title: Sensitivity to white matter FMRI activation increases with field strength.
abstract: Functional magnetic resonance imaging (fMRI) activation in white matter is controversial. Given that many of the studies that report fMRI activation in white matter used high field MRI systems, we investigated the field strength dependence of sensitivity to white matter fMRI activation. In addition, we evaluated the temporal signal to noise ratio (tSNR) of the different tissue types as a function of field strength. Data were acquired during a motor task (finger tapping) at 1.5 T and 4 T. Group and individual level activation results were considered in both the sensorimotor cortex and the posterior limb of the internal capsule. We found that sensitivity increases associated with field strength were greater for white matter than gray matter. The analysis of tSNR suggested that white matter might be less susceptible to increases in physiological noise related to increased field strength. We therefore conclude that high field MRI may be particularly advantageous for fMRI studies aimed at investigating activation in both gray and white matter.
authors.affiliation: Institute for Biodiagnostics (Atlantic), National Research Council, Halifax, Nova Scotia, Canada.
authors.forename: Erin L
authors.initials: EL
authors.lastname: Mazerolle
authors.forename: Jodie R
authors.initials: JR
authors.lastname: Gawryluk
authors.forename: Kim N H
authors.initials: KN
authors.lastname: Dillen
authors.forename: Steven A
authors.initials: SA
authors.lastname: Patterson
authors.forename: Kirk W
authors.initials: KW
authors.lastname: Feindel
authors.forename: Steven D
authors.initials: SD
authors.lastname: Beyea
authors.forename: M Tynan R
authors.initials: MT
authors.lastname: Stevens
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Newman
authors.forename: Matthias H
authors.initials: MH
authors.lastname: Schmidt
authors.forename: Ryan C N
authors.initials: RC
authors.lastname: D'Arcy
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005260:Female; D005385:Fingers / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D009044:Motor Cortex / Q000502:physiology*; D009413:Nerve Fibers, Myelinated / Q000502:physiology*; D059629:Signal-To-Noise Ratio