18F-flurpiridaz positron emission tomography segmental and territory myocardial blood flow metrics: incremental value beyond perfusion for coronary artery disease categorization.

Aims: We determined the feasibility and diagnostic performance of segmental 18F-flurpiridaz myocardial blood flow (MBF) measurement by positron emission tomography (PET) compared with the standard territory method, and assessed whether flow metrics provide incremental diagnostic value beyond relative perfusion quantitation (PQ).

Methods And Results: All evaluable pharmacological stress patients from the Phase III trial of 18F-flurpiridaz were included (n = 245) and blinded flow metrics obtained. For each coronary territory, the segmental flow metric was defined as the lowest 17-segment stress MBF (SMBF), myocardial flow reserve (MFR), or relative flow reserve (RFR) value. Diagnostic performances of segmental and territory MBF metrics were compared by receiver operating characteristic (ROC) areas under the curve (AUC). A multiple logistic model was used to evaluate whether flow metrics provided incremental diagnostic value beyond PQ alone. The diagnostic performances of segmental flow metrics were higher than their territory counterparts; SMBF AUC = 0.761 vs. 0.737; MFR AUC = 0.699 vs. 0.676; and RFR AUC = 0.716 vs. 0.635, respectively (P < 0.001 for all). Similar results were obtained for per-vessel coronary artery disease (CAD) ≥70% stenosis categorization and per-patient analyses. Combinatorial analyses revealed that only SMBF significantly improved the diagnostic performance of PQ in CAD ≥50% stenoses, with PQ AUC = 0.730, PQ + segmental SMBF AUC = 0.782 (P < 0.01), and PQ + territory SMBF AUC = 0.771 (P < 0.05). No flow metric improved diagnostic performance when combined with PQ in CAD ≥70% stenoses.

Conclusion: Assessment of segmental MBF metrics with 18F-flurpiridaz is feasible and improves flow-based epicardial CAD detection. When combined with PQ, only SMBF provides additive diagnostic performance in moderate CAD.