Ryuichi Arie, Presenter: Nothing to Disclose

Jun Horiguchi MD, PhD, Abstract Co-Author: Nothing to Disclose

Katsuhide Ito MD, Abstract Co-Author: Nothing to Disclose

Noriaki Matsuura, Abstract Co-Author: Nothing to Disclose

Minoru Ishifuro, Abstract Co-Author: Nothing to Disclose

Takashi Furukawa RT, Abstract Co-Author: Nothing to Disclose

The purpose of this study was to compare coronary artery calcium scores, the variability and radiation doses on 64-slice and 16-slice CT scanners by both prospective ECG-triggered and retrospective ECG-gated scans.

Coronary artery calcium models (240 HU, 600 HU and 1000 HU) of four sizes (1 mm, 3 mm, 5 mm and 10 mm in length) attached to coronary artery models on a cardiac phantom were scanned in variable heart rate sequences. The tube current-time-products were set to almost the same on all four protocols. A slice-thickness of 2.5 mm was used to maintain image quality. Overlapping reconstruction with 1.25 mm increment was applied on the retrospective ECG-gated scan. Coronary artery calcium scores (Agatston, volume and mass), the interscan variability on three repeated scans and the estimated effective doses were evaluated.

The coronary artery calcium scores were not different between CT scan protocols (Kruskal Wallis test, p=0.09 to 0.32). Repeated measures ANOVA test revealed that the interscan variability was different between CT scan protocols (p<0.01) and scoring algorithms (p<0.01). The average variability of Agatston/volume/mass scoring and effective doses were 16%/15%/11% and 0.5 mSv, 11%/11%/8% and 3.7 mSv, 20%/18%/13% and 0.6 mSv & 16%/15%/11% and 2.9 to 3.5 mSv (depending on the pitch) on 64-slice prospective, 64-slice retrospective, 16-slice prospective and 16-slice retrospective scans, respectively.

Prospective ECG-triggered 64-slice CT, with low radiation dose, shows low variability on coronary artery calcium measurement comparable to retrospective ECG-gated 16-slice CT.

For ‘ALARA’ coronary artery calcium measurement, 64-slice prospective ECG-triggered scan (0.5mSv) with low interscan variability comparable to 16-slice CT retrospective ECG-gated scan is recommended.

Arie, R, Horiguchi, J, Ito, K, Matsuura, N, Ishifuro, M, Furukawa, T, Variability of Coronary Artery Calcium Measurement and Radiation Dose on 64-slice and 16-slice CT by Prospective Electrocardiograph (ECG)-triggered and Retrospective ECG -gated CT.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5006587.html