MR enteroclysis: imaging technique of choice in diagnosis of small bowel diseases

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

BACKGROUND

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

OBJECTIVE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Small intestinal tumors: diagnostic accuracy of enhanced multi-detector CT virtual endoscopy

OBJECTIVE

To study the diagnostic accuracy of enhanced multi-detector CT virtual endoscopy (MDCT-VE) for small intestinal tumors.

MATERIALS AND METHODS

125 patients were examined by multi-detector CT (MDCT: 54 on 4-slice; 71 on 64-slice) following standard gastrointestinal tract cleansing, oral double contrast aerogenesis agent, and rectal gas administration. Unenhanced CT was performed, followed by enhanced CT in supine (30 and 80s delay after 100 mL standard intravenous contrast medium) and prone positions (180s delay). Supplementary CT in the lateral position was performed if small bowel was not well-filled. Images were reviewed on post-processing workstations with Virtual Endoscopy software.

RESULTS

33/125 patients had proven small intestinal tumors: ten stromal tumors, nine lymphoma, eight adenocarcinomas, three hemangiomas, one each lipoma, Brunner gland adenoma, and hamartoma. 92 were nontumors. MDCT-VE correctly identified 30/33 cases with one false-positive diagnosis: sensitivity 90.9%, specificity 98.9% and accuracy 96.8%.

CONCLUSION

Small intestinal MDCT-VE technique has high diagnostic accuracy for the detection of intestinal tumors. Contrast enhancement and adequate intestinal tract gas-filling can improve the detection rate for small intestinal tumors.

Small bowel Crohn's disease: MR enteroclysis and capsule endoscopy compared to balloon-assisted enteroscopy

New modalities are available to visualize the small bowel in patients with Crohn’s disease (CD). The aim of this study was to compare the diagnostic yield of magnetic resonance enteroclysis (MRE) and capsule endoscopy (CE) to balloon-assisted enteroscopy (BAE) in patients with suspected or established CD of the small bowel. Consecutive, consenting patients first underwent MRE followed by CE and BAE. Patients with high-grade stenosis at MRE did not undergo CE. Reference standard for small bowel CD activity was a combination of BAE and an expert panel consensus diagnosis. Analysis included 38 patients, 27 (71%) females, mean age 36 (20–74) years, with suspected (n = 20) or established (n = 18) small bowel CD: 16 (42%) were diagnosed with active CD, and 13 (34%) by MRE with suspected high-grade stenosis, who consequently did not undergo CE. The reference standard defined high-grade stenosis in 10 (26%) patients. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value of MRE and CE for small bowel CD activity were 73 and 57%, 90 and 89%, 88 and 67%, and 78 and 84%, respectively. CE was complicated by capsule retention in one patient. MRE has a higher sensitivity and PPV than CE in small bowel CD. The use of CE is considerably limited by the high prevalence of stenotic lesions in these patients.

Gastrointestinal tract imaging in children: current techniques

Imaging of the gastrointestinal (GI) tract in children continues to evolve, with new techniques, both radiological and non-radiological, being added to the repertoire. This article provides a summary of current imaging techniques of the GI tract (primarily the upper GI tract) and the relationship between those techniques. It covers the upper GI series and other contrast studies, US, CT and MRI. Note is also made of the contribution now made by capsule endoscopy (CE). Abdominal emergency imaging is not covered in this article.

Imaging of malignant neoplasms of the mesenteric small bowel: new trends and perspectives

This article describes the recent advances in radiological imaging of malignant neoplasms of the mesenteric small bowel and provides an outline of new trends and perspectives that can be anticipated. The introduction of multidetector row technology, which allows the acquisition of submillimeter and isotropic voxels, has dramatically improved the capabilities of computed tomography in the investigation of the mesenteric small bowel. This technology combined with optimal filling of small bowel loops through the use of appropriate enteral contrast agents has markedly changed small bowel imaging. Computed tomography-enteroclysis, which is based on direct infusion of enteral contrast agent into the mesenteric small bowel through a naso-jejunal tube, provides optimal luminal distension. By contrast, computed tomography-enterography is based on oral administration of enteral contrast agent. These two techniques are now well-established ones for the detection and the characterization of small bowel neoplasms. During the same time, combining the advantages of unsurpassed soft tissue contrast and lack of ionizing radiation, magnetic resonance imaging has gained wide acceptance for the evaluation of patients with suspected small bowel neoplasms. Rapid magnetic resonance imaging sequences used in combination with specific enteral contrast agents generate superb images of the mesenteric small bowel so that magnetic resonance-enteroclysis and magnetic resonance-enterography are now considered as effective diagnostic tools for both the detection and the characterization of neoplasms of the mesenteric small bowel. Recent improvements in image post-processing capabilities help obtain realistic three-dimensional representations of tumors and virtual enteroscopic views of the small bowel that are useful for the surgeon and the gastroenteroenteologist to plan surgical or endoscopic interventions. Along with a better knowledge of the potential and limitations of wireless capsule endoscopy and new endoscopic techniques, these recent developments in radiological imaging reasonably suggest that substantial changes in the investigation of small bowel tumors may be anticipated in a near future, thus potentially create a new paradigm shift after standard small bowel follow-through study has been universally abandoned.

