Andrew Plumb

Global Small Bowel Motility: Assessment with Dynamic MR Imaging

PURPOSE To assess the repeatability in human volunteers of software-quantified small bowel motility captured with magnetic resonance (MR) imaging and to test the ability to detect changes in motility induced by pharmacologic agents. MATERIALS AND METHODS The study was approved by the Royal Free Research Ethics Committee, and all subjects gave full written informed consent. Twenty-one healthy volunteers (14 men, seven women; mean age, 28 years) underwent cine MR imaging with a three-dimensional balanced turbo field-echo sequence to capture small bowel motility. Volume blocks (15 cm thick) were acquired every second during a 20-second breath hold. A randomized, blinded, placebo-controlled crossover study of either 0.5 mg neostigmine or saline (n = 11) or 20 mg intravenous butylscopolamine or saline (n = 10) was performed with motility MR imaging at baseline and repeated at a mean of 4 weeks (range, 2-7 weeks). Two readers independently drew regions of interest around the small bowel, and motility was quantified by using a registration algorithm that provided a global motility metric in arbitrary units. Repeatability of the motility measurements at baseline was assessed by using Bland-Altman and within-subject coefficient of variation measures. Changes in mean motility measurements after drug administration were compared with those after placebo administration by using paired t testing. RESULTS The repeatability between baseline measurements of motility was high; the Bland-Altman mean difference was -0.0025 (range, 0.28-0.4), the 95% limit of agreement was ±0.044 arbitrary units (au), and the within-subject coefficient of variation was 4.9%. Measured motility with neostigmine (mean, 0.39 au) was significantly higher than that with placebo (mean, 0.34 au; P < .001), whereas that with butylscopolamine (mean, 0.13 au) was significantly lower than that with placebo (mean, 0.30 au; P < .001). CONCLUSION Quantification of small bowel motility with use of MR imaging in healthy volunteers is repeatable and sensitive to changes induced by means of pharmacologic manipulation. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13130151/-/DC1.

Clinical indications for computed tomographic colonography: European Society of Gastrointestinal Endoscopy (ESGE) and European Society of Gastrointestinal and Abdominal Radiology (ESGAR) Guideline

This is an official guideline of the European Society of Gastrointestinal Endoscopy (ESGE) and the European Society of Gastrointestinal and Abdominal Radiology (ESGAR). It addresses the clinical indications for the use of computed tomographic colonography (CTC). A targeted literature search was performed to evaluate the evidence supporting the use of CTC. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) system was adopted to define the strength of recommendations and the quality of evidence. Main recommendations 1 ESGE/ESGAR recommend computed tomographic colonography (CTC) as the radiological examination of choice for the diagnosis of colorectal neoplasia. ESGE/ESGAR do not recommend barium enema in this setting (strong recommendation, high quality evidence). 2 ESGE/ESGAR recommend CTC, preferably the same or next day, if colonoscopy is incomplete. Delay of CTC should be considered following endoscopic resection. In the case of obstructing colorectal cancer, preoperative contrast-enhanced CTC may also allow location or staging of malignant lesions (strong recommendation, moderate quality evidence). 3 When endoscopy is contraindicated or not possible, ESGE/ESGAR recommend CTC as an acceptable and equally sensitive alternative for patients with symptoms suggestive of colorectal cancer (strong recommendation, high quality evidence). 4 ESGE/ESGAR recommend referral for endoscopic polypectomy in patients with at least one polyp  ≥  6  mm in diameter detected at CTC. CTC surveillance may be clinically considered if patients do not undergo polypectomy (strong recommendation, moderate quality evidence). 5 ESGE/ESGAR do not recommend CTC as a primary test for population screening or in individuals with a positive first-degree family history of colorectal cancer (CRC). However, it may be proposed as a CRC screening test on an individual basis providing the screenee is adequately informed about test characteristics, benefits, and risks (weak recommendation, moderate quality evidence).

Imaging of Anal Carcinoma

OBJECTIVE The purpose of this article is to review the role of imaging in the management of patients with anal cancer. The relevant anatomy, imaging techniques, and interpretation of images of patients before and after therapy will be discussed. CONCLUSION Anal carcinomas are uncommon but increasing in frequency. Radiologists must recognize typical patterns of disease at initial evaluation, posttherapy appearances, and when to suspect residual or recurrent disease to guide clinicians and achieve optimal patient outcome.

Magnetic resonance imaging-quantified small bowel motility is a sensitive marker of response to medical therapy in Crohn's disease

Magnetic resonance enterography (MRE) can measure small bowel motility, reduction in which reflects inflammatory burden in Crohns Disease (CD). However, it is unknown if motility improves with successful treatment.

