CT colonography practice in the UK: a national survey

doi:10.1016/j.crad.2003.09.008

Clinical Radiology

Volume 59, Issue 1, January 2004, Pages 39-43

https://doi.org/10.1016/j.crad.2003.09.008 Get rights and content

Abstract

AIM: To determine the provision of computed tomography (CT) colonography in UK radiology departments.

MATERIALS AND METHODS: A questionnaire relating to the availability of CT colonography, barriers to implementation, clinical indications, technique, and practitioners was posted to clinical directors of UK radiology departments.

RESULTS: One hundred and thirty-eight departments responded. Fifty (36%) offered CT colonography in day-to-day clinical practice. Of those that did not, 68 of 87 (64%) cited limited scanner capacity as the main barrier. Of the 50 departments offering a service, 39 (78%) offered CT after incomplete colonoscopy, 36 (72%), after failed barium enema, and 37 (74%) as an alternative to barium enema. Of those offering a service, the number of studies performed varied between one per month (38%) to more than one per day (8%). Total experience varied between 20 or fewer studies (28%) to more than 300 (12%). Full bowel preparation was common (92%), as was dual positioning (90%). Colonography was interpreted by radiologists with a subspecialty interest in gastrointestinal imaging in 64% of centres offering a service.

CONCLUSION: CT colonography is widely available in the UK, with approximately one-third of responders offering a service. Experience and throughput varies considerably. Limited CT scanner capacity is the major barrier to further dissemination.

Introduction

Computed tomography (CT) colonography (“virtual colonoscopy”) was first described in 1994¹ and has subsequently emerged as a robust technique for the detection of colon cancer and its precursor, the adenomatous polyp. It allows a rapid and complete colorectal examination with sensitivities and specificities that approach conventional colonoscopy2., 3., 4. while being both safer and more acceptable to patients.5., 6., 7. CT colonography has become widely disseminated in the USA, where it is promoted as a screening test for adenomatous polyps whereas in the UK the emphasis is more on detection of symptomatic colorectal cancer.

CT colonography is a relatively new technique, and there are several potential barriers to implementation both generally and in the United Kingdom. Critics cite the lack of randomized evidence supporting its use either for screening or symptomatic patients. CT scanner capacity is limited in the United Kingdom, and furthermore, it is generally accepted that CT colonography is both difficult to interpret and time-consuming. The precise technique employed also varies widely. However, it has attracted a great deal of professional and public attention with the result that there is considerable pressure on departments to provide it on a day-to-day basis. In the face of this, we aimed to determine the availability of CT colonography in the UK NHS, the technical parameters used, the number of examinations performed, by whom, and their experience.

Section snippets

Materials and methods

The Royal College of Radiologists database of UK departments of radiology was used to identify 236 departments of which 216 offered an adult gastrointestinal radiological service. A short questionnaire was addressed to the clinical director (or lead gastrointestinal radiologist if known) of these 216 departments and mailed in February 2003 along with a stamped, addressed envelope for reply. The questionnaire was designed so that it could be completed rapidly and without free text. It was

Results

Of the 138 departments who replied, 137 had a CT scanner, of which 74 (54%) were multi-detector row, and 81 (59%) had CT colonography software. Fifty (36%) offered CT colonography in day-to-day clinical practice. Of the 87 (64%) that did not, scanner capacity limited by competing clinical demands was the most frequent reason cited for non-implementation (68 of 87; 78%). Lack of radiological training or expertise in the technique was cited by 50 (57%) and financial restrictions by 38 (44%).

Discussion

There are several potential barriers to the widespread adoption of CT colonography in the UK. In the USA, the technique is extensively promoted as an effective screening tool for colorectal polyps whereas in the UK healthcare is primarily a national government responsibility and their agencies require randomized evidence of efficacy before implementation. In any event, limited CT scanner capacity effectively prevents CT screening in the UK at present.

However, symptomatic colorectal cancer is a

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Cited by (35)

