MRI in Crohn's disease

Prospective motion correction in kidney MRI using FID navigators

PURPOSE

Abdominal MRI scans may require breath-holding to prevent image quality degradation, which can be challenging for patients, especially children. In this study, we evaluate whether FID navigators can be used to measure and correct for motion prospectively, in real-time.

METHODS

FID navigators were inserted into a 3D radial sequence with stack-of-stars sampling. MRI experiments were conducted on 6 healthy volunteers. A calibration scan was first acquired to create a linear motion model that estimates the kidney displacement due to respiration from the FID navigator signal. This model was then applied to predict and prospectively correct for motion in real time during deep and continuous deep breathing scans. Resultant images acquired with the proposed technique were compared with those acquired without motion correction. Dice scores were calculated between inhale/exhale motion states. Furthermore, images acquired using the proposed technique were compared with images from extra-dimensional golden-angle radial sparse parallel, a retrospective motion state binning technique.

RESULTS

Images reconstructed for each motion state show that the kidneys' position could be accurately tracked and corrected with the proposed method. The mean of Dice scores computed between the motion states were improved from 0.93 to 0.96 using the proposed technique. Depiction of the kidneys was improved in the combined images of all motion states. Comparing results of the proposed technique and extra-dimensional golden-angle radial sparse parallel, high-quality images can be reconstructed from a fraction of spokes using the proposed method.

CONCLUSION

The proposed technique reduces blurriness and motion artifacts in kidney imaging by prospectively correcting their position both in-plane and through-slice.

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

PURPOSE

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

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

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

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

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

Ruticarpsides A-C, three new ester glycosides from the fruits of Tetradium ruticarpum

In the course of our ongoing phytochemical investigation on the n-butanol extract of the fruits of Tetradium ruticarpum (Rutaceae), three new compounds, ruticarpsides A-C (1-3), were obtained and their structures were elucidated by a comprehensive analysis of NMR and MS data. Compound 3 showed a weak inhibition effect on nitric oxide production in BV-2 microglial cells stimulated with lipopolysaccharide.

Oral distension methods for small bowel MRI: comparison of different agents to optimize bowel distension

Background Different methods for bowel distension prior to magnetic resonance imaging (MRI) examinations were described in recent years. Purpose To compare orally administered psyllium or locust bean gum / mannitol (LBM) with tylose administered through a duodenal catheter for bowel distension in patients undergoing MRI examination of the small bowel. Material and Methods Three different methods of bowel distension prior to MRI were compared: tylose applied through a duodenal catheter and orally administered psyllium and LBM in three groups with 15 patients each. Datasets were blinded and reviewed independently by two experienced radiologists, who assessed the diagnostic value and the maximum luminal diameter. Results Tylose was superior to psyllium and LBM in the examination of the duodenum and proximal jejunum. LBM was superior to the other methods for distension of the ileum and terminal ileum. The greatest luminal diameter of the duodenum was achieved after tylose and distension of the terminal ileum was the best in patients receiving LBM. The psyllium group was inferior to the other two groups in all segments. Conclusion By using LBM as an oral method of bowel distension, many patients can avoid the unpleasant placement of a duodenal catheter without compromising the diagnostic value of the examination.

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

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

Small-bowel MRI in children and young adults with Crohn disease: retrospective head-to-head comparison of contrast-enhanced and diffusion-weighted MRI

BACKGROUND

Small-bowel MRI based on contrast-enhanced T1-weighted sequences has been challenged by diffusion-weighted imaging (DWI) for detection of inflammatory bowel lesions and complications in patients with Crohn disease.

OBJECTIVE

To evaluate free-breathing DWI, as compared to contrast-enhanced MRI, in children, adolescents and young adults with Crohn disease.

MATERIALS AND METHODS

This retrospective study included 33 children and young adults with Crohn disease ages 17 ± 3 years (mean ± standard deviation) and 27 matched controls who underwent small-bowel MRI with contrast-enhanced T1-weighted sequences and DWI at 1.5 T. The detectability of Crohn manifestations was determined. Concurrent colonoscopy as reference was available in two-thirds of the children with Crohn disease.

