Prediction of the attenuation of the ascending aorta using bolus-tracking parameters and heart rate in coronary computed tomography angiography

Objective: The purpose of this study was to evaluate the correlation between bolus-tracking parameters and heart rate (HR) with attenuation of the ascending aorta and create a linear regression model for predicting coronary attenuation in coronary computed tomography angiography (CCTA). Methods: A total of 50 patients (31 men, 19 women; mean age, 67.2 ± 10.8 y) underwent CCTA using a 320-detector CT scanner. A bolus-tracking scan was performed to optimize the scan timing. The average HR under normal breathing for 10 s was recorded just before the bolus-tracking scan started. Attenuation values of the pulmonary artery at 7 s (PA7) and 10 s (PA10) after the beginning of the injection were recorded during the bolus-tracking scan and the ascending aortic attenuation (CEAAo) was measured during the diagnostic scan. Results: A positive correlation was observed between PA7 and CEAAo (r = 0.41, P = 0.003) and PA10 and CEAAo (r = 0.66, P < 0.0001), and weak negative correlation was observed between HR and CEAAo (r = −0.46, P = 0.15). A multivariable linear regression model for predicting CEAAo was evaluated, and the residual error between the predicted and the measured CEAAo was within approximately ±100 HU. Conclusions: Coronary attenuation could be predicted using HR and pulmonary artery attenuation during the bolus-tracking method.