Systolic acquisition of coronary DSCT angiography: feasibility in an unselected patient population

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.

Full text: Eur Radiol. 2010 Jun;20(6):1331-6. Epub 2009 Dec 23

Authors: Bamberg F, Sommer WH,  Schenzle JC, Becker CR, Nikolaou K, Reiser M, Johnson TR