MR enterography in the evaluation of small bowel dilation

Indications and Limitations Associated with the Patency Capsule Prior to Capsule Endoscopy

The retention of the capsule used during small bowel capsule endoscopy (SBCE) is a serious complication that can occur in patients with known or suspected small bowel stenosis, and a prior evaluation of the patency of the gastrointestinal (GI) tract is therefore essential. Patency capsule (PC) is a non-diagnostic capsule the same size as the diagnostic SBCE. To date, there are no clear guidelines regarding the contraindications for undergoing a PC evaluation prior to SBCE. Each small bowel disorder has specific occasions to inhibit the progress of PC and SBCE, even though they do not have any stenotic symptoms or abnormalities on imaging. In this review, we summarize the indications and limitations of PC prior to SBCE, especially the contraindications, and discuss clinical scenarios in which even PC should be avoided, and therefore such areas of stenosis should be evaluated by alternative modalities. We thus propose this new algorithm to evaluate the patency of the GI tract for patients with suspected and known small bowel stenosis in order that they may undergo SBCE safely.

ACR Appropriateness Criteria® Suspected Small-Bowel Obstruction

Small-bowel obstruction is a common cause of abdominal pain and accounts for a significant proportion of hospital admissions. Radiologic imaging plays the key role in the diagnosis and management of small-bowel obstruction as neither patient presentation, the clinical examination, nor laboratory testing are sufficiently sensitive or specific enough to diagnose or guide management. This document focuses on the imaging evaluation of the two most commonly encountered clinical scenarios related to small-bowel obstruction: the acute presentation and the more indolent, low-grade, or intermittent presentation. This document hopes to clarify the appropriate utilization of the many imaging procedures that are available and commonly employed in these clinical settings. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

MRI assessment of the postprandial gastrointestinal motility and peptide response in healthy humans

BACKGROUND

Feeding triggers inter-related gastrointestinal (GI) motor, peptide and appetite responses. These are rarely studied together due to methodological limitations. Recent MRI advances allow pan-intestinal, non-invasive assessment of motility in the undisturbed gut. This study aimed to develop a methodology to assess pan-intestinal motility and transit in a single session using MRI and compare imaging findings to GI peptide responses to a test meal and symptoms in a healthy volunteer cohort.

METHODS

Fifteen healthy volunteers (29.3±2.7 years and BMI 20.1±1.2 kg m^-2 ) underwent baseline and postprandial MRI scans, symptom questionnaires, and blood sampling (for subsequent GI peptide analysis, Glucagon-like peptide-1 [GLP-1], Polypeptide YY [PYY], Cholecystokinin [CCK]) at intervals for 270 minutes following a 400 g soup meal (204 kcal, Heinz, UK). Gastric volume, gall bladder volume, small bowel water content, small bowel motility, and whole gut transit were measured from the MRI scans.

KEY RESULTS

(mean±SEM) Small bowel motility index increased from fasting 39±3 arbitrary units (a.u.) to a maximum of 87±7 a.u. immediately after feeding. PYY increased from fasting 98±10 pg mL^-1 to 149±14 pg mL^-1 at 30 minutes and GLP-1 from fasting 15±3 μg mL^-1 to 22±4 μg mL^-1 . CCK increased from fasting 0.40±0.06 pmol mL^-1 to 0.94±0.1 pmol mL^-1 . Gastric volumes declined with a T_1/2 of 46±5 minute and the gallbladder contracted from a fasting volume of 19±2 mL^-1 to 12±2 mL^-1 . Small bowel water content increased from 39±2 mL^-1 to 51±2 mL^-1 postprandial. Fullness VAS score increased from 9±5 mm to 41±6 mm at 30 minutes postprandial.

CONCLUSIONS AND INFERENCES

The test meal challenge was effective in inducing a change in MRI motility end-points which will improve understanding of the pathophysiological postprandial GI response.

Diagnostic performance of multi-slice CT angiography combined with enterography for small bowel obstruction and intestinal ischaemia

INTRODUCTION

This study was performed to evaluate the diagnostic performance of multi-slice CT angiography combined with enterography in determining the cause and location of obstruction as well as intestinal ischaemia in patients with small bowel obstruction (SBO).

METHODS

This study retrospectively summarized the image data of 57 SBO patients who received both multi-slice CT angiography and enterography examination between December 2012 and May 2013. The CT diagnoses of SBO and intestinal ischaemia were correlated with the findings at surgery or digital subtraction angiography, which were set as standard references.

RESULTS

Multi-slice CT angiography and enterography indicated that the cause of SBO in three patients was misjudged, suggesting a diagnostic accuracy of 94.7%. In one patient the level of obstruction was incorrect, demonstrating a diagnostic accuracy of 98.2%. Based on the results of the receiver operating characteristic (ROC) curve analysis, the diagnostic criterion for ischaemic SBO was at least two of the four CT signs (circumferential bowel wall thickening, reduced enhancement of the intestinal wall, mesenteric oedema and mesenteric vascular engorgement). The criterion yielded a sensitivity of 94.4%, a specificity of 92.3%, a positive predicted value of 85.0% and a negative predicted value of 97.3%, and the area under curve (AUC) was 0.92 (95% CI, 0.85-0.99).

