High spatial resolution brain functional MRI using submillimeter balanced steady-state free precession acquisition
Journal
Medical Physics
Journal Volume
40
Journal Issue
12
Date Issued
2013
Author(s)
Abstract
Purpose: One of the technical advantages of functional magnetic resonance imaging (fMRI) is its precise localization of changes from neuronal activities. While current practice of fMRI acquisition at voxel size around 3 × 3 × 3 mm3 achieves satisfactory results in studies of basic brain functions, higher spatial resolution is required in order to resolve finer cortical structures. This study investigated spatial resolution effects on brain fMRI experiments using balanced steady-state free precession (bSSFP) imaging with 0.37 mm3 voxel volume at 3.0 T. Methods: In fMRI experiments, full and unilateral visual field 5 Hz flashing checkerboard stimulations were given to healthy subjects. The bSSFP imaging experiments were performed at three different frequency offsets to widen the coverage, with functional activations in the primary visual cortex analyzed using the general linear model. Variations of the spatial resolution were achieved by removing outer k-space data components. Results: Results show that a reduction in voxel volume from 3.44 × 3.44 × 2 mm3 to 0.43 × 0.43 × 2 mm 3 has resulted in an increase of the functional activation signals from (7.7 ± 1.7)% to (20.9 ± 2.0)% at 3.0 T, despite of the threefold SNR decreases in the original images, leading to nearly invariant functional contrast-to-noise ratios (fCNR) even at high spatial resolution. Activation signals aligning nicely with gray matter sulci at high spatial resolution would, on the other hand, have possibly been mistaken as noise at low spatial resolution. Conclusions: It is concluded that the bSSFP sequence is a plausible technique for fMRI investigations at submillimeter voxel widths without compromising fCNR. The reduction of partial volume averaging with nonactivated brain tissues to retain fCNR is uniquely suitable for high spatial resolution applications such as the resolving of columnar organization in the brain. ? 2013 American Association of Physicists in Medicine.
Subjects
Balanced steady-state free precession (bssfp); Functional magnetic resonance imaging (fmri); High resolution
SDGs
Other Subjects
Biomedical signal processing; Brain; Chemical activation; Frequency allocation; Image resolution; Magnetic resonance imaging; Signal to noise ratio; Contrast to noise ratio; Functional activation; Functional magnetic resonance imaging; General linear modeling; High resolution; High spatial resolution; Partial volume averaging; Steady state free precessions; Functional neuroimaging; article; brain cortex; brain function; contrast to noise ratio; functional magnetic resonance imaging; human; human experiment; normal human; signal noise ratio; steady state; adult; brain; female; image processing; male; methodology; nuclear magnetic resonance imaging; physiology; Adult; Brain; Female; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Signal-To-Noise Ratio
Type
journal article