Original article
ACR Colon Cancer Committee White Paper: Status of CT Colonography 2009

https://doi.org/10.1016/j.jacr.2009.09.007Get rights and content

Purpose

To review the current status and rationale of the updated ACR practice guidelines for CT colonography (CTC).

Methods

Clinical validation trials in both the United States and Europe are reviewed. Key technical aspects of the CTC examination are emphasized, including low-dose protocols, proper insufflation, and bowel preparation. Important issues of implementation are discussed, including training and certification, definition of the target lesion, reporting of colonic and extracolonic findings, quality metrics, reimbursement, and cost-effectiveness.

Results

Successful validation trials in screening cohorts both in the United States with ACRIN® and in Germany demonstrated sensitivity ≥90% for patients with polyps >10 mm. Proper technique is critical, including low-dose techniques in screening cohorts, with an upper limit of the CT dose index by volume of 12.5 mGy per examination. Training new readers includes the requirement of interactive workstation training with 2-D and 3-D image display techniques. The target lesion is defined as a polyp ≥6 mm, consistent with the American Cancer Society joint guidelines. Five quality metrics have been defined for CTC, with pilot data entered. Although the CMS national noncoverage decision in May 2009 was a disappointment, multiple third-party payers are reimbursing for screening CTC. Cost-effective modeling has shown CTC to be a dominant strategy, including in a Medicare cohort.

Conclusion

Supported by third-party payer reimbursement for screening, CTC will continue to further transition into community practice and can provide an important adjunctive examination for colorectal screening.

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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