title: Noninvasive measurement and imaging of liver iron concentrations using proton magnetic resonance.
abstract: Measurement of liver iron concentration (LIC) is necessary for a range of iron-loading disorders such as hereditary hemochromatosis, thalassemia, sickle cell disease, aplastic anemia, and myelodysplasia. Currently, chemical analysis of needle biopsy specimens is the most common accepted method of measurement. This study presents a readily available noninvasive method of measuring and imaging LICs in vivo using clinical 1.5-T magnetic resonance imaging units. Mean liver proton transverse relaxation rates (R2) were measured for 105 humans. A value for the LIC for each subject was obtained by chemical assay of a needle biopsy specimen. High degrees of sensitivity and specificity of R2 to biopsy LICs were found at the clinically significant LIC thresholds of 1.8, 3.2, 7.0, and 15.0 mg Fe/g dry tissue. A calibration curve relating liver R2 to LIC has been deduced from the data covering the range of LICs from 0.3 to 42.7 mg Fe/g dry tissue. Proton transverse relaxation rates in aqueous paramagnetic solutions were also measured on each magnetic resonance imaging unit to ensure instrument-independent results. Measurements of proton transverse relaxivity of aqueous MnCl2 phantoms on 13 different magnetic resonance imaging units using the method yielded a coefficient of variation of 2.1%.
authors.affiliation: School of Physics, University of Western Australia, Perth, Australia. stpierre@physics.uwa.edu.au
authors.forename: Timothy G
authors.initials: TG
authors.lastname: St Pierre
authors.forename: Paul R
authors.initials: PR
authors.lastname: Clark
authors.forename: Wanida
authors.initials: W
authors.lastname: Chua-anusorn
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Fleming
authors.forename: Gary P
authors.initials: GP
authors.lastname: Jeffrey
authors.forename: John K
authors.initials: JK
authors.lastname: Olynyk
authors.forename: Pensri
authors.initials: P
authors.lastname: Pootrakul
authors.forename: Erin
authors.initials: E
authors.lastname: Robins
authors.forename: Robert
authors.initials: R
authors.lastname: Lindeman
mesh_terms: D001706:Biopsy; D002712:Chlorides; D006801:Humans; D007501:Iron / Q000378:metabolism*; D019190:Iron Overload / Q000378:metabolism / Q000473:pathology*; D008099:Liver / Q000378:metabolism / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D017895:Manganese Compounds; D019047:Phantoms, Imaging; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D002712:Chlorides; D017895:Manganese Compounds; D011522:Protons; D007501:Iron; C025340:manganese chloride