title: Spleen R2 and R2* in iron-overloaded patients with sickle cell disease and thalassemia major.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  For spleen and liver tissue with the same R2* value, splenic R2 was significantly lower than hepatic R2, particularly for R2* > approximately 300 Hz. Splenic iron levels have little predictive value for R2* values of heart, pancreas, and kidney.
authors.affiliation: Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
authors.forename: Casey J
authors.initials: CJ
authors.lastname: Brewer
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Coates
authors.forename: John C
authors.initials: JC
authors.lastname: Wood
mesh_terms: D000293:Adolescent; D000328:Adult; D000755:Anemia, Sickle Cell / Q000150:complications*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D019190:Iron Overload / Q000150:complications*; D007668:Kidney / Q000737:chemistry; D008099:Liver / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009206:Myocardium / Q000737:chemistry; D010179:Pancreas / Q000737:chemistry; D012044:Regression Analysis; D012189:Retrospective Studies; D013154:Spleen / Q000737:chemistry*; D017086:beta-Thalassemia / Q000150:complications*