Small bowel

Crohn's disease of the small bowel: evaluation of ileal inflammation by diffusion-weighted MR imaging and correlation with the Harvey-Bradshaw index

PURPOSE

This study was undertaken to determine the diagnostic capabilities of diffusion-weighted magnetic resonance imaging (DWI) in detecting ileal inflammation in Crohn's disease (CD), and to verify the correlation between the DWI sequences and the Harvey-Bradshaw index (HBI).

MATERIALS AND METHODS

Twenty patients with an endoscopic-histological diagnosis of CD of the terminal ileum and MR enterography with DWI sequences and HBI were retrospectively selected. Disease activity was visually evaluated on the DWI sequences. In quantitative analysis, the apparent diffusion coefficient (ADC) of the terminal ileum was compared with that of normal ileal loops. Pearson's r was used to verify the correlation between the DWI findings and the HBI.

RESULTS

On visual assessment, the accuracy, sensitivity and positive predictive value of DWI for the detection of inflammation were 100%. In the quantitative assessment, the ADC value of the disease-active terminal ileum was significantly lower (p < 0.00001) than that of normal ileal loops. A correlation was found between visual assessment of the terminal ileum with the DWI sequences and HBI; no correlation was found between ADC of the terminal ileum and HBI.

CONCLUSION

DWI sequences may be useful in differentiating actively inflamed small bowel segments from normal small bowel in CD. Though partial, the correlation between DWI sequences and HBI confirms the utility of this technique in the study of patients with CD.

Contrast-enhanced ultrasonography (CEUS) vs. MRI of the small bowel in the evaluation of Crohn’s disease activity. Radiol Med. 2012;117:268-281. [PMID: 22271005 DOI: 10.1007/s11547-011-0783-5]

PURPOSE

The presence of disease activity in Crohn's disease (CD) is one of the main parameters used to establish whether optimal therapy should be drug therapy or surgery. However, a major problem in monitoring CD is the common mismatch between the patient's symptoms and imaging objective signs of disease activity. Bowel ultrasonography (US) has emerged as a low-cost, noninvasive technique in the diagnosis and follow-up of patients with CD. Accordingly, the use of contrast-enhanced US (CEUS) has made possible an evaluation of the vascular enhancement pattern, similar to the use of magnetic resonance imaging (MRI). The aim of our study was to evaluate the role of CEUS in comparison with small-bowel MRI for assessing Crohn's disease activity.

MATERIALS AND METHODS

We prospectively enrolled 30 consecutive patients with known CD. Clinical and laboratory data were compared with imaging findings obtained from MRI and CEUS of the small bowel. MRI was performed with a 1.5-T system using phased-array coils and biphasic orally administered contrast agent prior to and after gadolinium chelate administration. We performed US with a 7.5-MHz linear-array probe and a second-generation contrast agent. The parameters analysed in both techniques were the following: lesion length, wall thickness, layered wall appearance, comb sign, fibroadipose proliferation, presence of enlarged lymph nodes and stenosis. We classified parietal enhancement curves into two types in relation to the contrast pattern obtained with the time-intensity curves at MRI and CEUS: (1) quick washin, quick washout, (2) slow washin, plateau with a slow washout.

RESULTS

Comparison between Crohn's disease activity index (CDAI) and MRI showed a low correlation, with an rho=0.398; correlation between CDAI-laboratory data and CEUS activity was low, with rho=0.354; correlation between MRI activity and CEUS activity was good, with rho = 0.791; high correlation was found between CEUS and MRI of the small bowel when assessing wall-thickness, lymph nodes and comb sign; good correlation was fund when assessing layered wall appearance, disease extension and fibroadipose proliferation. At MRI, time-intensity curves for 12/30 patients were active, compared with for 14/30 patients at CEUS; therefore there was a poor correlation between curve on CEUS and curve on MRI (r=0.167; p=0.36).

CONCLUSIONS

The use of CEUS can be recommended if there is a discrepancy between MRI and clinical/laboratory parameters. MRI of the small bowel remains the most accurate method for evaluating disease activity.

