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Posted on Nov 21, 2006, 6 a.m.
By Bill Freeman
Three-dimensional CT scanning, also referred to as computed tomography or computed axial scanning -- CAT), is an accurate means of examining the colon for colorectal cancer -- and is less invasive and preferred by patients over traditional method of colon screening (colonoscopy) -- according to results of a study conducted at the University of Wisconsin Medical School in Madison.Combining the two techniques, appears to offer a "a synergistic approach" to colorectal screening, lead investigator Dr. Perry J. Pickhardt and his associates add in their paper, published in Radiology.
Three-dimensional CT scanning, also referred to as computed tomography or computed axial scanning -- CAT), is an accurate means of examining the colon for colorectal cancer -- and is less invasive and preferred by patients over traditional method of colon screening (colonoscopy) -- according to results of a study conducted at the University of Wisconsin Medical School in Madison.
Combining the two techniques, appears to offer a "a synergistic approach" to colorectal screening, lead investigator Dr. Perry J. Pickhardt and his associates add in their paper, published in Radiology.
Colorectal cancer is largely preventable, Pickhardt's team notes. Still, it is the second leading cause of cancer-related deaths in the U.S. because many people do not undergo colon screening.
Previous studies of the more patient-friendly screening using CT colonography have not established its accuracy. This new year-long study of the updated procedure using improved technology suggests that "virtual colonoscopy" may finally be ready for prime time.
Pickhardt and colleagues used 3-D CT colonography to screen 1,100 patients for colorectal; cancer. The subjects underwent another screening if the initial one revealed polyps measuring 6 millimeters or larger. For polyps 10 millimeters or larger, immediate traditionl colonoscopy was recommended. Patients with polyps between 6 and 9 millimeters were also offered either immediate surgical removal or CT surveillance of the colon for 1 to 2 years later.
Overall, virtual colon screening diagnosed 43 patients with large colorectal polyps, and 77 with growths 6- to 9-millimeter in size.
Of the patients who underwent traditional colonoscopy, 65 of the 77 patients were identified. Forty-nine patients had cancerous or precancerous tissue. The CT relies on visual inspection of the colon.
Patients seemed to appreciate the less invasive CT colonography. "Overall, there was a significant increase in the overall screening of our population, with a doubling of patients from the firstt quarter of 2004 to the first quarter of 2005," the investigators report.
Pickhardt and his associates attribute the high accuracy of CT colonography to improvements in software that enabled primary 3D evaluation, with results returned within 10 minutes. Also, more "patient-friendly" bowel preparation required less fluid consumption and was more reliable. Colonic distension using a small flexible rectal catheter with automated CO2 delivery improved distension with less postprocedural discomfort.
The authors say that "gastroenterologists should not be threatened by the implementation of CT colonography," since the two techniques are complementary procedures. "Furthermore, the percentage of truly therapeutic optical colonoscopic examinations would represent better use of a limited resource that is more costly and more invasive than CT colonography."
"To become a truly successful screening tool, however, CT colonography must be embraced by patients, referring physicians, national third-party payers, and gastroenterologists," Pickhardt and his associates conclude.
