Robust diffusion tensor imaging by spatiotemporal encoding: Principles and in vivo demonstrations.

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Neuroimaging

Background:

• Diffusion Tensor Imaging (DTI) is crucial for visualizing white matter tracts.
• Conventional single-shot DTI methods are susceptible to artifacts from magnetic field inhomogeneities and eddy currents.
• Developing robust DTI techniques is essential for accurate preclinical and clinical applications.

Purpose of the Study:

• To evaluate the utility of single-shot and interleaved spatiotemporally encoded (SPEN) methods for Diffusion Tensor Imaging (DTI).
• To assess SPEN DTI performance across diverse preclinical and clinical settings.
• To compare SPEN DTI against conventional single-shot DTI.

Main Methods:

• A novel formalism was developed to analyze SPEN DTI data, accounting for spatially dependent b-matrix weightings from swept pulses and gradients.
• SPEN DTI performance was rigorously tested using phantoms, ex vivo samples, and in vivo scans of mouse brains and human lactating breasts.
• Referenceless methods were explored for interleaved SPEN data acquisition to enhance resolution.

Main Results:

• SPEN DTI data demonstrated reduced sensitivity to B0 field inhomogeneities and eddy current-induced distortions compared to single-shot DTI, in both ex vivo and in vivo studies.
• Interleaved SPEN acquisitions, particularly with referenceless methods, offered further improvements in image resolution.
• Successful DTI measurements were obtained in challenging imaging scenarios.

Conclusions:

• SPEN-based DTI sequences exhibit significant robustness against magnetic field instabilities and heterogeneities.
• These SPEN sequences facilitate DTI experiments with high sensitivity and resolution, even in demanding preclinical and clinical environments.
• SPEN DTI represents a promising advancement for neuroimaging and other biomedical applications requiring robust diffusion measurements.