Martin J. Willemink MD, Presenter: Nothing to Disclose

Bronislaw Abramiuc, Abstract Co-Author: Nothing to Disclose

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

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

Marcel Greuter 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

Recent guidelines from the American Heart Association recommend coronary calcium scoring (CCS) with computed tomography (CT) for patients at low-to-intermediate and intermediate cardiovascular risk. Previous studies have shown that obesity is related to increased CCS. With the increasing prevalence of obesity it is essential to assess whether CCS is performed adequately in heavy patients. However, the effect of body size has not been evaluated yet on routinely used protocols of current state-of-the-art CT systems. The purpose of the current study is to evaluate the effect of body size on CCS as assessed with new-generation CT systems from the four major vendors.

An anthropomorphic chest phantom containing 100 small calcifications (diameters 0.5-2.0 mm) was evaluated with and without an extension ring using routine protocols of state-of-the-art CT systems from four vendors. The extension ring was used to mimic a heavy patient. Image acquisition was repeated five times with small translations and/or rotations. Routine acquisition protocols for both medium and heavy patients were used. CCS was quantified as Agatston and mass scores with software from the same manufacturer as the CT systems.

The medium sized phantom resulted in median (interquartiles) Agatston scores of 10 (9-35), 113 (72-133), 34 (30-37) and 87 (85-89) for Philips, GE, Siemens and Toshiba, respectively. Mass scores were 4 (3-9), 18 (14-21), 8 (8-9) and 20 (20-20) mg, respectively. Adding the extension ring resulted in reduced Agatston scores for all vendors (17-86%) and mass scores for three vendors (11-86%). Median Agatston scores decreased to 9 (5-10), 16 (15-20), 27 (24-32) and 45 (29-53) units, and median mass scores increased for Philips to 4 (4-6) and decreased for the other vendors to 2 (2-4), 8 (7-8) and 10 (8-13) mg, respectively.

This multivendor phantom study showed that CCS is underestimated up to 86% at a larger body size. Therefore, a correction factor should be used for CCS of heavy patients, or image acquisition protocols should be standardized across platforms of different vendors.

Body size is an important determinant of the coronary calcium score and may impact perceived risk for future cardiovascular events.

Willemink, M, Abramiuc, B, van der Werf, N, Willems, T, Greuter, M, Leiner, T, Coronary Calcium Scores are Underestimated at a Large Body Size: A Multivendor Phantom Study.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045418.html