Meeting Banner
Abstract #3772

Parallel Transmission Z-Shimming to Compensate GE-EPI Signal Voids at 7 Tesla

Benedikt A. Poser1, Soeren Johst2, Weiran Deng1, Stephan Orzada2, Mark E. Ladd2, 3, Victor Andrew Stenger1

1John A Burns School of Medicine, University of Hawaii, Honolulu, HI, United States; 2Erwin L Hahn Institute for Magnetic Resonance Imaging, University Duisburg-Essen, Essen, Germany; 3Department of Diagnostic and Interventional Radiology and Neuroradiology,, University Hospital Essen, Essen, Germany

Gradient-echo BOLD fMRI suffers signal voids in regions of strong susceptibility variation e.g. near ear canals and frontal sinuses. z-shimming can correct this by applying a z-gradient moment to counteract the local background gradient. The global correction affects all spins and dephases originally intact signal, hence an intermediate compromise is required.

Abstract PDF Presentation Video

Keywords

achieved activation affect allows always appear applied applying approval array arrows asymmetry attenuation audience beyond bilateral bilaterally blip bold bottom brains called canals channel channels closest coarse coil compensate compensation component consistently constable corrections corrects cortex custom default define dependent derived detection diagnostic differentiation distant double dual ears eight element elsewhere entire equivalent excitation explore extent falls feat field final flash frontal furthermore gradient grants head hence impractically improve individually induced intact limitation local localized long loss mainly maps mark matrix meander medicine methodologists moment moments near note numerical obdurate originally parallel performance phantom physicists poser preferable profile profiles prominent protocol pulse pulses recorded reduce reduction reflected refocusing relatively satisfactory school select sensitivities sensitivity shim shimmed shimming shims short shot since sinuses slice slices somewhat spatial specified spokes step still straightforward subjects surface surrounding susceptibility take target tilt transmission transmit turbo typically unacceptable unaffected unbalancing unique unlike vicinity void voids white