Signal-intensity-ratio MRI accurately estimates hepatic iron load in hemodialysis patients

BACKGROUND Iron overload, diagnosed by means of magnetic resonance imaging (MRI), is an increasingly recognized disorder in hemodialysis patients. Specific MRI protocols have been shown to provide a reliable estimation of tissue iron content in non-renal patient populations but have not been validated in dialysis patients. Such validation studies require liver biopsy for histological comparison, but this invasive and risky procedure raises ethical concerns, especially regarding frail patients with end-stage renal disease. MATERIALS AND METHODS We compared in a pilot study Scheuer's histological classification and Deugnier and Turlin's histological classification of iron overload (Perls staining) with signal-intensity-ratio MRI values obtained with the Rennes University algorithm in 11 hemodialysis patients in whom liver biopsy was formally indicated for their medical follow-up. RESULTS For Scheuer's histological classification, the Wilcoxon non-parametric matched-pairs test showed no significant difference in the ranking of iron overload by the two methods eg histology and MRI (sum of ranks = 1.5; p = 1). The MRI and Scheuer's histological classifications were tightly correlated (rho = 0.866, p = 0.0035, Spearman's coefficient), as were the absolute liver iron concentrations (LIC) at MRI (rho = 0.860, p = 0.0013, Spearman's coefficient). The absolute liver iron concentrations at MRI were also highly correlated with Deugnier and Turlin's histological scoring (rho = 0.841, p = 0.0033, Spearman's coefficient). CONCLUSIONS This pilot study shows that liver iron determination based on signal-intensity-ratio MRI (Rennes University algorithm) very accurately identifies iron load in hemodialysis patients, by comparison with liver histology.