Maximal RF energy storage in a probe of clinical MR tomograph using the system of flexible solenoids

This article shows that the flexible inductance coil, proposed by the author first in A.M. Khripov and A.A. Khripov, Patent of Russian Federation 2095949 (1997) and A.A. Khripov, Proc. 19/sup th/ Ann. Internat. Conf. of IEEE Engng. in Med. and Biol. Soc., Chicago, IL, USA, p. 889-93 (Oct.-Nov., 1997), can experimentally and theoretically be described as an infinite set of solenoidal coils which have a flexible form and a fixed radius within the range from the maximal to minimal one determined by the given coil construction. Here, the author calls the proposed device as a system of flexible solenoids (SFS). Both the energy and amplitude consideration of Signal to Noise Ratio (SNR) in Nuclear Magnetic Resonance (NMR) experiments of the low frequencies range up to 100 MHz tells about the optimal performance of the solenoidal coil for samples embraced by its winding. Many progressive NMR applications in medicine and biology reveal some restrictions with a conventional solenoid that can be expressed in its fixed, closed geometry and, as a consequence, low filling factor for in-vivo studies. The proposed device resolves the difficulties that becomes its main advantage. The test of the receiver SFS indicating the SNR improvement in comparison with a surface receiver and quadrature transmit/receive coils has been carried out on "Toross" 0.11 T (5 MHz) and "Vectra" 0.5 T (21.29 MHz) GEMS MRI system.