CONCLUSION

Multi-slice CT angiography and enterography have high diagnostic value in identifying the cause and site of SBO. In addition, the suggested diagnostic criterion using CT signs is helpful for diagnosing intestinal ischaemia in SBO patients.

Intestinal tuberculosis versus crohn's disease: Clinical and radiological recommendations

Intestinal tuberculosis is a common clinical problem in India. The clinical features of this disease are nonspecific and can be very similar to Crohn's disease. Radiological evaluation of the small bowel has undergone a paradigm shift in the last decade. This long tubular organ that has traditionally been difficult to evaluate can now be well-visualized by some innovative imaging and endoscopic techniques. This article highlights the state-of-the-art evaluation of ulceroconstrictive diseases of the bowel and provides recommendations for the differentiation of intestinal tuberculosis from Crohn's disease.

Radiation-Induced Problems in Colorectal Surgery

Radiotherapy not only plays a pivotal role in the cancer care pathways of many patients with pelvic malignancies, but can also lead to significant injury of normal tissue in the radiation field (pelvic radiation disease) that is sometimes as challenging to treat as the neoplasms themselves. Acute symptoms are usually self-limited and respond to medical therapy. Chronic symptoms often require operative intervention that is made hazardous by hostile surgical planes and unforgiving tissues. Management of these challenging patients is best guided by the utmost caution and humility.

Radiation enteritis

Radiation enteritis continues to be a major health concern in recipients of radiation therapy. The incidence of radiation enteritis is expected to continue to rise during the coming years paralleling the unprecedented use of radiotherapy in pelvic cancers. Radiation enteritis can present as either an acute or chronic syndrome. The acute form presents within hours to days of radiation exposure and typically resolves within few weeks. The chronic form may present as early as 2 months or as long as 30 years after exposure. Risk factors can be divided into patient and treatment-related factors. Chronic radiation enteritis is characterized by progressive obliterative endarteritis with exaggerated submucosal fibrosis and can manifest by stricturing, formation of fistulae, local abscesses, perforation, and bleeding. In the right clinical context, diagnosis can be confirmed by cross-sectional imaging, flexible or video capsule endoscopy. Present treatment strategies are directed primarily towards symptom relief and management of emerging complications. Recently, however, there has been a shift towards rational drug design based on improved understanding of the molecular basis of disease in an effort to limit the fibrotic process and prevent organ damage.

Effectiveness of MR enterography for the assessment of small-bowel diseases beyond Crohn disease

The use of cross-sectional imaging techniques for the noninvasive evaluation of small-bowel disorders is increasing. The effectiveness of magnetic resonance (MR) enterography for the evaluation of Crohn disease, in particular, is well described in the literature. In addition, MR enterography has an evolving though less well documented role to play in the evaluation of other small-bowel diseases, including various benign and malignant neoplasms arising in isolation or in polyposis syndromes such as Peutz-Jeghers, inflammatory conditions such as vasculitis and treatment-induced enteritis, infectious processes, celiac disease, diverticular disease, systemic sclerosis, and bowel duplication. MR enterography may be useful also for the evaluation of intermittent and low-grade small-bowel obstructions. Advantages of MR imaging over computed tomography (CT) for enterographic evaluations include superb contrast resolution, lack of associated exposure to ionizing radiation, ability to acquire multiplanar primary image datasets, ability to acquire sequential image series over a long acquisition time, multiphasic imaging capability, and use of intravenous contrast media with better safety profiles. MR enterography also allows dynamic evaluations of small-bowel peristalsis and distensibility of areas of luminal narrowing and intraluminal masses by repeating sequences at different intervals after administering an additional amount of the oral contrast medium. Limitations of MR enterography in comparison with CT include higher cost, less availability, more variable image quality, and lower spatial resolution. The advantages and disadvantages of MR enterography performed with ingestion of the oral contrast medium relative to MR enteroclysis performed with infusion of the oral contrast medium through a nasoenteric tube are less certain.

Advances in small bowel imaging

The small intestine has been difficult to examine by traditional endoscopic and radiologic techniques. Within the past 10 years, advances have led to an explosion of technologies that facilitate examination of the entire small intestine. Wireless video capsule endoscopy, deep enteroscopy using balloon-assisted or spiral techniques, computer tomography (CT) and magnetic resonance (MR) enterography have facilitated the diagnosis, monitoring, and management of patients with small intestinal diseases. These technologies are complementary, each with its advantages and limitations. Capsule endoscopy provides a detailed view of the mucosal surface and has excellent patient acceptance, but does not allow therapeutics. Deep enteroscopy allows careful inspection of the mucosa and therapeutics, but is time consuming and invasive. Enterography (CT or MR) allows examination of the small bowel wall and surrounding structures. The initial best test for detecting small intestinal disease depends on clinical presentation and an astute differential diagnosis.

