Shigehiro Ochi RT, Presenter: Nothing to Disclose

Nobusada Funabashi MD, PhD, Abstract Co-Author: Nothing to Disclose

Ryousuke Irie RT, Abstract Co-Author: Nothing to Disclose

Noriyuki Yanagawa MD, Abstract Co-Author: Nothing to Disclose

Miki Aiba RT, Abstract Co-Author: Nothing to Disclose

Ryo Morimoto RT, Abstract Co-Author: Nothing to Disclose

Yoshitada Masuda, Abstract Co-Author: Nothing to Disclose

Masae Uehara MD, Abstract Co-Author: Nothing to Disclose

Hiroyuki Takaoka MD, PhD, Abstract Co-Author: Nothing to Disclose

Toru Kabashima RT, Abstract Co-Author: Nothing to Disclose

Shota Fujii RT, Abstract Co-Author: Nothing to Disclose

Yoshio Kobayashi, Abstract Co-Author: Nothing to Disclose

We evaluated the utility of Adaptive Iterative Dose Reduction 3D (AIDR3D)® (Toshiba Medical) and multisector reconstruction method in 320 slice CT for measuring severe coronary arterial calcium with various pulsating rates and tube currents in vitro.

A calcified mock-vessel with maximum a CT value of 400 HU was made to pulsate at 40-100 beats/min (BPM) using a pulsating device (AZ-631N, Anzai Medical). Retrospective ECG gated 320 slice CT (Aquilion ONE) was performed with a fixed tube voltage of 120 kV and a tube current ranged of 50, 100, 200, 300, 400 or 500 mA, and images were reconstructed using half reconstruction (all BPM) or multisector reconstruction (only 65 BPM) at the most static phase both without and with AIDR3D. In addition, the Agatston calcium score (ACS) were measured.

Without the ADIR3D and with half reconstruction at all BPM, the ACS at 40-100 BPM relative to the static state was 93,100, 99, 94, 90, 103, and 82% at a tube current of 500 mA; 93, 95, 96, 101, 102, 99, and 83% at 400 mA; 96, 98, 96, 102, 100, 219, and 96% at 300 mA; 101, 94, 99, 97, 96, 92, and 216% at 200 mA; 165, 114, 157, 165, 171,100, and 104% at 100 mA; and 192, 213, 217, 184, 189, 180, and 209% at 50 mA. However, with the ADIR3D and with half reconstruction at all BPM, the ACS at 40-100 BPM relative to the static state was improved, especially at low tube current, to 155, 114, 106, 102, 96, 94, and 106% at 50 mA. Furthermore, if multisector reconstruction was performed only to 65 BPM, the ACS relative to the static state was improved to 155, 114, 106, 98, 96, 97, and 95% at 50 mA.

In 320 slice CT, when a volume exposure control (VEC) system is used to reduce radiation exposure, tube current is reduced, especially non-obese subjects. Our results demonstrate that the AIDR3D with multisector reconstruction method in 320 slice CT maintains accurate measurement of ACS of severe calcification, which is improved at higher pulsating beats (≧65 BPM) and low tube current.

At low tube current, ACS increases, especially at higher pulsating beats (≧65 BPM). Using combined the VEC with the AIDR3D and multisector reconstruction, accurate measurement of ACS is possible.

Ochi, S, Funabashi, N, Irie, R, Yanagawa, N, Aiba, M, Morimoto, R, Masuda, Y, Uehara, M, Takaoka, H, Kabashima, T, Fujii, S, Kobayashi, Y, Adaptive Iterative Dose Reduction 3D with Multisector Reconstruction Method in 320 Slice CT may Maintain Accurate Measurement of the Agatston Calcium Score of Severe Calcification Even at Higher Pulsating Beats and Low Tube Current in Vitro.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043748.html