Magnetic Resonance Enteroclysis Research Articles

Diagnostic Value of 3.0 T Magnetic Resonance Imaging in Active Crohn's Disease.

Magnetic resonance enteroclysis (MRE) has been widely applied to diagnose Crohn's disease (CD). Magnetic resonance (MR) at 3.0 T improves signal-to-noise ratio (SNR), shortens image acquisition time, and shows more advantages. This study aimed to retrospectively analyze the diagnostic value of 3.0 T MR imaging for active CD. 48 CD patients hospitalized in our hospital from January 2021 to December 2022 were selected as the study subjects. These 48 CD patients underwent both double-balloon enteroscopy and 3.0 T MRE. All patients' arterial phase signal, venous phase signal, bowel wall, and bowel lumen of MRE were observed to identify whether they suffered from active CD. Based on the results of enteroscopy, the number of true positives, true negatives, false negatives, and false positives diagnosed by MRE were screened; next, the diagnostic accuracy, sensitivity, and specificity of MRE in assessing active CD were calculated. Of the 48 patients, 39 were diagnosed with small bowel CD by MRE, which was not significantly different from the results of enteroscopy (P>0.05). According to MRE diagnostic results, the arterial phase predominantly presented high signal intensity, and the venous phase mainly presented low signal intensity or isointensity. Small bowel CD lesions were primarily characterized by bowel wall thickening, rare pneumatosis enhancement of the bowel wall, bowel lumen pneumatosis or dilatation, and rare strictures. Besides, MRE presented an accuracy of 93.75%, sensitivity of 97.37%, and specificity of 80.00% in diagnosing CD. 3.0 T MR imaging has diagnostic value for active CD and shows certain clinical application value.</P>.

Crohn\u2019s disease: prevalence, MR features, and clinical significance of enteric and colonic sinus tracts

ObjectivesEnteric and colonic sinus tracts are inflammatory complications that precede intestinal fistulas in patients with Crohn’s disease (CD). The aim of this study was to retrospectively determine the prevalence, morphologic features, and outcome of sinus tracts using MR imaging.MethodsA consecutive cohort of 642 patients with known CD, referred for MR enterography or MR enteroclysis (study period 01/2014–09/2019), was evaluated retrospectively for the presence of sinus tracts, their locations, presence and length of coexisting strictures, bowel wall thickness, CDMI score, upstream dilation, and bowel distension. Clinical outcome was assessed using medical records. For metric data, means and standard deviation, as well as one-way ANOVA and Pearson’s correlation coefficient, were calculated.ResultsIn 36/642 patients with CD undergoing MRE, 49 sinus tracts (forty in small intestine, nine in left-sided colon) were detected with a prevalence of 6.9% in patients with MR-visible signs of CD (n = 519, overall prevalence of 5.6%). Mean segmental bowel wall thickness was 8.9 mm, and mean CDMI score was 9.3. All sinus tracts were located within a stenotic segment, showing mesenteric orientation within the small bowel and upstream dilation in 13 patients. Of 36 patients, 19 underwent immediate surgery and seven developed clinical progression within the segment containing the sinus tract.ConclusionsSinus tracts occur in 6.9% of patients with visible signs of CD. They are located within stenotic, severely thickened bowel segments with high MR inflammation scores. Their detection is clinically important, because they indicate a more aggressive phenotype and, if left untreated, may show severe progression.Key Points• Sinus tracts occur in 6.9% of patients with MR-visible signs of Crohn’s disease.• Sinus tracts are a radiological indicator of early penetrating Crohn’s disease, with a high risk of progression, and require dedicated treatment.• Sinus tracts can be recognized by characteristic findings and typically occur in stenotic, severely thickened bowel segments with high MR inflammation scores.

