T1 mapping using spoiled FLASH-EPI hybrid sequences and varying flip angles

Area of Science:

• Magnetic Resonance Imaging
• Quantitative MRI

Background:

• T(1) maps are crucial for quantitative MRI analysis.
• Improving signal-to-noise ratio (SNR) in T(1) maps is essential for accurate diagnostics.
• Standard methods often require longer acquisition times for higher SNR.

Purpose of the Study:

• To propose and validate a novel method for enhancing SNR in T(1) maps.
• To evaluate the performance of hybrid spoiled fast low angle shot (FLASH) echo-planar imaging (EPI) sequences.
• To assess the impact of these sequences on T(1) map quality and measurement time.

Main Methods:

• Utilized spoiled FLASH EPI hybrid sequences with two echoes per excitation.
• Employed a variable flip angle approach for T(1) mapping.
• Conducted phantom measurements and in-vivo studies on healthy volunteers.

Main Results:

• Achieved significant SNR gains in T(1) maps, exceeding theoretical predictions.
• Demonstrated SNR increases ranging from 23% (shorter scan time) to 67% (identical bandwidth).
• Observed excellent image quality and visible SNR improvement in volunteer studies, with T(1) values comparable to standard methods.

Conclusions:

• The proposed hybrid sequence method substantially improves T(1) map SNR without extending experiment durations.
• This technique offers SNR gains equivalent to acquiring two averages, enhancing diagnostic potential.
• The method provides a more efficient approach to high-quality quantitative MRI T(1) mapping.