John M. Barlow

Small-bowel imaging in Crohn's disease: a prospective, blinded, 4-way comparison trial

BACKGROUND With the introduction of new techniques to image the small bowel, there remains uncertainty about their role for diagnosing Crohns disease. OBJECTIVE To assess the sensitivity and specificity of capsule endoscopy (CE), CT enterography (CTE), ileocolonoscopy, and small-bowel follow-through (SBFT) in the diagnosis of small bowel Crohns disease. METHODS Prospective, blinded trial. SETTING Inflammatory bowel disease clinic at an academic medical center. PATIENTS Known or suspected Crohns disease. Exclusion criteria included known abdominal abscess and non-steroidal anti-inflammatory drug (NSAID) use. Partial small-bowel obstruction (PSBO) at CTE excluded patients from subsequent CE. INTERVENTIONS Patients underwent all 4 tests over a 4-day period. MAIN OUTCOME MEASUREMENTS Sensitivity, specificity, and accuracy of each test to detect active small-bowel Crohns disease. The criterion standard was a consensus diagnosis based upon clinical presentation and all 4 studies. RESULTS Forty-one CTE examinations were performed. Seven patients (17%) had an asymptomatic PSBO. Forty patients underwent colonoscopy, 38 had SBFT studies, and 28 had CE examinations. Small-bowel Crohns disease was active in 51%, absent in 42%, inactive in 5%, and suspicious in 2% of patients. The sensitivity of CE for detecting active small-bowel Crohns disease was 83%, not significantly higher than CTE (83%), ileocolonoscopy (74%), or SBFT (65%). However, the specificity of CE (53%) was significantly lower than the other tests (P < .05). One patient developed a transient PSBO due to CE, but no patients had retained capsules. LIMITATION Use of a consensus clinical diagnosis as the criterion standard-but this is how Crohns disease is diagnosed in practice. CONCLUSIONS The sensitivity of CE for active small-bowel Crohns disease was not significantly different from CTE, ileocolonoscopy, or SBFT. However, lower specificity and the need for preceding small-bowel radiography (due to the high frequency of asymptomatic PSBO) may limit the utility of CE as a first-line test for Crohns disease.

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

Objective: To determine small bowel distention, scanning time, and side effects of commercially available oral contrast agents used in cross-sectional enterography. Methods: Ten healthy volunteers ingested 2000 mL of water, methylcellulose, polyethylene glycol (PEG), or 1350 mL of low-concentration barium (LCB) followed by 500 mL water on different days. Magnetic resonance imaging occurred every 10 minutes from 30 to 90 minutes after ingestion. Small bowel distention was compared between time points and agents. Volunteers ranked side effects, drinking difficulty, and preference. Results: By quantitative assessment, PEG and LCB distended small bowel loops better than water and methylcellulose (P < 0.0001). Time to optimal distention of the terminal ileum was from 51 to 72 minutes. Water and methylcellulose had the fewest side effects. Water was the most preferred contrast and PEG the least. Conclusions: Polyethylene glycol and LCB distend small bowel better than water and methylcellulose. Polyethylene glycol was the most difficult to drink and least preferred agent.

CT enterography and fistulizing Crohn’s disease: clinical benefit and radiographic findings

BackgroundTo estimate the clinical benefit of CT enterography (CTE) in patients with fistulizing Crohn’s disease and describe the appearance of fistulas at CTE.MethodsCrohn’s patients who had undergone CTE, which diagnosed an abscess or fistula, were identified. A gastroenterologist reviewed clinical notes prior to and following CTE to assess the pre-CTE clinical suspicion for fistula/abscess, and post-CTE alteration in patient management. A radiologist reassessed all fistula-positive cases, which were confirmed by a non-CT reference standard, to describe their radiologic appearance.ResultsFifty-six patients had CT exams identifying 19 abscesses and 56 fistulas. There was no or remote suspicion of fistula or abscess at pre-imaging clinical assessment in 50% of patients. Thirty-four patients (61%) required a change in or initiation of medical therapy and another 10 (18%) underwent an interventional procedure based on CT enterography findings. Among 37 fistulas with reference standard confirmation, 30 (81%) were extraenteric tracts, and 32 (86%) were hyperenhancing compared to adjacent bowel loops. Most fistulas (68%) contained no internal air or fluid.ConclusionCTE detects clinically occult fistulas and abscesses, resulting in changes in medical management and radiologic or surgical intervention. Most fistulas appear as hyperenhancing, extraenteric tracts, usually without internal air or fluid.