2613 A Rare Case of Undifferentiated Malignant Epithelioid Neoplasm

INTRODUCTION: The small bowel is rarely a site for development of tumor malignancy and accounts for less than 1% of all GI malignancies. We present a case of a 53-year-old male with recurrent episodes of gastrointestinal bleeding and negative upper and lower GI endoscopies found to have high-grade undifferentiated high-grade malignant epithelioid neoplasm. CASE DESCRIPTION/METHODS: A 53-year old male with history of peptic ulcer disease, duodenal ulcer perforation presented to the ED with right upper and lower extremity pain for last few weeks along with black stools. He had required several units of blood transfusion with recurrent admissions to hospital and had also lost about 20 lbs in last 2 months. EGD and colonoscopy 3 months before had shown duodenal angiectasia and colonic polyps which were removed. Outpatient capsule endoscopy was recommended but patient did not follow up. Bleeding scan was negative and CT abdomen pelvis with contrast showed thickening in distal jejunum concerning for mass-like lesion. Patient underwent laparoscopic small bowel resection of 18 cm and pathology showed high-grade undifferentiated malignant epithelioid neoplasm with macro-metastatic tumor. The tumor showed diffuse staining for vimentin,pancytokeratin, CK7 with subset moderate cytoplasmic staining for calretinin and CK8/18.Port-A-Cath was placed and patient was started on standard adjuvant chemotherapy including combination of 5-FU, leucovorin, and oxaliplatin. DISCUSSION: Small bowel tumors are very rare and aggressive and have poorer prognosis than colon cancer. They present a diagnostic challenge as access to small bowel is limited during conventional diagnostic procedures and symptoms present late. We present a patient who was having recurrent gastrointestinal bleeding requiring multiple blood transfusions and found to have high-grade undifferentiated high-grade malignant epithelioid neoplasm. The differential for this includes monophonic synovial sarcoma, malignant epithelioid mesothelioma, and large cell lung carcinoma vs others. Video capsule endoscopy has rapidly become the conventional standard for small bowel evaluation, followed by other methods such as magnetic resonance enteroclysis. Standard chemotherapy treatment closely resembles that of large bowel cancer, including combinations of 5-FU, leucovorin, and oxaliplatin/irinotecan/capecitabine.

The diagnostic evaluation of magnetic resonance enteroclysis in inflammatory bowel disease

Objective This study aims to investigate diagnosis accuracy of magnetic resonance enteroclysis (MRE) and evaluation of image quality in inflammatory bowel disease (IBD). Methods A total of 132 patients were assumed inflammatory bowel disease and their MRE were retrospectively evaluated. Imaging feature of MRE and histopathologic results by surgery and endoscope were compared. The sensitivity, specificity and diagnostic performance were calculated and image quality of MRE were evaluated by using the quadrature method. Results A total of 530 small intestine segments were analyzed according to evaluation criteria. Imaging quality of 323, 170, 29 and 8 small intestine segments were graded 1, 2, 3 and 4 respectively. Consistency for scoring of imaging quality and evaluation of IBD in intestine segments between observers was pretty good (k=0.73). Scoring of imaging quality was the highest in distal ileum (1.12) and terminal ileum(1.15) and scoring was the lowest in duodenum (1.92) and jejunum(1.6). The sensitivity, specificity and diagnostic agreement rate of MRE in inflammatory bowel disease were 94.3%, 92.6% and 94.7% respectively, including 2 false positive and 6 false negative result. Conclusions MRE can provide high performance in diagnosis of inflammatory bowel disease and good image quality. Key words: Inflammatory bowel diseases; Colitis, ulcerative; Crohn disease; Contrast media; Fluoroscopy; Magnetic resonance imaging

Contemporary diagnostic imaging of diseases of the small intestine – magnetic resonance enteroclysis and enterography

Contemporary diagnostic imaging of diseases of the small intestine – magnetic resonance enteroclysis and enterography

A Diagnostic Accuracy Meta-analysis of CT and MRI for the Evaluation of Small Bowel Crohn Disease

