A multi-inversion multi-echo spin and gradient echo echo planar imaging sequence with low image distortion for rapid...

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging Techniques
• Image Acquisition and Reconstruction

Background:

• Conventional brain imaging exams are time-consuming, often requiring 10-20 minutes with sequential acquisitions.
• Echo planar imaging (EPI) is a common MRI technique, but often suffers from distortion, limiting its applications.
• Developing efficient and accurate brain imaging methods is crucial for clinical diagnostics and research.

Purpose of the Study:

• To develop a low-distortion, whole-brain echo planar imaging (EPI)-based approach for efficient encoding of multiple contrasts in a single acquisition.
• To enable the calculation of quantitative parameter maps and the generation of synthetic contrast-weighted images.
• To reduce scan time and image distortion in brain MRI.

Main Methods:

• Inversion prepared spin- and gradient-echo EPI with slice-order shuffling was employed for T1, T2, and other weightings.
• Dictionary matching was used to generate quantitative parameter maps and synthetic weighted images.
• Dynamic slice-optimized multi-coil shimming and multi-shot EPI were implemented to minimize distortion and improve resolution, alongside a low-rank reconstruction approach.

Main Results:

• The optimized shimming and parallel imaging (4x acceleration) reduced EPI distortion by over eight-fold.
• The sequence acquired 40 contrasts across the whole brain in just over 1 minute at 1.2 x 1.2 x 3 mm resolution.
• A multi-shot variant achieved 1 x 1 x 4 mm resolution in 4 minutes with comparable quantitative map values to conventional methods.

Conclusions:

• The developed approach facilitates rapid whole-brain imaging with quantitative maps and synthetic contrasts.
• Slice-optimized multi-coil shimming and multi-shot reconstruction minimize EPI distortion.
• This technique holds potential for rapid screening applications in neuroimaging.