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

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 T 2 * Iterative Decomposition of water and fat with Echo Asymmetry and Least‐squares estimation (IDEAL) technique for volumetric estimation of hepatic T 2 * in the setting of iron overload. The weighted least squares T 2 * 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 T 2 * assessment with nonlinear exponential fitting, and (ii) a 3D T 2 * IDEAL technique, with and without a weighted least squares fit. Regression and Bland–Altman analysis demonstrated strong correlation between conventional 2D and T 2 * IDEAL estimation. In cases of severe iron overload, T 2 * IDEAL without weighted least squares reconstruction resulted in a relative overestimation of T 2 * compared with weighted least squares. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.