Spin-locked balanced steady-state free-precession (slSSFP).

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Pulse Sequence Development
• Biophysics

Background:

• Balanced steady-state free-precession (bSSFP) is a widely used MRI technique.
• High radio frequency (RF) power deposition is a limitation of bSSFP, especially at higher field strengths.
• Developing lower power alternatives is crucial for advanced MRI applications.

Purpose of the Study:

• To introduce and evaluate a novel spin-locked balanced steady-state free-precession (slSSFP) pulse sequence.
• To assess the performance of slSSFP in terms of magnetization dynamics, contrast, and signal-to-noise ratio (SNR) efficiency.
• To compare slSSFP with conventional bSSFP, particularly regarding RF power requirements.

Main Methods:

• Numerical simulations solving Bloch equations to analyze magnetization trajectories.
• Implementation and testing of the slSSFP sequence on a 7 Tesla (7T) MRI scanner.
• Acquisition of brain scans using both slSSFP and bSSFP sequences for direct comparison.

Main Results:

• The steady-state magnetization trajectory of slSSFP closely resembles that of bSSFP across various parameters.
• slSSFP maintains its steady-state with substantially reduced RF power compared to bSSFP.
• Simulations and in-vivo 7T brain scans demonstrate comparable contrast and SNR efficiency between slSSFP and bSSFP.

Conclusions:

• Spin-locked balanced steady-state free-precession (slSSFP) is a viable fast MRI technique.
• slSSFP offers a significant reduction in RF power deposition while maintaining comparable image quality to bSSFP.
• This technique holds promise for safer and more efficient MRI, particularly at high field strengths.