Original articleACR Colon Cancer Committee White Paper: Status of CT Colonography 2009
Introduction
CT colonography (CTC), also referred to as virtual colonoscopy, has attracted multidisciplinary attention as a minimally invasive structural evaluation of the entire colon and rectum for the detection of polyps and cancers. Colorectal cancer (CRC) remains the second leading cause of cancer-related deaths in the United States, with nearly 150,000 new cases each year [1]. It is estimated that 60% of CRC deaths could be prevented if all individuals aged ≥50 years underwent CRC screening [2]. Currently, only 57% of adults aged ≥50 years adhere to current colorectal screening guidelines [3]. CTC holds the potential to improve compliance for CRC screening and to select patients who would benefit from therapeutic colonoscopy [4, 5].
Since the introduction of CTC in the mid-1990s, rapid technological evolution has occurred, including improvements in patient preparation, image acquisition, advanced 3-D image display techniques, and computer-aided diagnosis. Continued efforts in simplifying and minimizing the bowel preparation are essential to CTC's success and may improve more widespread compliance. Extensive studies have been performed on numerous technical aspects of the examination and its clinical validation in different patient cohorts. After 2008, with the successful completion of the largest screening trial (the National CT Colonography Trial), along with the endorsement of CTC by the American Cancer Society and multidisciplinary societies as an acceptable screening test for CRC [6], the time has now come to transition CTC from research investigation at academic centers to clinical implementation in community practice. Although the CMS national noncoverage decision for screening CTC in May 2009 was disappointing, reimbursement by multiple private payers has allowed screening efforts using CTC to continue to grow. The ACR updated its 2005 guidelines in October 2009 for the performance of CTC [7, 8]. The purpose of this white paper position statement by the ACR Colon Cancer Committee is to review the current status of and rationale for these guidelines, discussed in the following sections.
Section snippets
CRC Screening and Detection
The clinical validation of the diagnostic accuracy of CTC for polyp detection has relied largely on the reference standard of optical colonoscopy (OC). During the rapid technological development of CTC, there were early mixed results in clinical trials, evaluating a range of patient cohorts (eg, largely symptomatic [9, 10, 11, 12, 13], surveillance [14, 15], screening [16]) and using various techniques that improved over time. Early single-center clinical trials of CTC often involved small,
Part II: Training and Certification
Training in CTC should be comprehensive and not only encompass examination interpretation but also provide instruction on examination indications and contraindications, patient preparation, CT acquisition, and quality assurance programs. Supplementary Table 3 (available online) summarizes the key aspects of training requirements.
Several large prospective studies have demonstrated significant interobserver variability among radiologists interpreting CT colonographic examinations [11, 12, 97],
Part III: Conclusions and Recommendations
In terms of the detection of advanced neoplasia, which is the primary goal of CRC screening and prevention, CTC is comparable with OC when state-of-the-art techniques are applied. Given the rapid ongoing evolution of this novel screening technique, the performance characteristics should continue to improve. Furthermore, because CTC is less invasive, leads to fewer complications, and is less costly than OC, it may serve as an effective adjunct to colonoscopy for screening average-risk,
Acknowledgments
We would like to recognize the dedicated efforts for CT colonography by many of the ACR leaders and staff, including Richard Duszak Jr, MD, Daniel Picus, MD, Bibb Allen Jr, MD, Diane Hayek, Joyce Kidwell, and Anita McGlothin. We would also like to thank Kris Nunez for her extensive help with the assembly of this manuscript.
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