Technical evaluation of immediate back-to-back rest-stress positron emission tomography scanning with 18F-flurpiridaz.

Background: ¹⁸F-flurpiridaz is the newest positron emission tomography myocardial perfusion tracer approved in the US for evaluating myocardial ischemia and infarction (Flyrcado™, GE HealthCare). The 110 minutes half-life of ¹⁸F enables flurpiridaz to be made and shipped regionally; however, it also results in high levels of residual tracer activity for same-day rest/stress scanning. This study provides a technical evaluation of immediate back-to-back rest/stress flurpiridaz positron emission tomography (PET) with no delay, using a commercially available software medical device (mfiVerse™, MultiFunctional Imaging LLC) to correct for residual activity effects.

Methods and results: Retrospectively obtained separate-scan dynamic rest and pharmacologic stress flurpiridaz images in 11 subjects were digitally shifted and combined to model a 15 minute rest/stress procedure with rest scan from 0 to 8 minutes and stress scan from 8 to 15 minutes, providing a paired-sample study design. The modeling of residual tracer effects included both distributed activity and stress effects upon residual arterial input. Residual activity biased mean stress pixel values and myocardial blood flow (MBF) by +31% and +64%, respectively, as compared with the reference stress images without residual activity. These biases were each reduced to less than 1% after residual activity correction. Linear regression analysis found that corrected stress pixel values (r = .998) and MBF (r = .994) closely matched reference stress values, both being equivalent to separate-scan values to less than half of test-retest variability (P < .001). Summed stress scores averaged 2.5 points lower for uncorrected images versus the reference images, and averaged .4 points lower after correction.

Conclusions: Within the study limitations, these results demonstrate that rest and stress flurpiridaz PET images can be obtained immediately back-to-back without rest-stress delay when accurate correction for residual activity is performed.