RESULTS

DWI and contrast-enhanced MRI correctly identified 32 and 31 patients, respectively. All 22 small-bowel lesions and all Crohn complications were detected. False-positive findings (two on DWI, one on contrast-enhanced MRI), compared to colonoscopy, were a result of large-bowel lumen collapse. Inflammatory wall thickening was comparable on DWI and contrast-enhanced MRI. DWI was superior to contrast-enhanced MRI for detection of lesions in 27% of the assessed bowel segments and equal to contrast-enhanced MRI in 71% of segments.

CONCLUSION

DWI facilitates fast, accurate and comprehensive workup in Crohn disease without the need for intravenous administration of contrast medium. Contrast-enhanced MRI is superior in terms of spatial resolution and multiplanar acquisition.

18F-Fluorodeoxyglucose positron-emission tomography (PET) can be used to assess inflammation non-invasively in Crohn's disease

BACKGROUND

Differential therapy requires repeated diagnostic assessment for mapping and monitoring of disease activity in Crohn's disease (CD).

PURPOSE

The purpose of this prospective study was to evaluate the accuracy of (18)F-fluorodexyglucose positron-emission tomography (FDG-PET) for non-invasive assessment of disease activity in CD.

METHODS

Forty-three patients with CD underwent ileocolonoscopy and hydromagnetic resonance imaging (hydro-MRI) as reference standards. In addition, FDG-PET was performed and correlated with clinical data, hydro-MRI, and endoscopy findings. Diagnostic accuracy was determined for all methods.

RESULTS

Two-hundred and forty-one bowel segments could be analyzed by all methods. Of 80 endoscopically inflamed segments in CD, FDG-PET detected 72 and hydro-MRI 53 segments. Overall sensitivity was 90 % (FDG-PET) versus 66 % (hydro-MRI), and specificity was 92.6 % versus 99 %. In the proximal ileum, hydro-MRI revealed inflammation in eight out of 49 patients and FDG-PET, also, detected all of these inflamed segments. Seventeen stenoses could be identified in 43 CD patients. With regard to assessment as inflammatory or fibrotic stenosis, there was good concordance between colonoscopy, hydro-MRI, and FDG-PET. In one case only, the nature of the stenosis was assessed differently. In contrast with leukocyte numbers and CDAI, there was significant correlation of FDG-PET activity with C-reactive protein and CDEIS levels (P = 0.019 and P = 0.007, respectively).

CONCLUSION

FDG-PET is able to detect mucosal inflammation in CD with high sensitivity and specificity and to enable proper assessment of inflammatory activity in stenoses. FDG-PET is, thus, a promising non-invasive technique for clinical management of CD.

Feasibility of 3-T MRI for the evaluation of Crohn disease in children

BACKGROUND

Crohn disease (CD) is a chronic inflammatory bowel disease that can affect any part of the gastrointestinal tract from the oral cavity to the anal canal. It occurs in all ages and is a significant cause for morbidity in children. Interest in MRI evaluation of CD has increased because of the concern regarding cumulative radiation dose from contrast fluoroscopic studies and CT. Several reports have demonstrated MRI to be a useful technique for CD. Most of these studies were performed at 1.5-T field strength. Imaging at a higher field strength, with a greater signal-to-noise ratio, has the potential of reducing scan times and increasing the resolution. However, there is a concurrent increase in artefacts, and these can be pronounced with abdominal imaging at 3 T.

OBJECTIVE

To determine the feasibility of 3-T MRI for CD in children and to assess the value of different sequences and the effect of artefacts that could potentially limit the role of bowel MR imaging at higher field strengths.

MATERIALS AND METHODS

A retrospective study of 46 children with biopsy-proven CD (ages 8-19 years, 53% boys) was performed. Sixty-eight consecutive MRI studies were performed on a 3-T scanner between 2005 and 2007; 42 of the abdomen (62%) and 26 of the pelvis/perineum (38%). Sorbitol was administered for the abdominal studies; orally for 36/42 (86%) studies and via a naso-jejunal (NJ) tube for 6/42 (14%) studies. For the abdomen, T2-W half-fourier acquisition single-shot turbo spin-echo (T2-W HASTE), true steady-state free precession (true FISP), pre-contrast and contrast-enhanced (CE) T1-volume interpolated gradient-echo (T1-W VIBE) and CE T1-W fast low-angle shot (T1-W FLASH) sequences were performed. For the perianal and pelvic assessment, fat-saturated T2-W turbo spin-echo (TSE), pre-contrast and CE T1-W FLASH or VIBE sequences were performed. The sequences were scored for diagnostic quality by two paediatric radiologists for visualisation of the bowel wall, whether normal or pathological and the visualization of extra intestinal manifestations. The effects of distension, susceptibility artefact and motion were assessed.

