T1 independent, T2* corrected MRI with accurate spectral modeling for quantification of fat: Validation in a fat-water-SPIO phantom

Abstract

Purpose: To validate a T1-independent, T2*- corrected fat quantification technique that uses accurate spectral modeling of fat using a homogeneous fat-water-SPIO phantom over physiologically expected ranges of fat percentage and T2* decay in the presence of iron overload. Materials and Methods: A homogeneous gel phantomconsisting of vials with known fat-fractions and iron concentrations is described. Fat-fraction imaging was performed using a multiecho chemical shift-based fat-water separation method (IDEAL), and various reconstructions were performed to determine the impact of T2* correction and accurate spectral modeling. Conventional two-point Dixon (inphase/ out-of-phase) imaging and MR spectroscopy were performed for comparison with known fat-fractions. Results: The best agreement with known fat-fractions over the full range of iron concentrations was found when T2* correction and accurate spectral modeling were used. Conventional two-point Dixon imaging grossly underestimated fat-fraction for all T2* values, but particularly at higher iron concentrations. Conclusion: This work demonstrates the necessity of T2* correction and accurate spectral modeling of fat to accurately quantify fat using MRI. © 2009 Wiley-Liss, Inc.