Patients Sometimes Equate "Virtual" with "No Discomfort" in CTC

Bettina Siewert, M.D. Beth Israel Deaconess Medical Center, Boston

Carlos Capuñay, M.D. Diagnóstico Maipú, Buenos Aires

While radiologists know the benefits of CT colonography (CTC), or virtual colonoscopy, they should be cognizant of how patients’ expectations about the procedure affect their willingness to undergo screening, according to scientific presentations at RSNA 2009.

Presenter Bettina Siewert, M.D., said the overriding issue is acceptance of the test itself. "You want people to be willing to come for a follow-up screening, but there are misperceptions that may affect their behavior."

While the level of discomfort with CTC may be very mild, patients hear the word "virtual" and may mistakenly believe there is no discomfort at all, said Dr. Siewert, an assistant professor at Beth Israel Deaconess Medical Center in Boston.

"The uncomfortable part of the procedure is the distending of the colon, which can cause a mild cramping. It’s more a matter of explaining this to our patients and being proactive," she said.

To help gauge future compliance rates, Dr. Siewert and her colleagues conducted a multicenter trial to determine patient acceptance and tolerance of CTC versus optical colonoscopy (OC). The study involved 2,600 patients over the age of 50 and was conducted between February 2005 and December 2006 as part of the American College of Radiology Imaging Network (ACRIN) CT Colonography Trial.

Researchers compared National CT Colonography Trial (NCTCT) participant experiences with CTC and OC, as well as their willingness to be rescreened with each procedure. NCTCT participants underwent a single bowel preparation and were scheduled to receive CTC, followed by sedation and OC.

Participants completed a questionnaire two weeks post-exam. They were asked questions about experiences ranging from physical discomfort and embarrassment during CTC to gender preference for a doctor. More than 2,300 participants responded, with results showing that 46 percent preferred CTC, 27.4 percent reported no preference and 24.9 percent preferred OC.

Severe discomfort was reported by 7.1 percent of participants who underwent bowel preparation, 6.3 percent with CTC and 2.2 percent with OC. Severe embarrassment was rare.

Rescreening with CTC is currently recommended every five years, as opposed to every 10 years with OC. Results also showed that if the screening interval for CTC were extended to 10 years as it is with OC, 93.7 percent of participants would be willing to be rescreened.

Second Study Concurs

Patient tolerance and expectations of CTC was also highlighted in a trial conducted in Argentina.

The second study was conducted from October 2006 to July 2008. More than 400 patient exams were completed with a 64-row multislice CT scanner.

Presenter Carlos Capuñay, M.D., said his team observed a large number of patients who complained about some degree of discomfort during or after the CTC procedure.

Before the procedure, half the patients thought that CTC would not produce any discomfort, 29 percent thought it would produce mild discomfort and 21 percent expected moderate discomfort, researchers noted. No patients expected severe discomfort.

"However, after the study, only 12 percent perceived no discomfort, 14 percent mild discomfort, 48 percent moderate discomfort and 26 percent severe discomfort," said Dr. Capuñay, subhead of the CT Department at Diagnóstico Maipú in Buenos Aires, Argentina. "In 79 percent of cases patients did not know what the procedure was about."

There was a clear difference between patient expectations and acceptance of CTC studies, according to researchers who added that referring physicians and also radiologists should explain to patients how the study is done in order not to create false expectations.

Dr. Siewert said the studies indicate that patients need more information about these procedures. "We really need to address patient expectations, bring awareness of the procedures themselves and make people understand that this screening is very important," she said.

The NCTCT study also indicated that improvements in technology that would extend screening intervals and eliminate the need for bowel preparation would most likely improve compliance rates, Dr. Siewert noted.

Non-cathartic CTC Screening Technique Shows Promise

Cathartic bowel preparation is a major obstacle to widespread colorectal cancer screening and is medically difficult for some patients, said Joel Fletcher, M.D., who presented a study of 564 patients who underwent CTC with no dietary modifications other than barium ingestion.

Dr. Fletcher and his colleagues used a technique that supplemented primary 2D interpretation with locally adaptive stool subtraction software and 3D problem solving. Results were compared to those of complete colonoscopy.

The method detected adenomas greater than 6 mm in 76 percent of patients, including the lone cancer in the study. The stool subtraction software was helpful in identifying polyps.

Researchers concluded that while non-cathartic CTC shows potential as a screening technique for patients wishing to forego cathartic bowel cleansing, mild dietary restrictions, improving tagging regimens and optimizing computer-aided detection software will further improve its performance.