This talk will describe the development of two new imaging system designs, from back-of-envelope to functioning prototypes. First the development of a low-cost, portable MRI scanner for human brain imaging, and second, a new method for functional brain imaging with Magnetic Particle Imaging (MPI).
As the premiere modality for brain imaging, there is strong motivation to develop low-cost, portable MRI scanners available for unconventional locations (e.g. ICUs, doctor offices, ambulances, ERs, rural clinics). It is infeasible to scale down conventional MRI scanners, which rely on large superconducting magnets and high-power linear gradient fields for image encoding. Instead, we co designed new imaging hardware and image reconstruction algorithms starting from a permanent magnet Halbach array to produce a magnetic field with an intrinsic image encoding field. The magnet will rotate around the patient’s head to perform generalized projection imaging with the built-in field variation of the magnet. Careful modeling of the system is conducted to enable generalized image reconstruction based on an image encoding matrix.
Magnetic Particle Imaging (MPI) is a young but promising technology, and an altogether separate imaging modality from MRI, that relies on the non-linear magnetic response of iron-oxide nanoparticles to a magnetic drive field. Our goal is to detect activation-induced Cerebral Blood Volume (CBV) changes by monitoring the local iron oxide concentration. This CBV-contrast source is well-proven in animal and human fMRI studies. However, while MRI uses secondary effects on the signal relaxation times, MPI directly detects the injected nanoparticle’s magnetization - which potentially provides a 120-fold increase in contrast-to-noise ratio (CNR) of neuronal activation. The preliminary design of a Magnetic Particle Detection system will be presented.
Clarissa Zimmerman Cooley is a Post-doctoral Research Fellow at the MGH A.A. Martinos Center for Biomedical Imaging. As a doctoral student, she led the ground-up development of a portable MRI scanner for human brain imaging, and recently began the development of a Magnetic Particle Imaging (MPI) animal scanner for functional brain imaging. She also worked on the development of educational NMR/MRI systems – including the classroom "tabletop" MRI systems currently used in 6.03 and several graduate-level classes at MIT. Dr. Cooley has a B.S., M.Eng, and Ph.D in Electrical Engineering from MIT. She was awarded the Young Investigator Award from the International Society for Magnetic Resonance in Medicine in 2014 for her work on low-cost portable MRI.