Computed tomographic colonography (CTC), also known as virtual colonoscopy, administered without laxatives is as accurate as conventional colonoscopy in detecting clinically significant, potentially cancerous polyps, according to a study performed jointly at the San Francisco VA Medical Center, the University of California, San Francisco and Massachusetts General Hospital.
"I think we have demonstrated that laxative-free CTC is a valid tool for detecting polyps that are clinically significant," said co-author and site principal investigator Judy Yee, MD, chief of radiology at SFVAMC and professor and vice chair of radiology at UCSF.
The study was published in the May 15 issue of Annals of Internal Medicine.
Virtual colonoscopy, which has been approved by the American Cancer Society as a valid screening test for colorectal cancer, uses a CT scanner to screen for cancers and polyps in the colon non-invasively. In standard optical colonoscopy (OC), a physician inserts a six-foot-long scope into the entire colon. Currently, both methods call for patients to take a bowel-cleansing laxative before the procedure.
With laxative-free CTC, explained Yee, patients do not have to go through bowel cleansing before the exam, but instead begin a low fiber diet two days before the test. They also ingest a tagging agent the day before the exam, which mixes with residual material in the colon and can then be identified and removed digitally when radiologists interpret the scans.
"The use of laxatives is often viewed as the worse aspect of having not only a virtual colonoscopy but an optical colonoscopy," said Yee, who has pioneered the use of virtual colonoscopy within the VA health care system and at UCSF. "I hope that this research will encourage patients who have delayed screening for colon cancer to be examined with this less invasive method."
The study of 605 patients, aged 50 to 85, assessed the accuracy of laxative-free CTC in detecting lesions 6 millimeters or larger in size compared with standard optical colonoscopy.
The authors found that laxative-free CTC exams detected clinically significant polyps 10 mm or larger with 91 percent accuracy compared to OC exams, which were 95 percent accurate. Statistically, there is no difference between these two numbers, said Yee.
Scan sensitivity using laxative-free CT colonography decreases with polyp size, as it does for regular CT colonography, she said. With polyps measuring 6 mm, sensitivity for CTC was 59 percent, compared with standard colonoscopy at 76 percent.
The smaller the polyp, the less likely it is to harbor malignancy. For diminutive polyps 5 mm or less, there is an extremely low risk of cancer, and these polyps may not need to be removed.
For polyps between 6 and 9 mm in size, the decision about whether to remove them depends on the patient's risk factors and how many are found, said Yee.
"Polyps 10 millimeters or larger unquestionably come out," she said.
During the study, three of the 605 subjects were found to have cancerous polyps. The cancers were identified by both the laxative-free virtual colonoscopy and the standard OC exam.
The researchers also surveyed the research participants about their experiences while preparing for the examinations. They found that laxative-free virtual colonoscopy scored higher on all survey questions, and was indicated by more participants to be their exam type of choice.
Yee noted that the current study is one of the first and largest to measure the effectiveness of the new, laxative-free procedure. Because the procedure is still in the early stages of development, additional studies still need to be conducted, she said.
She predicts that once radiologists are trained in reading the new images and gain experience with the exam process, laxative-free CTC exams will be available wherever virtual colonoscopies are performed.
Co-authors of the study are Michael E. Zalis, MD, Michael A. Blake, MB, BCh, Wenli Cai, PhD, Peter F. Hahn, MD, PhD, Elkan F. Halpern, PhD, Imarana G. Kazam, PhD, Myles Keroack, MD, Cordula Magee, PhD, Janne J. Nappi, PhD, Rocio Perez-Johnston, MD, Abhinav Vij, MD and Hiroyuki Yoshida, PhD, of Massachusetts General Hospital, and John R. Saltzman, MD, of Brigham and Women's Hospital, Boston, Massachusetts.
The authors had no conflicts of interest.
The study was supported by funds from GE Healthcare and the American Cancer Society, some of which were administered by the Northern California Institute for Research and Education.
NCIRE – The Veterans Health Research Institute – is the largest research based institute associated with a VA medical center. Its mission is to improve the health and well-being of veterans and the general public by supporting a world-class biomedical research program conducted by the UCSF faculty at SFVAMC.
SFVAMC has the largest medical research program in the national VA system, with more than 200 research scientists, all of whom are faculty members at UCSF.
UCSF is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care.
Steve Tokar | EurekAlert!
Inhaling air pollution-like irritant alters defensive heart-lung reflex for hypertension
19.06.2019 | University of South Florida (USF Innovation)
Nitric oxide-scavenging hydrogel developed for rheumatoid arthritis treatment
06.06.2019 | Pohang University of Science & Technology (POSTECH)
From June 25th to 27th 2019, the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau (Germany) will be presenting a new solution for acoustic quality inspection allowing contact-free, non-destructive testing of manufactured parts and components. The method which has reached Technology Readiness Level 6 already, is currently being successfully tested in practical use together with a number of industrial partners.
Reducing machine downtime, manufacturing defects, and excessive scrap
The quality of additively manufactured components depends not only on the manufacturing process, but also on the inline process control. The process control ensures a reliable coating process because it detects deviations from the target geometry immediately. At LASER World of PHOTONICS 2019, the Fraunhofer Institute for Laser Technology ILT will be demonstrating how well bi-directional sensor technology can already be used for Laser Material Deposition (LMD) in combination with commercial optics at booth A2.431.
Fraunhofer ILT has been developing optical sensor technology specifically for production measurement technology for around 10 years. In particular, its »bd-1«...
The well-known representation of chemical elements is just one example of how objects can be arranged and classified
The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...
Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.
Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...
Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.
The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...
24.06.2019 | Event News
29.04.2019 | Event News
17.04.2019 | Event News
24.06.2019 | Event News
24.06.2019 | Agricultural and Forestry Science
24.06.2019 | Life Sciences