MULTI-parametric MR imaging with fLEXible design (MULTIPLEX)

To introduce a gradient echo (GRE) -based method, namely MULTIPLEX, for single-scan 3D multi-parametric MRI with high resolution, signal-to-noise ratio (SNR), accuracy, efficiency, and acquisition flexibility.

With a comprehensive design with dual-repetition time (TR), dual flip angle (FA), multi-echo, and optional flow modulation features, the MULTIPLEX signals contain information on radiofrequency (RF) B_1t fields, proton density, T₁ , susceptibility and blood flows, facilitating multiple qualitative images and parametric maps.

MULTIPLEX was evaluated on system phantom and human brains, via visual inspection for image contrasts and quality or quantitative evaluation via simulation, phantom scans and literature comparison. Region-of-interest (ROI) analysis was performed on parametric maps of the system phantom and brain scans, extracting the mean and SD of the T₁ , $$ , proton density (PD), and/or quantitative susceptibility mapping (QSM) values for comparison with reference values or literature.

One MULTIPLEX scan offers multiple sets of images, including but not limited to: composited PDW/T₁ W/ $$ W, aT₁ W, SWI, MRA (optional), B_1t map, T₁ map, $$ / $$ maps, PD map, and QSM. The quantitative error of phantom T₁ , $$ and PD mapping were <5%, and those in brain scans were in good agreement with literature. MULTIPLEX scan times for high resolution (0.68 × 0.68 × 2 mm³ ) whole brain coverage were about 7.5 min, while processing times were <1 min. With flow modulation, additional MRA images can be obtained without affecting the quality or accuracy of other images.

The proposed MUTLIPLEX method possesses great potential for multi-parametric MR imaging.