Objectives
We validate a novel CT coronary angiography (CCTA) coronary calcium scoring system.
Methods
Calcium was quantified on CCTA images using a new patient-specific attenuation threshold: mean + 2SD of intra-coronary contrast density (HU). Using 335 patient data sets a conversion factor (CF) for predicting CACS from CCTA scores (CCTAS) was derived and validated in a separate cohort (n = 168). Bland–Altman analysis and weighted kappa for MESA centiles and Agatston risk groupings were calculated.
Results
Multivariable linear regression yielded a CF: CACS = (1.185 × CCTAS) + (0.002 × CCTAS × attenuation threshold). When applied to CCTA data sets there was excellent correlation (r = 0.95; p < 0.0001) and agreement (mean difference −10.4 [95 % limits of agreement −258.9 to 238.1]) with traditional calcium scores. Agreement was better for calcium scores below 500; however, MESA percentile agreement was better for high risk patients. Risk stratification was excellent (Agatston groups k = 0.88 and MESA centiles k = 0.91). Eliminating the dedicated CACS scan decreased patient radiation exposure by approximately one-third.
Conclusion
CCTA calcium scores can accurately predict CACS using a simple, individualized, semiautomated approach reducing acquisition time and radiation exposure when evaluating patients for CAD. This method is not affected by the ROI location, imaging protocol, or tube voltage strengthening its clinical applicability.
Publication information
Pavitt CW, Harron K, Lindsay AC, Zielke S, Ray R, Gordon D, Rubens MB, Padley SP, Nicol ED et al., 2016, Technical feasibility and validation of a coronary artery calcium scoring system using CT coronary angiography images, EUROPEAN RADIOLOGY, Vol: 26, Pages: 1493-1502, ISSN: 0938-7994