Nicolas Arango1, Jason Stockmann2,3, Elfar Adalsteinsson1,4, and Jacob White1
1Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, United States, 2A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 3Harvard Medical School, Boston, 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, 2A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, 3Harvard Medical School, Boston, MA, United States, 4Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, United States
We have developed tools for the computational design of additional local
shim coils to augment existing shim arrays using sparse factorization
techniques. A proof of concept computationally designed face shim coil for brain imaging improves static field in homogeneity in the cortex
Left: 32 channel AC/DC shim array. Right: 32 Channel AC/DC shim array with additional 7 channel shim faceplate.
EPI and $\db$ maps for global second order spheral harmonic, 32 channel AC/DC, and 7 channel augmented AC/DC coil coil shims for a single subject. Signal dropout reduction and distortion reduction through the addition of the 7 channel face plate indicated with red circles. ΔB0 maps show reduction in inhomogeneity in the pre-frontal cortex. EPI acquired with 1.7x1.7x2 mm resolution TE=30ms TR=5s. GRE phase maps with 1.7x1.7x2 mm resolution TE1=4.45ms TE2= 6.92ms