Coronary calcium scores are systematically underestimated at a large chest size: A multivendor phantom study

• Published in: Journal of cardiovascular computed tomography 2015-09, Vol.9 (5), p.415-421
• Main Authors: Willemink, Martin J., MD, Abramiuc, Bronislaw, MSc, den Harder, Annemarie M., MD, van der Werf, Niels R., BSc, de Jong, Pim A., MD, PhD, Budde, Ricardo P.J., MD, PhD, Wildberger, Joachim E., MD, PhD, Vliegenthart, Rozemarijn, MD, PhD, Willems, Tineke P., MD, PhD, Greuter, Marcel J.W., PhD, Leiner, Tim, MD, PhD
• Format: Article
• Language: English
• Subjects: Agatston score; Cardiovascular; Chest size; Computed tomography; Coronary Angiography - instrumentation; Coronary Artery Disease - diagnostic imaging; Coronary calcium score; Coronary Vessels - diagnostic imaging; Equipment Design; Humans; Phantoms, Imaging; Predictive Value of Tests; Radiographic Image Interpretation, Computer-Assisted; Reproducibility of Results; Severity of Illness Index; Software; Thorax - anatomy & histology; Tomography Scanners, X-Ray Computed; Tomography, X-Ray Computed - instrumentation; Vascular Calcification - diagnostic imaging
• ISSN: 1934-5925; 1876-861X
• DOI: 10.1016/j.jcct.2015.03.010

Abstract Objective To evaluate the effect of chest size on coronary calcium score (CCS) as assessed with new-generation CT systems from 4 major vendors. Methods An anthropomorphic, small-sized (300 × 200 mm) chest phantom containing 100 small calcifications (diameters, 0.5–2.0 mm) was evaluated with and without an extension ring on state-of-the-art CT systems from 4 vendors. The extension ring was used to mimic a patient with a large chest size (400 × 300 mm). Image acquisition was repeated 5 times with small translations and/or rotations. Routine clinical acquisition and reconstruction protocols for small and large patients were used. CCS was quantified as Agatston and mass scores with vendor software. Results The small-sized phantom resulted in median (interquartiles) Agatston scores of 10 (9–35), 136 (123–146), 34 (30–37), and 87 (85–89) for Philips, GE, Siemens, and Toshiba, respectively. Mass scores were 4 mg (3–9 mg), 23 mg (21–27 mg), 8 mg (8–9 mg), and 20 mg (20–20 mg), respectively. Adding the extension ring resulted in reduced Agatston scores for all vendors (17%–48%) and mass scores for 2 vendors (11%–49%). Median Agatston scores decreased to 9 (5–10), 79 (60–80), 27 (24–32), and 45 (29–53) units, and median mass scores remained similar for Philips at 4 mg (4–6 mg) and Siemens at 8 mg (7–8 mg) and decreased for the other vendors to 13 mg (11–14 mg) and 10 mg (8–13 mg), respectively. Conclusion This multivendor phantom study showed that CCS can be underestimated up to 50% (49%–66%) for Agatston scores and 49% (36%–59%) for mass scores at a larger chest size, which may be relevant for women and large patients. However, CCS underestimation by chest size differs considerably by vendor.