Automatic Selection of Tube Potential for Radiation Dose Reduction in Vascular and Contrast-Enhanced Abdominopelvic CT

OBJECTIVE The purpose of this study is to assess the ability of a novel automatic tube potential selection tool to reduce radiation dose while maintaining diagnostic quality in CT angiography (CTA) and contrast-enhanced abdominopelvic CT. MATERIALS AND METHODS One hundred one CTA examinations and 90 contrastenhanced abdominopelvic examinations were performed using an automatic tube potential selection tool on a 128-MDCT scanner. Two vascular radiologists and two abdominal radiologists evaluated the image quality for sharpness, noise, artifact, and diagnostic confidence. In a subset of patients who had undergone prior studies (CTA, 28 patients; abdominopelvic CT, 25 patients), a side-by-side comparison was performed by a separate radiologist. Dose reduction and iodine contrast-to-noise ratio resulting from use of the tool were calculated. RESULTS For CTA, 80 or 100 kV was selected for 73% of the scans, with a mean dose reduction of 36% relative to the reference 120-kV protocol. For abdominopelvic CT examinations, 80 or 100 kV was used for 55% of the scans, with a mean dose reduction of 25%. Overall dose reduction relative to the reference 120-kV protocol was 25% and 13% for CTA and abdominopelvic CT scans, respectively. Over 98% of scans had acceptable sharpness, noise texture, artifact, and diagnostic confidence for both readers and diagnostic tasks; 94-100% of scans had acceptable noise. Iodine contrast-to-noise ratio was significantly higher than (p < 0.001) or similar to (p = 0.11) that of prior scans, and equivalent quality was achieved despite the dose reduction. CONCLUSION Automatic tube potential selection provides an efficient and quantitativeway to guide the selection of the optimal tube potential for CTA and abdominopelvic CT examinations.

Multiphase CT Enterography Evaluation of Small-Bowel Vascular Lesions

OBJECTIVE By use of multiphase CT enterography (CTE), small-bowel vascular lesions associated with gastrointestinal bleeding can be classified into three categories--angioectasias, arterial lesions, and venous abnormalities--on the basis of common morphology and enhancement patterns. This article will review the unique patterns of enhancement and lesion morphology seen on multiphase CTE and how those findings enable detection and characterization of specific lesions in many cases. CONCLUSION Because of the high prevalence in nonbleeding patients and frequent multiplicity of angioectasias, determining the clinical benefit from their detection by multiphase CTE and endoscopy is problematic. Although arterial lesions are less commonly encountered clinically, their detection is critically important because of a high risk of life-threatening bleeding. Along with wireless capsule endoscopy and balloon-assisted endoscopy, multiphase CTE is a useful tool for the evaluation of patients with obscure gastrointestinal bleeding due to small-bowel vascular lesions.

Radiological Response Is Associated With Better Long-Term Outcomes and Is a Potential Treatment Target in Patients With Small Bowel Crohn's Disease

OBJECTIVES:Crohns disease (CD) management targets mucosal healing on ileocolonoscopy as a treatment goal. We hypothesized that radiologic response is also associated with better long-term outcomes.METHODS:Small bowel CD patients between 1 January 2002 and 31 October 2014 were identified. All patients had pre-therapy computed tomography enterography (CTE)/magnetic resonance enterography (MRE) with follow-up CTE or MRE after 6 months, or 2 CTE/MREs≥6 months apart while on maintenance therapy. Radiologists characterized inflammation in up to five small bowel lesions per patient. At second CTE/MRE, complete responders had all improved lesions, non-responders had worsening or new lesions, and partial responders had other scenarios. CD-related outcomes of corticosteroid usage, hospitalization, and surgery were assessed using Kaplan–Meier survival analysis and multivariable Cox models.RESULTS:CD patients (n=150), with a median disease duration of 9 years, had 223 inflamed small bowel segments (76 with strictures and 62 with penetrating, non-perianal disease), 49% having ileal distribution. Fifty-five patients (37%) were complete radiologic responders, 39 partial (26%), and 56 non-responders (37%). In multivariable Cox models, complete and partial response decreased risk for steroid usage by over 50% (hazard ratio (HR)s: 0.37 (95% confidence interval (CI), 0.21–0.64); 0.45 (95% CI, 0.26–0.79)), and complete response decreased the risk of subsequent hospitalizations and surgery by over two-thirds (HRs: HR, 0.28 (95% CI, 0.15–0.50); HR, 0.34 (95% CI, 0.18–0.63)).CONCLUSIONS:Radiological response to medical therapy is associated with significant reductions in long-term risk of hospitalization, surgery, or corticosteroid usage among small bowel CD patients. These findings suggest the significance of radiological response as a treatment target.

