|Baseline CAC||CAC Progression|
|AU||Reference measure||Absolute change||Variability increases as baseline of absolute CAC increases (18)|
|CVS||Percentage change||Underestimates changes at higher levels of baseline CAC (19)|
|CAC mass||54% reduced vs. AU (14)||Log transformation||Variability still depends on the mean CVS (rho = −0.66, p < 0.0001) (18)|
|Square root transformation (Hokanson)||Removes the relation between variability and the mean CVS (rho = 0.09, p < 0.15) (18)|
|Regression method||Variance increases with increased mean CAC area (20)|
AU = Agatston units; CAC = coronary artery calcification; CVS = calcium volume score.