Contrast dose determined by body weight and tube potential in coronary CT angiography improves attenuation consistency and reduces contrast dose.

OBJECTIVE

To compare non-standardized and standardized dosage of contrast medium in single-heartbeat coronary CT angiography examinations in relation to tube potential, and to assess the effect of a revised contrast administration protocol standardizing dose by body weight.

MATERIALS AND

METHODS

This single-center, retrospective, observational study included a total of 338 patients (189 men and 149 women) who had undergone high-pitch acquisition (single heartbeat) coronary CT angiography, performed with a fixed injection rate of 6.0 ml/s. Examination quality was objectively assessed by measuring the attenuation in Hounsfield Units [HU] in the ascending aorta (below optimal: <350 HU, optimal: 350-550 HU, above optimal: >550 HU) and subsequently compared to contrast dose in milligrams Iodine per kilogram of body weight, grouped by tube potential (low: 70-80 kVp, high: ≥90 kVp).

RESULTS

Comparing examinations performed prior to and after the protocol revision standardizing the dose by kilogram body weight, contrast medium dose was on average reduced by 14 % for low tube potential and 9 % for high tube potential. The number of examinations falling within optimal attenuation range increased from 13 % to 25 % for low tube potential, and 57 % to 74 % for high tube potential. However, examinations with suboptimal attenuation increased from 1 % to 8 %, typically with low body weight in conjunction with low tube potential.

CONCLUSION

Employing a body weight adjusted contrast medium dose, while adjusting for low versus high tube potential, increases the number of examinations with attenuation falling within the clinically recommended range and reduces contrast medium dose.