Evaluation of Crohn disease activity with magnetic resonance imaging

Magnetic resonance imaging of the small bowel in children with idiopathic inflammatory bowel disease: evaluation of disease activity

BACKGROUND

Examinations using ionizing radiation are frequently used in the evaluation of disease activity in children affected by idiopathic inflammatory bowel disease (IBD).

OBJECTIVE

To develop an MR imaging protocol without the need for fluoroscopic insertion of an enteral tube and to assess the disease activity in children with IBD.

MATERIALS AND METHODS

Included in the study were 37 children (22 girls and 15 boys; age range 7-15 years, mean 11.67 years) with IBD who underwent MR imaging of the small bowel. Of these 37 children, 32 had Crohn disease and 5 had indeterminate colitis. A water solution containing herbal fibres was administered orally or through a nasogastric tube. Patients were imaged on a 1.5-T MR scanner with T1-weighted and Tau2-weighted sequences followed by a dynamic study using 3-D T1-W images after intravenous administration of gadolinium.

RESULTS

The percentage enhancement of the bowel wall was significantly increased in patients with abnormal C-reactive protein (CRP) values compared to patients with CRP values in the normal range (P<0.001). A relatively weak but significant correlation between percentage enhancement of the bowel wall and CRP values was noted during all phases of enhancement.

CONCLUSION

This MR imaging protocol is a safe and well-tolerated method for evaluating disease activity and extraintestinal manifestations of IBD in children.

Mural inflammation in Crohn disease: location-matched histologic validation of MR imaging features

PURPOSE

To validate proposed magnetic resonance (MR) imaging features of Crohn disease activity against a histopathologic reference.

MATERIALS AND METHODS

Ethical permission was given by the University College London hospital ethics committee, and informed written consent was obtained from all participants. Preoperative MR imaging was performed in 18 consecutive patients with Crohn disease undergoing elective small-bowel resection. The Harvey-Bradshaw index, the C-reactive protein level, and disease chronicity were recorded. The resected bowel was retrospectively identified at preoperative MR imaging, and wall thickness, mural and lymph node/cerebrospinal fluid (CSF) signal intensity ratios on T2-weighted fat-saturated images, gadolinium-based contrast material uptake, enhancement pattern, and mesenteric signal intensity on T2-weighted fat-saturated images were recorded. Precise histologic matching was achieved by imaging the ex vivo surgical specimens. Histopathologic grading of acute inflammation with the acute inflammatory score (AIS) (on the basis of mucosal ulceration, edema, and quantity and depth of neutrophilic infiltration) and the degree of fibrostenosis was performed at each site, and results were compared with MR imaging features. Data were analyzed by using linear regression with robust standard errors of the estimate.

RESULTS

AIS was positively correlated with mural thickness and mural/CSF signal intensity ratio on T2-weighted fat-saturated images (P < .001 and P = .003, respectively) but not with mural enhancement at 30 and 70 seconds (P = .50 and P = .73, respectively). AIS was higher with layered mural enhancement (P < .001), a pattern also commonly associated with coexisting fibrostenosis (75%). Mural/CSF signal intensity ratio on T2-weighted fat-saturated images was higher in histologically edematous bowel than in nonedematous bowel (P = .04). There was no correlation between any lymph node characteristic and AIS.

CONCLUSION

Increasing mural thickness, high mural signal intensity on T2-weighted fat-saturated images, and a layered pattern of enhancement reflect histologic features of acute small-bowel inflammation in Crohn disease.

Assessment of the extension and the inflammatory activity in Crohn's disease: comparison of ultrasound and MRI

OBJECTIVE

The purpose of this prospective study was twofold: to examine the efficacy of MRI and sonography in the assessment of Crohn's disease (CD) activity in comparison with clinical scoring and biologic tests and to compare both techniques in the evaluation of extension and transmural complications.

MATERIAL AND METHODS

Thirty patients with histologically proven Crohn's disease were prospectively examined the same day first with sonography and after MRI. Sonographic exam included evaluation of bowel wall thickness, vascularity pattern, and perienteric changes. Thirty minutes prior to MRI imaging, patients were given 250 mL of dilute sodium phosphate solution and additional 750 mL of water orally. MRI images evaluation included bowel wall thickening, bowel wall enhancement, and perienteric changes. The gastrointestinal tract was divided into five segments. Findings and extension of the both techniques were verified by means of barium studies, surgery, or/and colonoscopy. The sonographic and MR findings were compared with clinical and laboratory data.

RESULTS

About 53 of 119 (45%) bowel segments showed pathological changes in gold standard tests. Sonography was superior to MRI in the localization of affected bowel segments (sensitivity: US 91%; MRI 83%; intertechniques agreement, kappa: 0.905) and in recognizing transmural complications (sensitivity: US 80%; MRI 72%), although significant differences were not found (p > 0.05). A statistically significant correlation between color Doppler flow and MR bowel wall enhancement (segment-by-segment analysis and per patient analysis; p > 0.5), and between perienteric changes in both techniques (p > 0.5) were found. Wall thickness measured on sonography was significantly greater in the group of patients with clinical activity (p = 0.023) or with clinical-biologic activity (p = 0.024). Grades of hyperemia and MR contrast enhancement of patients with clinical-biologic activity was higher than in patients without clinical-biologic activity (p = 0.019; p = 0.023).

CONCLUSION

In summary, both ultrasound and MRI are sensitive to localize the affected bowel segments and to detect transmural complications in patients with Crohn's disease. A significant correlation between color Doppler flow and bowel wall enhancement on MRI was found. Sonographic wall thickness, color Doppler flow, and bowel wall enhancement on MRI are related with clinical or biologic activity.

Free-breathing diffusion-weighted imaging for the assessment of inflammatory activity in Crohn's disease

PURPOSE

To investigate the application of free-breathing diffusion-weighted MR imaging (DWI) to the assessment of disease activity in Crohn's disease.

MATERIALS AND METHODS

Thirty-one patients with Crohn's disease were investigated using free-breathing DWI without special patient preparation or IV or intraluminal contrast agent. The bowel was divided into seven segments, and disease activity was assessed visually on DWI. For quantitative analysis, the apparent diffusion coefficient (ADC) was measured in each segment. The findings of a conventional barium study or surgery were regarded as the gold standard for evaluating the diagnostic ability of DWI to assess disease activity.

RESULTS

Upon visual assessment, the sensitivity, specificity, and accuracy for the detection of disease-active segments were 86.0, 81.4, and 82.4%, respectively. In the quantitative assessment, the ADC value in the disease-active area was lower than that in disease-inactive area in small and large bowels (1.61 +/- 0.44 x 10(-3) mm(2)/s versus 2.56 +/- 0.51 x 10(-3) mm(2)/s in small bowel and 1.52 +/- 0.43 x 10(-3) mm(2)/s versus 2.31 +/- 0.59 x 10(-3) mm(2)/s in large bowel, respectively, P<0.001).

CONCLUSION

Free-breathing DWI is useful in the assessment of Crohn's disease. The accuracy of DWI is high in evaluating disease activity, especially in the small bowel, and the ADC may facilitate quantitative analysis of disease activity.

Magnetic resonance imaging of the small bowel in children with idiopathic inflammatory bowel disease: evaluation of disease activity

BACKGROUND

Examinations using ionizing radiation are frequently used in the evaluation of disease activity in children affected by idiopathic inflammatory bowel disease (IBD).

OBJECTIVE

To develop an MR imaging protocol without the need for fluoroscopic insertion of an enteral tube and to assess the disease activity in children with IBD.

MATERIALS AND METHODS

Included in the study were 37 children (22 girls and 15 boys; age range 7-15 years, mean 11.67 years) with IBD who underwent MR imaging of the small bowel. Of these 37 children, 32 had Crohn disease and 5 had indeterminate colitis. A water solution containing herbal fibres was administered orally or through a nasogastric tube. Patients were imaged on a 1.5-T MR scanner with T1-weighted and Tau2-weighted sequences followed by a dynamic study using 3-D T1-W images after intravenous administration of gadolinium.

