Yamin Arefeen1, Borjan Gagoski2,3, and Elfar Adalsteinsson1,4,5
1Massachusetts Institute of Technology, Cambridge, MA, United States, 2Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Boston, MA, United States, 3Department of Radiology, Harvard Medical School, Boston, MA, United States, 4Harvard-MIT Health Sciences and Technology, Cambridge, MA, United States, 5Institute for Medical Engineering and Science, Cambridge, MA, United States
1Massachusetts Institute of Technology, Cambridge, MA, United States, 2Fetal-Neonatal Neuroimaging and Developmental Science Center, Boston Children’s Hospital, Boston, MA, United States, 3Department of Radiology, Harvard Medical School, Boston, MA, United States, 4Harvard-MIT Health Sciences and Technology, Cambridge, MA, United States, 5Institute for Medical Engineering and Science, Cambridge, MA, United States
A randomly undersampled, spiral-based trajectory yields 2-3x acceleration over fully sampled 3D-spiral acquisitions in 3D Magnetic Resonance Spectroscopy by inducing incoherent aliasing that can be resolved with SPICE-based low rank priors.
Figure 4: Metabolites maps, RMSE on image support, and example spectra from subspace reconstructions of fully sampled , uniformly undersampled (R = 2), and undersampled with the proposed trajectory (R = 2) on a spectroscopy phantom containing physiological concentrations of the major brain metabolites. The proposed trajectory yields similar spectra and metabolite maps to the fully sampled acquisition and achieves ~2x reduction in RMSE across the metabolites in comparison to uniform undersampling.
Figure 1: Schematic view of (a) the fully sampled 3D-spiral MRSI trajectory and (b) our proposed randomly undersampled trajectory. For demonstration purposes, we assume 1 temporal interleaf. In (a), the same angular interleaf and kz point is sampled at each timepoint in a TR. The proposed (b) trajectory samples random angular interleaves and kz points during each TR and can be accelerated by reducing the number of TR’s. Our proposed trajectory takes advantage of the 4D-encoding space by spreading incoherent aliasing across spatial and spectral dimensions.
