Aims: Coronary atherosclerosis with a large necrotic core has been postulated to reduce the vasodilatory capacity of vascular tissue. In the present analysis, we explored whether total plaque... Show moreAims: Coronary atherosclerosis with a large necrotic core has been postulated to reduce the vasodilatory capacity of vascular tissue. In the present analysis, we explored whether total plaque volume and necrotic core volume on coronary computed tomography angiography (CCTA) are independently associated with myocardial ischaemia on positron emission tomography (PET). Methods and results: From a registry of symptomatic patients with suspected coronary artery disease and clinically indicated CCTA with sequential [O-15]H2O PET myocardial perfusion imaging, we quantitatively measured diameter stenosis, total and compositional plaque volumes on CCTA. Primary endpoint was myocardial ischaemia on PET, defined as an absolute stress myocardial blood flow <= 2.4 mL/g/min in >= 1 segment. Multivariable prediction models for myocardial ischaemia were consecutively created using logistic regression analysis (stenosis model: diameter stenosis >= 50%; plaque volume model: +total plaque volume; plaque composition model: +necrotic core volume). A total of 493 patients (mean age 63 +/- 8 years, 54% men) underwent sequential CCTA/PET imaging. In 153 (31%) patients, myocardial ischaemia was detected on PET. Diameter stenosis >= 50% (P < 0.001) and necrotic core volume (P = 0.029) were independently associated with myocardial ischaemia, while total plaque volume showed borderline significance (P = 0.052). The plaque composition model (chi(2) = 169) provided incremental value for the prediction of ischaemia when compared with the stenosis model (chi(2) = 138, P < 0.001) and plaque volume model (chi(2) = 164, P = 0.021). Conclusion: The volume of necrotic core on CCTA independently and incrementally predicts myocardial ischaemia on PET, beyond diameter stenosis alone. Show less
Aims To test the hypothesis that virtual functional assessment index (vFAI) is related with regional flow parameters derived by quantitative positron emission tomography (PET) and can be used to... Show moreAims To test the hypothesis that virtual functional assessment index (vFAI) is related with regional flow parameters derived by quantitative positron emission tomography (PET) and can be used to assess abnormal vasodilating capability in coronary vessels with stenotic lesions at coronary computed tomography angiography (CCTA).Methods and results vFAI, stress myocardial blood flow (MBF), and myocardial flow reserve (MFR) were assessed in 78 patients (mean age 62.2 +/- 7.7 years) with intermediate pre-test likelihood of coronary artery disease (CAD). Coronary stenoses >= 50% were considered angiographically significant. PET was considered positive for significant CAD, when more than one contiguous segments showed stress MBF <= 2.3 mL/g/min for O-15-water or <1.79 mL/g/min for N-13-ammonia. MFR thresholds were <= 2.5 and <= 2.0, respectively. vFAI was lower in vessels with abnormal stress MBF (0.76 +/- 0.10 vs. 0.89 +/- 0.07, P < 0.001) or MFR (0.80 +/- 0.10 vs. 0.89 +/- 0.07, P < 0.001). vFAI had an accuracy of 78.6% and 75% in unmasking abnormal stress MBF and MFR in O-15-water and 82.7% and 71.2% in N-13-ammonia studies, respectively. Addition of vFAI to anatomical CCTA data increased the ability for predicting abnormal stress MBF and MFR in O-15-water studies [AUC(ccta+vfai) = 0.866, 95% confidence interval (CI) 0.783-0.949; P = 0.013 and AUC(ccta+vfai) = 0.737, 95% CI 0.648-0.825; P = 0.007, respectively]. An incremental value was also demonstrated for prediction of stress MBF (AUC(ccta+vfai) = 0.887, 95% CI 0.799-0.974; P = 0.001) in N-13-ammonia studies. A similar trend was recorded for MFR (AUC(ccta+vfai) = 0.780, 95% CI 0.632-0.929; P = 0.13).Conclusion vFAI identifies accurately the presence of impaired vasodilating capability. In combination with anatomical data, vFAI enhances the diagnostic performance of CCTA. Show less
