Inaccuracies in Cardiac PET-CT Imaging

Lead author K. Lance Gould, M.D., professor in the Division of Cardiology at The University of Texas Medical School at Houston, said he discovered the abnormalities upon his initial use of cardiac PET-CT scanners in the Weatherhead P.E.T. Center for Preventing and Reversing Atherosclerosis at Memorial Hermann-Texas Medical Center.

PET paired with CT should be an accurate, noninvasive tool for detecting or assessing severity of heart disease, said Gould, executive director of the Weatherhead P.E.T. Center. However, he said, an erroneous basic concept in the software functions make the PET-CT scanners prone to generating false-positive results.

The technology showed false-positive results in 40 percent of the 259 patients who participated in Gould’s study. In 23 percent of those patients, it showed severe false abnormalities suggesting heart disease, which Gould said could have resulted in unwarranted, emergency heart procedures if he had not run additional tests to confirm his suspicions of the inaccurate results.

The commercial software does not account for movement in the lungs and heart while the patient is breathing during the test, Gould said, and as a result, the PET and CT images don’t always match or co-register. “Consequently, the images have big holes or gaps where the processing is incorrect in areas where the PET and CT data fail to match,” Gould said. “It looks like someone has severe disease.”

On discovering the problems, Gould developed a solution with Tinsu Pan, Ph.D., associate professor in the Department of Imaging Physics at The University of Texas M. D. Anderson Cancer Center, by rewriting the software to account for breathing motions and correctly aligning PET and CT images.

“When done properly, PET-CT produces absolutely perfect images of blood flow in the heart muscle,” he said. “It’s the best way to assess and direct management of heart disease.” Unfortunately, according to Gould, the redesigned software is not generally commercially available at this time. Gould also says, “This medical product is out there on the market, and physicians and their patients trust it, yet there is a big problem with it. Since PET-CT proved ideal for cancer, body and brain imaging, everyone assumed its application to the heart would work with the same protocols and software – a big mistake.”; Source: University of Texas Health Science Center at Houston