (prophylactically) or Day 2 (therapeutically). T2-weighted and semidynamic T1-weighted contrast-enhanced MRI (CE-MRI) was repeated over 7-10 days to measure colon wall thickness and perfusion-related aspects of inflammation. Rectal bleeding, stool consistency, and disease activity were scored throughout and colon pathology determined terminally.

RESULTS

Principal component analysis of the CE-MRI time-series highlighted colon wall and mesenteric inflammation, which increased by 6-8x naïve values. Peristaltic artifacts were distinguished from perfusion changes using the normalized temporal standard deviation. MRI correlated strongly with terminal colon weight (mean correlation r = 0.8), well with body weight change (r = -0.7), but little with conventional clinical scores. Sulfasalazine reduced inflammation administered prophylactically and therapeutically.

CONCLUSIONS

Inflammation and therapeutic efficacy can be sensitively quantified noninvasively using MRI in TNBS-treated rats. This methodology provides unique and objective in vivo measures of inflammation that can guide dosing strategies, enhancing colitis research effectiveness and the assessment of potential IBD therapeutics.

MR imaging of the bowel: pediatric applications

Magnetic resonance enterography with oral contrast administration using fast T2-weighted and fat saturated, contrast-enhanced T1-weighted sequences is the most common technique for bowel evaluation. The main indication for bowel MR imaging in children has been evaluation of inflammatory bowel diseases. A less common application is appendicitis. Other potential applications include evaluation of vascular malformations and transplanted bowel.