This study aimed to evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) and computed tomography (CT) in assessing small bowel (SB) Crohn disease (CD). We systematically searched PubMed, Elsevier, ScienceDirect, Karger, Web of Science, Wiley Online Library, and Springer for studies in which CT or MRI were evaluated to assess SB CD. Bivariate random effect meta-analytic methods were used to estimate pooled sensitivity, specificity, and receiver operating characteristic curves. Diagnostic odds ratios (DORs) in a per-patient-based analysis were estimated. The area under the receiver operating characteristic curve was also calculated to measure the diagnostic accuracy. Twenty-one studies involving 913 patients were included in this meta-analysis. There was no significant difference observed between modalities. The diagnostic performances (lnDOR) for CT and MRI also showed no significant difference. Subgroup analysis was performed for MR imaging (MR enteroclysis, MR enterography, and CT enterography). The diagnostic performances (lnDOR) for MR enteroclysis, MR enterography, and CT enterography did not show a significant difference among them. No significant difference was found between these techniques. Deeks funnel plot asymmetry test for publication bias showed that no significant publication bias was observed in this analysis. This meta-analysis suggests that both MRI and CT have high diagnostic accuracy in detecting SB CD. MRI has the potential to be the first-line radiation-free modality for SB CD imaging.

Paediatric magnetic resonance enteroclysis under general anaesthesia - initial experience.

MR enterography is the accepted imaging reference standard for small bowel assessment in inflammatory bowel disease. There is an increasing cohort of children with inflammatory bowel disease presenting at an early age (<5years) with severe disease. Younger children present a technical challenge for enterography because of the need for sedation/general anaesthesia to allow image optimisation and the need for oral contrast to allow adequate luminal assessment. Through our experiences, MR enteroclysis under general anaesthesia has proven to be a successful imaging technique for the work-up of these patients. In this paper, we present our institutional practice for performing MR enteroclysis under general anaesthesia.

Quantification of inflammatory activity in patients with Crohn's disease using diffusion weighted imaging (DWI) in MR enteroclysis and MR enterography.

Background Individual studies have demonstrated the potential of diffusion-weighted magnetic resonance imaging (DWI-MRI) for identifying inflamed bowel segments. However, these studies were conducted with rather small patient cohorts and in most cases by means of MR enterography only. Purpose To demonstrate the feasibility of detecting inflamed bowel segments in a large collective of patients with Crohn's disease using DWI in MR enteroclysis and MR enterography and to compare the results of both techniques, also considering clinical parameters by means of the Harvey-Bradshaw Index (HBI). Material and Methods Ninety-six patients underwent MRI enteroclysis and 35 patients MR enterography, both with additional DWI. The HBI as well as apparent diffusion coefficients (ADC) in areas of inflamed and normal bowel wall were determined. Thus resulting in 208 bowel segments that were visualized and subsequently statistically analyzed. Results There were no significant differences in ADC values in MR enteroclysis and MR enterography ( P = 0.383 in inflammation, P = 0.223 in normal wall). Areas of inflammation showed statistically highly significant lower ADC values than areas of normal bowel wall ( P < 0.001). An ADC threshold of 1.56 × 10-3 mm2/s can distinguish between normal and inflamed bowel segments with a sensitivity of 97.4% and a specificity of 99.2%. A highly significant correlation could be shown between ADC and HBI values ( P = 0.001). Conclusion DWI-MRI facilitates recognition of inflamed bowel segments in patients with Crohn's disease and the ADC values show an excellent correlation to the HBI. There were no significant differences in ADC values in MR enteroclysis and MR enterography. An ADC threshold of 1.56 × 10-3 mm2/s differentiates between normal and inflamed bowel wall.

Su1258 Small-Bowel Surveillance in Patients With Peutz-Jeghers Syndrome: Comparing Magnetic Resonance Enteroclysis and Double Balloon Enteroscopy.

Su1258 Small-Bowel Surveillance in Patients With Peutz-Jeghers Syndrome: Comparing Magnetic Resonance Enteroclysis and Double Balloon Enteroscopy.

Magnetic resonance enterography for the evaluation of the deep small intestine in Crohn's disease.

