TY - JOUR T1 - Diagnostic Performance of PET vs. SPECT Myocardial Perfusion Imaging in Patients with Smaller Left Ventricles: a Substudy of the <sup>18</sup>F-Flurpiridaz Phase-III Clinical Trial JF - Journal of Nuclear Medicine JO - J Nucl Med DO - 10.2967/jnumed.120.252007 SP - jnumed.120.252007 AU - René R. Sevag Packard AU - Joel L. Lazewatsky AU - Cesare Orlandi AU - Jamshid Maddahi Y1 - 2020/11/01 UR - http://jnm.snmjournals.org/content/early/2020/11/27/jnumed.120.252007.abstract N2 - The performance of SPECT myocardial perfusion imaging (MPI) may deteriorate in smaller hearts, primarily due to the lower resolution of conventional Anger cameras. 18F-flurpiridaz is a novel PET MPI agent with superior image and defect resolution. We sought to determine the diagnostic performance of 99mTc-labeled SPECT MPI compared to 18F-flurpiridaz PET MPI according to left ventricular (LV) size. Methods: We conducted a substudy of the phase-III clinical trial of flurpiridaz (n = 750) and stratified diagnostic performance according to the median PET LV end-diastolic volume (LVEDV), with smaller LV’s defined as LVEDV &lt;113 mL (n = 369), and larger LV’s as LVEDV ≥113 mL (n = 381). Images were interpreted by the majority rule of three independent blinded readers. The reference standard was quantitative invasive angiography with ≥50% stenosis in ≥1 coronary artery considered significant. Results: SPECT performance decreased significantly from an area under the curve (AUC) =0.75 in larger LVs to 0.67 in smaller LVs (P = 0.03), whereas PET performance was similar in larger or smaller LVs (AUC=0.79 vs. 0.77, P = 0.49). Accordingly, in smaller LVs, PET had a higher AUC=0.77 than the SPECT AUC=0.67 (P&lt;0.0001), a phenomenon driven by female patients (P&lt;0.0001). There was a degradation of sensitivity of SPECT in smaller LVs that was highly significant (P&lt;0.001), whereas there was no significant change in PET sensitivity according to LV size (P = 0.07). Overall, PET had significantly higher sensitivity than SPECT in both smaller (67% vs. 43%, P&lt;0.001) and larger LVs (76% vs. 61%, P&lt;0.001). The specificity of PET and SPECT was similar in larger LVs (76% vs. 83%, P = 0.11). While SPECT specificity improved in smaller compared to larger LVs (90% vs. 83%, P = 0.03), the PET specificity did not change with LV size (76% vs. 76%, P = 0.9). Conclusion: The diagnostic performance of 18F-flurpiridaz PET MPI is not affected by LV size and is superior to SPECT MPI in patients with smaller LVs, highlighting the importance of appropriate test selection in these patients. ER -