Surface-coil methods

The measured responses to the combinations of multi-frequency selective pulse excitation can be unscrambled for each volume element by transformation with a super-Hadamard matrix. The dimension of this matrix equals the product of the dimensions of the Hadamard matrices used for encoding each space axis. 

But the Bi variation with distance from the coil centre can also be exploited for spatial localization by rotating-frame methods (cf. Section 6.3) [Botl, Sty 1]. If surface coils are used for excitation and detection the space dependence of signal excitation and signal detection enters into the acquired signal in a multiplicative fashion. 

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Little cardiac P MRS has been reported in animal models. Lee et al. describe methods for measuring myocardial energetics using surface-coil... 

In localized NMR spectroscopy a high-resolution spectrum in or (etc.) resonance is produced from a particular region of the organism, selected by techniques comparable to those used in imaging. Under favorable circumstances, metabolic processes may then be studied by standard NMR methods. Localization requires sufficiently large-volume rf coils, but superficial tissues may be studied with flat or shaped surface coils for better rf penetration, although the spatial response is then more complex. Such coils have been developed for different joints or limbs, the neck, head, spine, breasts, etc. 

A method has been worked out for eddy current testing of surfaces and surface cracks or corrosion under dielectric or non-magnetic metal layer of up to 10 mm. The method is based on excitation of eddy currents by a coil with U - type core and information reading by a sensitive gradientometric element located on a axis of symmetry of the core (fig. 1). 

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