For the control of Crohn's disease (CD) a thorough assessment of the small intestine is essential; several modalities may be utilized, with cross-sectional imaging being important. Magnetic resonance (MR) enterography, i.e., MRE is recommended as a modality with the highest accuracy for CD lesions. MRE and MR enteroclysis are the two methods performed following distension of the small intestine. MRE has sensitivity and specificity comparable to computed tomography enterography (CTE); although images obtained using MRE are less clear compared with CTE, MRE does not expose the patient to radiation and is superior for soft-tissue contrast. Furthermore, it can assess not only static but also dynamic and functional imaging and reveals signs of CD, such as abscess, comb sign, fat edema, fistula, lymph node enhancement, less motility, mucosal lesions, stricture, and wall enhancement. Several indices of inflammatory changes and intestinal damage have been proposed for objective evaluation. Recently, diffusion-weighted imaging has been proposed, which does not need bowel preparation and contrast enhancement. Comprehension of the characteristics of MRE and other modalities is important for better management of CD.

Small-Bowel Neoplasms: Role of MRI Enteroclysis.

Small-bowel neoplasms are the 3%–6% of all gastrointestinal tract neoplasms. Due to the rarity of these lesions, the low index of clinical suspicion, and the inadequate radiologic examinations or incorrect interpretation of radiologic findings, a delay in diagnosis of 6–8 months from the first symptoms often occurs. Even if conventional enteroclysis and capsule endoscopy are the most common procedures used to accurately depict the bowel lumen and mucosal surface, their use in evaluating the mural and extramural extents of small-bowel tumors is limited. Instead multidetector computed tomographic enteroclysis and magnetic resonance enteroclysis have the potential to simultaneously depict intraluminal, mural, and extraintestinal abnormalities. In particular MR enteroclysis has an excellent soft tissue contrast resolution and multiplanar imaging capability. It can provide anatomic, functional, and real time information without the need of ionizing radiation. MR findings, appearances of the lesions, combined with the contrast-enhancement behavior and characteristic of the stenosis are important to differentiate small-bowel neoplasm from other nonneoplastic diseases.

Modern MRI of the small bowell

The radiological diagnostics of diseases of the small intestine have undergone a great change in the last two decades. Through rapid progress with new treatments and an increasing therapeutic focus on transmural healing, a complete evaluation of the gastrointestinal tract is now crucial. With the introduction of endoscopy, gastrointestinal imaging with a relatively high radiation exposure had only limited applications. The development of cross-sectional imaging allowed a much broader radiological evaluation of abdominal diseases. Due to rapid investigation techniques, excellent soft tissue contrast and the distinct advantage of eliminating exposure to radiation, magnetic resonance imaging (MRI) of the gastrointestinal tract has gained increasing importance. With sufficient filling of the intestinal lumen, simultaneous imaging of all the intestinal wall layers, the perienteric structures and associated abdominal pathologies is now possible. New MR sequences, such as diffusion-weighted sequences, dynamic contrast-enhanced sequences and MR fluoroscopy, enable the detection of morphological changes, with additional characterization of affected bowel loops as well as the assessment of functional pathologies with dynamic information about intestinal motility disturbances. Recent guidelines of European radiological and gastroenterological organizations have confirmed the importance of cross-sectional imaging and particularly of MRI for diagnostics and follow-up in patients with Crohn's disease. Due to the possibility of assessment of all the layers of the intestinal wall and the presence of extramural complications, MRI has a significant impact on further therapeutic treatment in patients with inflammatory bowel disease. Especially in patients with inflammatory bowel disease, MR enterography and MR enteroclysis should be the methods of choice for the evaluation of small bowel pathologies because of radiation issues and the great diagnostic value they provide. A variety of MR sequences has enabled not only the detection but also the characterization of pathological changes of the small intestine, which are vital for further treatment of these patients.

Advances of magnetic resonance imaging in Crohn's disease

Crohn’s disease (CD) is a lifelong chronic inflammatory bowel disease associated with diarrhea, abdominal pain, bloody stool and often perianal fistulae. Inflammation in CD involves the entire gastrointestinal tract, especially including the small and large bowels, causing irreversible bowel damage. Frequent imaging examinations are necessary to monitor disease activity and to evaluate response to therapeutic interventions, and, furthermore, to predict recurrence in order to provide appropriate treatment. The suitable imaging modality should be reproducible, well tolerated, safe and free of ionizing radiation. In recent years, imaging used in CD has dramatically changed. Cross-sectional imaging techniques such as computed tomography and magnetic resonance imaging (MRI) are used to investigate not only extraluminal abnormalities, but also intraluminal changes. Recently, new techniques such as MR enteroclysis, enterography, colonography and enterocolonography have been developed. These

Diagnostic accuracy of three different MRI protocols in patients with inflammatory bowel disease.

