Chuanchen Zhang MD, Presenter: Nothing to Disclose

Zhaoqi Zhang, Abstract Co-Author: Nothing to Disclose

Lei Xu MD, PhD, Abstract Co-Author: Nothing to Disclose

Wei Yu MD, Abstract Co-Author: Nothing to Disclose

Rui Wang, Abstract Co-Author: Nothing to Disclose

To prospectively evaluate to what extent image quality, contrast material volume and radiation exposure in 320-row computed tomographic (CT) coronary angiography (CTCA) are influenced by 100 kilovoltage (kV) protocol in comparison with 120-kV protocol.

One hundred and seven consecutive patients with heart rate less than 65 beats per minute (bpm) undergoing CTCA were enrolled in this study. Forty patients with body mass index (BMI) of equal or less than 25 kg/m2 were scanned by using 100-kV tube voltage setting, the other 67 patients were scanned by using 120-kV protocol. Image quality was assessed by two readers unaware of patient information and scan parameters. Attenuation in the aorta and perivascular fat tissue and image noise were measured. Contrast-to-noise ratio (CNR) and contrast material volume were calculated. The effective radiation dose was estimated with a conversion coefficient 0.017 for the chest.

Diagnostic image quality was achieved in 98.2% coronary segments with the 100-kV CTCA and in 98.6% segments with 120-kV CTCA. There was no significant difference in image quality score for each coronary segment between the two protocols. Although calcification artifact in nonevaluable segments was more common in the 100-kV CTCA than that in120-kV CTCA (P = 0.048), total nonevaluable segments were not statistically different. Image attenuation, image noise and CNR were not significantly different between 100- and 120-kV protocols. The mean contrast material volume and mean effective radiation dose were 53.13 ± 3.77 ml and 2.12 ± 0.19 mSv for 100-kV CTCA, significantly lower than 62.40 ± 3.66 ml and 4.61 ± 0.82 mSv for 120-kV CTCA (P < 0.001).

The100-kV tube voltage setting for 320-row CTCA allows significant reductions of contrast material volume and effective radiation dose for patients with BMI ≤ 25 kg/m2 while maintaining adequate image quality.

100-kV tube voltage setting of 320-row CTCA is a robust technique to reduce contrast and radiation doses for patients with BMI ≤ 25kg/m2 while maintaining diagnostic image quality.

Zhang, C, Zhang, Z, Xu, L, Yu, W, Wang, R, 320-Row CT Coronary Angiography: Effect of 100 versus 120-kV Tube Voltage Settings on Image Quality, Radiation Exposure, and Contrast Material Volume.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9005668.html