Niels R. van der Werf, Abstract Co-Author: Nothing to Disclose

Martin J. Willemink MD, Abstract Co-Author: Nothing to Disclose

Bronislaw Abramiuc, Abstract Co-Author: Nothing to Disclose

Tineke Petra Willems MD, PhD, Abstract Co-Author: Nothing to Disclose

Tim Leiner MD, PhD, Abstract Co-Author: Speakers Bureau, Koninklijke Philips NV Research Grant, Bayer AG Research Grant, Bracco Group

Marcel Greuter PhD, Presenter: Nothing to Disclose

The amount of coronary calcium per patient can be expressed as coronary calcium score (CCS) in computed tomography (CT). Coronary arteries can reach velocities up to 60 mm/s during the scan phase, which can influence the CCS. Also, new iterative reconstruction (IR) techniques, which allow the dose in CT to be reduced, influence the CCS. The purpose of the current study was to evaluate the influence of motion on CCS in IR CT for the high-end CT systems of four major vendors.

A calcium hydroxyapatite-containing cylinder (198.4 mm3, 157.1 and 38.5 mg calcifications) attached to a computer controlled lever was moved in the center of an anthropomorphic thorax phantom at velocities ranging from 0-60 mm/s. An extension ring around the thorax simulated an averaged sized patient. Clinical acquisition protocols were used on Brilliance iCT (Philips), Aquilion One (Toshiba), Discovery CT 750 HD (GE) and Somatom Definition Flash (Siemens). Image reconstruction was performed with filtered back projection (FBP) and increasing levels of IR. CCS was quantified as Agatston scores with the vendor’s software.

For the 157.1 mg calcification the FBP CCS was 414±12, 414±13, 427±30 and 460±11 at 0 mm/s for Philips, Siemens, GE and Toshiba respectively. At 60 mm/s scores increased 64-182% to 838±88, 682±73, 1205±128 and 940±47. The highest IR level resulted in 2-5% reduced CCS relative to FBP to 820±89, 645±72, 1176±125 and 918±44. For 38.5 mg calcification FBP CCS decreased 22-65% with increasing velocity for all vendors from 100±12, 96±12, 109±10 and 120±6 at 0 mm/s to 34±23, 75±20, 83±16 and 48±20 at 60 mm/s. The highest IR level resulted in 14-42% reduced CCS relative to FBP to 29±22, 43±20, 62±17 and 35±20.

The influence of motion on coronary calcium scores (CCS) is much larger than the influence of iterative reconstruction (IR). For fast moving arteries, CCS are overestimated up to 300% for high density calcifications and underestimated up to 65% for a low density calcifications compared to the static score. The influence of IR is relatively small at 5% for high density and 42% for low density calcifications.

Coronary calcium scores are highly depended on motion, density and CT system. The influence of iterative reconstruction is relative small.

van der Werf, N, Willemink, M, Abramiuc, B, Willems, T, Leiner, T, Greuter, M, Influence of Motion on Calcium Scores in Iterative Reconstructed CT: A Multivendor Dynamic Phantom Study.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14006529.html