Simultaneous calculation of flow and diffusion sensitivity in steady-state free precession imaging

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biophysics

Background:

• Steady-state free precession (SSFP) is a widely used MRI technique.
• Understanding flow and diffusion effects is crucial for accurate SSFP imaging, particularly for diffusion studies.

Purpose of the Study:

• To quantitatively evaluate the combined effects of flow and diffusion in SSFP imaging.
• To introduce and validate a fast simulation technique for SSFP sequences.
• To assess the feasibility and artifact levels of SSFP for diffusion imaging in vivo.

Main Methods:

• Developed a fourth-order approximation (in E2) of the SSFP signal using partition analysis (PA).
• Introduced a novel, fast simulation technique based on circular convolution to model flow and diffusion.
• Implemented a 2D SSFP-echo sequence and acquired experimental data from phantoms.
• Validated the simulation algorithm using in vivo brain motion measurements.

Main Results:

• Excellent agreement was found between theoretical predictions, phantom experiments, and in vivo measurements.
• The developed simulation technique accurately accounts for both flow and diffusion.
• Artifacts in SSFP diffusion imaging of the brain were estimated to be comparable to pulsed gradient spin echo methods.
• An equivalence between SSFP flow sensitivity and RF spoiling was identified.

Conclusions:

• SSFP imaging can be effectively used for diffusion studies with predictable artifact levels.
• The novel simulation technique provides an accurate and efficient tool for analyzing SSFP sequences.
• SSFP demonstrates potential for fast and robust diffusion imaging applications.