Triaxial magnetic field gradient system for microcoil magnetic resonance imaging

There is a great advantage in signal to noise ratio (S/N) that can be obtai ned in nuclear magnetic resonance (NMR) experiments on very small samples ( having spatial dimensions similar to 100 mum or less) if one employs NMR "m icro" receiver coils, "microcoils," which are of similarly small dimensions . The gains in S/N could enable magnetic resonance imaging (MRI) microscopy with spatial resolution of similar to1-2 mum, much better than currently a vailable. Such MRI microscopy however requires very strong (> 10 T/m), rapi dly switchable triaxial magnetic field gradients. Here, we report the desig n and construction of such a triaxial gradient system, producing gradients substantially greater than 15 T/m in all three directions, x, y, and z (and as high as 50 T/m for the x direction). The gradients are switchable withi n time similar to 10 mus and adequately uniform (within 5% over a volume of [600 mum(3)] for microcoil MRI of small samples. (C) 2000 American Institu te of Physics. [S0034-6748(00)02011-6].