TC-99M SESTAMIBI AND TETROFOSMIN MYOCARDIAL SINGLE-PHOTON EMISSION TOMOGRAPHY - CAN WE USE THE SAME REFERENCE DATA-BASE

The aim of this study was to compare technetium-99m labelled tetrofosm in and sestamibi myocardial perfusion single-photon emission tomograph y (SPET) with one common sestamibi reference file for bull's eye imagi ng, with quantitation of the extent and severity of perfusion defects. Twenty patients suspected or known to have coronary artery disease pa rticipated in the study. Patients first underwent routine sestamibi my ocardial SPET over 2 days, receiving doses of 400-600 MBq at stress an d 600-800 MBq at rest, Then within the same week a 1-day tetrofosmin m yocardial SPET study was performed, with a dose of 300 MBq at stress, followed 2.5 h later by a dose of 750 MBq at rest. Bull's eye images w ere generated for visual evaluation. Black-out defects according to th e Cequal software analysis were only recorded if they comprised more t han 10 pixels in men and 20 in women. According to the Cequal program, extent score and severity scores were expressed as number of pixels a nd deviations below reference limits. Five patients had normal myocard ial SPET imaging with both radiotracers, while 15 had reversible, irre versible or partially reversible defects. The concordance of the resul ts was high. The only two significant differences were that one patien t had a reversible defect which appeared to be located in different my ocardial regions (LAD vs RCA), and another patient had a defect that w as partially reversible with sestamibi but irreversible with tetrofosm in. The results showed very high correlation coefficients for the exte nt and severity scores (linear correlation coefficient values of 0.99 and 0.94, respectively). In conclusion, it appears that changing betwe en sestamibi and tetrofosmin has little influence on the interpretatio n of bull's eye images from the data file of a common reference popula tion using one of the tracers.