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Logo of bmcmiBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Medical Imaging
 
BMC Med Imaging. 2012; 12: 14.
Published online Jul 2, 2012. doi:  10.1186/1471-2342-12-14
PMCID: PMC3443418
An alternative method for quantifying coronary artery calcification: the multi-ethnic study of atherosclerosis (MESA)
C Jason Liang,1 Matthew J Budoff,2 Joel D Kaufman,3 Richard A Kronmal,1 and Elizabeth R Browncorresponding author1,4
1Department of Biostatistics, University of Washington, Seattle, WA, USA
2Division of Cardiology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
3Environmental & Occupational Health Sciences, Medicine, and Epidemiology, University of Washington, Seattle, WA, USA
4Vaccine and Infectious Disease and Public Health Sciences Divisions, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
corresponding authorCorresponding author.
C Jason Liang: liangcj/at/uw.edu; Matthew J Budoff: mbudoff/at/labiomed.org; Joel D Kaufman: joelk/at/uw.edu; Richard A Kronmal: kronmal/at/uw.edu; Elizabeth R Brown: elizab/at/uw.edu
Received November 26, 2011; Accepted July 2, 2012.
Abstract
Background
Extent of atherosclerosis measured by amount of coronary artery calcium (CAC) in computed tomography (CT) has been traditionally assessed using thresholded scoring methods, such as the Agatston score (AS). These thresholded scores have value in clinical prediction, but important information might exist below the threshold, which would have important advantages for understanding genetic, environmental, and other risk factors in atherosclerosis. We developed a semi-automated threshold-free scoring method, the spatially weighted calcium score (SWCS) for CAC in the Multi-Ethnic Study of Atherosclerosis (MESA).
Methods
Chest CT scans were obtained from 6814 participants in the Multi-Ethnic Study of Atherosclerosis (MESA). The SWCS and the AS were calculated for each of the scans. Cox proportional hazards models and linear regression models were used to evaluate the associations of the scores with CHD events and CHD risk factors. CHD risk factors were summarized using a linear predictor.
Results
Among all participants and participants with AS > 0, the SWCS and AS both showed similar strongly significant associations with CHD events (hazard ratios, 1.23 and 1.19 per doubling of SWCS and AS; 95% CI, 1.16 to 1.30 and 1.14 to 1.26) and CHD risk factors (slopes, 0.178 and 0.164; 95% CI, 0.162 to 0.195 and 0.149 to 0.179). Even among participants with AS = 0, an increase in the SWCS was still significantly associated with established CHD risk factors (slope, 0.181; 95% CI, 0.138 to 0.224). The SWCS appeared to be predictive of CHD events even in participants with AS = 0, though those events were rare as expected.
Conclusions
The SWCS provides a valid, continuous measure of CAC suitable for quantifying the extent of atherosclerosis without a threshold, which will be useful for examining novel genetic and environmental risk factors for atherosclerosis.
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