title: Hepatic hemosiderosis in non-human primates: quantification of liver iron using different field strengths.
abstract: Using a non-human primate model of idiopathic hemochromatosis, hemosiderin-induced T2 shortening of the liver was assessed at nine different field strengths over a range of 0.05 to 1.5 Tesla. The 1/T2 values increased linearly with field strength, with all specimens having approximately the same zero-field intercept. The slope of the field increase, termed "field-dependent T2 proton relaxation enhancement (PRE)", appeared to be proportional to the chemically determined tissue iron content, viz. 10.8 s-1T-1(mg Fe/g wet tissue)-1. The correlation between iron content and field-dependent T2 PRE (r = 0.94) was better than the correlation between iron content and 1/T2 values obtained at single field strengths. For livers containing > or = 2 mg Fe/g wet weight, biexponential T2 relaxation behavior emerged at higher field strengths, with the short T2 component (intracellular water) exhibiting a linear dependence of 1/T2 on field, while T2 of the long component (extracellular/sinusoidal water) was nearly field-independent. After maceration of the specimens, all T2 relaxation curves became monoexponential, including those for high iron content at high field strengths. The present data suggest that the use of double-field MR imaging to assess the field-dependent T2 PRE has potential for specific quantification of (liver) tissue iron stores.
authors.affiliation: Laboratory of Diagnostic Radiology Research, National Institutes of Health, Bethesda, MD 20892-1074, USA.
authors.forename: J W
authors.initials: JW
authors.lastname: Bulte
authors.forename: G F
authors.initials: GF
authors.lastname: Miller
authors.forename: J
authors.initials: J
authors.lastname: Vymazal
authors.forename: R A
authors.initials: RA
authors.lastname: Brooks
authors.forename: J A
authors.initials: JA
authors.lastname: Frank
mesh_terms: D000818:Animals; D001706:Biopsy; D002144:Callithrix; D004195:Disease Models, Animal; D006486:Hemosiderosis / Q000378:metabolism* / Q000473:pathology; D007501:Iron / Q000032:analysis*; D008107:Liver Diseases / Q000378:metabolism* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D007501:Iron