Magnetic Resonance Enterography Protocol Research Articles

Proposal of an Abbreviated Noncontrast MR Enterography Protocol for Patients With Crohn Disease.

MR enterography (MRE) protocols used in patients with Crohn disease are burdened by long acquisition time, high cost, and suboptimal patient experience. For several indications, highly diagnostic MRE can be performed in five or fewer sequences, without IV contrast material or antiperistaltic medication and with an examination room time of less than 12 minutes. As such, MRE could be more patient friendly, more frequently performed, and require fewer health care resources.

MR enterography in small bowel diseases, adding multipoint Dixon sequence, is it worth?

BackgroundMR enterography (MRE) has been increased in the last decade as a modality of choice in diagnosis and evaluation of small bowel diseases in both children and adults. Lacking ionizing radiation, non-invasiveness, excellent soft tissue resolution, adequate luminal distension of small bowel loops are the advantages of this technique. Acquisition of images was used to be: T2WI, steady-state free precession, and T1WI, fat-suppressed gadolinium contrast-enhanced sequences. Multipoint Dixon sequence was added recently to the routine MR enterography protocol. The current study aimed to evaluate the added value of multipoint Dixon sequence as a valuable modification of MR enterography protocol for better assessment of small bowel lesions as activity of Crohn’s disease, small bowel polyps, fibrotic strictures, with modification of MRE protocol in the future with less time consumption and better radiological evaluation.MethodsThe current research was a prospective cross-sectional study. Data were collected prospectively after getting ethical approval from the ethical committee of the faculty of medicine, in our university.Study populationThe sample size was 69 adult patients with suspected small bowel lesions, within the period from January 2022 to 30th December 2022. Written informed consent was obtained from all studied cases before the study, who were enrolled in this study. This number was calculated by using MedCalc 19 program by setting alpha error significance of 0.05%, 95% confidence level, and 80% power sample.ResultsThis study enrolled 69 patients with recurrent abdominal pain and/or bleeding in stool. The patients’ age ranged from 18 to 50 years, with a mean of 32.6 ± 8.8. There is slightly higher female prevalence. The most common positive imaging findings in the studied patients were mucosal thickening in terms of submucosal fat deposition (36.23% of the MRE examination and 39.13% of the MRE with added Dixon sequence). Adding Dixon sequence yielded significantly higher AUC (97.2% vs. 90.5%, p = 0.047), higher sensitivity (100% vs. 92.16%), specificity (94.4% vs. 88.89%), accuracy (98.55% vs. 91.3%), positive predictive value (98.08% vs. 95.92%), and negative predictive value (100% vs. 80%).ConclusionsMRE is an excellent imaging modality in the assessment of small bowel diseases without the use of ionizing radiation. Developing MR-based sequences as multi-point Dixon sequence have the potential to improve the ability of MRE to image the subtle changes as Crohn’s accompanying early inflammatory changes and fibrosis, as well as small intestinal polyps. Familiarity with MR enterography is essential for radiologists and gastroenterologists who participate in the clinical management of small intestinal diseases.

Comparison of Sensitivity Encoding (SENSE) and Compressed Sensing-SENSE for Contrast-Enhanced T1-Weighted Imaging in Patients With Crohn Disease Undergoing MR Enterography.