BackgroundMagnetic resonance imaging (MRI) is used for workup and control of inflammatory bowel disease (IBD); however, disagreement remains as to how the MRI should be performed.PurposeTo compare prospectively the diagnostic accuracy of MRI with neither oral nor intravenous contrast medium (plain MRI), magnetic resonance follow-through (MRFT) and MR enteroclysis (MRE) using MRE as the reference standard in patients with inflammatory bowel disease.Material and MethodsPlain MRI and MRE were carried out in addition to MRFT. All patients underwent both plain MR and MRFT on the same day and MRE within seven days. For the evaluation, the bowel was divided into nine segments. One radiologist, blinded to clinical findings, evaluated bowel wall thickness, diffusion weighted imaging (DWI), mural hyperenhancement, and other inflammatory changes in each bowel segment.ResultsTwenty patients (6 men, 14 women; median age, 43.5 years; age range, 26–76 years) underwent all three examinations; 10 with Crohn’s disease (CD), three with ulcerative colitis (UC), and seven with IBD unclassified (IBD-U). Sensitivity, specificity, and accuracy were in the range of 0–75%, 81–96%, and 75–95% for wall thickening, and 0–37%, 59–89%, and 50–86% for DWI in plain MRI, respectively. Sensitivity, specificity, and accuracy were in the range of 0–50%, 96–100%, and 90–100% for wall thickening, 0–50%, 84–97%, and 82–95% for DWI, and 0–71%, 94–100%, and 85–100% for mural hyperenhancement in MRFT, respectively.ConclusionThe use of oral and intravenous contrast agent improves detection of bowel lesions resulting in MRFT remaining the superior choice over plain MRI for diagnostic workup in patients with IBD.

PTU-020 Diagnosing small bowel crohn’s disease – using capsule when the imaging is negative

Introduction The European Crohn’s and Colitis Organisation guidelines 1 state that small bowel capsule endoscopy (SBCE) should be reserved for patients in whom the clinical suspicion for Crohn’s disease remains high despite negative evaluations with ileocolonoscopy and radiological examinations. SBCE has been shown to detect a higher yield of non-stricturing small bowel Crohn’s disease compared to CT and small bowel barium radiology 2 and improved detection rates compared with MRI. 3 Southmead Hospital is a tertiary referral centre for SBCE which receives referrals throughout the Somerset region. We assessed the diagnostic yield from patients referred for CE for suspected Crohn’s Disease. Method All patients referred for SBCE to assess for small bowel Crohn’s disease between May 2013 and May 2014 were identified. Patients with known Crohn’s disease or positive findings on small bowel imaging were excluded. Patient demographics and CE findings were collected from patient notes, electronic results or referral information. CE videos were interpreted by one of three gastroenterology consultants experienced in interpreting SBCE video. Results 61 patients were referred for SBCE following negative small bowel imaging of which 14 (22.9%) patients had positive findings on SBCE. 9 (64.3%) were female (age range of 17–66 years; mean 42 years). 1 patient (7.1%) had pathology in the proximal SB, 2 (14.3%) in the mid SB, 6 (42.3%) in the distal SB whilst 6 (42.3%) had pathology throughout the SB. Prior to SBCE, 5 patients (35.7%) had negative small bowel MRI, 2 (14.3%) had negative CT abdomen, 5 had (35.7%) negative small bowel enema and 2 (14.3%) had both negative MRI and CT abdomen. Conclusion SBCE diagnosed Crohn’s disease in 22.9% of patients that was not detectable on small bowel imaging. In our experience, SBCE is a worthwhile investigation in patients in whom there is a high clinical suspicion of Crohn’s disease with previous negative imaging including small bowel MRI. Disclosure of interest None Declared. References Van Assche G, Dignass A, Panes J, Beaugerie L, Karagiannis J, Allez M, Stange E. The second European evidence-based consensus on the diagnosis and management of Crohn’s disease: definitions and diagnosis. J Crohns Colitis 2010;4(1):7–27 Triester SL, Leighton JA, Leontiadis GI, Gurudu SR, Fleischer DE, Hara AK, Sharma VK. A meta-analysis of the yield of capsule endoscopy compared to other diagnostic modalities in patients with non-stricturing small bowel Crohn’s disease. Am J Gastroenterol. 2006;101(5):954–964 Golder SK, Schreyer AG, Endlicher E, Feuerbach S, Scholmerich J, Kullmann F, Herfarth H. Comparison of capsule endoscopy and magnetic resonance (MR) enteroclysis in suspected small bowel disease. Int J Colorectal Dis. 2006;21(2):97–104

