Irene Kuang1, Jason Stockmann2,3, Elfar Adalsteinsson1,4, and Jacob White1
1Electrical 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
1Electrical 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 present a mechanically-tilted-magnet approach for generating gradient fields in a spokes-and-hub magnet topology for point-of-care and educational low-field permanent magnet MR systems without use of traditional MR gradient coils.
Figure 4. (a) Diagram of spokes-and-hub magnet with no tilt (blue outline) and a 0.25° tilt (orange outline) about the x-axis, creating a y-axis gradient field; (b) Simulated receive signal spectrum with and without tilt; (c) Measured spin echo obtained from 8mm diameter test tube of water using dithered ultrasound RF pulse with 100 kHz bandwidth with 0° (blue) and 0.25° (orange) tilted magnet; (d) Measured received signal spectrum with (orange) and without (blue) tilt.
Figure 5. Repeat of experiment in Figure 4, but with an 8mm diameter phantom containing two distinct tubes of water. In (a), tubes are side-by-side (along the y axis and in line with the tilt-induced gradient field); and in (b), tubes are stacked (along the z axis, orthogonal to the gradient field). Note the clear double hump in (a) showing spatial separation.
