Abstract #2574

Single-shot T2-weighted Fetal MRI with variable flip angles, full k-space sampling, and nonlinear inversion: towards improved SAR and sharpness

Yamin Arefeen¹, Borjan Gagoski^2,3, Esra Turk^2,3, Ellen Grant^2,3, Jacob White¹, Kawin Setsompop^3,4,5, and Elfar Adalsteinsson^1,5,6

¹Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States, ²Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Boston, MA, United States, ³Harvard Medical School, Boston, MA, United States, ⁴Athinoula A. Martinos Center for Biomedical Imaging, Boston, MA, United States, ⁵Harvard-MIT Health Sciences and Technology, Cambridge, MA, United States, ⁶Institute for Medical Engineering and Science, Cambridge, MA, United States

Fetal MRI utilizes Half-Fourier-acquisition-single-shot-turbo-spin-echo (HASTE) for rapid T2-weighted imaging to mitigate motion. However, T2-decay and partial fourier induce blurring, while refocusing trains extend total acquisition time due to specific absorption rate (SAR) constraints. Variable flip angles (VFA) with full Fourier acquisitions have been shown to improve image quality, maintain contrast, and accelerate acquisition through SAR reduction. We combine nonlinear reconstruction, VFA, and full Fourier undersampling to improve sharpness and reduce SAR while maintaining similar contrast to HASTE. Simulation and phantom experiments illustrate improved sharpness. Preliminary, in-vivo fetal results demonstrate improved sharpness and SAR with slight tradeoffs in contrast and SNR.

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