Malignant tumours of the small intestine: a review of histopathology, multidetector CT and MRI aspects

Small bowel neoplasms, including adenocarcinoma, carcinoid tumour, lymphoma and gastrointestinal stromal tumours, represent a small percentage of gastrointestinal cancers, yet are among those with the poorest prognosis compared with other gastrointestinal malignancies. Unclear clinical scenarios and difficult radiological diagnosis often delay treatment with negative effects on patient survival. Recently, multidetector CT (MDCT) and MRI have been introduced as feasible and accurate diagnostic techniques for the identification and staging of small bowel neoplasms. These techniques are gradually replacing conventional barium radiography as the tool of choice. However, the inherent technical and physiological challenges of small bowel imaging require a familiarity with patient preparation and scan protocols. Adequate knowledge of the histopathology and natural evolution of small bowel neoplasms is also important for differential diagnosis. The aim of this article is to review MDCT and MRI protocols for the evaluation of small bowel tumours and to provide a concise yet comprehensive guide to the most relevant imaging features relative to histopathology.

Guide to magnetic resonance in Crohn's disease: from common findings to the more rare complicances

Considering that multiple imaging examinations are often necessary for monitoring Crohn's disease (CD) activity and severity in order to guide and monitor appropriate treatment, the ideal imaging test would be reproducible, well tolerated by patients, and free of ionizing radiation. For these reasons recent studies have highlighted the role of a magnetic resonance imaging (MRI) technique optimized for small bowel imaging in the evaluation of small bowel disorders. In this regard there are two main methodological approaches represented by MR enterography, following administration of an oral contrast medium, and MR enteroclysis, following administration of contrast medium through a nasojejuneal tube. MRI may be used to demonstrate the pathologic findings and complications of CD. In particular, MR has excellent sensitivity and specificity, ranging from 88%-98% and 78%-100%, respectively, for the detection of active inflammation, wall thickening, ulcerations, increased wall enhancement, increased vascularity, perienteric inflammation, and reactive adenopathy. MR also allows more accurate identification of associated complications including penetrating and fibrostenotic disease as well as the more rare extraintestinal manifestations that are usually associated with severe and longstanding intestinal inflammation, the latter often guiding the therapeutic approach. In the progression of CD some rare complications can occur that, to our knowledge, were only briefly or never mentioned in the radiological literature regarding MR enterography or enteroclysis and in which the application of these techniques play a key role.

MR enterographic manifestations of small bowel Crohn disease

Magnetic resonance (MR) enterography is a clinically useful technique for the evaluation of both intraluminal and extraluminal small bowel disease, particularly in younger patients with Crohn disease. MR enterography offers the advantages of multiplanar capability and lack of ionizing radiation. It allows evaluation of bowel wall contrast enhancement, wall thickening, and edema, findings useful for the assessment of Crohn disease activity. MR enterography can also depict other pathologic findings such as lymphadenopathy, fistula and sinus formation, abscesses, and abnormal fold patterns. Even subtle disease manifestations may be detected when adequate distention of the small bowel is achieved, although endoscopic and double-contrast barium small bowel techniques remain superior in the depiction of changes in early Crohn disease (eg, aphthoid ulceration). Further research will be needed to determine whether MR imaging enhancement patterns may reliably help discriminate between active and inactive disease.

Magnetic resonance imaging of the small bowel with the true FISP sequence: intra- and interobserver agreement of enteroclysis and imaging without contrast material

PURPOSE

This study aimed to determine the reliability of magnetic resonance imaging (MRI) without luminal contrast medium versus MR enteroclysis for evaluating small bowel pathology, to compare MRI and MRE findings per observer, and to compare these findings with those of an expert reader in order to determine the influence of luminal contrast medium on morphological evaluations.

CONCLUSION

The use of luminal contrast medium bowel improves reliability for measuring bowel wall thickness and for the diagnosis and grading of obstruction when evaluating the small bowel.

Current status of MR imaging in the evaluation of IBD in a pediatric population of patients

Diagnosis and follow-up of inflammatory bowel disease (IBD) in children represent a challenging issue for pediatricians. Nowadays MR studies of the bowel represent a valid diagnostic tool especially in the diagnosis and follow-up of ileal and perianal Crohn's disease in children as well as in adults. The lack of ionizing radiation of MRI enhances the interest of clinicians with respect to CT studies of the bowel in children. Thanks to recent technical development in terms of fast MR images acquisition a reasonable image quality can be easily achieved in scholar-age children. A majority of authors prefer MR-enterography approach in children with respect to the more invasive MR-enteroclysis in the assessment of ileal Crohn's disease. Using rigorous technique of MR-enterography represents a feasible and accurate test in the diagnosis of ileal Crohn's disease. Less experience is collected on MR-colonography in pediatric IBD while MRI of the pelvis represents the most accurate non-invasive diagnostic test in the assessment of perianal Crohn's disease in children as well as in adults.

Antiglycan antibodies as serological markers in the differential diagnosis of inflammatory bowel disease

BACKGROUND

The objective of the study was to evaluate the diagnostic accuracy of recently developed antiglycan serological tests in clinical practice for the diagnosis of Crohn's disease.