RESULTS

Six (14%) abdominal MRI studies were normal. Thirty-six (86%) were abnormal with good correlation with endoscopic findings. The pelvic and perianal MRI studies were all abnormal (26/26, 100%) with good correlation with proctoscopy and examination under anaesthesia. All the sequences had high average scores (greater than or close to 3), except true FISP with a score of 2.4. The score was greatest in those who had NJ administration of sorbitol; however, satisfactory distension was also possible with oral administration of contrast. True FISP was the sequence most affected by a combination of suboptimal distension and artefact from colonic contents. With adequate distension, true FISP image quality improved remarkably. The overall score of this sequence was satisfactory in the absence of susceptibility and movement artefact.

CONCLUSION

With appropriate attention to technique, with optimal distension and control of movement, high-quality, 3-T assessment of the abdomen, pelvis and perineum is possible. All sequences used at 1.5 T can be used at 3 T, however true FISP was the most prone to artefact.

Magnetic resonance enterography in Crohn’s disease: Standard and advanced techniques

Crohn’s disease (CD) is a chronic autoimmune disorder that affects mainly young people. The clinical management is based on the Crohn’s Disease Activity Index and especially on biologic parameters with or without additional endoscopic and imaging procedures, such as barium and computed tomography examinations. Recently, magnetic resonance (MR) imaging has been a promising diagnostic radiologic technique with lack of ionizing radiation, enabling superior tissue contrast resolution due to new pulse-sequence developments. Therefore, MR enterography has the potential to become the modality of choice for imaging the small bowel in CD patients.

Normal small bowel wall characteristics on MR enterography

PURPOSE

To assess the normal small bowel parameters, namely bowel diameter, bowel wall thickness, number of folds (valvulae connivientes) per 2.5 cm (in.), fold thickness and interfold distance per small bowel segment (duodenum, jejunum, proximal ileum, distal ileum and terminal ileum) on MR enterography.

MATERIALS AND METHODS

Between September 2003 and January 2008, 280 MR enterography examinations were performed for investigation of known or suspected small bowel pathology. 120 of these examinations were normal. Sixty-five (m=29, f=36, mean age=34 years, range=17-73 years) of 120 examinations without a prior small bowel diagnosis, with no prior or subsequent abnormal radiology or endoscopy examinations, no prior small bowel surgery and with a minimum 3 years follow-up demonstrating normality were retrospectively evaluated for the described small bowel parameters.

RESULTS

We found the mean diameter of the duodenum to be 24.8mm (S.D.=4.5mm), jejunum to be 24.5mm (S.D.=4.2mm), proximal ileum to be 19.5mm (S.D.=3.6mm), distal ileum to be 18.9 mm (S.D.=4.2mm) and terminal ileum to be 18.7 mm (S.D.=3.6mm). The number of folds per 2.5 cm varied from 4.6 in the jejunum to 1.5 in the terminal ileum. The fold thickness varied from 2.1mm in the duodenum to 1.8mm in the terminal ileum. The small bowel parameters gradually decreased in size from the duodenum to the smallest measurements which were in the terminal ileum. The bowel wall is similar in size throughout the small bowel measuring 1.5+/-0.5mm.

CONCLUSION

These results provide the mean, range of normality and standard deviation of the small bowel parameters per segment on the current population on MR enterography. From our experience, knowledge of these parameters is extremely helpful and essential in the everyday assessment of MR enterography studies.

