Motion-corrected 3D-EPTI with efficient 4D navigator acquisition for fast and robust whole-brain quantitative imaging

Area of Science:

• Medical Imaging
• Neuroimaging
• Quantitative MRI

Background:

• Motion artifacts significantly degrade the quality of 3D quantitative imaging, particularly in echo-planar imaging techniques.
• Accurate motion estimation and correction are crucial for reliable quantitative measurements in brain imaging.

Purpose of the Study:

• To develop and validate a motion estimation and correction method for motion-robust three-dimensional (3D) quantitative imaging.
• To enhance the 3D-echo-planar time-resolved imaging (3D-EPTR) technique for reliable quantitative brain imaging despite head motion.

Main Methods:

• Implemented a four-dimensional (4D) navigator acquisition (x-y-z-echoes) integrated into the 3D-EPTR sequence during relaxation-recovery deadtime.
• Utilized optimized spatiotemporal encoding and partial-Fourier acquisition for the 4D navigator to capture motion and B0 inhomogeneity.
• Incorporated estimated motion and B0 changes into the image reconstruction process to correct artifacts.

Main Results:

• Simulations showed <1% SNR efficiency cost from the added 4D navigator acquisition.
• Both simulations and in vivo experiments demonstrated accurate 3D motion and B0 inhomogeneity estimation by the 4D navigator.
• Prospective undersampling acquisitions showed corrected motion-corrupted data matched motion-free scan quality and quantification.

Conclusions:

• The proposed 4D navigator acquisition effectively tracks head motion and B0 changes with negligible SNR cost.
• This method significantly improves the robustness and efficiency of 3D-EPTR for quantitative imaging.
• Enables reliable quantitative measurements even in the presence of head motion.