Scan time reduction for readout-segmented EPI using simultaneous multislice acceleration: Diffusion-weighted imaging...

Area of Science:

• Magnetic Resonance Imaging
• Diffusion Tensor Imaging
• Image Acquisition Techniques

Background:

• Readout-segmented echo-planar imaging (rs-EPI) provides higher quality diffusion data compared to single-shot EPI (ss-EPI).
• rs-EPI is less susceptible to distortion and blurring artifacts, especially at higher resolutions and magnetic fields.
• However, rs-EPI typically requires longer scan times due to multiple repetitions per segment.

Purpose of the Study:

• To shorten rs-EPI scan times by reducing repetition time (TR) using simultaneous multislice (SMS) acceleration.
• To evaluate the impact of SMS acceleration on image quality and diffusion postprocessing results.
• To compare the performance of accelerated rs-EPI with conventional ss-EPI.

Main Methods:

• Incorporated blipped-controlled aliasing in parallel imaging (CAIPI) for slice acceleration with minimal signal-to-noise ratio (SNR) loss.
• Acquired diffusion-weighted rs-EPI and ss-EPI sequences at various resolutions on 3 and 7 Tesla scanners.
• Assessed image fidelity and diffusion tractography outcomes.

Main Results:

• Demonstrated slice-accelerated rs-EPI yields clinically useful trace-weighted images and tractography results.
• Tractography analysis revealed superior tract discrimination with rs-EPI due to reduced artifacts compared to ss-EPI.
• Achieved shorter scan times for rs-EPI while maintaining high image quality.

Conclusions:

• Slice acceleration effectively reduces rs-EPI scan times, offering a practical alternative to diffusion-weighted ss-EPI.
• Accelerated rs-EPI provides high-resolution diffusion data with significantly reduced distortion and blurring.
• This technique enhances the utility of diffusion MRI for clinical applications.