Interleaved spiral-in/out with application to functional MRI (fMRI).

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Neuroimaging

Background:

• Conventional spiral-in/out MRI trajectories adequately sample k-space for separate image creation.
• Signal dropout due to susceptibility-induced field gradients and signal pileup artifacts are limitations in conventional spiral MRI.

Purpose of the Study:

• To introduce and evaluate an "interleaved spiral-in/out" MRI trajectory.
• To assess the benefits of reduced readout duration for image quality and artifact reduction.

Main Methods:

• Development of an interleaved spiral-in/out trajectory, acquiring half k-space data during spiral-in and the other half during spiral-out.
• Implementation of temporal filtering for artifact removal during image reconstruction.
• Comparison with conventional spiral-out methods using a hyperoxia stimulus in brain imaging.

Main Results:

• The interleaved trajectory reduces readout duration by approximately 50%.
• This leads to reduced signal dropout and potential for higher spatial resolution.
• Interleaved spiral-in/out imaging demonstrated freedom from signal pileup artifacts observed in conventional spiral-out methods.
• Hyperoxia challenge revealed greater frontal-orbital activation volumes with the interleaved method, alongside a slight reduction in other brain regions.

Conclusions:

• The interleaved spiral-in/out trajectory offers significant advantages in MRI, including reduced signal dropout and artifact mitigation.
• This technique enables higher spatial resolution imaging and provides more accurate activation volume measurements in functional neuroimaging studies.
• The method shows promise for improved brain imaging, particularly in challenging environments with susceptibility gradients.