Chikako Fujioka RT, Presenter: Nothing to Disclose

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

Kazushi Yokomachi RT, Abstract Co-Author: Nothing to Disclose

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

Fuminari Tatsugami, Abstract Co-Author: Nothing to Disclose

Kazuo Awai MD, Abstract Co-Author: Research Grant, Toshiba Corporation Research Grant, Hitachi Ltd Research Grant, Bayer AG Research Consultant, DAIICHI SANKYO Group Research Grant, Eisai Co, Ltd

Minoru Ishifuro, Abstract Co-Author: Nothing to Disclose

While 3.0-mm-thick slices are commonly used for calcium scoring at cardiac CT, the results vary widely and small calcium deposits can go undetected due to the partial volume effect. Using thinner slices reduces this effect but increases the image noise. Positing that the use of 0.5-mm-thick slices and adaptive iterative reconstruction (IR) reduces both the image noise and the partial volume effect and yields reproducible calcium scores at cardiac CT, we compared results obtained with 3.0-mm-thick slices and with 0.5-mm-thick-slices plus IR.  

We scanned a cardiac CT calibration phantom (QRM, Germany) that featured different calcium hydroxyapatite concentrations on a 320-detector CT scanner (Aquilion One, Toshiba) with prospective ECG-triggering. We scanned the phantom 5 times and reconstituted images from same-row data. We applied 4 IR strength levels (weak, mild, standard, strong; adaptive iterative dose reduction 3D: AIDR-3D; Toshiba) to the images of 0.5-mm-thick slices, calculated the Agatston scores on a workstation, and compared the variation coefficients to evaluate reproducibility and calcium detectability among the scans.

The average Agatston score for 3.0- and 0.5-mm slices without a filter was 808 and 768; it was 749, 724, 714, and 721 for 0.5 mm slices with weak, mild, standard, and strong IR, respectively. The total mean variation coefficient of the Agatston score for 3.0- and 0.5 mm slices without IR was 5.4 and 2.9; for 0.5 mm slices with weak, mild, standard, and strong IR it was 3.6, 2.1, 2.2, and 2.5%. The detection efficiency for small calcium deposits on 3.0- and 0.5-mm slices without a filter was 53- and 100%; for 0.5-mm slices with weak, mild, standard, and strong IR it was 100-, 100-, 100-, and 83%.

Using 0.5 mm-thick slices and IR reduced variations and improved detection for calcium scoring at cardiac CT.

The use of 0.5-mm thick-slices and iterative reconstruction yielded higher reproducibility and calcium detectability for coronary artery calcium scoring without an increase in the radiation dose.

Fujioka, C, Funama, Y, Yokomachi, K, Kiguchi, M, Tatsugami, F, Awai, K, Ishifuro, M, Reproducibility and Detectability of the Coronary Artery Calcium Score using Thinner Slices and Iterative Reconstruction at 320-detector CT.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14002246.html