"This work presents a new non-invasive cardiac imaging technology for the assessment of ischemic heart disease--also known as coronary artery or coronary heart disease--caused by the narrowing of heart arteries, which prevents blood and oxygen from reaching the heart muscle," said Zohar Keidar, deputy director of the nuclear medicine department at Rambam HealthCare Campus in Haifa, Israel. "This new modality (or technique) enables--in a single imaging session--accurate evaluation of cardiac blood vessel narrowing and blood supply to the heart muscles," said the co-author of "Assessment of Hemodynamically Significant Coronary Artery Lesions--Initial Experience With an Integrated SPECT/CT Device." He added, "These initial results suggest that this novel non-invasive imaging technology will enable more precise diagnosis of coronary artery disease, thus leading to treatment tailoring in the individual patient who may be directed to either invasive or conservative medical procedures."
In the United States, cardiovascular disease is the leading cause of death for both sexes. Coronary artery disease is the most common cause of cardiovascular disease, and as many as 3 to 4 million Americans may have ischemic episodes without knowing it.
Myocardial perfusion (blood flow) imaging using single photon emission computed tomography (SPECT) is an established method for assessing the physiologic significance of coronary lesions in patients with chest pain, said Keidar. Computed tomography coronary angiography (CTCA)--an emerging technique for non-invasive detection of the narrowing of a blood vessel (coronary stenosis)--is an X-ray-based exam of the blood vessels or chambers of the heart. Cardiac SPECT/CT technology combines two imaging modalities of the heart in a single device: the CT coronary angiography--showing the cardiac vessels--and SPECT perfusion imaging--detecting blood flow abnormalities in the cardiac muscle, he explained. "To the best of my knowledge these are the first results of cardiac SPECT/CT in a clinical setting," he added.
"These initial results indicate that cardiac SPECT/CT imaging enables the precise localization of an abnormal ischemic segment of the cardiac muscle to the responsible blood vessel, thus indicating if one or more coronary arteries are obstructed and can and should be treated," said Keidar. "On the other hand, the combined information can also demonstrate that a narrowed blood vessel has no significant impact on patient's heart perfusion, thus eliminating the need for further invasive treatment," he added.
These primary results indicate that SPECT/CTCA provides more accurate information as compared to data obtained when each of the two studies is performed as a stand-alone test, noted Keidar. Additional research must be done with large and homogenous groups, such as patients with diabetes or with a history of myocardial infarction and patients who have had bypass graft surgery, he added. Technological issues that need to be addressed and evaluated include assessment of improved CT technology (64 slices vs. the current 16 slices) and SPECT technology (shorter acquisition time), detailed Keidar.
Researchers used the experimental (not commercially available) Infinia LS SPECT/CT research device, combining an Infinia gamma camera and a Light Speed16 CT Scanner (from GE Healthcare Technologies) to enable a concurrent assessment of blood flow and coronary anatomy, said Keidar.
"Combining SPECT (physiological imaging) with CT (anatomical imaging) is a significant advance," said Josef Machac, SNM's Scientific Program Committee cardiovascular vice chair. "This work provides a more accurate picture of the severity of coronary artery disease," added the director of the Clinical PET Center and Nuclear Medicine at Mount Sinai School of Medicine in New York City.
Abstract: Z. Keidar, R. Bar-Shalom and O. Israel, nuclear medicine, Rambam HealthCare Campus, Haifa, Israel; S. Rispler, A. Roguin, R. Dragu and R. Beyar, cardiology, Rambam HealthCare Campus, Haifa, Israel; and E. Ghersin and A. Engel, diagnostic radiology, Rambam HealthCare Campus, Haifa, Israel, "Assessment of Hemodynamically Significant Coronary Artery Lesions--Initial Experience With an Integrated SPECT/CT Device," SNM's 53rd Annual Meeting, June 3–7, 2006, Scientific Paper 584.
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 resource in the field; sponsor research grants, fellowships and awards; host the premier annual meeting for medical imaging; 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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