Non-invasive measurement of liver iron concentration using 3-Tesla magnetic resonance imaging: validation against biopsy

Objectives To evaluate the performance and limitations of the R2* and signal intensity ratio (SIR) methods for quantifying liver iron concentration (LIC) at 3 T. Methods A total of 105 patients who underwent a liver biopsy with biochemical LIC (LICb) were included prospectively. All patients underwent a 3-T MRI scan with a breath-hold multiple-echo gradient-echo sequence (mGRE). LIC calculated by 3-T SIR algorithm (LICSIR) and by R2* (LICR2*) were correlated with LICb. Sensitivity and specificity were calculated. The comparison of methods was analysed for successive classes. Results LICb was strongly correlated with R2* (r = 0.95, p < 0.001) and LICSIR (r = 0.92, p < 0.001). In comparison to LICb, LICR2* and LICSIR detect liver iron overload with a sensitivity/specificity of 0.96/0.93 and 0.92/0.95, respectively, and a bias +/- SD of 7.6 +/- 73.4 and 14.8 +/- 37.6 mu mol/g, respectively. LICR2* presented the lowest differences for patients with LICb values under 130 mu mol/g. Above this value, LICSIR has the lowest differences. Conclusions At 3 T, R2* provides precise LIC quantification for lower overload but the SIR method is recommended to overcome R2* limitations in higher overload. Our software, available at www.mrquantif.org, uses both methods jointly and selects the best one.