@article {Packardjnumed.120.252007, author = {Ren{\'e} R. Sevag Packard and Joel L. Lazewatsky and Cesare Orlandi and Jamshid Maddahi}, title = {Diagnostic Performance of PET vs. SPECT Myocardial Perfusion Imaging in Patients with Smaller Left Ventricles: a Substudy of the 18F-Flurpiridaz Phase-III Clinical Trial}, elocation-id = {jnumed.120.252007}, year = {2020}, doi = {10.2967/jnumed.120.252007}, publisher = {Society of Nuclear Medicine}, abstract = {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{\textquoteright}s defined as LVEDV \<113 mL (n = 369), and larger LV{\textquoteright}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\<0.0001), a phenomenon driven by female patients (P\<0.0001). There was a degradation of sensitivity of SPECT in smaller LVs that was highly significant (P\<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\<0.001) and larger LVs (76\% vs. 61\%, P\<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.}, issn = {0161-5505}, URL = {https://jnm.snmjournals.org/content/early/2020/11/27/jnumed.120.252007}, eprint = {https://jnm.snmjournals.org/content/early/2020/11/27/jnumed.120.252007.full.pdf}, journal = {Journal of Nuclear Medicine} }