RESULTS

The percentage enhancement of the bowel wall was significantly increased in patients with abnormal C-reactive protein (CRP) values compared to patients with CRP values in the normal range (P<0.001). A relatively weak but significant correlation between percentage enhancement of the bowel wall and CRP values was noted during all phases of enhancement.

CONCLUSION

This MR imaging protocol is a safe and well-tolerated method for evaluating disease activity and extraintestinal manifestations of IBD in children.

Frequency and nature of incidental extra-enteric lesions found on magnetic resonance enterography (MR-E) in patients with inflammatory bowel diseases (IBD)

Background

The aim of this study was to determine the occurrence of extra-enteric findings in a large cohort of patients undergoing magnetic resonance enterography (MR-E) and to classify the clinical significance of these findings.

Materials and Methods

We retrospectively analyzed 1154 MR-E performed in 1006 patients referred to our radiological department between 1999–2005. The reasons for referral were suspected or proven inflammatory bowel diseases (IBD) (n = 710), further diagnostic work-up for small bowel disease because of non-specific abdominal symptoms (SBD; n = 182) or suspected small bowel malignancies (SBM; n = 114). All extra-enteric findings were reviewed by a radiologist and a gastroenterologist and were classified as having high, moderate, or low significance for further diagnostic or therapeutic procedures.

Results

The average age of all patients was 40±16 (Mean±SD) years (y) (IBD 35±13 y; SBD 49±16 y; SBM 57±15 y). A total of 1113 extra-enteric findings were detected in 600 of 1006 patients (59.6%). Of these findings 180 (16.2%) were judged as having a high, 212 (19.0%) a moderate and 721 (64.8%) a low significance. On a per group basis in patients with IBD 12.0% of the findings were of major clinical significance compared to 13.7% and 33.3% in patients with SBD and SBM, respectively. The most common major findings were abscesses (69.9%) in the IBD group and extraintestinal tumors, metastases or masses in the SBD and SBM groups (41.9% and 74.2%, respectively).

Conclusions

MR-E reveals a substantial number of extra-enteric findings, supporting the role of a cross-sectional imaging method for the evaluation of the small bowel.

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.

Assessment of Crohn's disease activity in the small bowel with MR-enteroclysis: clinico-radiological correlations

BACKGROUND

The aim of our study was to evaluate the accuracy of magnetic resonance imaging (MRI) in evaluating Crohn's disease (CD) activity compared to clinical/laboratory data.

METHODS

Ninety-three consecutive patients with CD were prospectively studied by MR imaging, before and after Gadolinium chelates administration, with use of a biphasic endoluminal contrast agent. MR image analysis included: number of lesions, presence/absence of bowel stenosis, upstream bowel dilation, wall thickness, presence of enhancement, enhancement pattern, presence/absence of comb sign, lymph nodes, and perianal fistulas/abscesses. Clinical evaluation was performed by means of Harvey & Bradshaw Index. Acute-phase reactants were considered standard of reference to monitor biological activity (BA). MR imaging findings were compared with clinical and laboratory data.

RESULTS

MR image analysis detected: In 96 exams multiple lesions in 16, 1 in 50; no lesions in 30; stenosis in 52; dilatation in 28; wall thickening in 59; significant enhancement in 57; layered pattern in 50; comb sign in 37; enlarged lymph nodes in 16; fibro-fatty proliferation in 40; fistulas in 9.

CONCLUSIONS

MRI is able to depict morphological changes and is helpful in assessing Crohn's inflammatory disease.

Assessment of dynamic contrast enhancement of the small bowel in active Crohn's disease using 3D MR enterography

PURPOSE

To retrospectively compare the dynamic contrast enhancement of the small bowel segments with and without active Crohn's disease at 3D MR enterography (MRE).

MATERIALS AND METHODS

Thirteen patients (five men, eight women; mean age 41.2 years; range 29-56) were imaged on a 1.5-T MR scanner (Sonata, Siemens Medical) with standard MR sequences after having ingested 1000 ml of a 3% mannitol solution. Subsequently, high resolution 3D gradient-echo (volumetric interpolated breath-hold examination=VIBE) data sets were obtained pre-contrast and 20-40s, 60-80s, and 120-140 s after i.v. Gd-DOTA administration (0.2 mmol/kg). Signal enhancement was measured on single slices both in normal and histologically confirmed (12/13) inflamed small bowel wall segments as well as in the aorta, the psoas muscle, and the background to calculate signal-to-noise (SNR) and contrast-to-noise ratios (CNR).

RESULTS

Small bowel wall enhancement was significantly higher (p<0.05) in inflamed compared to normal segments at 20-40s (SNR inflamed: 58.7+/-33.8 vs normal: 36.0+/-19.8; p=0.048; CNR inflamed: 34.8+/-23.4 vs normal: 16.3+/-11.2; p=0.017) and at 60-80s (SNR: 60.3+/-25.1 vs 41.9+/-20.0; p=0.049; CNR: 34.9+/-15.1 vs 19.3+/-13.2; p=0.01) after i.v. contrast administration, respectively. Even at 120-140 s CNR was still increased in inflamed segments (33.7+/-16.0 vs 18.1+/-13.2; p=0.04), while differences in SNR did not attain statistical significance (63.0+/-26.2 vs 45.3+/-23.3; p=0.15).

CONCLUSION

In active Crohn's disease, histologically confirmed inflamed small bowel wall segments demonstrate a significantly increased early uptake of gadolinium on 3D VIBE sequences compared to normal small bowel segments.

MR imaging of the small bowel in Crohn's disease

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 advantage of these techniques over tradition barium fluoroscopic examinations secondary 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 [Brenner DJ, Hall EJ. Computed tomography--an increasing source of radiation exposure. N Engl J Med 2007;357:2277-84]. 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 [Froehlich JM, Patak MA, von Weymarn C, Juli CF, Zollikofer CL, Wentz KU. Small bowel motility assessment with magnetic resonance imaging. J Magn Reson Imaging 2005;21:370-75]. A recent study showed that certain subgroups of patients with Crohn's disease may be exposed to higher doses of radiation; those diagnosed at an early age, those with upper tract inflammation, penetrating disease, requirement of intravenous steroids, infliximab or multiple surgeries [Desmond AN, O'Regan K, Curran C, et al. Crohn's disease: factors associated with exposure to high levels of diagnostic radiation. Gut 2008;57:1524-29]. Therefore it has been suggested that techniques that can reduce or eliminate radiation exposure should be considered for imaging [Brenner DJ, Hall EJ. Computed tomography--an increasing source of radiation exposure. N Engl J Med 2007;357:2277-84]. Owing to the excellent softtissue 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. In this article we will review the technical issues related to the performance of MR enterography and enteroclysis and discuss the role and controversies of using MR in the assessment of inflammatory bowel disease.

Prevalence and clinical significance of sonographic evidence of mesenteric fat alterations in Crohn's disease

BACKGROUND

Mesenteric adipose tissue hypertrophy is a frequent sonographic finding in Crohn's disease (CD). This study assessed its sonographic prevalence, the correlation with the degree of clinical or biochemical activity of the disease, and its impact on disease outcome in CD patients.

METHODS

In all, 185 consecutive CD patients underwent bowel ultrasound to assess the presence of mesenteric fat tissue alteration as well as thickness and echopattern of the bowel wall, site and extent of CD, and presence of stenosis, fistulas, and abscesses. Clinical and biochemical parameters of disease activity were also assessed. Multiple logistic regression analysis was used to identify variables related to mesenteric adipose tissue alteration.

