2. Statement of the Problem
In MRI, is it possible to create a mathematical model that will work with a novel
inhomogeneous magnetic field as opposed to a traditional homogeneous field?
3. Project Overview
In traditional MRIs, a large magnet provides a very homogenous magnetic field, which is not
the case in a smaller one. In order to make a portable MRI machine, one must deal with the
inhomogeneity of the primary magnetic field. This project focuses on the derivation of
mathematical solutions of an encoding technique that can be applied to an inhomogeneous
magnetic field, proving the feasibility of a portable MRI.
4. Research
• A novel radial sweep imaging technique is used during
imaging
• A new mathematical equation compensates for the
inhomogeneous field
• Combined, these two changes allow us to work with the
inhomogeneous field and produce satisfactory images
• This a proof of concept for a portable MRI, which has many
medicinal applications
5. Hypothesis
A radial imaging technique combined with an additional frequency sweep
term in the Powell magnetization equation will help compensate for the
inhomogeneous magnetic field and thus prove the feasibility of a portable
MRI
7. Results
The analytic image on the right panel
shown in Figure 1 is the image predicted
by the derived equation in this study. The
left is the imaging of a circular object
suspended in water. We see that the
analytical solution image is almost
identical to the simulation. This confirms
that the new inhomogeneous field can be
worked with and gives similar results to
traditional MRI.
Image obtained from CMRR,
University of Minnesota under
Dr. Garwood
8. Conclusion
The previous image is proof that a portable MRI will work. The
inhomogeneous magnetic field can be worked with to produce
satisfactory images. This has medicinal application to third-world
countries, war zones, and other clinics where expensive traditional
MRI machines may not be feasible.
9. Works Cited
Y Kadah, X Hu. IEEE Transactions on Medical Imaging, Vol.17, No.
3, June 1998. Algebraic Reconstruction for Magnetic Resonance
Imaging Under B0 Inhomogenity
J Pauly, D Nishimura, A Macovski. Journal of Magnetic Resonance. 7
December 1997. A k-Space analysis of Small-Tip-Angle Excitation
E Haacke, R Brown, M Thompson, R Venkatesan. 1999. Magnetic
Resonance Imaging – Physical Principles and Sequence Design
M. Bernstein, K King, X Zhou. 2004. The Handbook of MRI Pulse
Sequences
L. DelaBarre, M. Garwood. 2001. The Return of the Frequency
Sweep: Designing Adiabatic Pulses for Contemporary NMR
A. Snyder, C. Corum, S. Moeller, N. Powell, and M. Garwood.
Magnetic Resonance in Medicine. 2014. MRI by Steering Resonance
Through Space
