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Abstract #1583

The Role of Eddy Currents in EPI Thermometry for Transcranial MR-Guided Focused Ultrasound

Silke M. Lechner-Greite1, Beat Werner2, Lorne W. Hofstetter3, Timo Schirmer1, Dixon W Thomas3, Yoav Medan4, Desmond Yeo3

1Diagnostics and Biomedical Technologies, GE Global Research Europe, Garching n. Munich, Germany; 2MR-Center, University Childrens Hospital Zurich, Zurich, Switzerland; 3MRI Laboratory, GE Global Research Niskayuna, Albany, NY, United States; 4Insightec, Tirat Carmel, Israel

We report on echo planar imaging for fast image tracking and MR thermometry in the presence of a transcranial focused ultrasound setup, where the EPI images suffer from strong spatial distortions due to eddy currents induced in the ground plane of the transducer setup. Alternative ground plane segmentation patterns are evaluated to reduce the eddy current artifacts. Performance is predicted by finite element simulation and verified by EPI scans of a spherical phantom wrapped with thin copper strips of different segmentation patterns to mimic different transducer ground plane configurations.