FIGURE 6.  Correlation between MBF estimated from 1-¹¹C-acetate and MBF estimated from ¹⁵O-water (A) and the corresponding residual plot as a function of ¹⁵O-water MBF (B). No significant residual bias was observed. Mean residual error (MRE) was calculated as the average of the absolute difference between measured and predicted MBF values from the regression analysis in A.