Highly Accelerated Whole-Brain T<sub>2</sub> Mapping Using Non-Cartesian Acquisition and Model-Based Implicit Neural Representation Reconstruction.
Authors
Affiliations (3)
Affiliations (3)
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China.
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China. Electronic address: [email protected].
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China. Electronic address: [email protected].
Abstract
To propose a technique for highly accelerated T<sub>2</sub> mapping of the whole brain. A pulse sequence with T<sub>2</sub> preparation and a highly undersampled golden-angle stack-of-stars trajectory is used for data acquisition. A multiresolution hash encoding implicit neural representation, embedded with a physical model of signal evolution, is employed for unsupervised reconstruction. By rotating the trajectory at different kz encodings and effective echo times (TE<sub>eff</sub>) during acquisition, undersampling is applied to three dimensions, i.e., (kx, ky, TE<sub>eff</sub>) domain. In the phantom experiment, T<sub>2</sub> quantification using this T<sub>2</sub>-prepared stack-of-stars acquisition was compared with that using a Cartesian multi-echo spin-echo acquisition. In the human experiments, T<sub>2</sub> quantification using the undersampled acquisition was validated in comparison with those using the fully sampled acquisition and multi-echo spin-echo. In phantom test, T<sub>2</sub> quantification using the proposed reconstruction agreed well (slope = 0.999, R<sup>2</sup> > 0.99) with that obtained by fitting the NUFFT-reconstructed results for the fully sampled T<sub>2</sub>-prepared stack-of-stars acquisition. In human experiments, T<sub>2</sub> quantification using a 20-fold acceleration agreed well with that using fully sampled data (NRMSE = 0.0066) in retrospectively undersampled reconstruction. No significant difference in T<sub>2</sub> values was found between our technique and the reference method in prospective experiments, and our technique showed good inter-scan reproducibility and intra-scan repeatability. Using the proposed technique, whole-brain T<sub>2</sub> mapping can be acquired in 70 seconds with a 20-fold acceleration.