Figure 1

A) Box plot of percentage of the desired flip angle achieved in the cardiac ROI before and after RF-shimming. Correlation of cross-sectional area with achieved flip angle (%) (B) and with ratio of post-to-pre RF-shimming improvement in achieved flip angle (C). Significant correlations are observed indicating that animal size reduces achieved flip angle (as expected), but also that RF shimming has a more positive effect when imaging larger animals.