Objective: To determine the practicability and potential dose saving of an imaging algorithm incorporating a pulsing scheme applying systolic data acquisition at heart rates >75 beats per minute (bpm).
Methods: Patients clinically referred for coronary computed tomography angiography (CTA) underwent cardiac CTA using either a diastolic pulsing window (30-70%) or a narrow systolic pulsing window (150 ms at 300 ms). Independent investigators retrospectively determined image quality (1, excellent, to 5, unreadable) and derived effective radiation exposure.
Results: Among all 101 subjects (62 +/- 2 years, 59% male) the predicted decrease in the best reconstruction interval for diastolic phases was 12 ms per 1 bpm [95% confidence interval (CI): -13.5 to -11.2] and -1.9 ms for systolic phases (95% CI: -3.2 to -0.62, p = 0.004), independent of age, gender and body mass index (BMI). The systolic pulsing strategy in 47 subjects (23 subjects >75 bpm) resulted in significantly lower radiation exposure (4.97 +/- 2.3 vs 9.38 +/- 5.5 mSv, p < 0.001 for systolic versus diastolic, respectively), whereas there was no difference with respect to image quality or heart rate (p = 0.65 and p = 0.74, respectively).
Conclusions: Our results suggest that a systolic window for tube current modulation in subjects with higher heart rates represents a reliable tool to ensure high image quality at significantly lower dose in patients undergoing routine cardiac CTA.