Schematic illustrating time lag detection and quantification. Center of mass is calculated for each time course by finding the average liver iron and cardiac R2* for all of the consecutive time points (T1-T5), and the magnitude (area under the curve) and direction of the time course “rotation” is determined. (Top) No rotation, area = 0: HIC and cardiac R2* have a linear relationship with no delays. (Middle) Counterclockwise (positive) rotation indicates that cardiac R2* lags liver iron changes. (Bottom) Clockwise (negative) rotation indicates that HIC lags cardiac R2*.