Distortion-Free Diffusion Imaging Using Self-Navigated Cartesian Echo-Planar Time Resolved Acquisition and Joint...

Area of Science:

• Magnetic Resonance Imaging
• Diffusion Tensor Imaging
• Image Reconstruction

Background:

• Echo-planar time resolved imaging (EPTI) offers high-quality, distortion-free images using multi-shot EPI (ms-EPI).
• Inter-shot phase variations are a significant challenge for EPTI in diffusion-prepared sequences.

Purpose of the Study:

• To develop a self-navigated Cartesian EPTI (scEPTI) acquisition and reconstruction method.
• To achieve distortion-free diffusion imaging by addressing inter-shot phase variations.

Main Methods:

• Designed a self-navigated Cartesian EPTI diffusion-prepared pulse sequence.
• Analyzed EPTI diffusion signal phase components to synthesize a phase-matched navigator.
• Explored the use of temporal magnitude and phase correlations for enhanced reconstruction.
• Compared reconstruction results with and without phase matching and magnitude/phase constraints.

Main Results:

• Phase matching improved inter-shot phase correction accuracy and reduced signal corruption.
• Magnitude constraints enhanced image quality by increasing SNR.
• Phase constraints mitigated blurring introduced by magnitude constraints.
• Achieved high-quality, distortion-free diffusion images.

Conclusions:

• The proposed scEPTI method effectively corrects inter-shot phase variations in diffusion imaging.
• Combined magnitude and phase constraints optimize image quality and SNR.
• EPTI provides simultaneous diffusion-relaxometry, valuable for clinical and neuroscientific applications.