Extracting more for less: multi-echo MP2RAGE for simultaneous T₁ -weighted imaging, T₁ mapping, mapping, SWI, and...

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging
• Medical Physics

Background:

• Quantitative susceptibility mapping (QSM) and susceptibility-weighted imaging (SWI) are valuable neuroimaging techniques.
• Multi-echo (ME) sequences offer advantages in extracting quantitative information compared to single-echo (SE) sequences.
• MP2RAGE is a popular sequence for T1-weighted imaging and T1 mapping.

Purpose of the Study:

• To demonstrate the feasibility of acquiring simultaneous T1-weighted imaging, T1 mapping, $$ mapping, SWI, and QSM from a single multi-echo (ME) MP2RAGE acquisition.
• To evaluate the performance of the proposed ME-MP2RAGE method compared to standard SE-MP2RAGE and ME-gradient echo sequences.

Main Methods:

• A single-echo MP2RAGE sequence was extended to a multi-echo sequence with 4 bipolar gradient echo readouts at 7 tesla.
• T1-weighted images and T1 maps were generated by combining individual echoes.
• ME-combined SWI and QSM were reconstructed using specialized pipelines, including TE-adjusted homodyne filters and phase-offset correction with a novel coil combination method.

Main Results:

• The ME-MP2RAGE method achieved higher signal-to-noise ratios (SNRs) in T1-weighted, T1 map, and SWI images compared to SE results.
• The proposed coil combination method for QSM eliminated phase-singularity artifacts.
• Quantitative measurements (T1, $$, and susceptibility) from ME-MP2RAGE were comparable to those from SE-MP2RAGE and ME-gradient echo, although $$ maps showed reduced SNR and increased blurring.

Conclusions:

• High-resolution structural T1-weighted imaging, T1 mapping, $$ mapping, SWI, and QSM can be obtained from a single, time-efficient 8.5-minute ME-MP2RAGE acquisition.
• This integrated approach can replace separate SE-MP2RAGE and ME-gradient echo acquisitions, significantly reducing overall scan time.
• The developed customized reconstruction pipeline enables comprehensive brain tissue characterization in a single scan.