MRI-enema for the assessment of pelvic intestinal anastomotic integrity.

AIM: Anastomotic leak causes significant morbidity for patients undergoing pelvic intestinal surgery. Fluoroscopic assessment of anastomotic integrity using water-soluble contrast enema (WSCE) is of questionable benefit over examination alone. We hypothesized that MRI-enema may be more accurate. The aim of this study was to compare MRI-enema with fluoroscopic WSCE. METHOD: Patients referred for WSCE with pelvic intestinal anastomosis and defunctioning ileostomy (including patients with suspected or known leaks) were invited to participate. WSCE and MRI-enema were undertaken within 48 h of each other. MRI sequences were performed before, during and immediately after the introduction of 400 ml of 1% gadolinium contrast solution per anus. MRI examinations were reported to protocol by two blinded gastrointestinal radiologists. A Likert-scale patient questionnaire was administered to compare patient experience. Follow-up was >12 months after ileostomy reversal. Anastomotic leak was determined by unblinded consensus of examination and radiological findings. RESULTS: Sixteen patients were recruited, with a median age of 39 years (range 22-69). Ten were men, 11 had ileoanal pouch formation and five had low anterior resection. Five patients had anastomotic leak identified by MRI and four by WSCE. The radial location of the anastomotic defect was identified in all five patients by MRI versus two on WSCE. MRI revealed additional information including contents of a widened presacral space. Patient experience was equivalent. Eleven patients eventually had ileostomy reversal without complications. CONCLUSION: MRI-enema is a feasible and tolerable alternative to WSCE and offers greater anatomical detail in the context of pelvic intestinal anastomotic leak. Larger prospective studies are required to define its potential role in the UK National Health Service.

Colon cancer screening with CT colonography: logistics, cost-effectiveness, efficiency and progress.

Colorectal cancer (CRC) incidence and mortality can be significantly reduced by population screening. Several different screening methods are currently in use, and this review focuses specifically on the imaging technique computed tomographic colonography (CTC). The challenges and logistics of CTC screening, as well as the importance of test accuracy, uptake, quality assurance and cost-effectiveness will be discussed. With comparable advanced adenoma detection rates to colonoscopy (the most commonly used whole-colon investigation), CTC is a less-invasive alternative, requiring less laxative, and with the potential benefit that it permits assessment of extra colonic structures. Three large-scale European trials have contributed valuable evidence supporting the use of CTC in population screening, and highlight the importance of selecting appropriate clinical management pathways based on initial CTC findings. Future research into CTC-screening will likely focus on radiologist training and CTC quality assurance, with identification of evidence-based key performance indicators that are associated with clinically-relevant outcomes such as the incidence of post-test interval cancers (CRC occurring after a presumed negative CTC). In comparison to other CRC screening techniques, CTC offers a safe and accurate option that is particularly useful when colonoscopy is contraindicated. Forthcoming cost-effectiveness analyses which evaluate referral thresholds, the impact of extra-colonic findings and real-world uptake will provide useful information regarding the feasibility of future CTC population screening.

Volume assessment magnetic resonance imaging technique for monitoring perianal Crohn's fistulas.

BACKGROUND: Perianal Crohn's fistula and their response to anti-tumour necrosis factor (TNF) therapies are best assessed with magnetic resonance imaging (MRI), but radiologist reporting is subjective and variable. This study investigates whether segmentation software could provide precise and reproducible objective measurements of fistula volume. METHODS: Retrospective analysis of patients with perianal Crohn's fistula at our institution between 2007 and 2013. Pre- and post-biologic MRI scans were used with varying time intervals. A total of two radiologists recorded fistula volumes, mean signal intensity and time taken to measure fistula volumes using validated Open Source segmentation software. A total of three radiologists assessed fistula response to treatment (improved, worse or unchanged) by comparing MRI scans. RESULTS: A total of 18 cases were reviewed for this pilot study. Inter-observer variability was very good for volume and mean signal intensity; intra-class correlation (ICC) 0.95 [95% confidence interval (CI) 0.91-0.98] and 0.95 (95% CI 0.90-0.97) respectively. Intra-observer variability was very good for volume and mean signal intensity; ICC 0.99 (95% CI 0.97-0.99) and 0.98 (95% CI 0.95-0.99) respectively. Average time taken to measure fistula volume was 202 s and 250 s for readers 1 and 2. Agreement between three specialist radiologists was good [kappa 0.69 (95% CI 0.49-0.90)] for the subjective assessment of fistula response. Significant association was found between objective percentage volume change and subjective consensus agreement of response (p = 0.001). Median volume change for improved, stable or worsening fistula response was -67% [interquartile range (IQR): -78, -47], 0% (IQR: -16, +17), and +487% (IQR: +217, +559) respectively. CONCLUSION: Quantification of fistula volumes and signal intensities is feasible and reliable, providing an objective measure of perianal Crohn's fistula and response to treatment.