BACKGROUND. Long acquisition times for breath-hold contrast-enhanced (CE) T1-weighted imaging in MR enterography (MRE) protocols result in reduced image quality. OBJECTIVE. The purpose of this study was to compare CE T1-weighted imaging performed using sensitivity encoding (SENSE) and compressed sensing-SENSE (CS-SENSE) in terms of image quality and diagnostic performance for active inflammation in Crohn disease (CD). METHODS. This retrospective study included 41 patients (31 men, 10 women; mean age, 34 ± 12 [SD] years) who underwent MRE for known or suspected CD between June 2020 and September 2020. MRE was performed in one of two scanning rooms depending on scheduling availability. Per institutional protocol, in one room, the enteric phase was acquired using SENSE (acceleration factor, 3) and the portal phase was acquired using CS-SENSE (acceleration factor, 5); this order was reversed in the other room. Two radiologists independently assessed sequences for subjective image quality measures at the patient level and for active inflammation at the bowel-segment level. Mean image quality scores between readers were computed. Diagnostic performance for active inflammation was compared between SENSE and CS-SENSE using generalized estimating equations; a separate experienced radiologist reviewed the full MRE protocol to establish the reference standard. RESULTS. The mean acquisition time of CE T1-weighted imaging was 17.2 ± 1.1 seconds for SENSE versus 11.5 ± 0.8 seconds for CS-SENSE (p < .001). CS-SENSE scored significantly better than SENSE in overall image quality (4.2 ± 0.7 vs 3.7 ± 1.1; p = .02), motion artifacts (4.0 ± 0.8 vs 3.6 ± 1.2; p = .006), and aliasing artifacts (4.8 ± 0.4 vs 4.2 ± 0.6; p < .001). CS-SENSE scored significantly worse than SENSE in synthetic appearance (4.6 ± 0.5 vs 4.8 ± 0.4; p = .003). Contrast, sharpness, and blurring were not different between sequences (p > .05). For reader 1, CS-SENSE, compared with SENSE, showed a sensitivity of 86% versus 81% (p = .09), specificity of 88% versus 83% (p = .08), and accuracy of 87% versus 82% (p = .56). For reader 2, CS-SENSE, compared with SENSE, showed a sensitivity of 92% versus 79% (p = .006), specificity of 90% versus 98% (p = .16), and accuracy of 91% versus 86% (p = .002). CONCLUSION. Use of CS-SENSE for CE T1-weighted imaging in MRE protocols results in reduced scan times with reduced artifact and improved image quality. CLINICAL IMPACT. The benefits of CS-SENSE in MRE protocols may improve the diagnostic performance for active inflammation in CD.

Frequency and significance of incidental liver lesions on MR enterography in adult patients

PurposeTo evaluate the frequency and significance of incidental liver lesions identified on MR enterography (MRE) examinations to determine if dedicated sequences for liver evaluation are necessary in the routine MRE protocol. MethodsA retrospective departmental database search identified 353 adult (212 women and 141 men; mean [±SD] age, 41.4 [17.0] years; range 18.1–91.9 years) MRE examinations performed in 2017. Radiology reports were reviewed for the presence and characterization of liver lesions, follow-up recommendation, and known malignancy. Follow-up cross-sectional imaging reports were reviewed for liver lesion stability. A senior abdominal radiologist with expertise in liver imaging categorized liver lesions as benign, indeterminate, or malignant and re-characterized indeterminate lesions using follow-up imaging as benign or malignant. ResultsSeventy-nine MRE (22.4%) described liver lesions and follow-up imaging was recommended in 4/79 (5.1%). Seventy-six liver lesions (96.2%) were characterized as benign (cysts/hemangiomas) on routine interpretation and expert review. One of these was recommended for follow-up imaging on initial report, which was characterized as hemangioma by expert review. The remaining 3 lesions (3.8%) were characterized as indeterminate both by initial report and expert radiologist review but re-characterized as benign after reviewing follow-up examinations. ConclusionAll incidental liver lesions identified on MRE in our cohort were benign. Therefore, additional sequences evaluating the liver are unnecessary for routine MRE.

Evaluation of Crohn Disease Activity Using a Potential Abbreviated MRE Protocol Consisting of Balanced Steady-State Free Precession MRI Only Versus Full-Protocol MRE.

