MRI-based R2* mapping in patients with suspected or known iron overload

Abstract

Purpose R2* relaxometry is a quantitative method for assessment of iron overload. The purpose is to analyze the cross-sectional relationships between R2* in organs across patients with primary and secondary iron overload. Secondary analyses were conducted to analyze R2* according to treatment regimen. Methods This is a retrospective, cross-sectional, institutional review board-approved study of eighty-one adult patients with known or suspected iron overload. R2* was measured by segmenting the liver, spleen, bone marrow, pancreas, renal cortex, renal medulla, and myocardium using breath-hold multi-echo gradient-recalled echo imaging at 1.5\xa0T. Phlebotomy, transfusion, and chelation therapy were documented. Analyses included correlation, Kruskal–Wallis, and post hoc Dunn tests. p \u2009<\u20090.01 was considered significant. Results Correlations between liver R2* and that of the spleen, bone marrow, pancreas, and heart were respectively 0.49, 0.33, 0.27, and 0.34. R2* differed between patients with primary and secondary overload in the liver ( p \u2009<\u20090.001), spleen ( p \u2009<\u20090.001), bone marrow ( p \u2009<\u20090.01), renal cortex ( p \u2009<\u20090.001), and renal medulla ( p \u2009<\u20090.001). Liver, spleen, and bone marrow R2* were higher in thalassemia than in hereditary hemochromatosis (all p \u2009<\u20090.01). Renal cortex R2* was higher in sickle cell disease than in hereditary hemochromatosis ( p \u2009<\u20090.001) and in thalassemia ( p \u2009<\u20090.001). Overall, there was a trend toward lower liver R2* in patients assigned to phlebotomy and higher liver R2* in patients assigned to transfusion and chelation therapy. Conclusion R2* relaxometry revealed differences in degree or distribution of iron overload between organs, underlying etiologies, and treatment.