Computed tomographic colonography versus barium enema for diagnosis of colorectal cancer or large polyps in symptomatic patients (SIGGAR): a multicentre randomised trial.

BACKGROUND: Barium enema (BE) is widely available for diagnosis of colorectal cancer despite concerns about its accuracy and acceptability. Computed tomographic colonography (CTC) might be a more sensitive and acceptable alternative. We aimed to compare CTC and BE for diagnosis of colorectal cancer or large polyps in symptomatic patients in clinical practice. METHODS: This pragmatic multicentre randomised trial recruited patients with symptoms suggestive of colorectal cancer from 21 UK hospitals. Eligible patients were aged 55 years or older and regarded by their referring clinician as suitable for radiological investigation of the colon. Patients were randomly assigned (2:1) to BE or CTC by computer-generated random numbers, in blocks of six, stratified by trial centre and sex. We analysed the primary outcome-diagnosis of colorectal cancer or large (≥10 mm) polyps-by intention to treat. The trial is an International Standard Randomised Controlled Trial, number 95152621. FINDINGS: 3838 patients were randomly assigned to receive either BE (n=2553) or CTC (n=1285). 34 patients withdrew consent, leaving for analysis 2527 assigned to BE and 1277 assigned to CTC. The detection rate of colorectal cancer or large polyps was significantly higher in patients assigned to CTC than in those assigned to BE (93 [7.3%] of 1277 vs 141 [5.6%] of 2527, relative risk 1.31, 95% CI 1.01-1.68; p=0.0390). CTC missed three of 45 colorectal cancers and BE missed 12 of 85. The rate of additional colonic investigation was higher after CTC than after BE (283 [23.5%] of 1206 CTC patients had additional investigation vs 422 [18.3%] of 2300 BE patients; p=0.0003), due mainly to a higher polyp detection rate. Serious adverse events were rare. INTERPRETATION: CTC is a more sensitive test than BE. Our results suggest that CTC should be the preferred radiological test for patients with symptoms suggestive of colorectal cancer. FUNDING: NIHR Health Technology Assessment Programme, NIHR Biomedical Research Centres funding scheme, Cancer Research UK, EPSRC Multidisciplinary Assessment of Technology Centre for Healthcare, and NIHR Collaborations for Leadership in Applied Health Research and Care.

Computed tomographic colonography versus colonoscopy for investigation of patients with symptoms suggestive of colorectal cancer (SIGGAR): a multicentre randomised trial.

BACKGROUND: Colonoscopy is the gold-standard test for investigation of symptoms suggestive of colorectal cancer; computed tomographic colonography (CTC) is an alternative, less invasive test. However, additional investigation after CTC is needed to confirm suspected colonic lesions, and this is an important factor in establishing the feasibility of CTC as an alternative to colonoscopy. We aimed to compare rates of additional colonic investigation after CTC or colonoscopy for detection of colorectal cancer or large (≥10 mm) polyps in symptomatic patients in clinical practice. METHODS: This pragmatic multicentre randomised trial recruited patients with symptoms suggestive of colorectal cancer from 21 UK hospitals. Eligible patients were aged 55 years or older and regarded by their referring clinician as suitable for colonoscopy. Patients were randomly assigned (2:1) to colonoscopy or CTC by computer-generated random numbers, in blocks of six, stratified by trial centre and sex. We analysed the primary outcome-the rate of additional colonic investigation-by intention to treat. The trial is an International Standard Randomised Controlled Trial, number 95152621. FINDINGS: 1610 patients were randomly assigned to receive either colonoscopy (n=1072) or CTC (n=538). 30 patients withdrew consent, leaving for analysis 1047 assigned to colonoscopy and 533 assigned to CTC. 160 (30.0%) patients in the CTC group had additional colonic investigation compared with 86 (8.2%) in the colonoscopy group (relative risk 3.65, 95% CI 2.87-4.65; p<0.0001). Almost half the referrals after CTC were for small (<10 mm) polyps or clinical uncertainty, with low predictive value for large polyps or cancer. Detection rates of colorectal cancer or large polyps in the trial cohort were 11% for both procedures. CTC missed 1 of 29 colorectal cancers and colonoscopy missed none (of 55). Serious adverse events were rare. INTERPRETATION: Guidelines are needed to reduce the referral rate after CTC. For most patients, however, CTC provides a similarly sensitive, less invasive alternative to colonoscopy. FUNDING: NIHR Health Technology Assessment Programme, NIHR Biomedical Research Centres funding scheme, Cancer Research UK, EPSRC Multidisciplinary Assessment of Technology Centre for Healthcare, and NIHR Collaborations for Leadership in Applied Health Research and Care.

