Improved cine displacement-encoded MRI using balanced steady-state free precession and time-adaptive sensitivity...

Area of Science:

• Cardiovascular Imaging
• Medical Physics
• Biomedical Engineering

Background:

• Cine displacement-encoded MRI is valuable for quantifying regional myocardial function.
• Existing methods suffer from low signal-to-noise ratio (SNR) and inefficient data acquisition.
• These limitations hinder precise and timely assessment of cardiac mechanics.

Purpose of the Study:

• To enhance SNR and data acquisition efficiency in cine displacement-encoded MRI.
• To achieve incremental improvements through a combination of advanced imaging techniques.
• To optimize parameters for improved accuracy in myocardial function quantification.

Main Methods:

• Combined balanced steady-state free precession (b-SSFP) imaging with 3T MRI.
• Utilized echo-combination image reconstruction for phase correction.
• Implemented time-adaptive sensitivity encoding (TSENSE) parallel imaging for acceleration.
• Performed phantom experiments to determine optimal excitation angle (alpha) and assess errors.
• Evaluated SNR and strain accuracy in six healthy volunteers.

Main Results:

• Determined optimal excitation angle (alpha) to be 20 degrees.
• Echo-combination effectively reduced phase errors, leading to minimal displacement and strain errors.
• Non-accelerated b-SSFP showed a 65% SNR increase compared to cine echo-planar imaging.
• A 12-heartbeat, twofold accelerated b-SSFP acquisition improved SNR by 28% while maintaining high spatial (3.6x3.6 mm) and temporal (35 ms) resolution.
• Left ventricular strain values showed strong correlation (R2=0.91) and excellent agreement between non-accelerated and accelerated acquisitions.

Conclusions:

• The combined implementation of b-SSFP, 3T imaging, echo-combination, and TSENSE significantly improves cine displacement-encoded MRI.
• This integrated approach enhances both SNR and data acquisition efficiency.
• The optimized sequence provides accurate and efficient myocardial strain quantification, advancing cardiovascular MRI applications.