MRI of small bowel Crohn's disease: determining the reproducibility of bowel wall gadolinium enhancement measurements

This study aims to determine inter- and intra-observer variation in MRI measurements of relative bowel wall signal intensity (SI) in Crohn's disease. Twenty-one small bowel MRI examinations (11 male, mean age 40), including T1-weighted acquisitions acquired 30 to 120s post-gadolinium, were analysed. Maximal bowel wall SI (most avid, conspicuous contrast enhancement) in designated diseased segments was measured by two radiologists and two trainees using self-positioned "free" regions of interest (ROIs) followed by "fixed" ROIs chosen by one radiologist, and this procedure was repeated 1 month later. Relative enhancement (post-contrast SI minus pre-contrast SI/pre-contrast SI) was calculated. Data were analysed using Bland-Altman limits of agreement and intra-class correlation. Inter-observer agreement for relative enhancement was poor (spanning over 120%) using a free ROI-95% limits of agreement -0.69, 0.70 and -0.47, 0.74 for radiologists and trainees, respectively, only marginally improved by use of a fixed ROI -0.60, 0.67 and -0.59, 0.49. Intra-class correlation ranged from 0.46 to 0.72. Intra-observer agreement was slightly better and optimised using a fixed ROI-95% limits of agreement -0.52, 0.50 and -0.34, 0.28 for radiologists and trainees, respectively. Intra-class correlation ranged from 0.49 to 0.86. Relative bowel wall signal intensity measurements demonstrate wide limits of observer agreement, unrelated to reader experience but improved using fixed ROIs.

Crohn disease of the small bowel: comparison of CT enterography, MR enterography, and small-bowel follow-through as diagnostic techniques

PURPOSE

To prospectively compare the accuracy of computed tomographic (CT) and magnetic resonance (MR) enterography and small-bowel follow-through (SBFT) examination for detection of active small-bowel inflammation and extraenteric complications in patients with Crohn disease (CD).

MATERIALS AND METHODS

The institutional review board approved the study protocol; informed consent was obtained from all participants. Thirty-one consecutive patients who had CD or who were suspected of having CD underwent CT and MR enterography, SBFT, and ileocolonoscopy. Two independent readers reviewed CT and MR enterographic and SBFT images for presence of active terminal ileitis and extraenteric complications. Accuracy values of CT and MR enterography and SBFT for identification of active terminal ileitis were evaluated with the receiver operating characteristic method, with ileocolonoscopic findings as the reference standard. Sensitivity values of CT and MR enterography and SBFT for detection of extraenteric complications were compared by using the McNemar test, with results of imaging studies, surgery, and physical examination as reference standards.

RESULTS

The study population included 30 patients (17 men, 13 women; mean age, 29.0 years) with CD. Differences in areas under the receiver operating characteristic curves for CT enterography (0.900 and 0.894), MR enterography (0.933 and 0.950), and SBFT (0.883 and 0.928) for readers 1 and 2, respectively, in the detection of active terminal ileitis were not significant (P > .017). Sensitivity values for detection of extraenteric complications were significantly higher for CT and MR enterography (100% for both) than they were for SBFT (32% for reader 1 and 37% for reader 2) (P < .001).

CONCLUSION

Because MR enterography has a diagnostic effectiveness comparable to that of CT enterography, this technique has potential to be used as a radiation-free alternative for evaluation of patients with CD.

Imaging for Crohn disease: use of 3-T MRI in a paediatric setting

This study was carried out to review our experience with 3-T MRI in the assessment of Crohn disease in a paediatric population. Twenty-four patients with biopsy proven Crohn disease identified on the radiology information system underwent abdominal MRI, with or without pelvic MRI. Twenty-eight studies were carried out on a 3-T scanner at a tertiary paediatric hospital. Eight of 24 of these (30%) had a gastrointestinal barium study, 2 of 24 (8%) a CT and 9 of 24 (38%) an abdominal ultrasound. The different MRI sequences were rated for observation of the bowel wall and abnormalities (0-5). The findings were correlated to relevant findings on endoscopy, examination under anaesthesia (EUA) and where available surgery, barium studies, CT and ultrasound. In this study, the colon was involved in 5 of 28 (18%), small bowel in 7 of 28 (25%), terminal ileum in 5 of 28 (18%). All the perineal studies (9 of 9) showed abnormalities. Sinus tracts or fistulas were identified in 7 of 28 (25%) studies. The mean rating of the different MRI sequences in showing bowel wall and changes of Crohn disease was T2 TSE 3.6, T2 half fourier aquisition single shot turbo spin echo (HASTE) with a long TE 3.6, T2 HASTE with short TE 3.4, true fast imaging with steady state precession (FISP) 2.7, T1 4.1 and Post-contrast T1 4.3. The T2 HASTE sequences with thinner slices improved observation. Detection of superficial abnormalities was similar on the 3D VIBE images and on the post-contrast T1 spin-echo (SE) sequences. In five of nine (56%) of those that had ultrasound, both studies were abnormal, with incomplete correlation of the abnormalities. Computed tomography and MRI were abnormal in two of two (100%) patients with good correlation of the abnormalities in one; in the other there was a minimal discrepancy in the estimation of the length of involved bowel. In 7 of 11 (64%) the barium study was abnormal. Good correlation to MRI findings was found in five of seven (71%) of patients. In two of seven (29%) both studies were abnormal, with incomplete correlation of the abnormalities. Barium underestimated the length of involved segment in these patients with inflammatory ileal thickening and ulceration. Notably, in both studies compression was limited because of patient discomfort and the involved segments obscured by overlap. Abdominal and pelvic MRI at 3 T is a useful imaging technique for evaluation of Crohn disease in the children. The extent of bowel wall involvement and extra-intestinal complications, such as abscesses and fistulas can be accurately assessed non-invasively, without the use of ionizing radiation or sedation.