A diagnostic accuracy meta-analysis of endoanal ultrasound and MRI for perianal fistula assessment.

BACKGROUND: Imaging modalities such as endoanal ultrasound or MRI can be useful preoperative adjuncts before the appropriate surgical intervention for perianal fistulas. OBJECTIVES: We present a systematic review of published literature comparing endoanal ultrasound with MRI for the assessment of idiopathic and Crohn's perianal fistulas. DESIGN: A meta-analysis was performed to obtain pooled values for specificity and sensitivity. SETTINGS: Electronic databases were searched from January 1970 to October 2010 for published studies. PATIENTS AND INTERVENTIONS: Four studies were used in our analysis. There were 241 fistulas in the ultrasound group and 240 in the magnetic resonance group. RESULTS: The combined sensitivity and specificity of magnetic resonance for fistula detection were 0.87 (95% CI: 0.63-0.96) and 0.69 (95% CI: 0.51-0.82). There was a high degree of heterogeneity between studies reporting on MRI sensitivity (df = 3, I = 93%). This compares to a sensitivity and specificity for endoanal ultrasound of 0.87 (95% CI: 0.70-0.95) and 0.43 (95% CI: 0.21-0.69). There was a high degree of heterogeneity between studies reporting on endoanal ultrasound sensitivity (df = 3, I = 92%). CONCLUSIONS: From the available literature, the summarized performance characteristics for MRI and endoanal ultrasound demonstrate comparable sensitivities at detecting perianal fistulas, although the specificity for MRI was higher than that for endoanal ultrasound. Both specificity values are considered to be diagnostically poor, however. The high degree of data heterogeneity and the shortage of applicable studies precludes any firm conclusions being made for clinical practice. Future trials with improved study design (including prospective data collection and consideration of verification bias) may help to further clarify the role of MRI in the assessment and treatment response monitoring of perianal fistulas (particularly in patients with Crohn's disease).

Computed tomographic colonography: assessment of radiologist performance with and without computer-aided detection.

BACKGROUND & AIMS: In isolation, computer-aided detection (CAD) for computed tomographic (CT) colonography is as effective as optical colonoscopy for detection of significant adenomas. However, the unavoidable interaction between CAD and the reader has not been addressed. METHODS: Ten readers trained in CT but without special expertise in colonography interpreted CT colonography images of 107 patients (60 with 142 polyps), first without CAD and then with CAD after temporal separation of 2 months. Per-patient and per-polyp detection were determined by comparing responses with known patient status. RESULTS: With CAD, 41 (68%; 95% confidence interval [CI], 55%-80%) of the 60 patients with polyps were identified more frequently by readers. Per-patient sensitivity increased significantly in 70% of readers, while specificity dropped significantly in only one. Polyp detection increased significantly with CAD; on average, 12 more polyps were detected by each reader (9.1%, 95% CI, 5.2%-12.8%). Small- (< or =5 mm) and medium-sized (6-9 mm) polyps were significantly more likely to be detected when prompted correctly by CAD. However, overall performance was relatively poor; even with CAD, on average readers detected only 10 polyps (51.0%) > or =10 mm and 24 (38.2%) > or =6 mm. Interpretation time was shortened significantly with CAD: by 1.9 minutes (95% CI, 1.4-2.4 minutes) for patients with polyps and by 2.9 minutes (95% CI, 2.5-3.3 minutes) for patients without. Overall, 9 readers (90%) benefited significantly from CAD, either by increased sensitivity and/or by reduced interpretation time. CONCLUSIONS: CAD for CT colonography significantly increases per-patient and per-polyp detection and significantly reduces interpretation times but cannot substitute for adequate training.