ABSTRACT
Objective:To evaluate the feasibility of making individualized scanning and contrast injection protocol based on body mass index (BMI) and body weight during dynamic myocardial computed perfusion (CTP) imaging in order to get high-quality images while drastically reducing radiation dose.Methods:A total of 128 patients with coronary heart disease diagnosed by coronary CTA (CCTA) performed CTP from June, 2019 to March, 2020 were prospectively enrolled. Patients were divided into six groups: group 1, BMI<24 kg/m 2, ≤60 kg, 70 kV; group 2,BMI<24 kg/m 2, 61≤kg≤70, 70 kV; group 3, BMI 24-28 kg/m 2, 61≤kg≤70, 80 kV; group 4, BMI 24-28 kg/m 2, 71≤kg≤80, 80 kV; group 5, BMI 24-28 kg/m 2,>80 kg, 80 kV;group 6, BMI>28 kg/m 2,>80 kg, 100 kV. 200 mA was fixed for all patients. Contrast agent with iodine containing 370 mg/ml was used in all patients. The iodine delivery rates (IDR) for each group was 0.8, 1.0, 1.2, 1.4, 1.6, 2.0 g/s, respectively. The attenuation and noise of left ventricle (LV) and septal myocardial were measured to calculate signal to noise ratio (SNR) and contrast to noise ratio (CNR) of the images in each group. The Shapiro-Wilk test was conducted to assess the normality of quantitative data. Quantitative variables were compared using one-way ANOVA if normally distributed. Results:The LV attenuation of the six groups were (506±85), (513±77), (510±81), (456±74), (477±111), (462±43) HU, respectively. There was no significant difference among them ( F=2.249, P=0.054). SNR values of LV were 23±8, 20±5, 21±5, 19±4, 19±7, 19±4, and CNR values were 19±7, 17±4, 17±4, 16±4, 15±6, 15±4, respectively. There were no significant differences among them ( F=1.674, 1.736, all P>0.05). Under a single CTP scan, the radiation dose of 70, 80 and 100 kV groups were 1.6, 2.3 and 4.3 mSv, respectively. The does of the 70 kV group and 80 kV group were significantly lower than that of the 100 kV group, and the dose of the 70 kV group was also significantly lower than that of the 80 kV group (all P<0.001). Conclusions:The application of individualized scanning and contrast agent injection protocol based on IDR is feasible in myocardial CTP with successful image quality, and the radiation dose decreases significantly.