OBJECTIVE. The purpose of the present study was to compare the diagnostic performance of an abbreviated MR enterography (MRE) protocol consisting of balanced steady-state free-precession (b-SSFP) imaging only versus standard full-protocol MRE for the evaluation of Crohn disease activity. MATERIALS AND METHODS. This single-center retrospective study included 112 patients with Crohn disease (66 women and 46 men; age range, 18-84 years) who underwent MRE between January 2017 and March 2018. Utilizing binary and 5-point Likert confidence scales, two blinded readers independently interpreted and scored disease activity on b-SSFP sequences only and on full-protocol MRE images. Interreader and intrareader agreement on confidence regarding disease activity were calculated using weighted kappa indexes. Correlation between MRE findings of Crohn disease and the Harvey-Bradshaw index was also performed. RESULTS. Perfect intrareader agreement and strong interreader agreement on disease activity were observed (intrareader agreement: κ = 0.97, 0.96, and 0.96 for reader A, reader B, and both readers combined; interreader agreement: κ = 0.82 for b-SSFP imaging only and κ = 0.81 for MRE). For detecting active Crohn disease, b-SSFP sequences had a sensitivity and specificity of 97% and 100%, respectively, for reader A and 98% and 86%, respectively, for reader B. Strong-to-perfect intrareader agreement was achieved between b-SSFP imaging only and MRE for identification of penetrating disease (κ = 0.80 and 0.97) and stenosing disease (κ = 0.87 and 0.95). Perfect intrareader agreement was also obtained between b-SSFP imaging only and MRE for detecting abnormal bowel segments (κ = 0.91 for reader A; κ = 0.98 for reader B). Weak agreement was noted between both b-SSFP imaging only and MRE versus the Harvey-Bradshaw index (κ = 0.08 of reader A; κ = 0.04 for reader B). CONCLUSION. Robust agreement was observed between b-SSFP imaging only and full-protocol MRE for the assessment of Crohn disease activity and complications. An abbreviated MRE protocol that exclusively uses b-SSFP sequences appears feasible and has significant implications for health care resources.

Dynamic Contrast-Enhanced MR with Quantitative Perfusion Analysis of Small Bowel in Vascular Assessment between Inflammatory and Fibrotic Lesions in Crohn's Disease: A Feasibility Study.

Aim To assess the feasibility of dynamic contrast-enhanced perfusion-MRI in characterization of active small-bowel inflammation and chronic mural fibrosis in patients with Crohnʼs disease (CD). Methods We analyzed a total of 37 (11 women; 23–69 years) patients with known biopsy proven CD, who underwent MR-enterography (MRE) study, performed on a 1.5 T MRI system (Achieva, Philips), using a phased array sense body multicoil, after oral administration of 1.5–2 L of PEG solution. MRE protocol included T1 weighted, SSh T2, sBTFE, and gadolinium-enhanced THRIVE sequences acquired on coronal and axial planes. A dedicated workstation was used to generate perfusion color maps, on which we drown ROI on normal bowel and on pathological segment, thus obtaining related perfusion parameters: relative arterial, venous, and late enhancement (RAE, RVE, and RLE), maximum enhancement (ME), and time to peak (TTP). Results Quantitative perfusion analysis showed a good correlation with local degree of Crohn's inflammation activity. Twenty-nine out of 37 patients showed active inflammatory disease (reference standard of active disease: wall bowel thickness and layered enhancement) with following perfusion parameters: REA (%) = 116.1, RVE (%) = 125.3, RLE (%) = 127.1, ME (%) = 1054.7, TTP (sec) = 157. The same parameters calculated in patients with mural fibrosis were as follows: RAE (%): median = 56.4; RVE (%): 81.2; RLE (%): 85.4; ME (%):809.6; TTP (sec): 203.4. A significant difference (p < 0.001) between inflamed and fibrotic bowel wall vascularity, regarding all perfusion parameters evaluated, was found, with higher values in active CD localizations. Conclusion Vascular assessment of perfusion kinetics of bowel wall by dynamic contrast perfusion-MR analysis may represent a complementary diagnostic tool that enables a quantitative evaluation of local inflammation activity in CD patients.

Evaluation of noncontrast MR enterography for pediatric inflammatory bowel disease assessment.

