Gradient-echo EPI using a high-degree shim insert coil at 7 T: Implications for BOLD fMRI.

ABSTRACT:

Purpose

To quantitatively assess the effects of high degree and order (1^st -4^th+ ) relative to 1^st -2^nd degree B₀ shimming at 7 Tesla (T) on gradient-echo echo planar imaging (GE-EPI) and blood-oxygen-level dependent (BOLD) activation.

Methods

Simulations and GE-EPI were performed at (2mm)³ and (3mm)³ resolution, evaluating the temporal signal-to-noise ratio (tSNR), transverse relaxivity ( R2*), BOLD % signal change and activated pixel counts in a breath-hold task.

Results

Comparing the 1^st -4^th+ degree with 1^st -2^nd degree shimmed B₀ maps generated spatially varying regions of Δ|B0|=|B01-2|-|B01-4+|. As binned in 10-Hz intervals, the two

SUBMITTER: Kim T 

PROVIDER: S-EPMC6084307 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature