Determining optimal acquisition parameters for computed tomography coronary angiography: evaluation of a software-assisted, breathhold exam simulation

Abstract

Rationale and objectives: Scanning parameters used in multislice computed tomographic (MSCT) coronary angiography should be adapted to patients' heart rates. The aim of this study was to evaluate the rate of success of a software-assisted scan simulation to determine optimal gantry rotation time prior to MSCT coronary angiography.

Materials and methods: Data from 218 64-slice MSCT coronary angiographic studies were retrospectively analyzed. Prior to the MSCT examination, a scan had been simulated by giving a breath-hold command, after which a software program recorded the patient's heart rate from an electrocardiogram over the expected scanning time and predicted optimal scanning parameters. The success rate in predicting optimal parameters for the subsequent MSCT examination and the resulting acquisition window width were analyzed.

Results: There was a wide range of heart rates among the patients. The mean intraindividual variation during scan simulation and examination was 4.8 beats/min. Optimal scan parameters were selected in 179 of 218 cases (82%). The median acquisition window width achieved in this group was 174 ms (range, 100-200), compared with 192 ms (range, 149-225) in cases in which suboptimal settings were selected (P < .001). Correct prediction occurred significantly more often in patients with low heart rates (<66 beats/min) than in those with higher heart rates (>or=66 beats/min) (93% vs 66%; P < .001).

Conclusions: The software-assisted scan simulation was a fast and simple procedure that allowed the selection of optimal computed tomographic parameters in >80% of patients. The procedure may be a useful adjunct to avoid unwanted synchronicity of gantry rotation and heart cycle and optimize temporal resolution in MSCT coronary angiography.