Detection of Extracolonic Pathologic Findings with CT Colonography: A Discrete Choice Experiment of Perceived Benefits versus Harms

PURPOSE To determine the maximum rate of false-positive diagnoses that patients and health care professionals were willing to accept in exchange for detection of extracolonic malignancy by using computed tomographic (CT) colonography for colorectal cancer screening. MATERIALS AND METHODS After obtaining ethical approval and informed consent, 52 patients and 50 health care professionals undertook two discrete choice experiments where they chose between unrestricted CT colonography that examined intra- and extracolonic organs or CT colonography restricted to the colon, across different scenarios. The first experiment detected one extracolonic malignancy per 600 cases with a false-positive rate varying across scenarios from 0% to 99.8%. One experiment examined radiologic follow-up generated by false-positive diagnoses while the other examined invasive follow-up. Intracolonic performance was identical for both tests. The median tipping point (maximum acceptable false-positive rate for extracolonic findings) was calculated overall and for both groups by bootstrap analysis. RESULTS The median tipping point for radiologic follow-up occurred at a false-positive rate greater than 99.8% (interquartile ratio [IQR], 10 to >99.8%). Participants would tolerate at least a 99.8% rate of unnecessary radiologic tests to detect an additional extracolonic malignancy. The median tipping-point for invasive follow-up occurred at a false-positive rate of 10% (IQR, 2 to >99.8%). Tipping points were significantly higher for patients than for health care professionals for both experiments (>99.8 vs 40% for radiologic follow-up and >99.8 vs 5% for invasive follow-up, both P < .001). CONCLUSION Patients and health care professionals are willing to tolerate high rates of false-positive diagnoses with CT colonography in exchange for diagnosis of extracolonic malignancy. The actual specificity of screening CT colonography for extracolonic findings in clinical practice is likely to be highly acceptable to both patients and health care professionals. Online supplemental material is available for this article.

Use of CT colonography in the English Bowel Cancer Screening Programme

Objective To examine use of CT colonography (CTC) in the English Bowel Cancer Screening Programme (BCSP) and investigate detection rates. Design Retrospective analysis of routinely coded BCSP data. Guaiac faecal occult blood test (gFOBt)-positive screenees undergoing CTC from June 2006 to July 2012 as their first-line colonic investigation were included. Abnormalities found at CTC, subsequent polyp, adenoma and cancer detection and positive predictive value (PPV) were calculated. Detection rates were compared with those observed in gFOBt-positive screenees investigated by colonoscopy. Multilevel logistic regression was used to examine factors associated with variable detection. Results 2731 screenees underwent CTC. Colorectal cancer (CRC) or polyps were suspected in 1027 individuals (37.6%; 95% CI 33.8% to 41.4%); 911 of these underwent confirmatory testing. 124 screenees had CRC (4.5%) and 533 had polyps (19.5%), 468 adenomatous (17.1%). Overall detection was 24.1% (95% CI 21.5% to 26.6%) for CRC or polyps and 21.7% (95% CI 19.2% to 24.1%) for CRC or adenoma. Advanced neoplasia was detected in 504 screenees (18.5%; 95% CI 16.1% to 20.8%). PPV for CRC or polyp was 72.1% (95% CI 66.6% to 77.6%). By comparison, 9.0% of 72 817 screenees undergoing colonoscopy had cancer and 50.6% had polyps; advanced neoplasia was detected in 32.7%. CTC detection rates and PPV were higher at centres with experienced radiologists (>1000 examinations) and at high-volume centres (>175 cases/radiologist/annum). Centres using three-dimensional interpretation detected more neoplasia. Conclusions In the BCSP, detection rates after positive gFOBt are lower for CTC than colonoscopy, although populations undergoing the two tests are different. Centres with more experienced radiologists have higher detection and accuracy. Rigorous quality assurance of BCSP radiology is needed.

CT colonography in the English Bowel Cancer Screening Programme: National survey of current practice

