Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Virtual colonoscopy without laxative equals standard in identifying clinically significant polyps

15.06.2012
Study authors hope new method will increase colon exams and decrease colorectal cancer rates

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!
Further information:
http://www.ncire.org

More articles from Health and Medicine:

nachricht New study points the way to therapy for rare cancer that targets the young
22.11.2017 | Rockefeller University

nachricht Penn study identifies new malaria parasites in wild bonobos
21.11.2017 | University of Pennsylvania School of Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Corporate coworking as a driver of innovation

22.11.2017 | Business and Finance

PPPL scientists deliver new high-resolution diagnostic to national laser facility

22.11.2017 | Physics and Astronomy

Quantum optics allows us to abandon expensive lasers in spectroscopy

22.11.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>