New progress in CT and MRI examination and diagnosis of small intestinal tumors

Precise examination and diagnosis of small intestinal tumors is difficult because of the curved course and overlapping canal of the small intestine. Traditional technology for intestinal canal examination and endoscopy cannot exhibit the intestinal wall and extra-luminal structure well. With the development and advancement of multi-slice spiral computed tomography and magnetic resonance imaging (MRI), computed tomography enteroclysis (CTE) and magnetic resonance enteroclysis (MRE) are widely used in the examination and diagnosis of small intestinal tumors. CTE and MRE, with three-dimensional imaging capabilities and excellent soft-tissue contrast, can analyze the abnormalities of peripheral intestinal structure as well as the tunica mucosa. In addition, these two technologies can clearly reveal the localization, appearance, degree of mesenteric infiltration and remote tumor metastasis, which increases our cognition of the imaging diagnosis for intestinal tumors. Here we review recent progress in imaging (CT and MRI) examination and diagnosis of small intestinal tumors.

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.

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.

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.

Comparison of magnetic resonance enterography and video capsule endoscopy in evaluating small bowel disease

PURPOSE

The goal of this study was to compare magnetic resonance enterography (MRE) and video capsule endoscopy (VCE) in suspected small bowel disease.

MATERIALS AND METHODS

Nineteen patients with suspected small bowel disease participated in a prospective clinical comparison of MRE versus VCE. Both methods were evaluated separately and in conjunction with respect to a combined diagnostic endpoint based on clinical, laboratory, surgical, and histopathological findings. The Fisher's exact and j tests were used in comparing MRE and VCE.

RESULTS

Small bowel pathologies were found in 15 out of 19 patients: Crohn's disease (n= 5), lymphoma (n= 4), lymphangioma (n= 1), adenocarcinoma (n= 1), postradiation enteropathy (n= 1), NSAID-induced enteropathy (n =1), angiodysplasia (n= 1), and small bowel adhesions (n= 1). VCE and MRE separately and in conjunction showed sensitivities of 92.9, 71.4, and 100% and specificities of 80, 60, and 80% (kappa= 0.73 vs. kappa = 0.29; P= 0.31/kappa = 0.85), respectively. In four patients, VCE depicted mucosal pathologies missed by MRE. MRE revealed 19 extraenteric findings in 11 patients as well as small bowel adhesions not detected on VCE (n= 1).

CONCLUSION

VCE can readily depict and characterize subtle mucosal lesions missed at MRE, whereas MRE yields additional mural, perienteric, and extraenteric information. Thus, VCE and MRE appear to be complementary methods which, when used in conjunction, may better characterize suspected small bowel disease.

MR imaging of the bowel: pediatric applications

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

Updating magnetic resonance imaging of small bowel: Imaging protocols and clinical indications

High soft tissue contrast resolution, acquisition of multi-planar images and the possibility to obtain functional information make magnetic resonance an interesting imaging technique to evaluate the small bowel disease. The absence of ionizing radiation is an important feature of magnetic resonance imaging (MRI) examinations because inflammatory diseases such as Crohn’s disease (CD) are studied most frequently, which are prevalent among children and young adults. MRI, using modern equipment and a rigorous technical approach, can offer detailed morphologic information and functional data on the small bowel. This article discusses the MRI protocols for small bowel and the MR imaging findings of small bowel diseases, such as CD and small bowel neoplasms.

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.

Jejunum abnormalities at MR enteroclysis

OBJECTIVE

MR enteroclysis has become an important tool to visualize the complete small bowel wall and extramural structures. In many centers, this technique is rapidly becoming the first-line technique for small bowel visualization. MR enteroclysis yields a diagnosis of thickened jejunal loops in some patients. In this paper, we describe an MR enteroclysis protocol and review the literature on jejunum abnormalities with several sample cases.

CONCLUSION

Jejunum abnormalities are not uncommon. These abnormalities can be self-limiting, but some patients suffer from infectious and other pathologic conditions of the small bowel necessitating intervention.

CT features of jejunal pathology

The imaging of duodenal and ileal diseases is well documented in radiological literature but the jejunum has been relatively neglected. The aim of this review is to outline the current methods of investigation of the jejunum, and provide a comprehensive review of common pathologies affecting the jejunum, with particular emphasis on investigation by computed tomography.

Diagnosis and outcome of small bowel tumors found by capsule endoscopy: a three-center Australian experience

OBJECTIVE

The objective of the study was to examine diagnosis and outcome in a series of patients with small bowel tumors detected by capsule endoscopy (CE) in three Australian centers.

METHODS

Review of prospectively collected data from 416 CEs identified 27 tumors in 26 patients. Clinical parameters, tumor histology, and follow-up are reported.