AIM To obtain information regarding the provision of computed tomography colonography (CTC) services to the National Health Service (NHS) Bowel Cancer Screening Programme (BCSP). MATERIALS AND METHODS Specialist screening practitioners at the 58 BCSP screening centres and lead BCSP radiologists at 110 hospitals performing CTC for the Programme were contacted and completed a semi-structured questionnaire administered by telephone. Responses were collated and descriptive statistics derived. RESULTS One hundred and seven (98%) SSPs and 103 (94%) radiologists were surveyed. All screening centres had access to CTC at 110 hospital sites. All sites used CTC for failed or contraindicated colonoscopy, 24% used it for patients taking anticoagulants, and 17% for those with fear of colonoscopy. Patient preference was not an indication at any site. Multidetector CT (100%), carbon dioxide insufflators (94%), and CTC software (95%) were almost universal. Ninety-one percent of radiographers and 98% of radiologists were trained in CTC image acquisition and interpretation, respectively. Seventy-five percent of the radiologists were gastrointestinal subspecialists and two-thirds had interpreted more than 300 examinations in clinical practice, although 5% had interpreted fewer than 100. Eighty-one percent of radiologists favoured some form of accreditation for CTC interpretation. CONCLUSIONS CTC is widely available to the BCSP. Appropriate hardware and software is almost ubiquitous. Most radiographers and radiologists offering CTC to the BCSP have received specific training. Formal service evaluation is patchy. The majority of radiologists would welcome national accreditation for CTC.

Public perceptions and preferences for CT colonography or colonoscopy in colorectal cancer screening

OBJECTIVES To examine public perceptions of and preferences for colonoscopy vs. CT colonography (CTC) as technologies for colorectal cancer (CRC) screening. METHODS Six discussion groups were carried out with 30 adults aged 49-60 years (60% female). Information about different aspects of the tests (e.g. sensitivity, practical issues) was presented sequentially using a semi-structured, step-by-step topic guide. Discussions were recorded and analyzed using framework analysis. RESULTS CTC was favored on the parameters of invasiveness, extra-colonic evaluation and interference with daily life, whereas sensitivity, avoiding false-positives and the capacity to remove polyps immediately were perceived to be important advantages of colonoscopy. Ultimately, there was no strong preference for either test: with 46% preferring colonoscopy vs. 42% for CTC. CONCLUSION With comprehensive information, colonoscopy and CTC were seen as having different advantages and disadvantages, yielding no clear preferences between the two. The sensitivity of colonoscopy was a decisive factor for some people, but the lower invasiveness of CTC was seen as an asset in the screening context. PRACTICE IMPLICATIONS CTC may be an acceptable alternative to colonoscopy in CRC screening. Healthcare professionals working in the screening context should be sensitive to the range of characteristics that can determine preferences for CRC screening tests.

From medical imaging data to 3D printed anatomical models

Anatomical models are important training and teaching tools in the clinical environment and are routinely used in medical imaging research. Advances in segmentation algorithms and increased availability of three-dimensional (3D) printers have made it possible to create cost-efficient patient-specific models without expert knowledge. We introduce a general workflow that can be used to convert volumetric medical imaging data (as generated by Computer Tomography (CT)) to 3D printed physical models. This process is broken up into three steps: image segmentation, mesh refinement and 3D printing. To lower the barrier to entry and provide the best options when aiming to 3D print an anatomical model from medical images, we provide an overview of relevant free and open-source image segmentation tools as well as 3D printing technologies. We demonstrate the utility of this streamlined workflow by creating models of ribs, liver, and lung using a Fused Deposition Modelling 3D printer.

The challenge of segmental small bowel motility quantitation using MR enterography

Objective: Analysis of “cine” MRI using segmental regions of interest (ROIs) has become increasingly popular for investigating bowel motility; however, variation in motility in healthy subjects both within and between scans remains poorly described. Methods: 20 healthy individuals (mean age, 28 years; 14, males) underwent MR enterography to acquire dynamic motility scans in both breath hold (BH) and free breathing (FB) on 2 occasions. Motility data were quantitatively assessed by placing four ROIs per subject in different small bowel segments and applying two measures: (1) contractions per minute (CPM) and (2) Jacobian standard deviation (SD) motility score. Within-scan (between segment) variation was assessed using intraclass correlation (ICC), and repeatability was assessed using Bland–Altman limits of agreement (BA LoA). Results: Within-scan segmental variation: BH CPM and Jacobian SD metrics between the four segments demonstrated ICC R = 0.06, p = 0.100 and R = 0.20, p = 0.027 and in FB, the CPM and Jacobian SD metrics demonstrated ICC R = −0.26, p = 0.050 and R = 0.19, p = 0.030. Repeatability: BH CPM for matched segments ranged between 0 and 14 contractions with BA LoA of ±8.36 and Jacobian SD ranged between 0.09 and 0.51 with LoA of ±0.33. In FB data, CPM ranged between 0 and 10 contractions with BA LoA of ±7.25 and Jacobian SD ranged between 0.16 and 0.63 with LoA = ±0.28. Conclusion: The MRI-quantified small bowel motility in normal subjects demonstrates wide intersegmental variation and relatively poor repeatability over time. Advances in knowledge: This article presents baseline values for healthy individuals of within- and between-scan motility that are essential for understanding how this process changes in disease.