Meeting the new joint British Society of Gastrointestinal and Abdominal Radiology and Royal College of Radiologists CT colonography standards: a 6-year experience.

AIM: To audit the performance of computed tomography colonography (CTC) at St Mark's Hospital against the joint British Society of Gastrointestinal and Abdominal Radiology (BSGAR) and Royal College of Radiologists (RCR) standards. MATERIALS AND METHODS: A retrospective audit of all CTC studies between January 2012 to December 2017 was performed against the BSGAR/RCR standards along with additional data outwith the guidelines. Evidence was obtained from a central database, radiology information systems (RISs), picture archiving and communication systems (PACSs), and electronic patient records (EPRs). RESULTS: Over the 6 years, 13,143 CTCs were performed and 12,996 (99%) were adequate or better. Of the cases 1,867 had a >6 mm polyp or cancer reported (polyp identification rate [PIR] 14%) and the positive predictive value (PPV) was 93% (1,148/1,240). Median radiation dose was 458 mGy·cm, mean additional acquisition rate was 19% (2,505/13,143), subsequent endoscopy rate was 9% (1,222/13,143) and mean interpretation time for a negative study was 34.6 minutes. Nine perforations occurred (perforation rate of 0.068%) and one was symptomatic (symptomatic perforation rate of 0.008%). For suspected cancers, the same-day endoscopy rate was 27% (96/360) and same-day staging rate was 76% (272/360). Post-imaging colorectal cancer rates (PICRC) was 3.06 per 100 cancers detected and 0.23 per 1,000 CTCs. The service was always rated "good" or higher by patients. CONCLUSION: This audit shows the CTC service at St Mark's Hospital to be safe and of sufficiently high quality to meet the BSGAR/RCR standards with most outcomes equal to or above the aspirational target. Areas for service and individual reader improvement were also identified.

Implementation of a new CT colonography service: 5 year experience.

AIM: To describe our experience using a 5 year audit of computed tomography colonography (CTC) practice and identify factors that influence diagnostic performance to guide implementation in other centres. MATERIAL AND METHODS: Consecutive patients referred for CTC at a single institution over a 5 year period were identified, and reporting rates and positive predictive value (PPV) calculated for small polyps, large polyps, and colorectal cancer. Diagnostic performance was compared using the Chi-squared test, and trends over time were examined with logistic regression. The effect of faecal tagging and an intravenous spasmolytic were investigated using Fisher's exact test. RESULTS: In total, 4355 CTC examinations were performed. Overall reporting rates and PPV were 17% and 92%, respectively. Negative predictive value (NPV) for cancer was 99.9%. A significant decrease in reporting rate (p < 0.001) was accompanied by an increase in PPV for small polyps (p = 0.02) following the introduction of faecal tagging. Adequacy rates for CTC improved over time (96% to 99%), with improved adequacy rates when using a spasmolytic, 98% versus 96% without. A significant difference in reporting rates, but not PPV, was found between radiologists. CONCLUSION: Accurate colonic investigation using CTC can be delivered safely to a high-risk patient population at a single centre. Faecal tagging and an intravenous spasmolytic improve diagnostic performance.

CT colonography training for radiographers--a formal evaluation.

AIMS: To evaluate the efficacy of a new intensive "hands-on" course designed to train small teams of radiographers in computed tomography colonography (CTC) technique and initial interpretation for patient triage. MATERIALS AND METHODS: The course comprised small-group lectures, active participation in the daily CTC service with practical technique and image interpretation training by experienced radiologists and radiographers. Evaluation was by assessment of knowledge using randomized sets of multiple choice questions (MCQ; pre/post-course), practical technique using checklists and expert global scores, and interpretation performance outcomes using randomized pre/post-course test datasets (five validated CTC examinations each). Paired t-tests were used to investigate change in performance for MCQ score and interpretation accuracy. RESULTS: Thirteen courses with 49 participants were evaluated over 2 years. Practical skills were high, with mean (SD) checklist scores of 14/15 (0.85) and global scores of 26/30 (2.3). MCQ scores increased significantly from a mean of 59% pre-course to 69% post-course, p<0.001. Correct classification of CTC examination improved significantly from a mean of 55% pre-course to 71% post-course, p<0.001. Cancer and large polyp (>10mm) detection rates also improved significantly from 49% to 60%, p=0.002. CONCLUSION: Structured training in CTC can significantly improve knowledge and interpretation skills of radiographers, while assessing safe procedural performance. Implementation of similar programmes nationally may help reduce performance gaps between centres.

CT colonography: accuracy of initial interpretation by radiographers in routine clinical practice.

AIM: To investigate performance of computed-assisted detection (CAD)-assisted radiographers interpreting computed tomography colonography (CTC) in routine practice. MATERIALS AND METHODS: Three hundred and three consecutive symptomatic patients underwent CTC. Examinations were double-read by trained radiographers using primary two-dimensional/three-dimensional (2D/3D) analysis supplemented by "second reader" CAD. Radiographers recorded colonic neoplasia, interpretation times, and patient management strategy code (S0, inadequate; S1, normal; S2, 6-9 mm polyp; S3, > or = 10 mm polyp; S4, cancer; S5, diverticular stricture) for each examination. Strategies were compared to the reference standard using kappa statistic, interpretation times using paired t-test, learning curves using logistic regression and Pearson's correlation coefficient. RESULTS: Of 303 examinations, 69 (23%) were abnormal. CAD-assisted radiographers detected 17/17 (100%) cancers, 21/28 (72%) polyps > or = 10 mm and 42/60 (70%) 6-9 mm polyps. The overall agreement between radiographers and the reference management strategy was good (kappa 0.72; CI: 0.65, 0.78) with agreement for S1 strategy in 189/211 (90%) exams; S2 in 19/27 (70%); S3 in 12/19 (63%); S4 in 17/17 (100%); S5 in 5/6 (83%). The mean interpretation time was 17 min (SD = 11) compared with 8 min (SD = 3.5) for radiologists. There was no learning curve for recording correct strategies (OR 0.88; p = 0.12) but a significant reduction in interpretation times, mean 14 and 31 min (last/first 50 exams; -0.46; p < 0.001). CONCLUSION: Routine CTC interpretation by radiographers is effective for initial triage of patients with cancer, but independent reporting is currently not recommended.