Gadolinium deposition in normal tissues is being increasingly recognized. Children with inflammatory bowel disease (IBD) undergo frequent imaging with contrast-enhanced MR enterography (MRE). To determine the impact of intravenous (IV) gadolinium in assessment of pediatric IBD by MRE. Retrospective, case series. Radiology information system was searched to identify all children who underwent MRE and endoscopy within 30 days in 2016. 1.5T and 3T. Imaging studies were evaluated for bowel inflammation interpreted by two blinded radiologists in two sessions 6 weeks apart (session 1 pre-MRE; session 2 pre/postcontrast-MRE). Endoscopic histology was the reference standard. A logistic regression model was evaluated using receiver operating characteristics curves and expressed by c-statistics. Agreement between readers was evaluated using Cohen's or weighted kappa statistic, as appropriate. Two-sided P < 0.05 was considered statistically significant. Descriptive statistics were used for assessment of IBD complications. In all, 52 children (46% female), mean age 13.2 (SD 3.42) years formed the study cohort. 77% (40/52) had inflammation on endoscopic biopsy. Pre/post-MRE showed no significant increase in the c-statistic compared to pre-MRE for assessment of small bowel (Reader 1 P = 0.56, Reader 2 P = 1.00) or large bowel inflammation (Reader 1 P = 0.42, Reader 2 P = 1.00)). Intravenous contrast showed no improvement in interobserver agreement for assessment of inflammation in small (kappa 0.92 pre-MRE, 0.88 pre/post-MRE) or large bowel (kappa 0.83 pre-MRE, 0.73 pre/post-MRE). IV contrast had no meaningful impact on interobserver agreement for length of small bowel inflamed (intraclass correlation coefficient 0.90 pre-MRE, 0.95 pre/post-MRE). Assessment of IBD complications was improved with IV contrast, with 3/5 cases with perianal penetrating disease not recognized on pre-MRE. Routine administration of IV gadolinium has no impact on the assessment of bowel inflammation. However, there is potential for missing perianal complications using a noncontrast MRE protocol without dedicated pelvic imaging. 3 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2018;48:341-348.

Diagnostic value of MR enterography for the assessment of small-bowel diseases

Aim: We aim to evaluate the diagnostic efficiency of magnetic resonance (MR) enterography and mannitol %3 which have been gathered easily and provide good intestine distension. Methods: 42 patients whose ages are between 7 and 71 have been included in the project. MR enterography protocol has been done by 1.5 Tesla MRG (Magnetom Aera, Siemens Medical Solutions, Erlangen, Germany) device. Findings were compared to histopathology results obtained by surgery and fiberoptic endoscopy. Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy rate have been calculated statistically. Results: Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy rate were calculated as 83%, 93%, 83%, 93% and 90%, respectively. Two patients with false negative results were evaluated as normal in the radiologic manner but pathologic investigation came as nonspecific inflammation. Pathologic investigation was recognized as ulcerative colitis for a patient with false positive result and in another patient with false positive result, invagination caused by a polypoid bulky mass due to the ectopic pancreas tissue was detected. Nine real positive patients were evaluated as having Crohn’s disease according to the pathologic investigation and other patient was evaluated as having Crohn’s disease though it was atypical. Additionally involvement of two small intestinal segments was seen for a patient with Crohn’s disease and ileoileal fistula was seen for another patient. Conclusion: MR enterography is important for tracking of Crohn’s disease, inflammation in active process of the disease, strictures in fibro-stenotic phase, obstructions, determination of complications and evaluation of treatment options. There will be a need for comparative studies which have been done by current MR sequences and recently developing sequence techniques with inclusion of large number of patients. MR enterography is promising for evaluation of other diseases in the small intestine too.

Pediatric MR enterography: technique and approach to interpretation-how we do it.

Magnetic resonance (MR) enterography is an increasingly important pediatric imaging modality that is most often used to evaluate inflammatory bowel disease ( IBD inflammatory bowel disease ), while sparing children and adolescents from potential risks of ionizing radiation exposure. MR enterography allows for evaluation of the bowel lumen and wall, adjacent mesentery and soft tissues, as well as a variety of extraintestinal abdominopelvic IBD inflammatory bowel disease manifestations. While MR enterography can be used to initially confirm the diagnosis of IBD inflammatory bowel disease , particularly small bowel Crohn disease, it has also proven useful in assessing the degree inflammatory activity over time, serving as a radiologic biomarker for response to medical therapy, and identifying a variety of disease-related complications, including strictures, fistulae, and abscesses. The purpose of this review article is to provide radiologists with a systematic approach for MR enterography review and interpretation in children and adolescents with known or suspected of having IBD inflammatory bowel disease and to illustrate both common and infrequent but important imaging findings. Additionally, the authors will present their well-established and clinically successful pediatric MR enterography protocol, up-to-date clinical indications for MR enterography, and briefly mention the role of MR enterography in assessing non- IBD inflammatory bowel disease abnormalities affecting the bowel. Online supplemental material is available for this article .