RESULTS

Mesenteric adipose tissue alteration, detected in 88 (47.6%) patients, showed a significant correlation both with clinical and biochemical CD activity and with internal fistulas, bowel wall thickness, and length of thickened bowel wall. Logistic regression analysis showed that internal fistulas (odds ratio [OR] = 13.5), thickened bowel wall (OR = 7.6), C-reactive protein (OR = 6.1), CD Activity Index (CDAI) (OR = 3.1), and length of diseased bowel walls (OR = 2.6) were significantly associated with mesenteric adipose tissue alteration. Of the 111 patients with quiescent CD, 22 showed mesenteric adipose tissue hypertrophy. These patients did not show increased risk of relapse compared with quiescent patients without mesenteric fat alteration.

CONCLUSIONS

Mesenteric adipose tissue alteration is correlated with biochemical and clinical activity of CD and with internal fistulas and increased bowel wall thickness. In quiescent CD, mesenteric hypertrophy does not appear to be a risk factor of relapse.

Role of MRI in Crohn's disease

The traditional imaging of Crohn's disease has relied on barium and computed tomography (CT) examinations. In recent years magnetic resonance imaging (MRI) has emerged as an imaging method that can be used in the diagnosis and assessment of Crohn's disease. The advantages of MRI include lack of ionizing radiation and its superior tissue contrast resolution. The clinical progression of Crohn's disease can be variable, and MRI can be used to assess inflammatory status, disease progression, and complications of Crohn's disease. MRI of the small bowel is an evolving technique and it has the potential to become the preferred technique for imaging of small bowel Crohn's disease in the future.

Inflammatory activity in Crohn disease: ultrasound findings

Improvements in the ultrasound examination of bowel disease have registered in the last years the introduction of new technologies regarding high frequency probes (US), highly sensitive color or power Doppler units (CD-US), and the development of new non-linear technologies that optimize detection of contrast agents. Contrast-enhanced ultrasound (CE-US) most importantly increases the results in sonographic evaluation of Crohn disease inflammatory activity. CE-US has become an imaging modality routinely employed in the clinical practice for the evaluation of parenchymal organs due to the introduction of new generation microbubble contrast agents which persist in the bloodstream for several minutes after intravenous injection. The availability of high frequency dedicated contrast-specific US techniques provide accurate depiction of small bowel wall perfusion due to the extremely high sensitivity of non-linear signals produced by microbubble insonation. In Crohn's disease, CE-US may characterize the bowel wall thickness by differentiating fibrosis from edema and may grade the inflammatory disease activity by assessing the presence and distribution of vascularity within the layers of the bowel wall (submucosa alone or the entire bowel wall). Peri-intestinal inflammatory involvement can be also characterized. CE-US can provide prognostic data concerning clinical recurrence of the inflammatory disease and evaluate the efficacy of drugs treatments.

Correlation of magnetic resonance enteroclysis (MRE) and wireless capsule endoscopy (CE) in the diagnosis of small bowel lesions in Crohn's disease

BACKGROUND

The aim was to evaluate and compare the diagnostic performance of magnetic resonance enteroclysis (MRE) and wireless video capsule endoscopy (CE) in detecting and classifying small bowel Crohn's disease (CD) proximal to the terminal ileum.

METHODS

Nineteen patients with histologically proven CD (M:F = 13:6; mean 34 years, range 17-65) were prospectively included in the study when presenting with clinical signs suggesting stricturing or inflammatory lesions of CD in the proximal small bowel. All patients underwent MRE with an infusion technique and were then admitted to CE.

RESULTS

As for the presence or absence of pathology, results of MRE and CE were in total agreement for 44/52 (85%) evaluated segments. In judging lesion severity, MRE and CE yielded identical results in 29/52 (56%) segments. MRE underestimated pathology in 7/52 (14%) segments and revealed more severe pathology in 6/52 (12%) segments. CE identified subtle (n = 7) or severe (n = 2) mucosal pathology while MRE was normal. CE entirely missed severe inflammatory mural changes depicted in MRE in 1/52 (2%) segments.

CONCLUSIONS

MRE and CE show good correlation in the detection and localization of inflammatory bowel disease. As for disease activity, MRE is inferior in the detection of superficial mucosal disease but reliably discloses the presence of severe inflammatory changes within the bowel wall and beyond, which may be underestimated from the endoscopic aspect of the mucosal surface. MRE helps to rule out severe stenoses that should be referred for immediate surgical intervention. In conclusion, both modalities are complementary and MRE should be used in more severe cases of Crohn's disease and in patients who might have involvement beyond the mucosa of the small bowel.

Dynamic contrast enhanced magnetic resonance imaging of the terminal ileum: differentiation of activity of Crohn's disease

AIM

To prospectively investigate a new high resolution MRI technique for dynamic evaluation of the enhancement kinetics of bowel parietal layers and to correlate it with CDAI, CRP, endoscopic activity and histologic features.

METHODS

About 16 consecutive patients with proven diagnosis of CD underwent ileocolonoscopy with biopsy and serial bowel dynamic contrasted-MRI (D-CE-MRI) evaluated in blind fashion. Quantitative analysis of bowel wall enhancement kinetics was performed basing on signal to noise ratio (SNR) of inner parietal layers (Mucosa-Submucosa, M-SM) and outer parietal layers (Muscular-Serosa, Ms-S). Disease activity was defined by CDAI > 150, serum CRP > 5 mg/dL and histologic results.

RESULTS

About 9 patients showed a layered enhancement of bowel wall (8 active, 1 inactive), whereas inactive (7 cases) group presented a homogeneous pattern. In active patients we found a significant difference in parietal layered enhancement curves (M-SM vs. Ms-S, P < 0.03) not observed in inactive disease and controls (intra-group analysis). M-SM and Ms-S enhanced curves in clinically active patients were significantly different respect to those of patients with inactive CD (P < 0.001) (inter-group analysis). Parietal D-CE-MRI pattern well correlated with histologic features (r = 0.8; P < 0.001, Spearman test).

CONCLUSIONS

D-CE-MRI can be a useful tool for clinical follow-up and in the treatment strategies in CD patients.

Crohn's disease and color Doppler sonography: response to treatment and its relationship with long-term prognosis

PURPOSE

To evaluate the ability of sonography to detect changes in patients undergoing treatment for Crohn's disease and whether these findings are related to the patient's long-term outcome.

METHODS

Twenty-eight patients with Crohn's disease were examined prospectively using gray-scale and color Doppler sonography before and during treatment. Three sonographic examinations were made: on the first day of treatment, between 3 and 8 days later, and approximately 4 weeks after starting the treatment. Sonographic examination included an evaluation of maximum bowel wall thickness and vascularity pattern. The sonographic data were compared with clinical and laboratory data, and possible relation with the patient's long-term outcome was considered.

RESULTS

Initial baseline sonograms revealed at least 1 thickened segment of the bowel wall in all of the patients. In this initial examination, 18 of 22 patients (81%) with clinically active disease had moderate or marked parietal vascularity. A statistically significant reduction in the vascularity of the affected bowel was observed on the third sonographic examination (p < 0.05). Seventeen patients who were in clinical remission had relapses and were treated with immunosuppressive therapy or surgery during the follow-up. Eighty-six percent of the patients with residual hyperemia on sonographic examination after treatment had an unfavorable clinical course compared with only 30% of the patients with no, or barely visible, residual hyperemia (p < 0.01).

CONCLUSION

Sonography can identify bowel inflammation and its changes during treatment. In patients with Crohn's disease, hyperemia on color Doppler sonography during clinical remission after treatment may reflect an increased risk of relapse.

