To demonstrate the feasibility of an MRI system for human brain imaging in real world environments. See Figure 1.In response to the White House BRAIN Initiative, we won a grant to test the feasibility of a portable, self-supporting, MRI system capable of 1.5T clinical quality imaging anywhere in the world.(1) Imaging of neuroanatomy and function by MRI continues to play a critical role in understanding the human brain. Yet many technical aspects of current MRI technology and methodology significantly limit the diversity of information that it can provide due to confined space in the magnet bore, large physical size of the magnet, lack of portability, and infrastructure requirements such as helium supply. Drawbacks of current MRI technology for neuroimaging are multifold. The need to image the brain inside a whole-body magnet restricts broad use for studying populations engaged in real world activities. With the current whole-body magnets, immobilized subjects must lie prone or supine in a narrow “tube”; consequently, brain imaging must be performed in conditions that preclude behavior in a natural environment, thus preventing or distorting studies of cognitive behavior such those invoked in social interactions. Similarly, whole body magnets restrict body movements, making it impossible to study vestibular disorders. The supporting infrastructure, including the cost of the scanner, siting, maintenance, liquid helium, and reliable energy supply, limits its use in developing nations; consequentially neuroimaging studies in diverse populations, environments, and cultures are rare. Because the availability of MRI scanners in neuroscience is limited mainly to academic settings, the bulk of neuroimaging studies are performed on young healthy normal student volunteers. Finally, due to lack of portability, current MRI is not available in many field locations such as doctor’s offices, sports clinics, war and natural disaster field hospitals.

We are making good progress toward demonstrating the feasibility of our new portable MRI system by the following methods.

1. Demonstrate feasibility of a new reliable and portable magnet technology that can operate anywhere in the world, at liquid nitrogen temperature.

2. Demonstrate capability to image the brain with extreme B₀ inhomogeneity using STEREO, a new spatiotemporal imaging method. The first step in this direction will be accomplishing true simultaneous transmit and receive imaging.

3. Achieve maximal tolerance to B₀ inhomogeneity using novel multi-coil (MC) arrays.

4. Demonstrate feasibility of a new high efficiency, multi-channel distributed RF spectrometer including simultaneous transmit and receive capability.

In the first year of our project, we have demonstrated the feasibility of a YBCO, head only magnet by building and testing a pair of full size (43 cm inside diameter) double pancake coils. Supercooled with liquid nitrogen to 77K and charged, we have generated a central field of 710 Gauss. (Figure 2a.) By this demonstration we know that we can build a head-only magnet by the configuration of (Figure 2b) to achieve 1.5T over a head sized volume, with the field profile shown in (Figures 2c, 2d). Figure 3 shows the 2D Stereo RF pulses (left) and the MRI simulation images (right) showing the coherence region (bright spot) as it traverses the object during the STEREO pulse duration T_p. By simultaneous transmit and receive (STAR) with continuous SWIFT (2, 3) we have been able to acquire the images of (Figure 5) using a MRI scanner equipped with a 4T (human) magnet and a Varian Direct Drive console. Acquisition parameters: sweep frequency span = 32.5 kHz, 128000 views (spokes in k-space), 256 complex points per view, the diameter of field of view was 44 cm, isotropic resolution of 1.7 mm, and total acquisition time 10 minutes and only 50 mW peak RF power. By this low power level, we plan to extend the 16 channel TEM coil used to a configuration as shown in Figure 4, complete with distributed, local power amplifiers, preamplifiers and duplexer hardware all packaged per element in the black boxes shown in the figure. The entire RF front end of the spectrometer fits into the package shown, which is inserted into the bore of the magnet in Figure 1. The digital console for this system is simply a laptop connected to the cloud.We are well on our way to demonstrating the feasibility of a portable (800 lb) off-the-grid, 1.5T MRI system for imaging the human brain.