Extracting more for less: multi-echo MP2RAGE for simultaneous T₁-weighted imaging, T₁ mapping, R2∗ mapping, SWI, and QSM from a single acquisition

Purpose: To demonstrate simultaneous T₁-weighted imaging, T₁ mapping, R₂ ^* mapping, SWI, and QSM from a single multi-echo (ME) MP2RAGE acquisition. Methods: A single-echo (SE) MP2RAGE sequence at 7 tesla was extended to ME with 4 bipolar gradient echo readouts. T₁-weighted images and T₁ maps calculated from individual echoes were combined using sum of squares and averaged, respectively. ME-combined SWI and associated minimum intensity projection images were generated with TE-adjusted homodyne filters. A QSM reconstruction pipeline was used, including a novel phase-offsets estimation from multi-echoes (POEM) method to properly combine the phase images from the 32 receiver channels. Measurements of susceptibility, R₂ ^*, and T₁ of brain tissue from ME-MP2RAGE were compared with those from standard ME-gradient echo and SE-MP2RAGE. Results: The ME combined T₁-weighted, T₁ map, SWI, and minimum intensity projection images showed increased SNRs compared to the SE results. The proposed POEM coil combination method led to QSM results free of phase-singularity artifacts, which were present in the standard adaptive combination method. T₁-weighted, T₁, and susceptibility maps from ME-MP2RAGE were comparable to those obtained from SE-MP2RAGE and ME-gradient echo, whereas R₂ ^* maps showed increased blurring and reduced SNR. T₁, R₂ ^*, and susceptibility values of brain tissue from ME-MP2RAGE were consistent with those from SE-MP2RAGE and ME-gradient echo. Conclusion: High-resolution structural T₁ weighted imaging, T₁ mapping, R₂ ^* mapping, SWI, and QSM can be extracted from a single 8.5-min ME-MP2RAGE acquisition using a customized reconstruction pipeline. This method can be applied to replace separate SE-MP2RAGE and ME-gradient echo acquisitions to significantly shorten total scan time.