Remote detection for more sensitive NMR and MRI

Remote detection of NMR is a novel technique in which an NMR-active sensor surveys an environment of interest and retains memory of that environment to be recovered at a later time in a different location. The NMR information is encoded as spin-polarization of the sensor at the first location and subsequently moved to a different location for optimized detection. Therefore parameters that influence the quality of the data---such as field strength, coil size and geometry, and type of detector---can be chosen with a flexibility unparalleled by conventional NMR experiments where the same coil is used to encode and detect signal.; Remote detection NMR has thus far been performed using Xe-129 gas as the NMR-active sensor that carries information from the first environment to the sensitive detector. Xe-129 has a large chemical shift range and is thus very sensitive to its surroundings and its interactions with them. This extraordinary sensitivity allows Xe-129 to discern between two very similar environments, making it an excellent sensor. Xe is also non-toxic and chemically inert, and thus compatible with biological samples and even living organisms. More importantly for remote detection, it has a long longitudinal relaxation time (T1), which describes the timescale on which the spin system loses the stored memory of its prior surroundings. The successful application of remote detection requires that the longitudinal magnetization last long enough for transfer to the detector. The stored magnetization can be recorded by any detector of magnetization (i.e. Faraday coil, SQUID, or optical detection) to provide, in a point-by-point fashion, the signal representative of the environment in which it is encoded.; Remote detection NMR is applicable to systems in which the NMR-active spins are dilute, where it is advantageous to encode and detect in different field strengths, or where the use of a more portable alternative detector is desired. Thus far, this technique has been applied to systems in which the sensor is dilute. Results will be presented in which the sensitivity is enhanced by concentrating the sensor, including void-space gas imaging of porous materials, and spectroscopy of Xe-129 in materials and biologically-relevant solutions.