Quantitative T2 mapping using accelerated 3D stack-of-spiral gradient echo readout

Purpose: To develop a rapid T-2 mapping protocol using optimized spiral acquisition, accelerated reconstruction, and model fitting. Materials and methods: A T-2-prepared stack-of-spiral gradient echo (GRE) pulse sequence was applied. A model-based approach joined with compressed sensing was compared with the two methods applied separately for accelerated reconstruction and T-2 mapping. A 2-parameter-weighted fitting method was compared with 2- or 3-parameter models for accurate T-2 estimation under the influences of noise and B-1 inhomogeneity. The performance was evaluated using both digital phantoms and healthy volunteers. Mitigating partial voluming with cerebrospinal fluid (CSF) was also tested. Results: Simulations demonstrates that the 2-parameter-weighted fitting approach was robust to a large range of B-1 scales and SNR levels. With an in-plane acceleration factor of 5, the model-based compressed sensing-incorporated method yielded around 8% normalized errors compared to references. The T-2 estimation with and without CSF nulling was consistent with literature values. Conclusion: This work demonstrated the feasibility of a T-2 quantification technique with 3D high-resolution and whole-brain coverage in 2-3 min. The proposed iterative reconstruction method, which utilized the model consistency, data consistency and spatial sparsity jointly, provided reasonable T-2 estimation. The technique also allowed mitigation of CSF partial volume effect.