Evolving Role of 18F-Flurpiridaz in Myocardial Perfusion Imaging

Introduction: Coronary artery disease (CAD) is the leading cause of morbidity and mortality worldwide; however, non-invasive assessment of CAD still remains a challenging task. Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) agents has been an important evaluating tool in CAD. With the emerging role of positron emission tomography (PET), PET MPI has demonstrated improvement in diagnostic and prognostic value.

Methods: We reviewed multiple databases, including PubMed, Google Scholar, and compiled a comprehensive body of literatures related to the MPI used in CAD. Findings from multiple research papers were then analyzed and synthesized. We will discuss the difference between SPECT and PET MPI, available radiotracers in PET MPI, and the evolving role of ¹⁸F-flurpiridaz in PET MPI.

Results: Prior to the exponential growth in the use of PET imaging, SPECT MPI is the most commonly used standard screening tool in CAD with sensitivity and specificity of approximately 87% and 73%, respectively. However, its limitations include inferior spatial and temporal resolution, incapability of absolute quantification, non-uniform attenuation correction, and high uptake in the organs adjacent to the heart prompting researchers to explore new reliable methods to evaluate CAD. Compared with SPECT, PET imaging was found to have better resolution and quantification of regional myocardial blood flow and coronary flow reserve; therefore, PET MPI has been receiving increased interest. The common radiotracers used in PET MPI are ¹³N-NH₃, ⁸²Rb, and ¹⁵O-H₂O. However, their half-lives are extremely short and on-site supply is often challenging and not feasible in exercise stress test; therefore, new ¹⁸F-labelled tracers have been recently studied. ¹⁸F-flurpiridaz is the current favorite for PET MPI due to favorable performance in preclinical studies. Clinical research has found that ¹⁸F-flurpiridaz will remain in the system up to 5 hours post injection with liver clearance in 2 hours, which make it a feasible tool to be used in exercise stress test and can even identify subtle stress-induced wall motion abnormalities. It was shown in experimental and clinical reports that these radiotracers allow good quality rest/stress MPI studies and provide a reliable quantitation of myocardial blood flow.

Conclusions: Recent evidence suggests that PET MPI with ¹⁸F-flurpiridaz may provide superior diagnostic accuracy for obstructive CAD and will likely increase the acceptance of cardiac PET as a routine diagnostic tool in future.