Spleen R2 and R2* in iron‐overloaded patients with sickle cell disease and thalassemia major

Abstract

Purpose To evaluate the magnetic properties of the spleen in chronically transfused, iron‐overloaded patients with sickle cell disease (SCD) and thalassemia major (TM) and to compare splenic iron burdens to those in the liver, heart, pancreas, and kidneys. Materials and Methods A retrospective analysis of 63 TM and 46 SCD patients was performed. Spleen R2 and R2* values were calculated from spin‐echo and gradient‐echo images collected between April 2004 and September 2007. Results The spleen showed a different R2–R2* relationship than that previously established for the liver. At high iron concentrations (R2* > 300 Hz), spleen R2 was lower than predicted for liver. The proportion of splenic to hepatic iron content was greater in SCD patients compared with TM patients (23.8% vs. 13.8%). A weak association was found between splenic and liver iron—this association was stronger in SCD patients. Little correlation was found between splenic iron and extrahepatic R2* values. Conclusion For spleen and liver tissue with the same R2* value, splenic R2 was significantly lower than hepatic R2, particularly for R2* > ≈300 Hz. Splenic iron levels have little predictive value for R2* values of heart, pancreas, and kidney. J. Magn. Reson. Imaging 2009;29:357–364.