Dynamic CT-perfusion parameters as indicators of microcirculation: Investigation in patients without obstructive coronary artery disease

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BackgroundQuantitative analysis of stress dynamic myocardial CT perfusion (CTP) can provide various parameters related to coronary microcirculation. This study aimed to investigate the relationship between each CTP parameter and that between CTP parameters and patient characteristics in patients without obstructive coronary artery disease (CAD). MethodsSeventy-seven (28 female; 65.0 ± 10.3 years) patients with suspected CAD who underwent coronary CT angiography (CCTA) and dynamic CTP with vasodilator stress were included. Patients with obstructive coronary stenosis (≥50%) on CCTA were excluded. Myocardial blood flow (MBF) and myocardial blood volume (MBV) were calculated using the slope and peak of the time attenuation curves of the myocardium and blood. Perfused capillary blood volume (PCBV), extravascular extracellular volume (EEV), and flow extraction product (FE) were calculated using the extended Tofts model. ResultsMBF, MBV, and PCBV were strongly correlated with each other (all r>0.80 and all p<0.001), whereas FE and EEV were strongly correlated with each other (r=0.88 and p<0.001). In univariate linear regression analysis, male-sex and smoking status significantly associated with MBF, MBV, and PCBV, while age significantly associated with FE and EEV (all p<0.05). In stepwise multivariate analysis, smoking status was independently associated with MBF, MBV. and PCBV, while age was the only factor associated with FE and EEV (all p<0.05). ConclusionsFE and EEV may reflect different mechanisms of microvascular dysfunction than MBF, MBV, and PCBV.