Validation of a CT-Derived Method for Osteoporosis Screening in IBD Patients Undergoing Contrast-Enhanced CT Enterography

OBJECTIVES:Osteoporosis and bone fractures are of particular concern in patients with inflammatory bowel disease (IBD). Biomechanical computed tomography (BCT) is an image-analysis technique that can measure bone strength and dual-energy X-ray absorptiometry (DXA)-equivalent bone mineral density (BMD) from noncontrast CT images. This study seeks to determine whether this advanced technology can be applied to patients with IBD undergoing CT enterography (CTE) with IV contrast.METHODS:Patients with IBD who underwent a CTE and DXA scan between 2007 and 2011 were retrospectively identified. Femoral neck BMD (g/cm2) and T-scores were measured and compared between DXA and BCT analysis of the CTE images. Femoral strength (Newtons) was also determined from BCT analysis.RESULTS:DXA- and CTE-generated BMD T-score values were highly correlated (R2=0.84, P<0.0001) in this patient cohort (n=136). CTE identified patients with both osteoporosis (sensitivity, 85.7%; 95% confidence interval (CI), 48.7–97.4 and specificity, 98.5%; 95% CI, 94.5–99.6) and osteopenia (sensitivity, 85.1%; 95% CI, 72.3–92.6 and specificity, 85.4%; 95% CI, 76.6–91.3). Of the 16 patients who had “fragile” bone strength by BCT (placing them at the equivalent high risk of fracture as for osteoporosis), 6 had osteoporosis and 10 had osteopenia by DXA.CONCLUSIONS:CTE scans can provide hip BMD, T-scores, and clinical classifications that are comparable to those obtained from DXA; when combined with BCT analysis, CTE can identify a subset of patients with osteopenia who have clinically relevant fragile bone strength. This technique could markedly increase bone health assessments in IBD patients already undergoing CTE to evaluate small bowel disease.

Retained Capsule Endoscopy in a Large Tertiary Care Academic Practice and Radiologic Predictors of Retention

Background:Capsule retention reported rates range between 1% and 13%. This study aims to determine the incidence of, risk factors for, and clinical outcomes of capsule retention in a large heterogenous cohort of patients and define cross-sectional imaging findings predictive of capsule retention. Methods:A retrospective review of all capsule endoscopy (CE) examinations performed at our center from January 2002 to January 2013 was undertaken. Data on patient demographics, CE indication, findings, and details of management were analyzed. Radiologic images of patients with computed tomography scan performed 6 months before CE for patients with CE retention and for controls without CE retention but at high risk based on clinical computed tomography reports were examined by a gastrointestinal radiologist, blinded to history, and classified as worrisome based on the presence of stricture, partial obstruction, or small bowel (SB) anastomosis. Results:Seventeen CE retentions (0.3%) occurred in 15 patients. Obscure gastrointestinal bleeding (47%) was the most common indication. Outcomes included surgical intervention (n = 10), endoscopic retrieval (n = 2), passing of capsule after treatment of inflammation (n = 3), passage after conservative measures for SB obstruction (n = 1), and loss to follow-up (n = 1). Patients with CE retention were more likely to have SB anastomoses (88% versus 23%) and partial obstruction (63% versus 38%) than patients with high-risk features for capsule retention who passed the capsule. Conclusions:In a tertiary care population without obstructive symptoms, capsule retention occurred in only 0.3% of cases. Review of surgical history and prior imaging for obstruction or SB anastomoses may help to reduce retention.

NSAID enteropathy: appearance at CT and MR enterography in the age of multi-modality imaging and treatment.

CT and MR enterography and capsule endoscopy are increasingly used as routine diagnostic tests for patients with potential small bowel disorders and obscure gastrointestinal bleeding. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used drugs that disrupt prostaglandin synthesis and result in a variety of localized complications within the small bowel ranging from ulcer formation to characteristic circumferential strictures, or diaphragms. NSAID enteropathy encompasses this spectrum of acute and chronic inflammatory sequelae, and is associated with typical findings at capsule endoscopy and surgery. Herein we review the typical clinical presentation of NSAID enteropathy, in addition to its endoscopic appearances, focusing on imaging findings at cross-sectional enterography. Multiple, short-segment strictures are the hallmarks of imaging diagnosis. Strictures may have minimal hyperenhancement or wall thickening, but these findings are typically symmetric and circumferential with respect to the bowel lumen. Multifocal Crohn’s strictures, and occasionally radiation-induced strictures or adhesions, will mimic NSAID diaphragms. Multi-phase or multi-sequence imaging at CT and MR enterography increase diagnostic confidence in stricture presence. Strategies for subsequent workup and therapy after enterography are also discussed. Given the frequent use of NSAIDs and typical appearance of these strictures, knowledge of characteristic imaging findings can be particularly useful when evaluating patients with anemia and recurrent small bowel obstruction.

Endoscopic and Radiographic Assessment of Crohn's Disease

Crohns disease is a chronic inflammatory disorder that can progress to obstructive and penetrating complications. Although clinical symptoms are an important component of therapy, they correlate poorly with objective measures of inflammation. The treatment targets have evolved from clinical improvement only to the addition of more objective measures, such as endoscopic mucosal healing and radiologic response, which have been associated with favorable long-term outcomes, including reduced hospitalizations, surgeries, and need for corticosteroids. There are multiple endoscopic and radiologic scoring systems that can aid in quantifying disease activity and response to therapy. These modalities and scoring tools are discussed in this article.