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Abstract #2397

A Robust Field-map Estimation Method Using Dual-echo GRE with Bipolar Readout Gradient Structure

Yeo D, Chenevert T, Fessler J, Kim B
University of Michigan, University of Michigan Medical School

Field-maps are generally required to correct for field-inhomogeneity artifacts like geometric distortion in EPI images and blurring in spiral acquisitions. The standard static field-map estimation method using two separate acquisitions with different echo times is prone to motion errors due to the relatively long period of time between the two acquisitions. A simple phase error correction technique to estimate a field-map from a dual-echo GRE sequence is presented. A dual-echo sequence offers a more efficient and accurate way of generating a magnetic field-map compared to two separate single-echo acquisitions since the data are collected from a consistent subject position, therefore minimizing motion artifacts, without the additional scan time. A pulse sequence that is typically used to acquire fat-water in-phase and out-of-phase gradient echo images simultaneously is used without any modification. The dual echo fast gradient echo (DEFGRE) sequence utilizes two back-to-back continuous readout gradients,