Anastomotic recurrence of Crohn's disease after ileocolic resection: comparison of MR enteroclysis with endoscopy

The purpose of this study was to assess the accuracy of MR enteroclysis in patients with Crohn's disease recurrence after ileocolic resection and to establish an MR scoring sytem. MR enteroclysis and endoscopy were performed in 30 patients with suspected Crohn's disease recurrence after ileocolic resection. Findings were evaluated by three radiologists, using an MR score based on image quality, contrast enhancement, and mural and extramural bowel-wall changes: MR0 (no abnormal features), MR1 (minimal mucosal changes), MR2 (diffuse aphtoid ileitis, moderate recurrence), and MR3 (severe recurrence with trans- and extramural changes). The endoscopic Rutgeerts score defines changes at the ileum on a scale from I0 to I4. In 3/30 (10%) patients, evaluation was not possible. The mean overall image quality was rated as 1.7 (kappa 0.78). Comparing MR and Rutgeerts score, the mean observer agreement for the total score rating was 77.8% (kappa 0.67). When comparing only scores below or above MR2-the threshold indicative of the necessity of medical treatment-there was a total agreement of 95.1% (kappa 0.84). MR enteroclysis allows assessment of Crohn's disease recurrence after ileocolic resection. The MR score is reproducible and shows high agreement with the approved endoscopic Rutgeerts score.

Grey-scale and colour Doppler sonography in the evaluation of children with suspected bowel inflammation: correlation with colonoscopy and histological findings

AIM

To evaluate the correlation of grey-scale and colour Doppler sonography with colonoscopy and histology to detect bowel inflammation in children.

MATERIAL AND METHODS

The records of 72 patients with suspected bowel inflammation were reviewed retrospectively. Patients were included in the study if sonography had been performed up to 30 days before colonoscopy. Grey-scale and colour Doppler sonography were used to evaluate bowel wall thickness and vascularity for the detection of distal bowel inflammation. Findings were correlated with colonoscopy and histological findings. The sensitivity and specificity of sonographic wall thickness to detect inflammation was determined. Spearman's coefficient (rs) was used to determine the correlation of Doppler findings with colonoscopy/histology.

RESULTS

Sonograms of 372 bowel segments were evaluated and results were correlated with colonoscopy and histological findings of 352 segments. The sensitivity and specificity of sonographic bowel thickness to detect inflammation in the terminal ileum and the right colon were high; in the other segments, specificity was high but sensitivity was low. The correlation of Doppler sonography with colonoscopy and histology to detect inflammation in the terminal ileum was strong (rs: 0.84; p<0.001) and in the other segments, weak to moderate; when the interval between examinations was shorter than 10 days, the correlation was stronger in all segments. Of nine patients with abnormal small bowel sonograms but normal colonoscopies, three had Crohn's disease.

CONCLUSION

Sensitivity and specificity of grey-scale sonography to detect inflammation in the terminal ileum and the right colon were high, and the correlation of Doppler with colonoscopy and histology was very strong in the same segments.

Head-to-head comparison of oral contrast agents for cross-sectional enterography: small bowel distention, timing, and side effects

OBJECTIVE

To determine small bowel distention, scanning time, and side effects of commercially available oral contrast agents used in cross-sectional enterography.

METHODS

Ten healthy volunteers ingested 2000 mL of water, methylcellulose, polyethylene glycol (PEG), or 1350 mL of low-concentration barium (LCB) followed by 500 mL water on different days. Magnetic resonance imaging occurred every 10 minutes from 30 to 90 minutes after ingestion. Small bowel distention was compared between time points and agents. Volunteers ranked side effects, drinking difficulty, and preference.

RESULTS

By quantitative assessment, PEG and LCB distended small bowel loops better than water and methylcellulose (P < 0.0001). Time to optimal distention of the terminal ileum was from 51 to 72 minutes. Water and methylcellulose had the fewest side effects. Water was the most preferred contrast and PEG the least.

CONCLUSIONS

Polyethylene glycol and LCB distend small bowel better than water and methylcellulose. Polyethylene glycol was the most difficult to drink and least preferred agent.

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.

Ingested matter affects intestinal lesions in Crohn's disease

BACKGROUND

Environmental factors of the modern Western lifestyle may trigger Crohn's disease (CD) in susceptible individuals. Because such factors could be part of ingested matter, we intended to improve intestinal Crohn's lesions by exclusion thereof.

METHODS

At first we tested a highly restricted diet (based on spelt bread and red meat, both derived from intensively monitored organic farming) in 5 pilot cases. In a subsequent controlled trial, 18 patients with mild-to-moderate CD were randomly assigned to receive either this active diet or a control diet (low-fiber, low-fat, and high-carbohydrate). Mucosal improvement was assessed by magnetic resonance imaging (MRI) and endoscopy. Secondary endpoints included sonography, the Crohn's Disease Activity Index (CDAI), and the Inflammatory Bowel Disease Questionnaire (IBDQ).

RESULTS

Four of 5 pilot patients showed significant improvement within 4 weeks. From 18 patients in the controlled trial, 8 were randomized to the active and 10 to the control group; 4 decided to quit immediately after dietary counseling, 3 in the active and 1 in the control group (P = 0.183). At 6 weeks MRI and endoscopy showed improvement of intestinal lesions in 3 of 4 assessable patients of the active group and 1 of 9 patients of the control group (P = 0.027). Sonography showed improvement in 4 of 5 patients of the active group and in 1 of 8 assessable patients of the control group (P = 0.016). CDAI and IBDQ improved in both groups to a similar extent.

CONCLUSIONS

Ingested matter as part of the modern Western lifestyle may cause persistence of intestinal Crohn's lesions.

MRI scoring system including dynamic motility evaluation in assessing the activity of Crohn's disease of the terminal ileum

RATIONALE AND OBJECTIVES

We sought to investigate the value of a MRI scoring system including dynamic motility evaluation in the assessment of small bowel Crohn's disease activity.

MATERIALS AND METHODS

From March 2005 to December 2006, 52 patients with suspected Crohn's disease onset or relapse underwent MRI on a 1.5-T magnet. Bowel distention was achieved orally assuming a mean of 1.6 L of a polyethyleneglycol (PEG) preparation. Per-patient assessment of disease activity was based on a scoring system including evaluation of morphology and motility of the small bowel and perivisceral structures (true-FISP, cine-true-FISP, and HASTE T2W sequences) and dynamic assessment of parietal contrast enhancement (FLASH T1W sequence). Patients were included in three categories, using endoscopic biopsy as the standard reference: no activity/quiescent disease, mild activity, or moderate-to-severe activity. Patients without terminal ileum involvement were excluded from data analysis.

RESULTS

MRI allowed a detailed and panoramic evaluation of the small bowel in all subjects examined. MRI properly assessed 14 of 16 (87.5%) cases of no activity/quiescent disease, 12 of 14 (85.7%) cases of mild activity, and 15 of 15 (100%) cases of severe activity. Overall, activity score led to a per-patient misdiagnosis of disease activity in a nonsignificant proportion of subjects (4 of 45; 8.8%) (P > .05), determining two false-positive and two false-negative results of mild disease activity. Sensitivity, specificity, PPV, NPV, and overall accuracy in assessing disease activity were 93.1%, 87.5%, 93.1%, 87.5%, and 91.1%, respectively.

CONCLUSION

Accurate assessment of Crohn's disease activity is achieved by using an activity score providing an overall interpretation of MRI findings.

Adult celiac disease: MRI findings

The purpose of our report is to describe a spectrum of findings of celiac disease at MR enterography. MR enterography is a non-invasive, feasible, and reproducible imaging technique for the evaluation of small bowel. Findings on MR enterography, similar to those of conventional barium studies, may suggest a diagnosis of celiac disease.

[What can be expected from digestive tract MRI?]

With recent technological progress, MRI can now reliably explore the digestive tract. Gastrointestinal MRI can map small intestine involvement in Crohn disease, with no irradiation in young patients. In addition, MRI provides supporting arguments for inflammatory or fibrous involvement of the intestine. MRI of anoperineal fistulae is useful in the preoperative stage to plan surgical treatment so as to reduce the recurrence rate of complex fistulae or recurring fistulae. In rectal cancer, MRI is the best examination to evaluate perirectal fascia for choosing neoadjuvant treatment.