Implementation of a new CT colonography service: 5 Year experience
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Citation Excerpt :
This patient was well and discharged after 3 h. CTC was first described in 1994,16 and in the UK has been mainly used in older symptomatic patients.1–3 There is a large body of peer-reviewed research relating to CTC technique and performance, but a paucity scrutinizing diagnostic performance in daily practice or describing how a CTC service changes over time.
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.
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.
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.
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 in the English Bowel Cancer Screening Programme: National survey of current practice
2013, Clinical Radiology
Citation Excerpt :
In terms of experience, radiologists broadly fell into one of three groups of approximately equal size: those who had interpreted fewer than 300 cases, those who had interpreted 300–999 cases, and those with experience of >1000 cases. There has been a clear increase in average experience of CTC in the UK since 2004, when only 12% of departments had performed more than 300 studies in total19; 67% of radiologists in this survey had interpreted more than 300 studies. Although the majority appeared to have adequate training and experience, there was a small number who were less experienced: 5% of radiologists interpreting CTC in the BCSP had interpreted fewer than 100 cases; for mammographic screening, 5000 cases per annum must be reported.20
To obtain information regarding the provision of computed tomography colonography (CTC) services to the National Health Service (NHS) Bowel Cancer Screening Programme (BCSP).
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.
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.
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.
CT colonography: Who attends training? A survey of participants at educational workshops
2011, Clinical Radiology
Citation Excerpt :
Consequently, CTC is currently disseminating widely into clinical practice, both in Europe4,5 and the USA.6 For example, a survey from the UK revealed that over one-third of National Health Service (NHS) hospitals were providing a CTC service.5 It is now well recognized that CTC is difficult and time-consuming to interpret, at least initially, because data display is more complex than that used for standard abdomino-pelvic CT and the interpretive task (for example, searching for small polyps) is more tedious.
To obtain information regarding the demographics of attendees of computed tomography colonography (CTC) training workshops organized by the European Society of Gastrointestinal and Abdominal Radiology (ESGAR), in particular their prior expertise and current practice.
Attendees at five CTC training workshops conducted in Edinburgh (UK), Malmo (Sweden), Amsterdam (Netherlands), Pisa and Stresa (Italy) between February 2007 and April 2010 completed an online questionnaire. Responses were collated and descriptive statistics produced.
Three hundred and forty-eight delegates responded; a response rate of 73%. There was wide geographical variability encompassing 20 European member-states and seven countries outside Europe. The overwhelming majority were radiologists (336; 97%). Of the respondents, 299 (86%) were already interpreting CTC in clinical practice but of these, 158 (54%) had no prior formal training in CTC whereas 21 (8%) had attended a previous workshop. Furthermore, of those reporting CTC, 227 (76%) had interpreted fewer than 50 cases.
Despite political imperatives for other groups to interpret CTC, the vast majority of those attending training are radiologists. Worryingly, a significant proportion of these are apparently reporting CTC in clinical practice without adequate training.
CT colonography training for radiographers-a formal evaluation
2010, Clinical Radiology
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.
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.
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 (>10 mm) detection rates also improved significantly from 49% to 60%, p = 0.002.
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.
Audit of the introduction of CT colonography for detection of colorectal carcinoma in a non-academic environment and its implications for the national bowel cancer screening programme
2009, Clinical Radiology
To compare the sensitivity of double-contrast barium enema (DCBE) with computed tomography colonography (CTC) to determine whether CTC is superior for the detection of colorectal cancer (CRC) locally, and to compare the results to those of a national barium enema audit.
All patients undergoing diagnostic DCBE or CTC between January 2003 and December 2005 were identified from the picture archiving communication system (PACS). Patients with a confirmed diagnosis of CRC were identified from the local cancer registry. Patients who were not diagnosed as having CRC on imaging were assumed true negatives if they were not listed in the cancer registry by December 2007, giving a minimum of 2 years follow-up. DCBE and CTC reports of all patients with CRC were analysed, and cancer detection was considered to have occurred (positive test result) if the report stated the definite presence of CRC or possible CRC requiring further investigation.
2520 DCBEs and 604 CTCs were included. Twenty-one of 33 patients with CRC were detected using DCBE (incidence 1.31%, sensitivity 63.7%). Thirty-two of 33 patients with CRC were -detected using CTC (incidence 5.46%, sensitivity 97.7%).
CTC is more sensitive for the detection of CRC, and its introduction in a district general hospital is justified. However, there has been a consequent decline in DCBE sensitivity, which, if reflected nationally, suggests CTC is the preferential screening test for CRC.
Virtual colonoscopy: effect of computer-assisted detection (CAD) on radiographer performance
2008, Clinical Radiology
To investigate the effect of a virtual colonoscopy (VC) computed-assisted detection (CAD) system on polyp detection by trained radiographers.
Four radiographers trained in VC interpretation and utilization of CAD systems read a total of 62 endoscopically validated VC examinations containing 150 polyps (size range 5–50 mm) in four sessions, recording any polyps found and the examination interpretation time, first without and then with the addition of CAD as a “second reader”. After a temporal separation of 6 weeks to reduce recall bias, VC examinations were re-read using “concurrent reader” CAD. Interpretation times, polyp detection, and number of false-positives were compared between the different reader paradigms using paired t and paired exact tests.
Overall, use of “second reader” CAD significantly improved polyp detection by 12% (p < 0.001, CI 6%,17%)) from 48 to 60%. There was no significant improvement using CAD as a concurrent reader (p = 0.20; difference of 7%, CI −3%, 16%) and no significant overall difference in recorded false-positives with second reader or concurrent CAD paradigms compared with unassisted reading (p = 0.25 and 0.65, respectively). The mean interpretation time was 21.7 min for unassisted reading, 29.6 (p < 0.001) min for second reader and 19.1 min (p = 0.12) for concurrent reading paradigms.
CAD, when used as a second reader, can significantly improve radiographer reading performance with only a moderate increase in interpretation times.

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View full text

CT colonography practice in the UK: a national survey

Abstract

Introduction

Section snippets

Materials and methods

Results

Discussion

Am J Gastroenterol

Clin Radiol

Clin Radiol

Clin Radiol

Non-invasive colonoscopy using helical CT scanning, 3D reconstruction, and virtual reality

Colorectal neoplasia: performance characteristics of CT colonography for detection in 300 patients

Radiology

Optimization of CT colonography technique: prospective trial in 180 patients

Radiology

A comparison of virtual and conventional colonoscopy for the detection of colorectal polyps

N Engl J Med