Improving fMRI in signal drop-out regions at 7 T by using tailored radio-frequency pulses: application to the ventral occipito-temporal cortex

Catarina Rua, Stephen J. Wastling, Mauro Costagli, Mark R. Symms, Laura Biagi, Mirco Cosottini, Alberto Del Guerra, Michela Tosetti, Gareth J. Barker

Research output: Contribution to journalArticle

Abstract

Objective: Signal drop-off occurs in echo-planar imaging in inferior brain areas due to field gradients from susceptibility differences between air and tissue. Tailored-RF pulses based on a hyperbolic secant (HS) have been shown to partially recover signal at 3 T, but have not been tested at higher fields. Materials and methods: The aim of this study was to compare the performance of an optimized tailored-RF gradient-echo echo-planar imaging (TRF GRE-EPI) sequence with standard GRE-EPI at 7 T, in a passive viewing of faces or objects fMRI paradigm in healthy subjects. Results: Increased temporal-SNR (tSNR) was observed in the middle and inferior temporal lobes and orbitofrontal cortex of all subjects scanned, but elsewhere tSNR decreased relative to the standard acquisition. In the TRF GRE-EPI, increased functional signal was observed in the fusiform, lateral occipital cortex, and occipital pole, regions known to be part of the visual pathway involved in face-object perception. Conclusion: This work highlights the potential of TRF approaches at 7 T. Paired with a reversed-gradient distortion correction to compensate for in-plane susceptibility gradients, it provides an improved acquisition strategy for future neurocognitive studies at ultra-high field imaging in areas suffering from static magnetic field inhomogeneities.

Original languageEnglish
Pages (from-to)1-11
Number of pages11
JournalMagnetic Resonance Materials in Physics, Biology and Medicine
DOIs
Publication statusAccepted/In press - Sep 20 2017

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Keywords

  • Functional MRI
  • Signal drop-out recovery
  • Tailored radio-frequency pulse
  • Ultra high field

ASJC Scopus subject areas

  • Biophysics
  • Radiological and Ultrasound Technology
  • Radiology Nuclear Medicine and imaging

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