A major revamp of virtual colonoscopy practice guidelines has been published in a white paper by the Reston, VA-based American College of Radiology (ACR). The update, the first since the ACR Colon Cancer Committee's guidelines debuted in 2005, will affect virtually every aspect of VC practice, from insufflation to radiation dose to training.
At last month's 10th International Symposium on Virtual Colonoscopy, panel member Dr. Judy Yee from the University of California, San Francisco (UCSF) discussed the practice guideline changes that have emerged in response to the maturation and improvement in VC (also known as CT colonography or CTC) technology and practice.
A lot has happened to VC practice in four years, most importantly in research. Multicenter trials screening thousands of patients in the U.S. and Germany have shown a 90% or greater sensitivity for clinically significant polyps 1 cm and larger. But proper training and technique are still critical to achieving these results, as emphasized in the new white paper, and low radiation doses have been highlighted as central to patient care.
In addition, this year, for the first time, detailed data resulting from CTC exams are being comprehensively tracked in a national data registry that will benefit individual providers, while compiling national performance data on a large scale.
"The new ACR practice guidelines, the quality metrics developed for CTC, have been rolled into the National Radiology Data Registry," said Yee, who is professor and vice chair of radiology at UCSF and chief of radiology at the San Francisco Veterans Affairs Medical Center. "Hopefully, this will play an important role in helping [the Centers for Medicare and Medicaid Services (CMS)] cover CTC via Coverage with Evidence Development."
Coverage with Evidence Development (CED) status would permit Medicare reimbursement for screening while further data are being gathered on the efficacy of virtual colonoscopy screening -- despite CMS' May 12, 2009, rejection of the more comprehensive National Coverage Determination that would have mandated VC coverage on a more permanent basis.
Major update
The ACR's colorectal cancer committee "performed a major revision of practice guidelines for the performance of CTC in adults," Yee said, outlining its major changes.
The four principal indications for virtual colonoscopy remain unchanged from 2005:
- Colorectal cancer screening and surveillance in average or elevated-risk individuals
- Surveillance in patients with a prior colonic neoplasm
- Diagnostic exam in patients with known or prior CTC and in symptomatic patients
- Screening, diagnostic, or surveillance exam in patients with incomplete optical colonoscopy
"This year, we expanded the patients at increased risk from colonoscopy," who may undergo CTC, she said "It's not just those who are on anticoagulation therapy or thought to be a sedation risk, but also those with a history of failed colonoscopy or those with advanced age."
New this year are "relative" contraindications to VC because "there are always exceptions," Yee said. The new contraindications include symptomatic acute colitis, acute diarrhea, recent acute diverticulitis, recent colorectal surgery, symptomatic polypectomy/mucosectomy, known or suspected colonic perforation, and symptomatic or high-grade small bowel obstruction, she said.
Additionally, it is specified that CTC is not indicted for routine follow-up of inflammatory bowel disease, hereditary polyposis or nonpolyposis cancer syndromes, evaluation of pregnant patients, or patients with anal canal disease.
Regarding the latter indication, with virtual colonoscopy "we know we're just not good at looking down below the anorectal junction," Yee said.
Training in two tracks
The white paper section covering personnel qualifications and responsibilities "underwent major revision in acknowledgement of the fact that the committee wanted to adhere to more rigorous criteria for the definition of qualifications and efficacy safety standards that have evolved," Yee said. For the first time, training criteria have been divided into two tracks: one for radiologists, especially those with abdominal CT experience, and another for physicians who are not experts in imaging.
In a nutshell, those with prior qualifications in general or abdominal/pelvic CT should receive education limited to virtual colonoscopy itself: patient preparation, bowel insufflation, CT image acquisition, etc. And they should receive formal hands-on interactive training in CTC that includes the interpretation, reporting, and supervised review of at least 50 endoscopically confirmed CTC cases, Yee explained.
On the other hand, physicians who do not have prior qualifications in general or abdominal/pelvic CT exams would undergo extensive preliminary training prior to the actual CTC instruction.
