TY - JOUR T1 - Diagnostic Performance of PET Versus 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 SP - 849 LP - 854 DO - 10.2967/jnumed.120.252007 VL - 62 IS - 6 AU - René R. Sevag Packard AU - Joel L. Lazewatsky AU - Cesare Orlandi AU - Jamshid Maddahi Y1 - 2021/06/01 UR - http://jnm.snmjournals.org/content/62/6/849.abstract N2 - The performance of SPECT myocardial perfusion imaging (MPI) may deteriorate in smaller hearts, primarily because of 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 with 18F-flurpiridaz PET MPI according to left ventricle (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 LVs defined as having an LVEDV of less than 113 mL (n = 369) and larger LVs defined as having an LVEDV of at least 113 mL (n = 381). Images were interpreted by the majority rule of 3 independent masked readers. The reference standard was quantitative invasive angiography, with at least 50% stenosis in at least 1 coronary artery considered significant. Results: SPECT performance decreased significantly from an area under the curve (AUC) of 0.75 in larger LVs to 0.67 in smaller LVs (P = 0.03), whereas PET performance was similar in larger and 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). In smaller LVs, there was a degradation of SPECT sensitivity 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 LVs (67% vs. 43%, P &lt; 0.001) and larger LVs (76% vs. 61%, P &lt; 0.001). The specificities of PET and SPECT were similar in larger LVs (76% vs. 83%, P = 0.11). Although SPECT specificity improved in smaller compared with 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 -