title: MRI R2 and R2* mapping accurately estimates hepatic iron concentration in transfusion-dependent thalassemia and sickle cell disease patients.
abstract: Measurements of hepatic iron concentration (HIC) are important predictors of transfusional iron burden and long-term outcome in patients with transfusion-dependent anemias. The goal of this work was to develop a readily available, noninvasive method for clinical HIC measurement. The relaxation rates R2 (1/T2) and R2* (1/T2*) measured by magnetic resonance imaging (MRI) have different advantages for HIC estimation. This article compares noninvasive iron estimates using both optimized R2 and R2* methods in 102 patients with iron overload and 13 controls. In the iron-overloaded group, 22 patients had concurrent liver biopsy. R2 and R2* correlated closely with HIC (r2 > or = .95) for HICs between 1.33 and 32.9 mg/g, but R2 had a curvilinear relationship to HIC. Of importance, the R2 calibration curve was similar to the curve generated by other researchers, despite significant differences in technique and instrumentation. Combined R2 and R2* measurements did not yield more accurate results than either alone. Both R2 and R2* can accurately measure hepatic iron concentration throughout the clinically relevant range of HIC with appropriate MRI acquisition techniques.
authors.affiliation: Department of Pediatrics, Children's Hospital Los Angeles, 4650 Sunset Blvd, Los Angeles, CA 90027-0034, USA. jwood@chla.usc.edu
authors.forename: John C
authors.initials: JC
authors.lastname: Wood
authors.forename: Cathleen
authors.initials: C
authors.lastname: Enriquez
authors.forename: Nilesh
authors.initials: N
authors.lastname: Ghugre
authors.forename: J Michael
authors.initials: JM
authors.lastname: Tyzka
authors.forename: Susan
authors.initials: S
authors.lastname: Carson
authors.forename: Marvin D
authors.initials: MD
authors.lastname: Nelson
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Coates
mesh_terms: D000293:Adolescent; D000328:Adult; D000755:Anemia, Sickle Cell / Q000378:metabolism* / Q000628:therapy; D001803:Blood Transfusion; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D007501:Iron / Q000032:analysis*; D019190:Iron Overload; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D013789:Thalassemia / Q000378:metabolism* / Q000628:therapy
chemical_list: D007501:Iron