Magnetic resonance enterography in pregnant women with Crohn's disease: case series and literature review.

BackgroundEvaluation of pregnant women with known or suspected Crohn’s disease (CD) remains a challenge. Magnetic Resonance Enterography (MRE) is a promising diagnostic tool in these patients; however, the clinical data on MRE utilization in pregnancy is scarce. The aim of the study was to describe the experience with MRE in pregnant CD patients in a tertiary referral center.MethodsWe retrospectively reviewed MRE studies performed in pregnant women with known or suspected CD that were performed between January 2007 and November 2012. Imaging findings, clinical management and outcome were extracted from patient’s file and electronic records. Image quality was evaluated.ResultsTen studies of 9 patients were included. MRE protocol was modified to maximize maternal and fetal safety, and intravenous gadolinium was not used. In 7 patients, CD diagnosis was previously established; six were admitted with clinical symptoms consistent with CD exacerbation, and an additional patient with a recurrent groin abscess without apparent luminal symptoms. In all seven patients, imaging features consistent with active CD were detected; new penetrating complications were detected in 4 patients. Two patients underwent MRE for suspected CD which was not comforted by study results. The clinical management was significantly impacted by MRE results in all positive cases. The image quality of the fast MRE sequences obtained without gadolinium was satisfactory and allowed meaningful interpretation.ConclusionMRE with an adapted protocol for pregnancy is a reliable imaging modality to manage in pregnant women with known or suspected CD.

Software-assisted quantitative analysis of small bowel motility compared to manual measurements

To validate a newly developed software prototype that automatically analyses small bowel motility by comparing it directly with manual measurement. Forty-five patients with clinical indication for small bowel magnetic resonance imaging (MRI) were retrospectively included in this institutional review board-approved study. MRI was performed using a 1.5 T system following a standard MR-enterography protocol. Small bowel motility parameters (contractions-per-minute, luminal diameter, amplitude) were measured three times each in identical segments using the manual and the semiautomatic software-assisted method. The methods were compared for agreement, repeatability, and time needed for each measurement. All parameters were compared between the methods. A total of 91 small-bowel segments were analysed. No significant intra-individual difference (p > 0.05) was found for peristaltic frequencies between the methods (mean: 4.14/min manual; 4.22/min software-assisted). Amplitudes (5.14 mm; 5.57 mm) and mean lumen diameters (17.39 mm; 14.68) differed due to systematic differences in the definition of the bowel wall. Mean duration of single measurement was significantly (p < 0.01) shorter with the software (6.25 min; 1.30 min). The scattering of repeated measurements was significantly (p < 0.05) lower using the software. The software-assisted method accomplished highly reliable, fast and accurate measurement of small bowel motility. Measurement precision and duration differed significantly between the two methods in favour of the software-assisted technique.

Feasibility of an optimized MR enterography protocol in the evaluation of pediatric inflammatory bowel disease

Cross-sectional imaging forms an important alternative and complimentary tool to endoscopy in aiding the clinician with diagnosis and management of pediatric inflammatory bowel disease (IBD). The purpose of the study was to evaluate the feasibility of an optimized Magnetic Resonance Enterography (MRE) protocol in the evaluation of patients with suspected IBD. 31 children (18 boys and 13 girls) were evaluated by a pediatric gastroenterologist prior to MRE and given a grading for clinical severity of disease. Imaging was then performed with oral contrast and a tailored protocol using fast T1/T2 weighted pulse sequences. Additionally, contrast and glucagon were administered intravenously. Imaging findings were then correlated with the clinical data. Excellent distension was achieved in the small bowel. The majority of the studies were of diagnostic quality with no motion artifacts. Imaging findings showed statistically significant correlation with disease activity. An optimized pediatric MRE protocol is feasible and correlates well with clinical disease activity. This in turn aids the clinician in the management of children with this chronic debilitating disease.

