Andrew Douglas McQuiston BS, Presenter: Nothing to Disclose

U. Joseph Schoepf MD, Abstract Co-Author: Research Grant, Bracco Group Research Grant, Bayer AG Research Grant, General Electric Company Research Grant, Siemens AG

Carlo Nicola de Cecco MD, Abstract Co-Author: Nothing to Disclose

Stefan Baumann MD, Abstract Co-Author: Nothing to Disclose

Matthias Renker MD, Abstract Co-Author: Nothing to Disclose

Felix G. Meinel MD, Abstract Co-Author: Nothing to Disclose

Christian Canstein, Abstract Co-Author: Employee, Siemens AG

The application of coronary artery calcium scoring as a screening test in a priori healthy, asymptomatic subjects mandates the use of the lowest possible radiation dose. We investigated, whether high-pitch spiral acquisition using a 3rd generation dual-source CT scanner allows performing accurate coronary artery calcium quantification with substantially decreased radiation dose.

Image acquisition was performed on a 3rd generation dual-source CT scanner using a calcium scoring phantom. This phantom contains calcium inserts of three different densities (800, 400 and 200HU) in grains of three different sizes for each density. A standard prospectively ECG-triggered sequential acquisition protocol with a reference tube current of 80mAs served as the reference standard. The high-pitch spiral acquisition was performed at four different dose levels with reference tube currents of 80, 60, 40, and 20mAs. Volume CT dose indices (CTDIvol) were recorded. Images were reconstructed with standard parameters recommended for coronary artery calcium scoring (filtered back projection, 3mm section thickness). Image noise was measured for each reconstructed series. Agatston scores were obtained using a dedicated image analysis platform.

CTDIvol for the standard prospectively ECG-triggered sequential acquisition technique was 1.2mGy. At the same reference tube current setting (80mAs), high-pitch spiral acquisition had a CTDI of 0.48mGy, which further decreased to 0.36, 0.24 and 0.17mGy for reference tube currents of 60, 40 and 20mAs. Image noise was 13HU for sequential acquisition and 18-34HU for the high-pitch spiral acquisition depending on the reference tube current. The high-pitch spiral acquisition resulted in a moderate relative underestimation of calcium scores by 4.2-5.1%, which was largely independent of the reference tube current in the investigated dose range.

High-pitch spiral acquisition with reduced tube current using 3rd generation dual-source CT allows performing coronary artery calcium scoring with a CTDI as low as 0.2mGy. This represents a six-fold dose reduction compared to standard sequential acquisition with a moderate underestimation of calcium scores by 4.2-5.1%.

The proposed protocol may enable accurate coronary artery calcium quantification with an effective dose of <0.1mSv, thus further increasing the acceptance of this test among clinicians and the public. 

McQuiston, A, Schoepf, U, de Cecco, C, Baumann, S, Renker, M, Meinel, F, Canstein, C, Ultra-Low Radiation Dose Coronary Calcium Scoring Using High-Pitch Spiral Acquisition and Reduced Tube Current at Third Generation Dual-Source CT.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14015067.html