Radiation doses from small-bowel follow-through and abdominopelvic MDCT in Crohn's disease

OBJECTIVE

The purpose of our study was to compare organ and effective doses for small-bowel follow-through (SBFT) and abdominopelvic MDCT in adults with Crohn's disease, to retrospectively evaluate the number of radiographic examinations performed for Crohn's disease indications, and to identify those patients undergoing serial examinations to better delineate the use of radiology in the diagnosis and clinical management of Crohn's disease.

MATERIALS AND METHODS

Using an anthropomorphic phantom and metal-oxide semiconductor field-effect transistor (MOSFET) dosimeters, specific organ doses were measured for 5 minutes of continuous fluoroscopy (kVp, 120; mA, 0.6) of each of the following: right lower quadrant, central abdomen, and pelvis. Effective doses were determined based on International Commission on Radiological Protection (ICRP) 60 weighting factors. Organ and effective doses were determined for abdominal and pelvic 16-MDCT: detector configuration, 16 x 0.625 mm; pitch, 1.75; 17.5 mm per rotation; rotation time, 0.5 second; 140 kVp; 340 mA. Electronic records were reviewed to determine the number of patients imaged for Crohn's disease indications and the number of studies per patient.

RESULTS

The highest fluoroscopic organ doses were as follows: in the right lower quadrant, right kidney (0.78 cGy) and marrow (0.66 cGy); in the central abdomen, kidneys (1.5 and 1.6 cGy) and marrow (0.76 cGy); and in the pelvis, marrow (0.67-0.95 cGy). Effective doses for the right lower quadrant, central abdomen, and pelvis were 1.37, 2.02, and 3.83 mSv, respectively. For MDCT, the highest organ doses were to the liver (2.95-3.33 cGy). The effective dose for abdominopelvic MDCT was 16.1 mSv. Three hundred seventy-three patients underwent imaging for Crohn's disease. The average number of SBFT and CT examinations was 1.8 and 2.3, respectively. Thirty-four (9%) of 373 patients underwent more than five CT examinations and 11 (3%) had more than 10.

CONCLUSION

Organ and effective doses are up to five times higher with MDCT than with SBFT. Crohn's disease is more frequently imaged with CT. For a subset of patients who undergo numerous CT examinations, efforts should be made to minimize the number of CT examinations, decrease the CT dose, or consider MR enterography.

Internal fistulas in Crohn disease: magnetic resonance enteroclysis

Internal fistulas (IFs) and abscesses are the most common complications of Crohn disease (CD). To reliably diagnose and clearly distinguish inflammatory or fibrostenotic manifestations of CD from its complications is of paramount importance to appropriately guide therapeutic decisions. Magnetic resonance enteroclysis (MRE), a recently introduced technique for small bowel imaging, has proved a high efficacy in the depiction of luminal and extraluminal manifestations of CD and holds great promise as a powerful diagnostic tool in the comprehensive diagnostic workup of this disease. As of yet, the characteristic imaging appearance of IFs on MRE has not been described in detail. This article reviews the performance of conventional imaging techniques and the current potential of MRE in the depiction of IFs in CD. Typical imaging morphology and characteristic imaging findings of IFs on MRE are described in detail and a newly defined and highly indicative imaging finding, the "star-sign," is presented and discussed.

MR imaging of the small bowel

Cross-sectional imaging techniques such as CT and MR imaging have advantages over traditional barium fluoroscopic techniques in their ability to visualize superimposed bowel loops better and to improve visualization of extraluminal findings and complications. This article discusses MR imaging of the small bowel with enterography and enteroclysis techniques. It reviews the advantages, limitations, technique, and indications and reviews the results that have been obtained in evaluating different disease processes.

MR imaging of acute right lower quadrant pain in pregnant and nonpregnant patients

The use of magnetic resonance (MR) imaging in the evaluation of acute abdominal pain is increasing, particularly in those circumstances where computed tomography (CT) is not desirable (eg, pregnancy, allergy to iodinated contrast material). Although ultrasonography (US) is considered the imaging study of choice for evaluation of abdominal pain in pregnant patients, MR imaging is a valuable adjunct to US in evaluation of pregnant patients with acute right lower quadrant (RLQ) pain who have inconclusive US results. MR imaging is also frequently used in patients with renal failure, in whom the use of iodinated contrast material is contraindicated, as well as in cases where CT results are inconclusive. In patients with acute RLQ pain, the breadth of abnormalities visible at MR imaging is very broad, with pathologic conditions potentially originating from multiple organ systems, but most commonly from the gastrointestinal and genitourinary systems. MR imaging is an excellent imaging modality for evaluation of RLQ pain and should be strongly considered in those patients in whom use of iodinated contrast media or radiation is not desirable.

Técnicas seccionales de imagen en la enfermedad de Crohn: ecografía, tomografía computarizada y resonancia magnética

Colonoscopy and Barium contrast studies continue to be the techniques of choice for the evaluation of mucosal lesions in Crohn's disease. However, these techniques have limited capacity for demonstrating the transmural and extramural extension of the disease. Although ultrasound, CT, and MRI cannot detect early lesions, these techniques satisfactorily show parietal and extraparietal changes caused by the disease, thus complementing the information provided in conventional studies. These three techniques enable the evaluation of the pathological segments, the presence of stenosis and dilatation, and extramural disease (fibrofatty proliferation, fistulae, phlegmons, and abscesses). This information is essential for classifying each patient into one of the three subtypes of Crohn's disease (inflammatory, stenotic, or fistulating). These techniques also enable the evaluation of signs that indicate inflammatory activity (hyperemia, wall enhancement, and increased mesenteric vascularization), and this information, together with the subtype, will determine the treatment. Ultrasound, CT, and MRI should be included in the complete evaluation of the patient with Crohn's disease, together with clinical examination, laboratory tests, and conventional imaging studies. We review the role of ultrasound, CT, and MRI in the diagnosis and evaluation of Crohn's disease, describing patient preparation and examination protocols, as well as the findings in these three techniques. We also discuss the advantages and limitations of each of these techniques and their current clinical roles in this context.

Ultrasound assessment of vascularization of the thickened terminal ileum wall in Crohn's disease patients using a low-mechanical index real-time scanning technique with a second generation ultrasound contrast agent

OBJECTIVE

To prospectively evaluate the vascularization of the thickened terminal ileum in Crohn's disease patients using contrast enhanced ultrasound (CEUS) and to compare the clinical activity measured by the Crohn's disease activity index (CDAI) with the CEUS findings.

PATIENTS AND METHODS

Forty-eight of 104 consecutive patients (17 females and 31 males, aged 42.4+/-13.8 years) with a thickened terminal ileum at sonography were recruited for the study. CEUS examinations were performed using a real-time low mechanical index harmonic ultrasound technique after intravenous injection of a second generation contrast agent. We used two parameters to assess the vascularization of the bowel wall: a semi-quantitative method, the pattern of enhancement (which is the description of the arrangement of the enhanced layer in the bowel wall) and a quantitative method, the E/W ratio (which is the ratio between the major thickness of the enhanced layer, E, and the thickness of the entire wall section, W). In order to assess the accuracy of the CEUS findings in discriminating between active and inactive patients according to CDAI values (>150 and < or =150, respectively), the patterns of enhancement (four patterns) were dichotomized in two groups and an E/W ratio cutoff value was calculated to differentiate between poor and abundant bowel wall enhancement.

RESULTS

The CEUS findings, namely the pattern of enhancement and the E/W ratio (best cutoff value ranging between 0.43 and 0.47), had a sensitivity of 81.0% and 81.0%, respectively, a specificity of 63.0% and 55.6%, respectively, a positive predictive value of 63.0% and 58.6%, respectively, and a negative predictive value of 81.0% and 78.9%, respectively, in distinguishing patients with active and inactive disease.

