Molin Zhang1, Nicolas Arango1, Jason Stockmann2, Jacob White1, and Elfar Adalsteinsson1,3,4
1Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States, 2Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, 3Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States, 4Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, United States
1Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States, 2Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, MA, United States, 3Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States, 4Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, United States
We jointly design the non-linear B0 field generated by shim array and RF pulse to do the inner volume excitation with 1/3 of the background. Compared with previous work optimizing the static non-linear B0 field and predefined Sinc shape RF pulse, we gain 62% improvements in L2 error.
On the left hand side, the desired pattern is shown which is a 3D volume. On the right hand, the excited results under the four different experiments settings are shown. The error is based on the pixel-wise L2 norm. We could see that proposed joint designed time-varying field and RF pulse achieves best among all experiments.
The optimization results for different initializations for setting 3 and 4. We could see from the figure that the proposed method is more robust to the initialization with similar error ~6.2, while setting 3 is sensitive to the initialization as the error for initialization 2 is 13.85. Another thing to notice is that for the proposed method, different initializations may require different current and RF power levels.