When should abdominal magnetic resonance imaging be used?

When assessing the use of an imaging study, historically 2 criteria were used, diagnostic accuracy and cost of the study. However, as the awareness of risk for radiation-induced cancer in the general population increases as a direct result of more computed tomography (CT) studies being performed, reevaluation of the approach to imaging studies is necessary. The new imaging paradigm considers patient safety as an important aspect of assessing the role of an imaging modality. The primary goals of the new imaging paradigm should be diagnostic accuracy and patient safety, with the secondary goal being more affordable cost of study. In formulating a plan for when to use body magnetic resonance imaging (MRI), one has to consider all of these criteria and should also consider the question of when CT has unmatched diagnostic accuracy. The advantages of the spatial resolution of CT are mainly realized when there is great contrast between what is being looked for and background tissue; examples include small lung nodules and renal calculi. The greater intrinsic soft tissue contrast resolution and greater sensitivity for the presence or absence of intravenous contrast are appreciated in MRI studies, circumstances in which lesions occur within an organ without altering its exterior contour. This is well-shown for liver lesions. Adding patient safety into the equation, MRI should be indicated in exams in which there is no greater difference in diagnostic accuracy between CT and MRI, in patients with greater concern for radiation safety such as pediatric patients, and in cases of multiple or serial exams.

Developing role of magnetic resonance imaging in Crohn's disease

PURPOSE OF REVIEW

There is growing concern among the medical community that diagnostic radiation adds to the already increased risk of developing lymphoma that may be inherent in, or related to the treatment of, inflammatory bowel disease. This article describes recent progress in magnetic resonance enterography techniques, and examines the role of MRI in the evaluation of Crohn's disease.

RECENT FINDINGS

Recent advancements in magnetic resonance technology and imaging protocol have made MRI of the small bowel feasible. With improved coils, breath-hold sequences and faster acquisition techniques, MRI capably depicts disease location, extent, and complications. Most of the current literature recognizes MRI as an excellent tool in characterizing transmural and extraluminal changes of Crohn's disease.

SUMMARY

The lack of ionizing radiation is the main driving force for MRI of Crohn's disease. This advantage is magnified by the relatively young age of Crohn's disease patients. While intrinsic susceptibility to air and motion may limit its use in some patients, MRI shows promising potential as an alternative to computed tomography in monitoring disease progression or response to therapy.

Myocutaneous flaps and proctocolectomy in severe perianal Crohn's disease--a single stage procedure

BACKGROUND

Complex perianal wounds can be extremely difficult to treat and primary closure of these defects can be a challenge even for experienced surgeons. So far, myocutaneous flaps for wound closure after removal of malignant tumors are a well-accepted option, but there are only a few reports focusing on the primary closure of the perineal wound after proctocolectomy for Crohn's disease. We describe our experience with wide excision of the diseased perineum using a combined abdominoperineal two-team approach.

MATERIALS AND METHODS

We performed proctocolectomy with permanent ileostomy in five patients with longstanding extensive Crohn's disease. All five patients had fistulizing perineal Crohn's disease combined with Crohn's colitis. Each patient received at least one flap for primary wound closure, either a rectus abdominis myocutaneous flap or a gracilis flap.

