Compartmental modeling of technetium-99m-labeled teboroxime with dynamic single-photon emission computed tomography - Comparison with static thallium-201 in a canine model

RATIONALE AND OBJECTIVES. A compartmental modeling approach to deriving kinetic parameters from a time series of single-photon emission computed tomography (SPECT) images of technetium-99m-labeled (Tc-99m-) teboroxime may have value for semiquantitative assessment of myocardial perfusion. This study investigated the value of the kinetic parameters derived from a two-compartment model of Tc-99m-teboroxime for measuring myocardial perfusion and compared it with static thallium-201 ((TI)-T-201) uptake and microsphere-measured blood flow in dogs. METHODS. Experiments were successfully conducted in 9 of 11 open-chest dogs. During adenosine stress, a single complete set of projections of (TI)-T-201 uptake was acquired. Tc-99m-teboroxime was then injected during adenosine stress, and a complete set of projections was acquired every 5.7 seconds for 17 minutes. Resting studies were performed on 4 of the animals. All of the projection sets were reconstructed with an iterative algorithm and incorporated corrections for attenuation and the geometric response of the collimators. Regional kinetic parameters (washin and washout) were determined semiautomatically from the time series of reconstructed Tc-99m-teboroxime images and registered with microsphere data. Regional washin estimates were compared with (TI)-T-201 intensities and myocardial blood flows determined from microspheres. RESULTS. Optimally scaled Tc-99m-teboroxime washin parameters and (TI)-T-201 uptakes were correlated with microsphere-determined blood Rows (r = 0.91, y = 0.99x + 0.01, and r = 0.92, y = 0.88x + 0.28, respectively). In six of the studies, the left anterior descending coronary artery was occluded, and stress occluded-to-normal (O/N) ratios were calculated. The O/N ratios were 0.32 +/- 0.17 as determined from microspheres injected with (TI)-T-201 and 0.38 +/- 0.29 from microspheres injected with Tc-99m-teboroxime (P = NS), The O/N ratios were 0.48 +/- 0.16 for static (TI)-T-201 uptake and 0.27 +/- 0.21 for Tc-99m-teboroxime washin (P < 0.05). CONCLUSIONS. Both (TI)-T-201 uptake and Tc-99m-teboroxime kinetic parameters were well correlated with flow. The Tc-99m-teboroxime washin parameters offer semiquantitative flow values and provide greater defect contrast than can be obtained with (TI)-T-201 uptake values.