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Abstract #4531

Frequency Mapping without Phase Wraps

Issel Anne Lei Lim1,2, Jonathan A. D. Farrell2,3, Craig K. Jones2,3, Deepti S. Vikram2,3, Carlos Augusto Renjifo4, Peter C. M. van Zijl2,3

1Biomedical Engineering, Johns Hopkins University, Baltimore, MD, United States; 2F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States; 3Neuroscience Section, Division of MR Research, Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, United States; 4The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, United States

Susceptibility imaging currently employs gradient echo imaging (GRE) to measure local field (frequency) differences from spatial differences in signal phase. We compare single-echo GRE to the WAter Saturation Shift Referencing (WASSR) method, which uses direct water saturation as a function of RF pulse offset frequency to pinpoint spatial differences in resonance frequency. Results from five normal volunteers show comparable frequency shifts at 3T in frequency maps generated from both methods.