Feasibility of Using MR Enterography for the Assessment of Terminal Ileitis and Inflammatory Activity in Children With Crohn Disease

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. 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). 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). 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.

Small bowel MR enterography: problem solving in Crohn's disease.

Magnetic resonance enterography (MRE) is fast becoming the first-line radiological investigation to evaluate the small bowel in patients with Crohn’s disease. It can demonstrate both mural and extramural complications. The lack of ionizing radiation, together with high-contrast resolution, multiplanar capability and cine-imaging make it an attractive imaging modality in such patients who need prolonged follow-up. A key question in the management of such patients is the assessment of disease activity. Clinical indices, endoscopic and histological findings have traditionally been used as surrogate markers but all have limitations. MRE can help address this question. The purpose of this pictorial review is to (1) detail the MRE protocol used at our institution; (2) describe the rationale for the MR sequences used and their limitations; (3) compare MRE with other small bowel imaging techniques; (4) discuss how MRE can help distinguish between inflammatory, stricturing and penetrating disease, and thus facilitate management of this difficult condition.Main Messages• MR enterography (MRE) is the preferred imaging investigation to assess Crohn’s disease. T2-weighted, post-contrast and diffusion-weighted imaging (DWI) can be used.• MRE offers no radiation exposure, high-contrast resolution, multiplanar ability and cine imaging.• MRE can help define disease activity, a key question in the management of Crohn’s disease.• MRE can help distinguish between inflammatory, stricturing and penetrating disease.• MRE can demonstrate both mural and extramural complications.

Contrast-enhanced MRI of the small bowel in Crohn’s disease

Recently, magnetic resonance imaging has emerged as a valuable tool in evaluation of small bowel Crohn's disease. MRI provides several advantages to other imaging modalities, including the lack of ionizing radiation, multiplanar capability, and functional information. Intravenous contrast administration is a routine portion of MR enterography protocol, and aids in detection of disease extent, extramural complications such as fistula and abscess, and assessment of activity. Additionally, promising techniques such as dynamic contrast-enhanced MRI may provide quantitative measures to assess bowel perfusion, which may enhance evaluation of disease activity. This article will provide an overview of the technical aspects of contrast-enhanced MR enterography, describe common pathologic findings involving the small bowel in Crohn's disease, summarize its role in determination of activity with an emphasis on endoscopic and histologic correlation, and compare its efficacy with other imaging modalities.

MR motility imaging in Crohn’s disease improves lesion detection compared with standard MR imaging

To evaluate retrospectively in patients with Crohn's disease (CD) if magnetic resonance (MR) motility alterations correlate with CD typical lesions leading to an increased detection rate. Forty patients with histologically proven CD underwent MR enterography (MRE), including coronal cine sequences (cine MRE), in addition to the standard CD MR protocol. Two blinded readings were performed with and without cine MRE. Locations presenting motility alterations on the cine sequences were analysed on standard MRE for CD-related lesions. This was compared with a second reading using the standard clinical MRE protocol alone. The number of lesions localised by cine MRE and identified on standard MRE compared with standard MRE alone were 35/24 for wall thickening (p = 0.002), 24/20 for stenoses (p = 0.05), 17/11 for wall layering (p = 0.02), 5/3 for mucosal ulcers (p = 0.02) and 21/17 for the comb sign (p = 0.05). Overall, cine MRE detected 35 more CD-specific findings than standard MRE alone (124/89; p = 0.007) and significantly more patients with CD-relevant MR findings (34/28; p = 0.03). CD lesions seem to be associated with motility changes and this leads to an increased lesion detection rate compared with standard-MRE imaging alone.

