Effect of LV positional variations on detection of perfusion changes in serial studies

Background: We evaluated the effect of LV positional differences on detection of serial perfusion changes. Methods: We used the NCAT software phantom to simulate three different shaped LVs based on actual patient studies. A small (∼10% of the myocardium) single defect was simulated for each of the three patients; the severity of each defect was varied in 5% increments from .5 of LV maximum perfusion for 6 steps, with each severity repeated. This provided a total of 12 simulations for each patient. Random LV rotations (stdev=2.5°), translations (stdev=0.5cm), and small scaling factors ( Results: In the repeated studies, where no difference in defect severity should be detected, a mean difference of 1.3% of LV maximum was seen; this difference was significant (p Conclusion: Current perfusion quantification methods may underestimate actual perfusion changes in serial studies. Noise, detector response, and orientation differences may make small changes in small defects difficult to detect with statistical significance.