LIVER IRON QUANTIFICATION - STUDIES IN AQUEOUS IRON SOLUTIONS, IRON-OVERLOADED RATS, AND PATIENTS WITH HEREDITARY HEMOCHROMATOSIS

For the noninvasive liver iron quantification by MRI in human iron ove rload diseases, fundamental proton relaxation mechanisms were studied in aqueous solutions with ferritin and other iron compounds, in experi mentally iron overloaded rats, and in patients with iron overload dise ases. MR-relaxation rates as a function of iron concentrations in the range of 0-7.5 mg Fe/g aqueous iron solutions, 0-5.4 mg Fe/g rat liver in vivo, and 0.16-4.9 mg Fe/g human liver in vivo were determined fro m multi- and sets of single-spin echo sequences (1.5 T imager). As pre dicted by theory, transverse relaxation Fates (1/T-2) in aqueous iron solutions, in liver tissue of rats, and in human liver tissue increase d linearly with the iron concentration. A preliminary calibration for the liver iron quantification by MRI was performed from in vivo measur ements of liver 1/T-2-relaxation rates and liver iron quantification b y atomic absorption spectroscopy in biopsies from 13 patients. With th e single spin-echo method, precise in vivo liver iron quantification i n humans also above 2.0 mg Fe/g liver tissue (T-2 < 15 ms) should be a ccomplished on any imager with shortest spin-echo time available, at l east TE < 20 ms.