RESULTS

Twenty-seven tumors were identified in 26 patients (mean age 61 +/- 13.7 yr). Indications for CE were obscure gastrointestinal (GI) bleeding (21), suspected tumor (3), abdominal pain (1), diarrhea (1). Prior radiology found a possible lesion in 8 of 23 (35%). Nine tumors were proven benign: hamartoma (4), cystic lymphangioma (1), primary amyloid (1), lipoma (1). Two lesions were non-neoplastic: heterotopic gastric mucosa and inflammatory fibroid polyp. Seventeen tumors were malignant: five adenocarcinomas, six carcinoids, two melanoma metastases, two gastrointestinal stromal tumors (GIST), one colon carcinoma metastasis, one non-Hodgkin's lymphoma. Tumors were surgically resected in 23 patients. Resection was considered curative in 12 (52%). Mean duration of follow-up was 26 +/- 13.7 months. Of the five patients with primary adenocarcinoma only one remains disease free. Three of the six with carcinoid tumors have had no recurrence up to 51 months postresection. Both patients with GIST are disease free. Anemia resolved after surgery in the patients with melanoma.

CONCLUSIONS

Small bowel tumors are a significant finding at CE and are often missed by other methods of investigation. In many patients, detection of a tumor alters management and improves outcome. Even in malignant lesions, treatment is potentially curative in the absence of metastatic disease.

Detection of small-bowel neuroendocrine tumors by video capsule endoscopy

OBJECTIVES

Carcinoid tumors are the most common GI neuroendocrine tumors (NET). They often originate in the small intestine. The primary tumor is often difficult to locate, and resection in an early phase is recommended to prevent complications. This study evaluated the value of videocapsule endoscopy (VCE) in the detection of small-intestinal primary carcinoid tumor.

DESIGN

Prospective descriptive study.

SETTING

Tertiary referral center.

PATIENTS

Twenty consecutive patients (13 men, 7 women; 60.5 +/- 9.3 years) with metastatic NET of unknown primary tumor.

INTERVENTIONS

All patients underwent CT, enteroclysis, nuclear imaging, and VCE of the small bowel.

RESULTS

CTs and enteroclysis did not detect a primary small-intestinal carcinoid tumor. Nuclear imaging demonstrated abnormalities in the abdominal area in 13 patients but was unable to relate this to an intestinal localization in any patient. VCE revealed a small-intestinal tumor in 9 patients. Three other patients showed external compression and erosions. At surgery, 5 patients had a small-intestinal carcinoid tumor, and, in 2 patients, a small-intestinal ischemic segment was present.

LIMITATIONS

The number of false-positive VCE findings was not clear, because not all patients underwent surgery. The absence of abnormalities at VCE in patients with abnormalities at nuclear imaging might be related to the presence of carcinoid tumor restricted to the mesenterium or to a false-negative VCE.

CONCLUSIONS

VCE had a high diagnostic yield of 45% for identification of primary small-intestinal carcinoid tumors. Although nuclear imaging had a comparable diagnostic yield, it could not differentiate between intestinal and mesenterial localization of the carcinoid.

Pediatric inflammatory bowel disease

Inflammatory bowel disease is an important cause of gastrointestinal pathology in children and adolescents. The incidence of pediatric inflammatory bowel disease is increasing; therefore, it is important for the clinician to be aware of the presentation of this disease in the pediatric population. Laboratory tests, radiology studies, and endoscopic procedures are helpful in diagnosing inflammatory bowel disease and differentiating between Crohn’s disease and ulcerative colitis. Once diagnosed, the goal of medical management is to induce remission of disease while minimizing the side effects of the medication. Specific attention needs to be paid to achieving normal growth in this susceptible population. Surgical management is usually indicated for failure of medical management, complication, or malignancy. Algorithms for diagnostic evaluation and treatment of pediatric inflammatory bowel disease are presented. The specific psychosocial issues facing these patients are also discussed in this review as are the future goals of research in the complex problem of pediatric inflammatory bowel disease.

Small bowel imaging- a rapidly changing field and a challenge to radiology

There was a time when the small bowel follow-through (SBFT) was the primary method of diagnosing diseases of the small intestine. Enteroclysis was reinvented in the 70's and with the SBFT remained the dominant methods of investigating the mesenteric small intestine to the late 90's. Since the introduction of the first commercial computed tomography (CT) scanner in 1973, the ability of monoslice CT to diagnose different causes of intestinal obstruction and inflammatory bowel diseases emerged. The introduction of helical CT technology in 1989 and subsequently multichannel CT further changed small bowel imaging. Faster acquisition of a large volume of data with thinner collimation allowed multiplanar reformatting a distinct advantage in evaluating an organ which is longer than wide. The introduction of magnetic resonance (MR) imaging with its increased soft tissue contrast, lack of ionizing radiation, and the ability to acquire ultrafast sequences has made MR imaging an important tool in small bowel imaging (1).

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.