Contrast agent bolus tracking with a fixed threshold or a manual fast start for coronary CT angiography.

OBJECTIVES

Comparison of bolus tracking with a fixed threshold versus a manual fast start for coronary CT angiography.

METHODS

We retrospectively analysed 320-row coronary CT angiography of 50 patients with suspected or known coronary artery disease. Twenty-five examinations were initiated by a bolus tracking method (group 1), 25 examinations with a manual fast surestart (group 2).

RESULTS

Mean attenuation values in the ascending aorta were 519 ± 111 Hounsfield units (HU) in group 1 and 476 ± 65 HU in group 2 (p = 0.10). Assessable vessel lengths were 171 ± 44 mm vs 172 ± 29 mm for the right coronary artery (p = 0.91), 11 ± 4 mm vs 12 ± 4 mm for the left main (p = 0.9), 163 ± 28 mm vs 151 ± 26 mm for the left anterior descending coronary artery (p = 0.11) and 125 ± 41 mm vs 110 ± 37 mm for the left circumflex coronary artery (p = 0.18). Image quality for all coronary arteries was not significantly different between the groups (p > 0.41). The attenuation ratio between the left and right ventricle was 2.8 ± 0.7 vs 3.6 ± 1.0 (p = 0.003). Significantly less contrast agent was used in group 2 (64 ± 6 ml vs 80 ± 0 ml; p < 0.001).

CONCLUSIONS

Bolus tracking with a fixed threshold and with a manual fast start are both suitable methods; the fast start allowed a reduction of contrast agent volumes.

KEY POINTS

Fixed threshold bolus tracking is suitable for coronary 320-row CT angiography. Manual fast start bolus tracking can reduce contrast agent volumes. Manual fast start and fixed threshold initiation achieve good image quality. Fixed threshold bolus tracking achieves a more reliable contrast bolus position.