Estimation of liver T*2 in transfusion-related iron overload in patients with weighted least squares T*2 IDEAL

Abstract

MRI imaging of hepatic iron overload can be achieved by estimating T 2* values using multiple-echo sequences. The purpose of this work is to develop and clinically evaluate a weighted least squares algorithm based on T2* Iterative Decomposition of water and fat with Echo Asymmetry and Least-squares estimation (IDEAL) technique for volumetric estimation of hepatic T2* in the setting of iron overload. The weighted least squares T2* IDEAL technique improves T 2* estimation by automatically decreasing the impact of later, noise-dominated echoes. The technique was evaluated in 37 patients with iron overload. Each patient underwent (i) a standard 2D multiple-echo gradient echo sequence for T2* assessment with nonlinear exponential fitting, and (ii) a 3D T2* IDEAL technique, with and without a weighted least squares fit. Regression and Bland-Altman analysis demonstrated strong correlation between conventional 2D and T2* IDEAL estimation. In cases of severe iron overload, T2* IDEAL without weighted least squares reconstruction resulted in a relative overestimation of T 2* compared with weighted least squares. Copyright © 2011 Wiley-Liss, Inc.