Some previous medical studies have found no significant difference in the diagnostic accuracy of CT colonography, also known as "virtual colonoscopy," and traditional optical colonoscopy. This study looks at whether both exams are as effective for adults over 65 as they are for adults between 50 and 65 years of age.
In the study, C. Daniel Johnson, M.D., professor and chair of radiology at Mayo Clinic in Scottsdale, Ariz., and a team of researchers conducted a follow-up analysis of data from the National CT Colonography Trial, in which 2,600 patients over the age of 50 underwent both virtual and optical colonoscopies at 15 centers around the country.
Dr. Johnson's team analyzed trial data from 477 patients over the age of 65 and 2,054 patients between the ages of 50 and 65 who were screened with the two procedures for clinically significant pre-cancerous growths called polyps. Patients in the study were comprised of both men and women at predominantly an average risk for colorectal cancer.
Cancerous lesions 1 centimeter or larger were found in 6.9 percent of patients in the 65 and older group and in 3.7 percent of the younger patients.
There was no significant difference in the accuracy of CT colonography for the detection of large and intermediate-sized cancers in the older participants compared to the younger participants. Sensitivity and specificity among the older and younger groups were 0.82 and 0.83 and 0.92 and 0.86, respectively.
"We found no statistical difference in the diagnostic performance between the two patient groups," Dr. Johnson said. "This is good information for patients of any age, as they can consider CT colonography as a valid option for colorectal cancer screening."
Colorectal cancer is the third most commonly diagnosed cancer in both men and women and the third leading cause of cancer deaths in the U.S. According to the American Cancer Society (ACS), a decline in colorectal cancer incidence rates over the last two decades is largely attributable to screening tests that allow polyps to be removed before they progress to cancer.
"I don't believe there is any screening test that can intervene as early in the biology of the tumor as colorectal cancer screening," Dr. Johnson said. "We have the opportunity to detect pre-malignant polyps, remove them and prevent an entire class of cancers."
Despite the effectiveness of colorectal cancer screening, the ACS estimates that only half of the U.S. population over the age 50 is being screened as recommended for the disease. Experts point to cost and a lack of access to health care as contributing factors.
Although both optical and virtual colonoscopy procedures typically require the use of laxatives to empty the colon prior to the test, there are major differences between the two exams.
In the traditional colonoscopy, an optical instrument called a colonoscope allows a physician to visually examine the colon and to remove polyps by passing a wire loop through the scope. In this procedure, the risk of perforating the bowel is higher and sedation is required.
"For the older patient, the risks of and recovery from sedation are issues," Dr. Johnson said.
Introduced in the 1990s, CT colonography produces cross-sectional, three-dimensional images of the entire colon and rectum. While the CTC exam itself is quicker to perform and about half the cost of the optical colonoscopy, it involves exposure to low doses of radiation and it must be repeated more often. When polyps 6 millimeters or larger are detected by CT colonography, the patient must undergo an optical colonoscopy to have them removed. In addition, incidental CT findings outside the colon might require additional follow-up.
"There isn't a fight between CT colonography and colonoscopy, but there is a fight in medicine against colon cancer," Dr. Johnson said. "We want patients to be screened. CT colonography is a preferred test for some patients and should be an option. Patients should talk to their doctor and choose the best option for them."
"The National CT Colonography Trial: Assessment of Accuracy in Participants Aged 65 and Older." Collaborating with Dr. Johnson were Benjamin A. Herman, S.M., Mei-Hsiu Chen, Ph.D., Alicia Y. Toledano, Sc.D., Jay P. Heiken, M.D., Abraham H. Dachman, M.D., Mark D. Kuo, M.D., Christine O. Menias, M.D., Bettina Siewert, M.D., Jugesh I. Cheema, M.D., Richard G. Obregon, M.D., Jeff L. Fidler, M.D., Peter Zimmerman, M.D., Karen M. Horton, M.D., Kevin J. Coakley, M.D., Revathy B. Iyer, M.D., Amy K. Hara, M.D., Robert A. Halvorsen Jr, M.D., Giovanna Casola, M.D., Judy Yee, M.D., Meredith Blevins, S.M., Lawrence J. Burgart, M.D., Paul J. Limburg, M.D., M.P.H., and Constantine A. Gatsonis, Ph.D.
Radiology is edited by Herbert Y. Kressel, M.D., Harvard Medical School, Boston, Mass., and owned and published by the Radiological Society of North America, Inc. (http://radiology.rsna.org/)
RSNA is an association of more than 48,000 radiologists, radiation oncologists, medical physicists and related scientists committed to excellence in patient care through education and research. The Society is based in Oak Brook, Ill. (http://www.RSNA.org)
For patient-friendly information on CT colonography, visit http://www.RadiologyInfo.org
Advanced analysis of brain structure shape may track progression to Alzheimer's disease
26.10.2016 | Massachusetts General Hospital
Indian roadside refuse fires produce toxic rainbow
26.10.2016 | Duke University
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
26.10.2016 | Power and Electrical Engineering
26.10.2016 | Awards Funding
26.10.2016 | Power and Electrical Engineering