Researchers discovered that the time spent on a myocardial perfusion single photon emission computed tomography (SPECT) imaging study--also called a cardiac stress/rest test--can be cut in half using a trademarked, innovative reconstruction technology. These results--from researchers at Cardiac Imaging of Augusta and the Medical College of Georgia--were presented at SNM's 53rd Annual Meeting June 3-7 in San Diego.

"Using UltraSPECT's Wide Beam Reconstruction (WBR)TM can reduce imaging time by 50 percent and improve image quality--without introducing artifacts (distortions) or deleting useful information," said Danny Basso, a certified nuclear medicine technologist and manager with Cardiac Imaging of Augusta. "This allows for increased patient comfort, less patient motion and increased throughput (rate of receiving data) for the nuclear medicine department," added the co-author of "A Clinical Evaluation of a Wide Beam Reconstruction Method for Shortening Scan Time of Gated Cardiac Rest/Stress SPECT." WBR is an algorithm "that uses modeling to reduce the bad counts and increase the good counts by placing the counts where they are suppose to be," explained Basso. "This same technology can be used to improve other molecular imaging/nuclear medicine procedures as well," he added.

A myocardial perfusion SPECT imaging study--also called a cardiac stress/rest test--helps evaluate a patient's heart's blood supply. About 7.5 million individuals--or 1 in every 40 Americans--undergo these cardiac scans every year. A radiotracer, a compound containing both a radioactive isotope and a pharmaceutical agent, is injected into a patient's vein. The radioactive isotope releases energy, and a technologist uses a special gamma camera to acquire multiple images from numerous angles of that energy. A computer can be used to apply a tomographic (sectional) reconstruction algorithm to the multiple projections, yielding 3-D information. Physicians will use this information captured by technologists to diagnose, manage and treat cardiac disease.

There is a trade-off between image quality and scan time with filtered back projection (FBP)--the most commonly used technology for processing myocardial perfusion imaging studies, noted Basso. In this research, 47 patient studies were reconstructed using both WBR and FBP SPECT protocols in clinical conditions. Each study comprised two scans: the first scan utilized the FBP reconstruction method, where the full-scan time images were acquired and reconstructed, and the second utilized half-scan times and was reconstructed using WBR. Each set of images was blinded and sent to three physicians, who rated the images for image quality, myocardial normality, lesion reversibility and treatment recommendation.

The ability to scan patients in half the time with improved image quality opens many doors, said Basso. "It may allow patients who can't tolerate laying still for 15 to 25 minutes to be scanned in half the time, and it provides the opportunity for smaller or community hospitals that have only a single-head camera to be as efficient as those that have dual-head cameras," he explained. The researchers found that the WBR method "proved to have no significant differences from FBP for myocardial normality, lesion reversibility detection and treatment recommendation," he added.

In the short term, this technology could allow departments to increase the number of patients scanned without the need for additional floor space or the expense of buying a new camera, said Basso. "In the long term, who knows? With all of the research in molecular imaging with microSPECT cameras, there will be a need for better resolution and faster scan times in the future," he added.

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