RESULTS

Indication for surgical intervention included anal or bowel stenosis, septic condition, fecal incontinence, or a combination of these features. One patient had a simultaneous adenocarcinoma of the sigmoid colon. Five patients underwent a total of seven flaps. Three months after surgery, complete healing was achieved in all patients; one patient suffered recurrence in the region of his right thigh. Mean follow up was 19.6 months (range-12-43 months).

CONCLUSIONS

Myocutaneous flaps are a promising therapeutic option in patients with chronic perianal disease. With the transposition of well-vascularized tissue into the perineal defect, complete healing and control of sepsis can be achieved in the majority of patients.

CT and MRI of paediatric Crohn disease

Over the past two decades there has been considerable evolution in cross-sectional imaging modalities for the evaluation of Crohn disease (CD) in children. CT and MRI have contributed to conventional techniques so that now radiology has an even greater role in the management of CD, monitoring disease progression and detecting complications. The role of CT and MRI, their limitations, and the various imaging features that the radiologist should be aware of are discussed in this review.

Comparison of MR enteroclysis with MR enterography and conventional enteroclysis in patients with Crohn's disease

To prospectively compare the diagnostic accuracy of MR enteroclysis with duodenal intubation with MRI after drinking oral contrast agent only (MR enterography) with conventional enteroclysis (conv-E) as reference standard in patients with Crohn's disease. Forty consecutive patients (22 males and 18 females; mean age 36; range 16-74 years) with proven Crohn's disease underwent conv-E and MR imaging. Twenty-two patients underwent MR enteroclysis with intubation (MRE) and 18 underwent MR-enterography (MR per OS). Two radiologists reached a consensus about the following imaging findings: luminal distension and visualization of superficial mucosal, mural and mesenteric abnormalities. Standard descriptive statistics and a Wilcoxon rank sum test were used. Statistical significance was inferred at P < 0.05. There was no significant difference in the adequacy of luminal distention between the MRE and conv-E (P = 0.08), and both were statistically superior in comparison to MR per OS in the distension of the jejunum (P < 0.01) and less significant at the ileum and terminal ileum levels (P < 0.05). MRE and conv-E were comparable for the accuracy of superficial mucosal abnormalities; meanwhile conv-E compared with MR per OS was statistically superior (P < 0.01). MRE compared with MR per OS was statistically better when visualizing superficial abnormalities (P < 0.01). No statistically significant differences were found in assessing the diagnostic efficacy between MR examinations for the depiction of mural stenosis (P = 0.105) and fistulae (P = 0.67). The number of detected mesenteric findings was significantly higher with both MRE and MR per OS compared to conv-E (P < 0.01). MRE can serve as the diagnostic procedure for initially evaluating patients suspected of having Crohn's disease. MR per OS may have a role in patients that refuse or have failed intubation and also for follow-up.

Magnetic resonance imaging of abdominal pain during pregnancy

The objective of this review is to demonstrate magnetic resonance imaging as an important adjunct to ultrasound and computed tomography in the evaluation of the pregnant patient with abdominal pain. With the advent of ultrafast T2-weighted pulse sequences, fetal and bowel motion cause minimal artifact on the images. An accurate diagnosis can often be made in a few minutes based on these high-contrast images performed in 2 or 3 planes. T1-weighted gradient echo images with and without fat saturation are useful for identifying blood and fat, especially in the case of adnexal masses. Gadolinium-diethylenetriamine pentaacetic acid is rarely used to diagnose inflammatory or obstructive disease and is reserved for those patients with suspected malignancies.

MR Imaging Evaluation of Acute Abdominal Pain During Pregnancy

MR imaging enables diagnosis of a variety of maternal diseases presenting as acute abdominal pain in pregnant patients. MR imaging is a valuable complement to ultrasound in the determination of the exact etiology of acute abdominal pain, and it is important for the radiologist to recognize the MR imaging appearance of common causes of acute abdominal pain during pregnancy. This article reviews the MR imaging technique and findings of various abnormalities causing acute abdominal pain in pregnant patients.

