Myocardial Perfusion Imaging with Technetium-99m Sestamibi SPECT in the Evaluation of Coronary Artery Disease Jamshid Maddahi, MD, Hosen Kiat, MD, Kenneth F. Van Train, BS, Florence Prigent, MD,” John Friedman, MD, Ernest V. Garcia, PhD,‘k’k Naomi Alazraki, MD,~” E. Gordon DePuey, MD,” Ken Nichols, PhD, and Daniel S. Berman, MD echnetiumd9m (Tc-SSm) sestamibi is a new myo- cardial perfusion imaging agent that offers signifi- cant advantages over thallium-201 (TI-201) for myocardial perfusion imaging. The results of the current clinical trials using acquisition and process- ing parameters similar to those for TI-201 and a separate (2-day) injection protocol suggest that Tc- SSm sestamibi and TI-201 single photon emission computed tomography (SPECT) provide similar in- formation with respect to detection of myocardial perfusion defects, assessment of the pattern of de- fect reversibility, overall detection of coronary ar- tery disease (CAD) and detection of disease in indi- vidual coronary arteries. Tc-SSm sestamibi SPECT appears to be superior to Tc-SSm sestamibi planar imaging because the former provides a higher de- fect contrast and is more accurate for detection of disease in individual coronary arteries. Research is currently under way addressing optimization of ac- quisition and processing of Tc-SSm sestamibi stud- ies and development of quantitative algorithms for detection and localization of CAD and sizing of transmural and nontransmural myocardial perfu- sion defects. It is expected that with the implemen- tation of the final results of these new develop- ments, further significant improvement in image quality will be attained, which in turn will further increase the confidence in image interpretation. De- velopment of algorithms for analysis of end-diastol- ic myocardial images may allow better evaluation of small and nontransmural myocardial defects. Furthermore, gated studies may provide valuable information with respect to regional myocardial wall motion and wall thickening. With the imple- entation of algorithms for attenuation and scatter correction, the overall specificity of Te-99m sesta- From the Departments of Medicine (Division of Cardiology) and Nu- clear Medicine, Cedars-Sinai Medical Center, and the Department of Medicine, University of California School of Medicine, Los Angeles, California; the **Department of Nuclear Medicine, Emory University School of Medicine, Atlanta, Georgia; and *St. Luke’s/Roosevelt Hos- pital, New York, New York. This study was supported in part by a grant (IROl-HL41628-01) from the National Institute of Health, Be- thesda, Maryland, and by a grant from the American Heart Associa- tion, Greater Los Angeles Affiliate. Address for reprints: Jamshid Maddahi, MD, Director, Clinical Positron Emission Tomography Ccntcr, UCLA School of Medicine 172115, Los Angeles, California 90024. mibi SPECT should improve significantly because of a substantial decrease in the occurrence of at- tenuation-related image artifacts. Simultaneous as- sessment of ventricular function by performing first-pass studies may provide important additional information to that obtained from analysis of myo- cardial perfusion. (Am J Cardiol 1990;66:55E-62E) echnetium-99m (Tc-99m) sestamibi’ is a new myocardial perfusion imaging agent with physical characteristics superior to thoseof thalli- ife 01 (Tl-201). Compared to Tl-201, the shorter half- (6 hours) of Tc-99m sestamibi, coupled with its prompt hepatobiliary and renal excretion, results in more favorable radiation dosimetry. Approximately 10 times the doseof Tl-201 can be administered for similar radia- tion exposure. The higher injectable dose alsoallows first- pass2 studies and cardiac gating3 for the assessment of ventricular function and wall motion. In addition, due to its photon energy of 140 keV, which is optimal for stan- dard gamma camera imaging, better overall image quali- ty has been demonstrated compared with Tl-201.4 Recently, single photon emission computed tomogra- phy (SPECT) has beenwidely usedasan imaging modal- ity because it provides a higher defect contrast and better resolves overlapping myocardial regions than convention- al planar imaging. Both characteristics improve the de- tection and localization of coronary artery disease (CAD).5-7 We review several aspects of myocardial per- fusion imaging using Tc-99m sestamibi and SPECT. ECHNETIUM-SSm SESTAMIBI OMOGRAPHY VERSUS THALLIUM-20 TOMOGRAPHY FOR MY~CARDIAL ERFUSION IMAGING After initial clinical trials that establishedthe safety of Tc-99m sestamibi in humans8 extensiveclinical infor- mation has been generated on the clinical utility of Tc- 99m sestamibi myocardial perfusion SPECT imaging through the North American Multicenter Clinical Trial’ and studies by severalinvestigators.4,‘0J1 In the PhaseIII Multicenter North American Clinical Trial, 22 centersin the United States and 2 centersin Canada participated in an open-label study designed to compare Tc-99m sesta- mibi with Tl-201 imaging and coronary angiography. All patients underwent maximal exercise Tl-201 and Tc-99m sestamibi SPECT studies separated by an average of 4 THE AMERICAN JOURNAL OF CARDIOLOGY OCTOBER 16,199O