Indications and selection of MR enterography vs. MR enteroclysis with emphasis on patients who need small bowel MRI and general anaesthesia: results of a survey.

AimsTo survey the perceived indications for magnetic resonance imaging of the small bowel (MRE) by experts, when MR enteroclysis (MREc) or MR enterography (MREg) may be chosen, and to determine how the approach to MRE is modified when general anaesthesia (GA) is required.Materials and methodsSelected opinion leaders in MRE completed a questionnaire that included clinical indications (MREg or MREc), specifics regarding administration of enteral contrast, and how the technique is altered to accommodate GA.ResultsFourteen responded. Only the diagnosis and follow-up of Crohn’s disease were considered by over 80 % as a valid MRE indication. The remaining indications ranged between 35.7 % for diagnosis of caeliac disease and unknown sources of gastrointestinal bleeding to 78.6 % for motility disorders. The majority chose MREg over MREc for all indications (from 100 % for follow-up of caeliac disease to 57.7 % for tumour diagnosis). Fifty per cent of responders had needed to consider MRE under GA. The most commonly recommended procedural change was MRI without enteral distention. Three had experience with intubation under GA (MREc modification).ConclusionViews were variable. Requests for MRE under GA are not uncommon. Presently most opinion leaders suggest standard abdominal MRI when GA is required.Main messages• Experts are using MRE for various indications.• Requests for MRE under general anaesthesia are not uncommon.• Some radiologists employ MREc under general anaesthesia; others do not distend the small bowel.

CT enterography: technical and interpretive pitfalls.

CT enterography is a first-line test at many institutions to investigate potential small bowel disorders. While numerous articles have focused on the ability of CT enterography to diagnose and stage Crohn's disease, small bowel neoplasia, and malabsorptive or vascular disorders, this article reviews CT enterography limitations, technical and interpretive pitfalls, image review tactics, and complementary radiologic and endoscopic examinations to improve diagnostic accuracy. CT enterography limitations include its inability to demonstrate isolated mucosal abnormalities such as aphthous ulcers and its use of ionizing radiation. The most common technical pitfall of CT enterography is inadequate small bowel distention resulting from inadequate ingestion, gastric retention, or rapid small bowel transit of a large volume of neutral enteric contrast material. Additionally, segments of jejunum are frequently collapsed. Interpretive pitfalls commonly result from peristaltic contractions, transient intussusception and opaque intraluminal debris. Opaque debris is especially problematic during multiphasic CT enterography performed to identify potential small bowel sources of obscure gastrointestinal bleeding. False-negative examinations may result from inadequate radiation dose. Examinations complementary to CT enterography include small bowel follow through, enteroclysis, CT enteroclysis, MR enterography, MR enteroclysis, capsule endoscopy, and balloon-assisted endoscopy. Properly performed and accurately interpreted CT enterography contributes to the diagnosis and management of small bowel disease by itself and as a complement to other radiologic and optical small bowel imaging examinations.

