Fast 3D fMRI acquisition with high spatial resolutions over a reduced FOV

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging

Background:

• Functional MRI (fMRI) is crucial for understanding brain function.
• Existing fMRI techniques face limitations in balancing spatial resolution and temporal speed.
• High spatial resolution and rapid volume acquisition are essential for detailed fMRI studies.

Purpose of the Study:

• To develop and validate a novel 3D fMRI acquisition technique named k-t 3D reduced FOV imaging (3D-rFOVI).
• To achieve high spatial resolution within a reduced field of view (FOV) for accelerated fMRI.
• To demonstrate the capability of 3D-rFOVI for fast and precise brain activity detection.

Main Methods:

• k-t 3D-rFOVI is based on 3D gradient-echo EPI, utilizing a 2D RF pulse to reduce FOV and enhance spatial resolution.
• Image acceleration is achieved through partial k-space sampling along the through-slab direction (k_z), with full sampling in the center.
• Data acquired at 3T were reconstructed using a partial separability-based method and analyzed via simulations and human fMRI experiments.

Main Results:

• Simulations demonstrated k-t 3D-rFOVI's ability to detect 100% of fMRI activations at R=2 and ~80% at R=6.
• Human fMRI with 1.5-mm resolution and 800-ms TR_vol showed 3D-rFOVI (R=4) detected 46% more activated voxels than commercial multiband EPI.
• Further experiments achieved a TR_vol of 480 ms with R=6, reliably detecting visual activation.

Conclusions:

• k-t 3D-rFOVI enables simultaneous high spatial resolution (1.5-mm isotropic) and short volume TR (480 ms) at 3T.
• This technique offers a robust solution for rapid fMRI studies focusing on specific brain regions.
• 3D-rFOVI significantly improves the detection of neural activity compared to conventional methods.