Moving MRI: Imaging a Moving Body with a Moving MRI Magnet

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In response to BRAIN RFA-EB-19-001 we propose to demonstrate a novel noninvasive brain imaging method, Moving MRI (mMRI). In mMRI, a high resolution, high field, superconducting MRI magnet moves such that the subject's head and body effectively remain stationary with respect to the magnet. (This is neither portable nor head-mounted MRI.) By eliminating the relative motion between head and magnet, massive motion artifacts are largely suppressed. Moving MRI would for the first time enable recording of high quality anatomic and functional images in subjects experiencing true motion stimulation (i.e., rotations, tilts, and translations). Neuronal activation associated with naturalistic stimulation of the vestibular system can thereby be revealed with functional MRI (fMRI). The three- dimensional deformation of brain tissue and fluid displacement may be mapped using displacement- and flow- sensitive MRI, with applications to traumatic brain injury (TBI) and aerospace physiology. Brain functional networks responding to vestibular stimuli might be studied to enhance our knowledge of vestibular physiology or to diagnose disorders such as vestibular migraine. Tissue deformation in response to motion might be studied safely, noninvasively and in real time, yielding accurate three-dimensional maps of tissue strain tensors, and blood and synovial fluid perfusion and flow. New superconducting magnet technology (cryogen-free magnets in which the main coil is conduction-cooled by an electrically powered cryocooler while eliminating the need for liquid helium or nitrogen) makes possible the construction of MRI magnets that can be safely tilted and moved while at field. Our laboratory has such a magnet, which has been tested to confirm its high field stability under conditions of dynamic tilt and translation. In this project, this magnet will be equipped with a simple motion platform to demonstrate the concept of mMRI. While vestibular testing in both the clinic and laboratory uses motion platforms, high spatial resolution imaging technologies for these motion applications do not exist. Although methodologies such as electroencephalography (EEG), which does not offer high spatial resolution, and functional near-infrared spectroscopy (fNIRS), which can image only the cortical surface, are established for human research, mMRI promises to introduce high quality information-rich imaging to the field of brain activation during motion. This could yield a singular advance for our understanding of brain activation during motion that could dramatically advance TBI research. The specific aims are: 1) Adapt an existing cryogen-free magnet so that it can be moved via a simple motion platform; 2) Demonstrate anatomic and functional mMRI in phantoms, and in a pilot study using live rats. Motion paradigms will include large-scale dynamic tilt and Earth-vertical rotation. The ultimate goal of this work is to lay the groundwork for the development of a human-scale mMRI scanner.