P280. Comparison of MR enteroclysis and MR enterography findings with endoscopic findings in paediatric patients with small bowel disease

P280. Comparison of MR enteroclysis and MR enterography findings with endoscopic findings in paediatric patients with small bowel disease

Small bowel masses

The diagnosis of small-bowel tumours, particularly early detection and differential diagnosis, is still somewhat challenging, although many sensitive direct and indirect techniques have been adopted. Although spatial resolution of MR imaging is lower than that of a CT scan, the main advantages of the former are the combination of good soft-tissue contrast, detection of extraenteric abnormalities, and lack of radiation exposure, which allows repeated data acquisition for functional bowel evaluation. Enteroclysis provides greater distention of the entire small bowel than does enterography in patients suspected of having small-bowel neoplasms, because small polypoid masses that do not produce obstruction are most likely difficult to detect by using oral contrast material distention. Moreover, MR enteroclysis delineates superficial changes more accurately than does MR enterography and the evaluation of endoluminal abnormalities is particularly important in the detection of early-stage small-bowel neoplasms. MR enteroclysis has yielded a 96.6% accuracy in the detection of small-bowel neoplasms, thereby proving to be an effective means of diagnosing or ruling out small-bowel neoplasms. MR enterography is an accurate, well-tolerated, promising imaging modality with which to diagnose or exclude small-bowel tumours in symptomatic patients with negative upper and lower endoscopy findings. MR enterography might allow clinicians to select patients in whom more invasive diagnostic methods are indicated. MR enterography, which allows improved localization of small-bowel polyps in patients with Peutz- Jeghers syndrome, is performed to identify larger lesions that should be resected at double-balloon enteroscopy or surgery. It may also be helpful for excluding the presence of lesions in bowel segments not examined at endoscopy or surgery. MRI has proved to be more sensitive than CT for the detection of endoluminal esions of the small bowel, owing to improved detection of segments with subtle abnormalities. These findings may be due both to the better soft-tissue contrast afforded by MR imaging, which is required for tissue characterization and the detection of subtle areas of abnormality, and to its functional capabilities. Another advantage of MR imaging over CT is that the enhanced soft-tissue contrast produced by MR imaging may provide more information regarding the nature of mesenteric small bowel tumors, thereby allowing better characterization of small-bowel tumors. In this regard, benign tumors such as hemangiomas are typically strongly hyperintense on T2-weighted MR images, whereas lipomas or tumors with a marked fat content are spontaneously hyperintense on T1-weighted MR images. With few exceptions (lymphoma being one), thickening of a long segment of the small bowel is indicative of a benign condition. MR enteroclysis and enterography are accurate non-invasive modalities in assessing the intraluminal, parietal and extraluminal neoplastic manifestations. MR signal appearances of the lesions, combined with the contrast enhancement behaviour and the characteristic of the stenosis, can help in differentiating from other non-neoplastic diseases of the small-bowel. Radiologists should therefore be familiar with the MR appearance of various small-bowel neoplasms and their mimickers.

Gastroenteropancreatic endocrine tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NET) are a rare, heterogeneous group of neoplasms. Only 2% of gastrointestinal tumors belong to the group of neuroendocrine neoplasms. A wide spectrum of diagnostic imaging modalities is available: apart from ultrasound not only computed tomography (CT) but also magnetic resonance imaging (MRI) and positron emission tomography CT (PET-CT) play an important role in detection and staging of GEP-NETs. The PET-CT technique with somatostatin analogues is used for staging as well as for evaluation and monitoring of treatment with peptide radionuclide radiation therapy. According to the literature NETs of the small bowel with a size over 3 cm can be detected with a sensitivity of 84.7% and a specificity of 96.6% using CT enteroclysis and MR enteroclysis provides the detection of NETs of the small bowel in 93.3% of cases. 'The sensitivity of MRI in detection of pancreatic NETs is between 74% and 100% and is, therefore, higher than CT. Detection of small primary tumors is carried out using PET-CT and seems to be the most sensitive imaging modality to identify the exact location. On the other hand MRI has to be regarded as the best imaging modality for detection of liver metastases compared to CT and PET-CT. The role of diagnostic imaging is to identify the exact location of the primary tumor and possible metastases, to define an appropriate therapy and to monitor treatment effects; however, the choice of the most appropriate diagnostic imaging modality varies depending on the location and type of the primary tumor. The GEP-NETs are predominantly well-vascularized; therefore, dual-phase CT/MR imaging with the arterial and venous phases after contrast media injection is mandatory for detection and localization of primary tumors and metastases. For whole body staging CT and PET-CT should be performed.