Is coronary artery calcium mass related to Agatston score?

The objective of this study was to investigate the relationship between the coronary calcium mass and Agatston score measured on multidetector row computed tomography.

Eighty-three consecutive subjects (60 men and 23 women) referred for coronary screening were examined prospectively by electrocardiogram-triggered sequential multidetector row computed tomography scan (4 x 2.5-mm collimation). Their coronary calcium was quantitated by means of the Agatston scoring and mass method. The values of score and mass were transformed by taking the natural logarithm (ln(value + 1)) to reduce skewness. The relationship between the mass and score was analyzed with multiple regression analysis.

Fifty-one subjects had a total of 328 calcified lesions detected and measured. The relationship between the calcium mass and score in 51 subjects conformed well to a linear relationship (r2 = 0.96). When analyzed in the total of 328 lesions, the relationship had a good empiric fit with a nonlinear (quadratic) model (r2 = 0.96). The best-fit equation was ln(lesion mass + 1) = -0.87 + 0.67 x ln(lesion score + 1) + 0.10 x (ln(lesion score + 1) - 2.86)2. This relationship was consistent in different coronary vessels and at different heart levels (r2 = 0.96 - 0.99), although there was a higher image noise at lower heart levels (paired t-tests, P < .0001).

A nonlinear (quadratic) relationship existed strongly and consistently between coronary calcium mass and score, demonstrating a possible cross-sectional conversion between the two measurements.