Assessment of Crohn's disease in the small bowel: Prospective comparison of magnetic resonance enteroclysis with conventional enteroclysis

Our objective was to assess the diagnostic value of magnetic resonance enteroclysis (MRE) compared with conventional enteroclysis (CE) in patients with Crohn's disease. A secondary objective was to evaluate the diagnostic accuracy of each different MR sequence. Sixty-six consecutive patients with known Crohn's disease underwent MRE and CE. Fast imaging employing steady-state acquisition (FIESTA), single-shot fast spin-echo (ssFSE), and contrast-enhanced T1-weighted sequences were assessed by two radiologists who reached a consensus about the following findings: visualization of wall ulcers, pseudopolyps, fistulae, mural stenosis, and mesenteric abnormalities. Standard descriptive statistics and the McNemar test were used. The sensitivity, specificity and accuracy of MRE were 90-87% and 83% for the depiction of parietal ulcers, 84%-88% and 86% for pseudopolyps, 100-94% and 96% for mural stenosis, 93-100% and 94% for fistulae. The number of detected extraluminal findings was significantly higher with MRE (P < 0.01). The accuracy of FIESTA sequence was statistically higher in the depiction of wall ulcers and fistulae than that of three-dimensional fast spoiled gradient echo (3D-FSPGR) (P < 0.01) and ssFSE (P < 0.05) sequences. Contrast-enhanced 3D-FSPGR was superior for mural stenosis visualization compared to ssFSE (P < 0.05) and FIESTA (P < 0.05). MRE correlates accurately with CE in the detection of superficial and transmural abnormalities and has the advantage of assessing the mesenteric manifestations.

Incidence of visualization of the normal appendix on different MRI sequences

The purpose of this paper is to assess the incidence of visualization of the normal appendix on magnetic resonance imaging (MRI) examinations of the pelvis in a large adult population and to compare the yield of commonly used sequences. Pelvic MRI scans of 111 randomly selected patients were retrospectively reviewed by two fellowship-trained body imagers. Thirty-six cases, where the entire cecum and terminal ileum were not included in the field of view, were excluded. A normal appendix was definitively visualized in 55 of 71 patients on T1 spin echo (SE) sequences (78%). The appendix was seen on 25 of 42 (60%) half-Fourier single-shot turbo spin echo T2. Visualization rates were 42% on pre-gadolinium T1 FS GRE, 54% on post-gadolinium T1 fat-suppressed gradient echo, and 17% of short tau inversion recovery sequences. MRI is an effective modality for visualization of the normal appendix. This may have important implications in patients with abdominal or pelvic pain, as visualization of a normal appendix should exclude the possibility of acute appendicitis from the differential diagnosis.

Ultrasound and magnetic resonance imaging assessmentof active bowel segments in Crohn's disease

AIM

Determining bowel disease activity in Crohn's patients can be difficult on clinical and laboratory assessment. Endoscopy is invasive and barium studies use ionising radiation. The aim of this study was to compare ultrasound and magnetic resonance imaging (MRI) in detecting Crohn's disease activity in the small or large bowel.

MATERIALS AND METHODS

Thirty patients, previously diagnosed with Crohn's disease, had bowel ultrasound and MR imaging, and were deemed active or inactive on each test. The 'gold standard' was based on clinical assessment and one or more of the following: endoscopy, barium studies or surgery.

RESULTS

For determining Crohn's disease activity, the sensitivities and specificities of bowel ultrasound and MRI were 87 percent and 100 percent, and 87 percent and 71 percent, respectively. Significant parameters that defined disease activity were bowel wall thickening on ultrasound and MRI, and contrast enhancement of the bowel wall and mesenteric vascularity/stranding on MRI.

CONCLUSION

Ultrasound and MRI were both sensitive for determining Crohn's disease activity in the bowel, but MRI with gadolinium enhancement was less specific.

Dynamic studies of gadolinium uptake in brain tumors using inversion-recovery echo-planar imaging

Echo-planar imaging has been used to observe the dynamics of Gd-DTPA uptake in brain tumors. It has been possible to examine both vascular uptake and diffusion across the blood-brain barrier in a single experiment, by using the IR-MBEST echo-planar sequence which combines a high temporal resolution (approximately 3 s) with strong T1 weighting. To model the uptake it is necessary to know the arterial concentration of Gd-DTPA; in this study the signal in the sagittal sinus was measured to avoid the need to take repeated blood samples. The time constant for transfer across the blood-brain barrier was measured to be between 20 and 1050 s for different tumors. The results of the modeling correlated with the results of other assessments of tumor vascularity.