CONCLUSIONS

CEUS assessment of diseased bowel wall vascularization may be a sensitive tool for the detection of inflammatory activity.

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.

CT enterography as a diagnostic tool in evaluating small bowel disorders: review of clinical experience with over 700 cases

Computed tomographic (CT) enterography combines the improved spatial and temporal resolution of multi-detector row CT with large volumes of ingested neutral enteric contrast material to permit visualization of the small bowel wall and lumen. Adequate luminal distention can usually be achieved with oral hyperhydration, thereby obviating nasoenteric intubation and making CT enterography a useful, well-tolerated study for the evaluation of diseases affecting the mucosa and bowel wall. Unlike routine CT, which has been used to detect the extraenteric complications of Crohn disease such as fistula and abscess, CT enterography clearly depicts the small bowel inflammation associated with Crohn disease by displaying mural hyperenhancement, stratification, and thickening; engorged vasa recta; and perienteric inflammatory changes. As a result, CT enterography is becoming the first-line modality for the evaluation of suspected inflammatory bowel disease. CT enterography has also become an important alternative to traditional fluoroscopy in the assessment of other small bowel disorders such as celiac sprue and small bowel neoplasms.

Evaluating bowel wall vascularity in Crohn’s disease: a comparison of dynamic MRI and wideband harmonic imaging contrast-enhanced low MI ultrasound

This was a prospective comparison of dynamic MRI (1.5 T) and echo-signal enhanced ultrasound in evaluating vascularization in thickened bowel walls cases of Crohn's disease. Twenty-one patients with histologically confirmed Crohn's disease and bowel wall diameters >5 mm were examined by MRI and ultrasound (US). MR sequences: T1w fl2D, T2w, FLASH T1w post-contrast media (CM) applications with fat saturation were used. Dynamic Turbo-FLASH T1w sequences were acquired in the area of maximal thickening of the ileal wall every 1.5 s post-CM application for a total duration of 1 min. US was performed after the application of 1.2 ml of echo-signal enhancer. Contrast uptake was measured by the semiquantitative score and brightness analysis in regions of interest (ROI). Clinical and laboratory findings including Crohn's disease activity indices were documented; MRI and US parameters were correlated. The length of sonographically documented lesions (122+/-75 mm) correlated significantly with the length of thickened bowel segments in MRI (128+/-76 mm; r=0.466; P=0.033). The maximum percent signal enhancement in the terminal ileum at ultrasound (217.5+/-100.1%) showed a high correlation with the findings of MRI (262+/-108%; r=0.623; P=0.003). With both methods, a plateau phase was observed. US and MRI are capable of evaluating local vascularization in the bowel wall objectively.

Magnetic resonance imaging of experimental mouse colitis and association with inflammatory activity

BACKGROUND

Ulcerative colitis and Crohn's disease are the major chronic inflammatory bowel diseases affecting the gastrointestinal tract in humans. Imaging techniques such as endoscopy and computed tomography are used to monitor disease activity. Magnetic resonance imaging (MRI) is emerging as a diagnostic modality, and studies have shown that MRI can be used in the diagnostic procedure of patients with inflammatory bowel disease. The aim of the present study was to investigate the role of MRI in quantitatively reflecting inflammation in an experimental mouse colitis model.

METHODS

Colonic inflammation was induced by exposing mice to dextran sulfate sodium. MRI was used to assess colon wall thickness, T2-weighted (T2w) signal, and contrast-enhanced T1-weighted (T1w) signal in inflamed and healthy animals in vivo. Haptoglobin and interleukin-1beta served as systemic and local inflammatory markers, and macroscopic ex vivo scoring of the colon was performed to assess colonic inflammation.

RESULTS

Dextran sulfate sodium-exposed animals displayed increased levels of inflammatory markers and higher inflammatory score compared with healthy animals. Colon wall thickness and contrast-enhanced T1w signal were significantly increased in dextran sulfate sodium-exposed compared with healthy animals. In addition, the T2w signal was positively correlated with haptoglobin levels and colon wall thickness in the inflamed animals.

CONCLUSIONS

Our results show that MRI can be used to depict healthy and inflamed mouse colon and that the T2w signal, contrast-enhanced T1w signal, and colon wall thickness may be used to characterize inflammation in experimental colitis. These potential biomarkers may be useful in the evaluation of putative drugs in longitudinal studies in both mice and humans.

Imaging of small intestinal Crohn’s disease: comparison between MR enteroclysis and conventional enteroclysis

The purpose of this study was to compare MR enteroclysis (MRE) with conventional enteroclysis (CE) in patients with small intestinal Crohn's disease. Fifty-two consecutive patients with known or suspected Crohn's disease underwent MR and conventional enteroclysis, which was considered the gold standard. Eleven imaging features, classified in three groups, mucosal, transmural and extraintestinal, were subjectively evaluated by two experienced radiologists. MRE and CE were in full agreement in revealing, localizing and estimating the length of all involved segments of the small bowel. The sensitivity of MRE for the detection of superficial ulcers, fold distortion and fold thickening was 40, 30 and 62.5%, respectively. The sensitivity of MRE for the detection of deep ulcers, cobble-stoning pattern, stenosis and prestenostic dilatation was 89.5, 92.3, 100 and 100%, respectively. Additional findings demonstrated on MRE images included fibrofatty proliferation in 15 cases and mesenteric lymphadenopathy in 19 cases. MRE strongly correlates with CE in the detection of individual lesions expressing small intestinal Crohn's disease. It provides additional information from the mesenteries; however, its capability to detect subtle lesions is still inferior to conventional enteroclysis.

Dynamic Contrast-Enhanced MRI of the Bowel Wall for Assessment of Disease Activity in Crohn's Disease

OBJECTIVE

The purpose of this study was to evaluate the role of contrast-enhanced dynamic MRI in predicting the disease activity of Crohn's disease.

MATERIALS AND METHODS

Forty-eight patients in two hospitals who had clinically suspected exacerbation of Crohn's disease were included in this study. In three levels of thickened small-bowel wall, axial dynamic T1-weighted sequences were performed every 4-6 sec for a total duration of 2-3 min after contrast administration; static T1-weighted turbo spin-echo sequences were acquired both before and after contrast administration. The slope of enhancement, enhancement ratio, time to enhancement, enhancement time, and thickness of the small-bowel wall were determined. These MRI results were compared with overall clinical grade, Crohn's disease activity index (CDAI), and Van Hees activity index. Clinical grade was based on clinical information, physical findings, laboratory studies, endoscopy, surgery, and other imaging studies. Spearman's correlation coefficient and p values were determined per hospital. Fisher's z-transformation was applied before pooling the correlation coefficients from both hospitals.

RESULTS

The enhancement ratio based on the static series showed significant correlation with the clinical grade (r = 0.29, p = 0.045), CDAI (r =0.31, p = 0.033), and Van Hees activity index (r = 0.36, p = 0.016). The enhancement ratio based on the dynamic series correlated significantly with the CDAI (r = 0.38, p = 0.016). Wall thickness correlated significantly with clinical grade (r = 0.47, p = 0.003) and Van Hees activity index (r = 0.41, p = 0.007).

CONCLUSION

These data suggest that the enhancement ratio of bowel wall after IV administration of gadodiamide and bowel wall thickness are weak to moderate indicators of the severity of Crohn's disease.

Three-dimensional MR and axial CT colonography versus conventional colonoscopy for detection of colon pathologies

AIM: To evaluate the sensitivity and specificity of MR colonography (MRC) and CT performance in detecting colon lesions, and to compare their sensitivity and specificity with that of conventional colonoscopy.