METHODS

This study was a cohort analysis of both clinical and biochemical parameters of patients with diagnosed inflammatory bowel disease compared with those in a control population. Antiglycan antibodies were determined using commercially available enzyme immunoassays. The setting was the outpatient unit of the gastroenterology department of a large, tertiary-care referral academic hospital. Participants were 214 consecutive patients, enrolled over a 5-month period, including 116 with Crohn's disease and 53 with ulcerative colitis, as well as 45 with other gastrointestinal diseases and 51 healthy controls.

RESULTS

Anti-Saccharomyces cerevisiae antibodies showed the best performance (54% sensitivity and 88%-95% specificity for Crohn's disease). Among patients with negative anti-Saccharomyces antibodies, 19 (34%) had high titers of at least another tested antiglycan antibody. Anti-Saccharomyces and anti-laminaribioside antibodies were associated with disease involving the small bowel and with penetrating or stricturing phenotype. Anti-laminaribioside was significantly higher in patients with a familial history of inflammatory bowel disease.

CONCLUSIONS

The new proposed serological markers are significantly associated with Crohn's disease, with low sensitivity but good specificity. About one third of anti-Saccharomyces-negative patients may be positive for at least 1 of those markers. Antiglycan antibodies appear to be associated with characteristic localization and phenotype of the disease.

Optimization of contrast agents for small intestine computed tomography enteroclysis

AIM: To evaluate which contrast agents can fully distend the intestinal canal and demonstrate the enteric cavity and intestinal wall in computed tomography (CT) enteroclysis.

METHODS: After 8 healthy grown-up Beagles were anesthetized, a catheter was inserted to the Treitz ligament of duodenum, 654-2 was injected through the veins, and different contrast agents including pure water and milk and 10 mL/L angiografin were infused through the catheter. After MSCT plain scanning, enhancement scanning was performed. Width of the enteric cavity and thickness of the intestinal wall measured through the transverse section and multi-planar reconstruction were statistically analyzed. Plain scanning of intestinal wall was performed. CT values, contrast coefficient of enteric cavity and intestinal wall density, and difference in enteric cavity and intestinal wall density were measured 20 s, 30 s, 40 s, and 50 s after enhancement scanning.

RESULTS: All the beagles finished small-intestine CT enteroclysis. The enteric cavity widths were compared between pure milk, pure water and angiografin groups (F = 28.115, P < 0.01). There was no statistical significance in enteric cavity width between the pure water and angiografin groups, as well as in the thickness of intestinal wall between the three groups. The difference in CT value was 69.25 ± 6.28 HU when the contrast coefficient for the enteric cavity and intestinal wall was the best in pure milk and pure water groups.

CONCLUSION: Pure milk is an ideal contrast agent for small-intestine CT enteroclysis, which can fully distend the intestinal canal and demonstrate the enteric cavity and intestinal wall.

Capsule enteroscopy and radiology of the small intestine

In a very few years, the video capsule for small bowel enteroscopy has gained widespread clinical acceptance. It is readily ingested, disposable, and allows for a complete, low-invasive endoscopic examination of the entire mucosa of the small bowel. It is a patient-friendly method and a first-line procedure in the difficult evaluation of obscure gastrointestinal bleeding. It has the highest proven figure of diagnostic sensitivity for detecting lesions of the mucosa, irrespective of aetiology. The limitations of capsule endoscopy include difficulty in localising mucosal lesions anatomically and its restricted use in patients with dysphagia, strictures or motor dysfunction. Strictures, transmural and extra-mural lesions in patients with small bowel Crohn's disease are evaluated by MRI- enterography and CT-enterography.

Evolving diagnostic modalities in inflammatory bowel disease

Over the past several years, significant advances have been made in the diagnostic techniques used in the management of ulcerative colitis and Crohn's disease. These advances have occurred mainly in the area of gastrointestinal endoscopy and radiology. Capsule endoscopy and double-balloon endoscopy have permitted better visualization of the small bowel mucosa. Advanced imaging techniques, including chromoendoscopy, magnification endoscopy, confocal endomicroscopy, and spectroscopy, may aid in the diagnosis of colorectal neoplasia in patients with long-standing disease. Improved radiographic imaging techniques based on computed tomography and magnetic resonance imaging allow noninvasive means of evaluating the small bowel in patients with known or suspected Crohn's disease. Finally, positron emission tomography is an investigative tool for inflammatory bowel disease that may also aid in the detection of inflammation in these diseases.

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.