Gradient Distortion Correction for Low Frequency Current Density Imaging

Abstract

Current density imaging (CDI) is a technique that uses magnetic resonance imaging (MRI) to measure the distribution of externally applied electric current inside tissues. However, CDI processing is rendered inaccurate by the distortion caused by the nonlinearity of MRI gradient fields. The distortion interferes with the proper registration and the curl operation required for correct computation of current density vectors. To address this problem, a calibration phantom was imaged to determine the distortion and to generate calibration maps to correct the distorted current density images. A validation experiment involving a cylindrical phantom was performed to verify this method. Comparison of the distorted and corrected images reveals that both the registration and the curl operation are successfully corrected by this method.