Purpose: To develop a rapid T mapping protocol using optimized spiral acquisition, accelerated reconstruction, and model fitting.
Materials And Methods: A T-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 mapping. A 2-parameter-weighted fitting method was compared with 2- or 3-parameter models for accurate T estimation under the influences of noise and B 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 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 estimation with and without CSF nulling was consistent with literature values.
Conclusion: This work demonstrated the feasibility of a T 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 estimation. The technique also allowed mitigation of CSF partial volume effect.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7571618 | PMC |
| http://dx.doi.org/10.1016/j.mri.2020.08.007 | DOI Listing |
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