METHODS: Forty-two patients suspected of having colonic lesions, because of rectal bleeding, positive fecal occult blood test results or altered bowel habits, underwent the examinations. After insertion of a rectal tube, the colon was filled with 1000-1500 mL of a mixture of 9 g/L NaCl solution, 15-20 mL of 0.5 mmol/L gadopentetate dimeglumine and 100 mL of iodinized contrast material. Once colonic distension was achieved, three-dimensional gradient-echo (3D-GRE) sequences for MR colonography and complementary MR images were taken in all cases. Immediately after MR colonography, abdominal CT images were taken by spiral CT in the axial and supine position. Then all patients were examined by conventional colonoscopy (CC).

RESULTS: The sensitivity and specificity of MRC for colon pathologies were 96.4% and 100%, respectively. The percentage of correct diagnosis by MRC was 97.6%. The sensitivity and specificity of CT for colon pathologies were 92.8%, 100%, respectively. The percentage of correct diagnosis by CT was 95.2%.

CONCLUSION: In detecting colon lesions, MRC achieved a diagnostic accuracy similar to CC. However, MRC is minimally invasive, with no need for sedation or analgesics during investigation. There is a lower percentage of perforation risk, and all colon segments can be evaluated due to multi-sectional imaging availability; intramural, extra-intestinal components of colonic lesions, metastasis and any additional lesions can be evaluated easily. MRC and CT colonography are new radiological techniques that promise to be highly sensitive in the detection of colorectal mass and inflammatory bowel lesions.

Ulcerative colitis: value of MR imaging

Recent technologic advances have greatly improved the quality of abdominal magnetic resonance imaging (MRI) by allowing the identification of abnormalities in inflammatory bowel disease. Thus far, the role of MRI has been extensively investigated in Crohn disease (CD) and, to a minor extent, in ulcerative colitis (UC), likely due to intrinsic differences between these two diseases. In UC the inflammatory lesions, unlike CD, are confined to the colon, have a predictable spreading, and affect only the inner wall layer; thus endoscopy alone can assess the extent and severity of disease in most cases. However, preliminary studies have demonstrated that MRI also can be a reliable diagnostic tool for UC because it is useful for integrating clinical and endoscopic data. MRI can be valuable in distinguishing CD from UC in uncertain cases by assessing the sparing of the distal ileum and the continuity of colonic involvement. Moreover, MRI can provide important information if endoscopy is incomplete, e.g., due to tight strictures, or contraindicated, e.g., in severely acute disease, due to a high risk of perforation. MRI can detect most of the typical findings of the diseases, such as wall thickening, mural stratification, loss of haustrations, and several complications including fibrotic or neoplastic strictures. In addition, MRI can be extremely valuable in assessing disease activity by monitoring the degree of wall gadolinium enhancement and T2 signal at the level of the affected bowel segments, thus influencing pharmacologic and surgical planning. In the next few years, MRI will likely become the imaging modality of choice in the clinical management of this disease.

Crohn Disease: mural attenuation and thickness at contrast-enhanced CT Enterography--correlation with endoscopic and histologic findings of inflammation

PURPOSE

To determine retrospectively if quantitative measures of small-bowel mural attenuation and thickness at computed tomographic (CT) enterography correlate with endoscopic and histologic findings of small-bowel inflammation and to estimate the performance of these measures in predicting inflammatory Crohn disease.

MATERIALS AND METHODS

The institutional review board approved this HIPAA-compliant retrospective study, which was conducted with patient informed consent. CT enterography data in 96 patients (31 male patients and 65 female patients) who underwent ileoscopy with or without biopsy were examined for CT signs of active Crohn disease. The most highly enhancing segment of terminal ileum and a normal-appearing ileal loop were identified. After it was confirmed that semiautomated software could accurately measure mural attenuation and thickness, the selected terminal ileal and normal-appearing (control) ileal loops were examined (20 automated measurements at each location) to quantify mural attenuation and wall thickness. Results were compared with endoscopy and histology reports by using logistic regression analysis and receiver operating characteristic curves.

RESULTS

Quantitative measures of terminal ileal mural attenuation and wall thickness correlated significantly with active Crohn disease (P < .001). Small-bowel wall thickness was not a significant factor after attenuation was taken into account. A threshold attenuation value with a sensitivity of 90% (18 of 20) for definite Crohn disease (compared with a sensitivity of 80% [16 of 20] for radiologist assessment) was selected. In patients who underwent ileal biopsy, threshold attenuation had a sensitivity identical to that of ileoscopy (81% [26 of 32]; 95% confidence interval: 64%, 93%) in predicting histologic inflammation.

CONCLUSION

Quantitative measures of mural attenuation and wall thickness at CT enterography correlate highly with ileoscopic and histologic findings of inflammatory Crohn disease. Quantitative measures of mural attenuation are sensitive markers of small bowel inflammation.

Magnetic resonance imaging evaluation of small intestinal Crohn's disease

Imaging evaluation in patients with Crohn's disease is based on morphological abnormalities, traditionally disclosed by barium studies including conventional enteroclysis, and more recently by cross-sectional imaging. A major prerequisite for optimal image quality and a more confident diagnosis is the adequate luminal distension of the bowel, which is usually achieved by administering an intraluminal contrast agent through a nasojejunal catheter. Magnetic resonance enteroclysis is a new technique that combines the advantages of volume challenge with state-of-the-art ultrafast pulse sequences, resulting in an excellent demonstration of the anatomy of the small bowel. Magnetic resonance enteroclysis compares favourably with conventional enteroclysis in detecting, localising and assessing the extent of involved small bowel segments. Luminal narrowing and extramural manifestations or complications of the disease can also be accurately assessed by the technique. Imaging features including the presence of deep ulcers, extensive wall thickening and mesenteric lymph nodes exhibiting marked gadolinium enhancement correlate strongly with disease activity. Although the clinical utility of magnetic resonance enteroclysis in Crohn's disease has been widely recognised, its routine application is currently limited to academic centres. Its clinical indications may include follow-up studies of known disease, the classification of Crohn's disease subtypes, an estimation of disease activity and a determination of the extramucosal extent and spread of the disease process.

MR colonography in inflammatory bowel disease

Colonography based on magnetic resonance imaging (MRI) appears to be a promising technique for polyp assessment in the colon. Several studies have evaluated this method for colonic assessment in patients with inflammatory bowel disease. We briefly review different methodologies such as dark lumen and bright lumen techniques for abdominal MRI. In addition, recently published studies concerning the sensitivity and accuracy in detecting inflammatory bowel changes in inflammatory bowel disease using MRI are discussed.

[Value of contrast-enhanced MR enterography in pediatric Crohn's disease: preliminary study]

OBJECTIVE

Feasibility study of contrast enhanced MR enterography without enteroclysis as a new diagnostic tool for children with known or suspected Crohn's disease.

METHODS

We prospectively included 15 children, 8-18 years old, with clinical suspicion of Crohn's disease. MR enterography without enteroclysis was performed on a 1,5 T clinical MR system. A total of 1000 ml of mannitol 5% was orally administered 60 minutes prior to MRI. Coronal and axial breath-hold sequences were acquired. The following sequences were obtained: True-FISP, FLASH T1 2D/3D with Fat saturation before and after gadolinium injection. Two radiologists, blinded to patient information, independently reviewed all examinations to record image quality, the degree of distension of the distal ileum, the presence of abnormal bowel segments and the presence of extra-intestinal complications. MRI findings were correlated to sonographic, endoscopic and biological results (sensitivity, specificity, Kappa test).

RESULTS

The examinations were considered of satisfactory diagnostic quality in 93.3% of patients. Respiratory artifacts were present in one case. The entire GI tract could be identified on all sequences. Distention of the distal ileum was recorded as good to excellent in 89% of healthy subjects. Five MR examinations were considered abnormal with isolated ileal involvement in 2 cases, ileocolic involvement in 2 cases, and isolated colonic involvement in 1 case. The sensitivity and specificity of MR for the positive diagnosis of Crohn's disease were 100% and 83% respectively. Three extra-intestinal complications were detected: one case of ileo-ileal fistula, not identified on ultrasonography, an asymptomatic anal fistula and a symptomatic inflammatory stricture.

