Comparison of 99m Tc-sestamibi- 18 F- fluorodeoxyglucose dual isotope simultaneous acquisition and rest±stress 99m Tc-sestamibi single photon emission computed tomography for the assessment of myocardial viability J. DE BOER, 1 R.H.J.A. SLART,* ,1 P.K. BLANKSMA, 2 A.T.M. WILLEMSEN, 3 P.L. JAGER, 1 A.M.J. PAANS, 3 W. VAALBURG 3 and D.A. PIERS 1 Departments of 1 Nuclear Medicine, 2 Cardiology and 3 PET, University Hospital Groningen, The Netherlands Received 2 May 2002, in revised form 29 August 2002 and accepted 21 October 2002 Summary Dual isotope simultaneous acquisition single photon emission computed tomography (DISA SPECT) offers the advantage of obtaining information on myocardial perfusion using 99m Tc-sestamibi ( 99m Tc-MIBI) and metabolism using 18 F-fluorodeoxyglucose ( 18 F-FDG) in a single study. The prerequisite is that the 99m Tc- MIBI images are not degraded by scattered 511 keV photons or poor count statistics due to the lower efficiency of the extra high energy (EHE) collimator. Therefore, we compared the registered 99mTc-MIBI uptake and image quality of DISA and single isotope acquisition. Furthermore, we investigated whether DISA yields additional information for the assessment of myocardial viability in comparison with rest± stress 99m Tc-MIBI. Nineteen patients with known coronary artery disease and irreversible perfusion defects on previous rest±stress MIBI test studies were investigated. After oral glucose loading and simultaneous injection of 600 MBq of 99m Tc-MIBI and 185 MBq of 18 F-FDG at rest, DISA was performed using energy windows of 140 (+15%), 170 (+20%) and 511 keV (+15%). Planar 140 keV images were corrected for scatter by subtraction using the 170 keV window. The single and dual isotope 99m Tc-MIBI images were both displayed in a polar map with 128 segments normalized to maximum counts. 18 F-FDG and 99m Tc- MIBI images were visually scored for a perfusion±metabolism mismatch pattern using nine regions per heart. There was an excellent correlation (r = 0.93, P50.0001) between the 99m Tc-MIBI uptake detected in the single and dual isotope acquisition. The average difference between the dual and single isotope 99mTc- MIBI uptake was 71.2% (not significantly different from zero) and the coefficient of variation of the difference was 8.7%. Of the 79 regions with irreversible perfusion defects on previous rest±stress 99m Tc- MIBI, six regions in five patients showed a perfusion±metabolism mismatch pattern. We conclude that DISA does not affect the quality of the 99mTc-MIBI images. Furthermore, 18 F-FDG- 99m Tc-MIBI DISA may show viability in a small but significant (7.6%, P50.0034) number of regions with irreversible perfusion defects on rest±stress 99m Tc-MIBI. (# 2003 Lippincott Williams & Wilkins) Keywords: dual isotope simultaneous acquisition, SPECT, 99m Tc-MIBI, 18 F-fluorodeoxyglucose, myo- cardial viability. Introduction In patients with coronary artery disease and poor left ventricular function, the identification of viable myocar- dium is needed prior to revascularization. When viable 0143±3636/03 # 2003 Lippincott Williams & Wilkins DOI: 10.1097/01.mnm.0000061046.24401.ff *Address all correspondence to Riemer H.J.A. Slart, Department of Nuclear Medicine, University Hospital Groningen, Hanzeplein 1, P.O. Box 30001, 9700 RB, Groningen, The Netherlands. Tel.: ++31-50-3613541. Fax: ++31-50-3611712. E-mail: r.slart@nucl.azg.nl Nuclear Medicine Communications, 2003, 24, 251±257