Materials and Methods: The low-dose comprehensive cardiac CT technique, which consists of whole-organ CT blood flow, CT angiography, and coronary flow reserve (CFR), was evaluated in twelve swine (43 ± 11 kg) under rest and stress conditions by direct comparison to a previously validated whole-organ CT blood flow technique. In three of the swine, intermediate stenoses with fractional flow reserve severities of 0.70 - 0.90 were also assessed. Contrast and saline were injected peripherally (370 mgI/mL contrast: 1 mL/kg at 5 mL/s; saline: 0.5 mL/kg at 5 mL/s) followed by dynamic volume scan acquisition with a 320-slice CT scanner. For each flow condition, only two volume scans were acquired for the low-dose comprehensive cardiac CT technique, while 20 volume scans were acquired for the reference standard retrospective technique. All of the comprehensive cardiac CT flow measurements were then compared to corresponding reference standard flow measurements through regression analysis. The and size-specific dose estimate of the comprehensive cardiac CT technique were also computed and used to estimate effective dose.
Results: Low-dose comprehensive cardiac CT flow measurements (FLOW) were in good agreement with reference standard flow measurements (FREF) (FLOW = 1.04 FREF - 0.08, r = 0.94, RMSE = 0.32 mL/min/g). The of rest flow, stress flow, CFR, rest flow combined with CT angiography, and CFR combined with CT angiography were 2.30, 2.30, 4.60, 5.75, and 8.05 mGy, respectively, with corresponding size-specific dose estimates of 3.66, 3.66, 7.31, 9.14, and 12.80 mGy. In combination, the maximum effective dose and size-specific effective dose of the comprehensive cardiac CT technique were 1.8 and 2.87 mSv, respectively.
Conclusion: Accurate morphological and physiological assessment of coronary artery disease is feasible with a low-dose comprehensive cardiac CT technique based on a whole-organ CT blood flow measurement technique.