Ultrahigh Resolution fMRI at 7T Using Radial-Cartesian TURBINE Sampling.

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging (MRI)

Background:

• Functional Magnetic Resonance Imaging (fMRI) at 7 Tesla offers enhanced signal but faces challenges with image distortion and blurring.
• Conventional 3D Echo-Planar Imaging (EPI) can suffer from spatial inaccuracies, limiting high-resolution applications.

Purpose of the Study:

• To investigate the TURBINE (3D radial-Cartesian) acquisition scheme for high-fidelity, ultrahigh isotropic resolution fMRI at 7 Tesla.
• To minimize distortion and blurring in fMRI acquisitions, enabling precise localization of brain activity.

Main Methods:

• Developed an improved, self-navigated TURBINE sampling scheme for fMRI at 7 Tesla.
• Acquired thin-slab (0.67 mm isotropic) and whole-brain (0.8 x 0.8 x 2.0 mm) BOLD fMRI data.
• Employed temporally regularized reconstruction to enhance sensitivity and spatial fidelity.

Main Results:

• TURBINE acquisitions yielded high structural fidelity with minimal distortion, dropout, and T2* blurring for thin-slab scans.
• Demonstrated precise localization of motor task activation, correlating well with T1-MPRAGE structural images.
• Showcased robust BOLD activation at both ultrahigh isotropic and anisotropic resolutions, though benefits were reduced with longer EPI trains in whole-brain scans.

Conclusions:

• TURBINE is a promising fMRI acquisition technique for achieving high resolution and minimal distortion at 7 Tesla.
• The method is particularly advantageous for fMRI in regions with high B0 inhomogeneity.
• Offers potential for improved spatial specificity in functional neuroimaging studies.