Steady-state free precession for T₂* relaxometry: All echoes in every readout with k-space aliasing

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biomedical Engineering
• Medical Physics

Background:

• Multi-echo gradient echo imaging is vital for applications like relaxometry and susceptibility mapping.
• Conventional methods often use long-TR FLASH sequences, acquiring one echo per readout.
• This sequential acquisition can limit temporal resolution in dynamic studies.

Purpose of the Study:

• To propose an alternative strategy for simultaneous multi-echo acquisition using N-periodic SSFP sequences.
• To enable efficient, short-TR relaxometry by measuring all signal components in a single readout.
• To compare the proposed method with traditional multi-echo FLASH for R2* relaxometry.

Main Methods:

• Utilized N-periodic SSFP sequences to simultaneously record multiple echoes.
• Separated echoes based on differing phase evolution across multiple TRs.
• Compared R2* relaxometry results from the proposed method and multi-echo FLASH in phantoms and volunteers.

Main Results:

• The proposed SSFP method demonstrated close agreement with multi-echo FLASH for R2* estimation.
• Achieved more rapid temporal sampling compared to conventional sequential echo acquisition.
• Validated the approach in both phantom and human volunteer studies.

Conclusions:

• The simultaneous multi-echo SSFP approach is a promising alternative for relaxometry.
• It offers efficient data acquisition by measuring multiple echo pathways concurrently.
• The method relies on a simple analytical model for signal separation.