These physicians must achieve sufficient training and experience to comply with the ACR practice guidelines for diagnostic CT. This includes completing a training program in their particular specialty, plus 200 hours of continuing medical education (CME) in abdominal-pelvic CT; supervision, interpretation, and reporting of 500 CT cases including at least 100 abdominal pelvic cases in three years; and formal CTC training with supervised completion of at least 75 cases -- a few more than are required for imaging experts, Yee said.
"Also new in the 2009 practice guidelines are criteria for the maintenance of competence," with suggested review of cases every two years, Yee said.
Educational topics will include correlation of CTC findings with those of optical colonoscopy, the use of teaching files, the use of computer-aided detection (CAD) software as a second reader, and more, she said.
Suggested exam technique
"We came down pretty strongly to say that use of antispasmodics like glucagon is not necessary for routine CTC," Yee said. "For oral contrast [e.g., fecal and fluid tagging], although it is not required absolutely, it's encouraged."
The use of MDCT is definitely recommended, i.e., at least a four-detector-row scanner with ≤ 3 mm slice thickness, reconstruction interval of ≤ 2 mm, and a breath-hold not exceeding 25 seconds.
The new guidelines also feature an expanded section on dose. There is a new CTDIvol limit of ≤ 6.25 mGy per position (prone, supine) or ≤ 12.5 mGy for both. In practice, this means that at the 120 kVp setting, effective mAs should be in the range of 50 to 80.
"The ACR reaffirmed that it does not believe polyps 5 mm or smaller should be reported," Yee said. Polyps ≥ 6 mm are reported per 2008 American Cancer Society (ACS) recommendations, and, in general, optical colonoscopy is suggested for such a finding, Yee said.
"However, there are sites, the University of Wisconsin being among them, that offer short-term follow-up CTC," for patients with one or two polyps in the 6- to 8-mm range, Yee added. Polyp surveillance remains a controversial topic in virtual colonoscopy, pending the accumulation of additional results in patients who have decided to forego immediate colonoscopy after presenting with one or two small polyps at VC.
More precise polyp-measurement requirements are also new: Polyps should be measured using either the optimized multiplanar reconstruction (in other words, whichever view maximizes lesion length), with lesion size based on the largest diameter of the polyp head (excluding stalk, if present) or at the base of a sessile lesion, the guidelines state.
"We stressed again that although potentially important extracolonic findings should be reported, be cautious in reporting findings that are likely to be benign," Yee said. "We emphasized that reporting must be consistent and clear, and we felt the C-RADS scheme was a good option."
Quality control criteria were modified in 2009 to say it's important to review images while the patient is on the table to ensure adequate distention for a diagnostic CTC exam, Yee said.
When necessary, "we recommend focused rescans -- for example, of the sigmoid colon -- when you have suboptimal cleansing or distention, recognizing the fact that most polyps and cancers occur in the distal colon," she said.
More information on the new guidelines is available in the November American Journal of Roentgenology, while the 2009 white paper is available at the ACR's Web site.
National Radiology Data Registry adds VC
The ACR added CTC to its National Radiology Data Registry in January 2008. The initiative is aimed at helping facilities improve their quality control programs and efforts to improve patient care using comparative national and regional data.
"You enter your data and then the ACR will generate for you semiannual benchmark reports -- so you can analyze local versus national trends," Yee said. The data will include detection sensitivity, false-positive rates, significant extracolonic findings, adequacy of distention, and other measures, she said. Costs are low and, in any case, the new practice guidelines are free for ACR members and nonmembers alike, she said. There are about 2,000 cases in the database to date.
By Eric Barnes
AuntMinnie.com staff writer
November 27, 2009
Related Reading
How 2009 went right and wrong: VC's own worst enemies, October 28, 2009
JACR editorial: Medicare used double standard in VC decision, September 22, 2009
NEJM editorial lauds CMS rejection of VC, May 28, 2009
CMS rejects Medicare coverage for virtual colonoscopy, May 12, 2009
American Cancer Society recognizes virtual colonoscopy screening benefit, March 5, 2008
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