An Abscess in Crohnʼs Disease Identified by MR Enterography that Could Not be Diagnosed by CT Scan

Purpose: Crohn's disease can lead to penetrating complications in the gastrointestinal tract and result in abscess formation. Accurate identification of complications is important when selecting appropriate therapies. Methods: We report a patient with Crohn's disease with an abdominal abscess that was correctly identified with Magntetic Resonance Enterography (MRE), but not confirmed by CT scan. Results: A 27 year old man with known Crohn's disease was admitted to the hospital with abdominal pain, vomiting, and a fever. He was diagnosed with Crohn's ileitis one year prior to admission. At that time he reported abdominal pain and diarrhea and a CT scan revealed a markedly thickened, inflamed ileum with several enteroenteric and enterocolic fistulae and right hydronephrosis. A colonoscopy confirmed the diagnosis of Crohn's disease. His ureter was stented and he was treated with antibiotics and initiated on certolizumab. His symptoms resolved and he remained in remission for several months on certolizumab. He later developed recurrent abdominal pain with vomiting and a fever. He was admitted to the hospital and an MRE revealed dilated small bowel with a thickened, inflamed ileum and several fistulae. On initial review of the standard T2-weighted and enhanced fat-suppressed Tlweighted images, multiple fluid filled loops of small bowel were present in the right lower quadrant, and the confident distinction between intraenteric and extraenteric fluid was considered difficult by a MR trained radiologist with experience in MR enterography. However, diffusion-weighted images obtained as part of the MR enterography protocol clearly defined an extraluminal fluid collection with restricted diffusion, interpreted as abscess. Percutaneous drainage was attempted using CT-guidance to allow for an elective surgery at a later date. However, CT was unable to confidently delineate between the abscess and adjacent bowel loops, and the drainage procedure was aborted. The patient was taken for urgent surgery where the findings of the MRE were confirmed including a thickened, inflamed ileum with fistulae and a large abscess. The abscess was drained, the ileum was resected, and a temporary ileostomy was created. Conclusion: While traditional imaging with CT is often used to evaluate for complications of Crohn's disease, confident distinction between abscess and adjacent bowel loops can be difficult in the absence of excellent opacification of the bowel with enteric contrast material. Most CT enterography protocols utilize negative enteric contrast material to allow for better depiction of bowel wall enhancment. MRE with diffusion-weighted imaging provides an alternate imaging technique, without radiation, that may provide more accurate information in select cases. Disclosure: Dr Leyendecker: Speaker, Bracco Diagnostics; Speaker, Bayer Healthcare; Research grant, Bracco Diagnostics.

MR enterography with polyethylene glycol as oral contrast medium in the follow-up of patients with Crohn disease: comparison with CT enterography

To compare magnetic resonance enterography (MRE) and computed tomography enterography (CTE) in detecting inflammatory bowel disease activity (IBD) in patients with Crohn's disease (CD). A total of 29 patients (M 20; F 9; mean age 43.8 ± 15.9) with known CD underwent MRE. MRE was performed at 1.5 T using phased-array sense body coil, after oral administration of 1.5-2 L of PEG solution as oral contrast agent. MRE protocol included T1-weighted, sSShT2, sBTFE and gadolinium-enhanced THRIVE sequences acquired on coronal and axial planes. CTE was performed using a 16 multidetector-row computed-tomography before and after intravenous administration of 120 mL of iodinated contrast. MRE images and CTE scans were reviewed by a radiologist for bowel thickness and enhancement, mesenteric lymph nodes, vascular engorgement, fibrofatty proliferation, fistulas and abscesses. The disease activity was also defined by CDAI > 150. MRE has demonstrated a good sensitivity in detection of CD activity, particularly in depiction of mural thickening, mural enhancement, and vascular engorgement. The level of agreement between the two technique was excellent in evaluating wall thickening with mucosal hyperenhancement (κ = 1), comb (κ = 0.90) and halo signs (κ = 0.86). In detecting fibrofatty proliferation and mesenteric lymph nodes, CTE was superior to MRE (accuracy: P < 0.05), while MRE was superior in visualization of fistulas. MRE is an accurate method in monitoring the activity of CD as compared to CTE and may be considered an alternative to CTE in assessing degree of CD and evaluating therapeutic effectiveness.