CONCLUSION

MR enterography without enteroclysis is a well tolerated, effective non invasive method in the evaluation of known or suspected Crohn's disease. Because of the absence of ionizing radiation, MR enterography should become the gold standard in pediatric patients.

MR imaging in patients with Crohn disease: value of T2- versus T1-weighted gadolinium-enhanced MR sequences with use of an oral superparamagnetic contrast agent

PURPOSE

To prospectively compare oral contrast-enhanced T2-weighted half-Fourier rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging with T1-weighted gadolinium-enhanced fast low-angle shot (FLASH) MR and standard examinations in the evaluation of Crohn disease.

MATERIALS AND METHODS

Institutional review board approval and informed consent were obtained. Fifty-nine patients with Crohn disease underwent MR imaging after oral administration of a superparamagnetic contrast agent; RARE plain and fat-suppressed sequences and FLASH sequences were performed before and after intravenous injection of gadolinium chelate. References were endoscopic, small-bowel barium, computed tomographic, ultrasonographic, and clinical-biochemical scoring of disease activity. Two radiologists analyzed MR images for presence and extent of Crohn disease lesions, presence of strictures or other complications, and degree of local inflammation. MR findings were correlated with endoscopic, radiologic, and clinical data (kappa statistic and Spearman rank correlation test).

RESULTS

T2-weighted MR was 95% accurate, 98% sensitive, and 78% specific for detection of ileal lesions. Agreement between T1- and T2-weighted images ranged from 0.77 for ileal lesions to 1.00 for colic lesions. T2-weighted MR enabled detection of 26 of 29 severe strictures, 17 of 24 enteroenteric fistulas, and all adhesions and abscesses; T1-weighted MR enabled detection of 20 of 29 severe strictures, 16 of 24 enteroenteric fistulas, and all adhesions and abscesses. Complications leading to surgery were found in 12 (20%) patients; these were assessed correctly with either T1- or T2-weighted images. T2-weighted signal intensities of the wall and mesentery correlated with biologic activity (P < .001, r of 0.774 and 0.712, respectively). Interobserver agreement was 0.642-1.00 for T2-weighted and 0.711-1.00 for T1-weighted images.

CONCLUSION

T2-weighted MR can depict Crohn disease lesions and help assess mural and transmural inflammation with the same accuracy as gadolinium-enhanced T1-weighted MR. Combination of gadolinium-enhanced T1- and T2-weighted sequences is useful in the assessment of Crohn disease.

Magnetic resonance imaging compared with ileocolonoscopy in evaluating disease severity in Crohn's disease

BACKGROUND & AIMS

Abdominal magnetic resonance imaging (MRI) has shown promising results in the detection of Crohn's disease (CD)-related lesions. The purpose of this study was to assess the value of MRI in measuring disease activity in CD patients in comparison with ileocolonoscopy.

METHODS

Thirty-one patients undergoing ileocolonoscopy because of suspicion of relapsing CD underwent MRI with water as intraluminal contrast medium. At endoscopy, disease severity was graded (4-point scale), and Crohn's Disease Endoscopic Index of Severity (CDEIS) was determined. Two radiologists independently interpreted the MRI scans. Radiologic grading (4-point scale) was compared with endoscopic grading of disease severity and CDEIS (overall, for all segments). Wall thickness and enhancement were compared with CDEIS. Patient experience and preference were determined.

RESULTS

In, respectively, 14 and 14 patients (radiologist 1) and 16 and 11 patients (radiologist 2) an exact match or 1 level of difference in grading was scored with the endoscopist. Correlation between severity rated at MRI and CDEIS was moderate to strong with r = 0.61 (P < .001) for observer 1 and r = 0.63 (P < .001) for observer 2. Per segment, best correlation was seen in the terminal ileum (r = 0.63; P < .001, for both observers). Wall thickness correlated moderately to strongly with CDEIS (r = 0.57, P < .001 and r = 0.50, P < .001 for observers 1 and 2), whereas enhancement correlated weakly to moderately (r = 0.45, P < .001 and r = 0.42, P < .001). Patients experienced more pain during endoscopy, and all patients except 2 preferred MRI to endoscopy.

CONCLUSION

MRI can correctly identify disease severity in patients with CD and is a patient-friendly alternative to ileocolonoscopy.

Nuclear medicine imaging of inflammatory/infective disorders of the abdomen

Different nuclear medicine modalities are currently used to study inflammatory and infective disorders of the abdomen. They are usually complementary to radiology and endoscopy, but they play a pivotal role in particular clinical situations. Several radiopharmaceuticals (e.g., 111In or 99mTc labelled white blood cells, monoclonal antibodies, human polyclonal immunoglobulins, 75Ga citrate) are commercially available, but they can not be used indifferently to study abdominal inflammatory disorders. The lack of comparative studies showing the accuracy of each radiopharmaceutical for the study of inflammatory/infective abdominal diseases does not allow the best nuclear medicine technique(s) to be chosen in an evidence-based manner. To this end we performed a meta-analysis of peer reviewed articles published between 1984 and 2004 describing the use of nuclear medicine imaging for the study of inflammatory bowel disorders, appendicitis and vascular graft infections. A guideline for the optimal radiopharmaceutical(s) to be used in each clinical condition and for different aims is provided.

MRI in Crohn's disease

Technological developments have extended the role of MRI in the evaluation of the gastrointestinal tract. The potential of MRI to evaluate disease activity in Crohn's disease has been investigated extensively, as MRI has intrinsic advantages over other techniques, including noninvasiveness and the absence of ionizing radiation. For perianal fistulizing disease MRI has become a mainstay in evaluation of disease, as localization and extent of disease can be very well appreciated using both T2-weighted and T1-weighted sequences, fat suppression, and intravenous contrast medium. Imaging of the small bowel and colon in Crohn's disease is more complicated due to bowel peristalsis and respiratory movement. However, using fast breathhold sequences and intravenous spasmolytic medication, images of good diagnostic quality can be acquired. To obtain sufficiently distended bowel, which in our estimation is a prerequisite for evaluation of the bowel, MR enteroclysis can be performed. However, applicability of different oral contrast media has been studied, as a noninvasive method for bowel distension would be preferable. Abdominal MRI is a valuable imaging technique for evaluation of luminal, transmural, and extraintestinal manifestations of Crohn's disease as degree of disease activity, presence of luminal pathology (e.g., stenoses), and extraintestinal manifestations of disease (e.g., abscesses, fistulas) can be accurately assessed.

Comprehensive Magnetic Resonance Imaging of the Small and Large Bowel Using Intraluminal Dual Contrast Technique With Iron Oxide Solution and Water in Magnetic Resonance Enteroclysis

OBJECTIVE

The objective of this study was to improve delineation of small and large bowel (SB, LB) anatomy and pathology with postoperative or complex multisegmental inflammatory changes using dual-contrast-technique (DCT) for magnetic resonance enteroclysis (MRE) with luminal contrast media of opposed signal characteristics.

MATERIALS AND METHODS

Sixty patients underwent MRE with iron oxide-based negative contrast in the SB. Thirty patients received additional rectal instillation of water for positive contrast (DCT). Two observers evaluated the degree of distention and the ease of identification of bowel anatomy and pathologies (none n=22, stenosis n=16, abscess n=4, fistulae n=5, postoperative changes and adhesions n=13) using a 4-point scale. Mann-Whitney U-test and kappa statistics were applied.

RESULTS

LB and the terminal ileum were significantly better distended and identified with DCT (P<or=0.0001; P=0.034). Interobserver agreement improved with DCT for all pathologies except for "prestenotic dilatation."

CONCLUSIONS

Comprehensive MR imaging of SB and LB with DCT improves the identification of modified anatomy and most pathologies in inflammatory and postsurgical bowel.