Magnetic nuclear magnetic resonance (NMR) imaging with multiple surface coils.

摘要

A method for simultaneously receiving a different NMR response signal from each of a plurality of closely-spaced surface coils, first provides an array of a plurality of the surface coils, each positioned so as to have substantially no interaction with all adjacent surface coils. A different NMR response signal is received from an associated portion of the sample enclosed within an imaging volume defined by the array. Each different NMR response signal is used to construct a different one of a like plurality of NMR images of the sample, with the plurality of different images then being combined, on a point-by-point basis, to produce a single composite NMR image of a total sample portion from which NMR response signal contribution was received by any of the array of surface coils. Interactions between non-adjacent surface coils are minimized by coupling each onto an associated preamplifier. A nuclear magnetic resonance (NMR) signal acquisition apparatus includes a cylindrical array of overlapping coils. Coupling of currents between coils due to re-radiation of received signals, in particular noise currents, is reduced by presenting a high impedance to each coil, thereby reducing the current circulating in each coil. A PREDAMP circuit is disclosed which utilizes the input impedance of a preamplifier, transformed through a quarter-wavelength transmission line segment, to achieve the high input impedance for the coil. As a result, multiple images, each with a high signal-to-noise ratio (SNR), can be simultaneously obtained. A method is disclosed for combining the multiple images into a composite image with optimum SNR, taking into account the phase shifts between images resulting from the spatial orientation of the coils.