Chikako Fujioka RT, Presenter: Nothing to Disclose

Yoshinori Funama PhD, Abstract Co-Author: Nothing to Disclose

Masao Kiguchi RT, Abstract Co-Author: Nothing to Disclose

Minoru Ishifuro, Abstract Co-Author: Nothing to Disclose

Shuji Date, Abstract Co-Author: Nothing to Disclose

Kazuo Awai MD, Abstract Co-Author: Research grant, Toshiba Corporation Research grant, Hitachi, Ltd Research grant, Bayer AG

Akira Morimoto, Abstract Co-Author: Nothing to Disclose

Hiromi Ito, Abstract Co-Author: Nothing to Disclose

Masahiro Hatemura, Abstract Co-Author: Nothing to Disclose

Yasushi Nagata MD, Abstract Co-Author: Nothing to Disclose

In the follow-up of calcium scores in patients with coronary artery disease, reproducibility among CT scanners is necessary because different scanners may be used. We hypothesized that a low tube voltage (low kV) technique may help to reduce variability in the calcium score among different scanners because the CT number of calcium is increased on low kV scans. We compared the accuracy and reproducibility of coronary calcium scores obtained on 4 different 64- detector CT scanners using standard- (120 kVp) and low tube voltage (80 kVp) techniques.

Using a non-moving cardiac CT calibration phantom (QRM, Germany) we obtained prospectively-gated step-and-shoot scans on 64-detector CT scanners from 4 manufacturers (Aquilion64, LightSpeed VCT, SOMATOM Definition AS +, and Brilliance-64). Scanning was at 80 and 120 kVp with the tube current adjusted to set the image noise level at 20 HU for all scans. Reconstructed images were analyzed on a workstation (Virtual Place Raijin, AZE, Japan) and Agatston-, calcium volume-, and calcium mass scores were determined as the coronary artery calcium scores. We compared the variation coefficients of the calcium scores to evaluate reproducibility among the scanners.

The total Agatston- and volume scores were 16.8% and 10.6% higher at 80- than 120 kVp. The total mean mass score was almost constant irrespective of the tube voltage. The mean variation coefficients for the 4 CT scanners were lower at 80- than 120 kVp [4.1 % vs. 10.2 % (total Agatston score), 3.2 % vs. 9.6 % (total volume score), and 3.2 % vs. 9.4 % (total mass score)]. The difference in the variation coefficients between 120- and 80 kVp was affected by the score for smaller calcium sizes and lighter calcium density.

The low voltage technique (80 kVp) can reduce variations in the calcium scores obtained on different CT scanners. Calcium scoring with the low tube voltage technique is highly accurate and reproducible and useful in the follow-up of patients with coronary artery disease.

Use of the 80 kVp technique facilitates the reproducible evaluation of coronary artery calcium scores obtained on different CT scanners.

Fujioka, C, Funama, Y, Kiguchi, M, Ishifuro, M, Date, S, Awai, K, Morimoto, A, Ito, H, Hatemura, M, Nagata, Y, Improved Reproducibility of Coronary Artery Calcium Scores on Different 64-detector Scanners with a Low-Tube Voltage Scan Technique.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11001929.html