Morphological and physiological assessment of coronary artery disease (CAD) is necessary for proper stratification of CAD risk. The objective was to evaluate a low-dose cardiac CT technique that combines morphological and physiological assessment of CAD. The low-dose technique was evaluated in twelve swine, where three of the twelve had coronary balloon stenosis. The technique consisted of rest perfusion measurement combined with angiography followed by stress perfusion measurement, where the ratio of stress to rest was used to derive coronary flow reserve (CFR). The technique only required two volume scans for perfusion measurement in mL/min/g; hence, four volume scans were acquired in total; two for rest with angiography and two for stress. All rest, stress, and CFR measurements were compared to a previously validated reference technique that employed 20 consecutive volume scans for rest perfusion measurement combined with angiography, and stress perfusion measurement, respectively. The 32 cm diameter volumetric CT dose index ([Formula: see text]) and size-specific dose estimate (SSDE) of the low-dose technique were also recorded. All low-dose perfusion measurements (PLOW) in mL/min/g were related to reference perfusion measurements (PREF) through regression by PLOW = 1.04 PREF - 0.08 (r = 0.94, RMSE = 0.32 mL/min/g). The [Formula: see text] and SSDE of the low-dose cardiac CT technique were 8.05 mGy and 12.80 mGy respectively, corresponding to an estimated effective dose and size-specific effective dose of 1.8 and 2.87 mSv, respectively. Combined morphological and physiological assessment of coronary artery disease is feasible using a low-dose cardiac CT technique.
Keywords: Computed tomography angiography; Coronary artery disease; Coronary flow reserve; Myocardial perfusion imaging.