Magnetic resonance enterography findings of chronic radiation enteritis

The diagnosis of chronic radiation enteritis (CRE) is considerably challenging both for clinicians and radiologists. The aim of this study was to evaluate the role of magnetic resonance enterography (MRE) in the diagnosis of CRE. To the best of our knowledge, there are no reports on the role of MRE in the diagnosis of CRE specifically. In this report, we present MRE findings of 4 patients with CRE. The most important factors in CRE diagnosis are the clinical findings and medical history, but focal abnormal bowel loop in the region of a known radiation field is the most important information. This abnormal loop is generally located in the distal ileum as present in our patients. Other associated findings helpful for the diagnosis are small bowel thickening, contrast material enhancement in a long segment, mesenteric stranding and luminal narrowing. MRE can be sufficient and useful in the diagnosis of CRE and for treatment planning, especially in patients with significant comorbidities who have had radiotherapy in the past. Adding MRE into the diagnostic algorithm can be helpful in post-radiotherapy patients with acute/subacute gastrointestinal symptoms.

Small bowel MRI in adult patients: not just Crohn's disease-a tutorial

Objectives

To provide an overview of less well-known small bowel and mesenteric diseases found at small bowel magnetic resonance (MR) enterography/enteroclysis and to review the imaging findings. MR enterography and enteroclysis are important techniques for evaluation of small bowel diseases. In most centres these techniques are primarily used in Crohn’s disease, and most radiologists are familiar with these MRI findings. However, the knowledge of findings in other diseases is often sparse, including diseases that may cause similar clinical symptoms to those of Crohn’s disease.

Methods

We present a spectrum of less common and less well-known bowel and mesenteric diseases (e.g. internal hernia, intussusception, neuroendocrine tumour) from our small bowel MR database of over 2,000 cases.

Results

These diseases can be found in patients referred for bowel obstruction, abdominal pain or rectal blood loss. Further, in patients with (or suspected to have) Crohn’s disease, some of these diseases (e.g. neuroendocrine tumour, familial Mediterranean fever) may mislead radiologists to erroneously diagnose active Crohn’s disease.

Conclusion

Radiologists should be familiar with diseases affecting the small bowel other than Crohn’s disease, including diseases that may mimic Crohn’s disease.

Current management of small bowel obstruction

SBO is a common disease with multiple causes. The most significant advances over the past several years have involved, first, decision-making techniques to promptly and accurately identify patients who will require exploration, and, second, the increasing use of laparoscopic techniques. "Complete" bowel obstruction is becoming an outdated term, as treatment algorithms use predictive models and oral contrast challenges to select patients for operation without recourse to the notion of "complete obstruction." Laparoscopic techniques are gaining acceptance as a primary modality in the treatment of SBO. Appropriate patient selection is necessary for success, but successful laparoscopic SBO management can reduce postoperative pain, minimize hospital stay, and may lead to fewer adhesions, possibly preventing further adhesive SBO. Strangulation obstruction is the major cause of morbidity and mortality in SBO. Although unrecognized strangulation obstructions remain, their incidence is decreasing with the new protocols in development. Future efforts should focus on incorporating predictive models into management with the goal of eliminating unrecognized strangulation obstructions. Further refinement of the predictive models incorporating outcomes of oral contrast challenges and molecular biomarker data may allow surgeons to reach this goal. In addition, the benefit of the elimination of interpractitioner variability conferred by standardized protocols will in itself improve patient outcomes.

Diagnosis and treatment of small bowel diseases are advanced by capsule endoscopy and double-balloon enteroscopy

In 2001, new endoscopic procedures for the small bowel, capsule endoscopy (CE) and double-balloon enteroscopy (DBE), were introduced into regular clinical practice. These methods were significant breakthroughs for imaging examination of the small bowel. The methods have different characteristics with regard to their approach into the target organ; however, common to both is the feature of enabling rapid total observation of the small bowel. CE is the first safe, non-invasive well-tolerated procedure and can be performed in any condition. The examination time is about 8 h and the patient can spend the time freely. CE can demonstrate active bleeding or neoplasm in the small bowel, which other modalities cannot detect. DBE, which was developed by Yamamoto, employs two balloons combined with an overtube and allows deeper insertion into the small bowel, and can be a modality for examination of the entire small bowel with combined oral and anal approaches. This modality enables biopsy specimens to be taken, polyps to be resected and hemostatic procedures to be performed throughout the small bowel. The understanding of small bowel disease is being extended by using CE and DBE for diagnosis. CE is considered to be superior for the first examination of the small bowel and DBE is useful for detailed examination and endoscopic therapy. Further clinical study of unknown small bowel disorders using these two modalities and algorithms for the management of small bowel disorders are required.

[Mechanical obstruction as a cause of acute abdomen. Radiological differential diagnosis]

Mechanical obstruction is a common cause of acute abdomen. Besides the diagnosis of the obstruction itself it is crucial to recognize the cause of the obstruction for planning of conservative or operative treatment.This article gives a general overview of the methods available for imaging obstructions in the setting of an acute abdomen. In the second part the differential diagnoses of the most common causes of obstruction will be discussed.