A Self-Tuning Liquid Metal Coil Conforming to Movement for High-Resolution Brachial Plexus MRI

PROJECT SUMMARY Abnormality of the brachial plexus (BP), i.e. brachial plexopathy, can result in profound functional, psychological and economic consequences. Dedicated peripheral nerve MRI, or MR neurography (MRN), is an important adjunct to the physical exam and electrodiagnostic testing to evaluate brachial plexopathies, and influences clinically decision making, including surgical planning, and outcomes. MRN affords direct visualization of individual nerves and their relationship to osseus and soft tissue structures but suffers from insufficient spatial resolution (~1.0mm-isotropic) resulting from poor signal-to-noise ratio (SNR). This is largely due to the inherently concave anatomy of the neck-shoulder junction that precludes close proximity of conventional MRI coils to the skin. The inherent, complex branching and intertwining anatomy of the BP requires higher spatial resolution (~0.5 mm-isotropic) than possible with current radiofrequency (RF) coils. Current RF coils are either rigid or not adequately flexible, and do not conform to the curvatures of the neck, shoulder and axillary regions. We will develop novel, non-toxic, robust liquid metal RF coil technology to enable the design of a conformal and flexible neck-BP array. This design will ensure that coil elements conform to the body contour (to maximize SNR) in their entirety and with the arm in different positions. The characteristics of bendability and form-fitting stretchability are feasible with liquid metal technology, but this technology has not been previously implemented commercially. This project proposes the design and construction of a dedicated RF coil array for brachial plexus MRN, to enable higher spatial-resolution and 3D imaging, with unprecedented detail, in patients with clinically suspected thoracic outlet syndrome (TOS). We will systematically evaluate liquid metal coils against standard coils for BP MRN. We hypothesize that the achievable spatial resolution will be ~0.5 mm isotropic, greater than the ~1 mm isotropic currently achieved with commercial coils, and will therefore better depict regional anatomy and pathology. Impact: The proposed research will not only address TOS but will also facilitate evaluation of (1) other brachial plexopathies and more peripheral neuropathies (of traumatic, inflammatory, iatrogenic etiologies, e.g.), and (2) other complex/curved anatomies including the breast/chest wall region, perineal/groin region, and digits. This technology would also facilitate dynamic imaging of the extremities to elucidate pathology such as femoroacetabular impingement (hip), ligamentous laxity (multiple joints), and meniscal incompetence (knee), not borne out with conventional, static MRI.