R2 versus HIC estimated by biopsy and by R2^*. R2 versus iron (Figure 2) has been replotted to include all 102 iron overloaded patients (132 examinations). HIC was estimated by R2^* (solid dots) in all examinations and by biopsy (+ signs) in 20 patients (22 examinations). Open circle represents mean R2 from 13 control subjects, plotted using an HIC value estimated from normative data (no biopsy). R2 follows a curvilinear relationship with HIC that is continuous with the mean value observed in non-iron-overloaded subjects. Solid line denotes calibration curve empirically derived by St Pierre et al.18 Agreement between this curve and estimated HIC was excellent for both biopsy-estimated iron (R = 0.97) and R2^*-estimated iron (R = 0.96). All repeat MRI and biopsy examinations as well as control data were excluded from statistical calculations.