When it counts: Shortening imaging time for individuals with suspected heart problems

Time spent for cardiac stress/rest tests may be cut in half, note researchers at SNM's 53rd Annual Meeting June 3–7 in San Diego

SAN DIEGO, Calif.--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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Abstract: D. Basso, M. Holman, W. Rogers and L. Walters, all with Cardiac Imaging of Augusta, Augusta, Ga., and G. Passmore, Medical College of Georgia, Augusta, Ga., "A Clinical Evaluation of a Wide Beam Reconstruction Method for Shortening Scan Time of Gated Cardiac Rest/Stress SPECT," SNM's 53rd Annual Meeting, June 3–7, 2006, Technologist Paper 2013.

About SNM

SNM is holding its 53rd Annual Meeting June 3–7 at the San Diego Convention Center. Research topics for the 2006 meeting include molecular imaging in clinical practice in the fight against cancer; the role of diagnostic imaging in the management of metastatic bone disease; metabolic imaging for heart disease; neuroendocrine and brain imaging; new agents for imaging infection and inflammation; and an examination of dementia, neurodegeneration, movement disorders and thyroid cancer.

SNM is an international scientific and professional organization of more than 16,000 members dedicated to promoting the science, technology and practical applications of molecular and nuclear imaging to diagnose, manage and treat diseases in women, men and children. Founded more than 50 years ago, SNM continues to provide essential resources for health care practitioners and patients; publish the most prominent peer-reviewed journal in the field; host the premier annual meeting for medical imaging; sponsor research grants, fellowships and awards; and train physicians, technologists, scientists, physicists, chemists and radiopharmacists in state-of-the-art imaging procedures and advances. SNM members have introduced--and continue to explore--biological and technological innovations in medicine that noninvasively investigate the molecular basis of diseases, benefiting countless generations of patients. SNM is based in Reston, Va.; additional information can be found online at http://www.snm.org.


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