Correlation between 15O-water PET–detected myocardial ischaemia and CT-derived FFR: Predicting the functional significance of anatomical stenosis
J Vornanen, M K Okkonen, A P Ronkainen, T M Laitinen, T Laitinen, M HedmanAbstract
Aims
Coronary artery disease (CAD) is a major global cause of morbidity and mortality. While coronary computed tomography angiography (CCTA) offers excellent anatomical assessment, its ability to determine the functional relevance of intermediate stenoses remains limited. Computed tomography–derived fractional flow reserve (CT-FFR) has emerged as a noninvasive method for assessing lesion-specific ischaemia. This study evaluated the diagnostic performance of CT-FFR using 15O-water positron emission tomography (PET) myocardial perfusion imaging as the reference standard.
Methods and results
A retrospective cohort of 193 patients who underwent hybrid CCTA and 15O-water PET at Kuopio University Hospital (2017–2022) was reviewed. Patients with a low-to-intermediate pretest probability of CAD and at least one stenosis >50% were eligible. After exclusions, 165 patients were included. The CT-FFR values were derived using a research prototype algorithm and compared with PET-derived perfusion abnormalities. PET identified impaired perfusion in 58 patients (35%). In the overall cohort, CT-FFR demonstrated moderate diagnostic performance, with area under the curve (AUC) values of 0.740 (right coronary artery), 0.681 (left anterior descending artery), and 0.672 (left circumflex artery). In a subset of 83 patients with high-quality CCTA and stenosis >50%, diagnostic performance improved substantially (AUC 0.836). Using a CT-FFR threshold of 0.80, sensitivity was 85% and specificity was 87%.
Conclusion
CT-FFR provides a clinically meaningful assessment of the functional significance of coronary stenoses in selected patients with high-quality CCTA. Its performance is reduced in unselected populations, particularly when image quality is suboptimal. Therefore, CT-FFR should be considered a complementary tool rather than a replacement for 15O-water PET in complex diagnostic settings.