A comparative evaluation of "depth pulses" and related sequences for spatial discrimination in in-vivo NMR spectroscopy with surface coils

The performance of a range of "depth pulses" and related pulse sequences for achieving enhanced spatial resolution in surface coil magnetic resonance spectroscopy (MRS) has been compared both experimentally and by computer simulation. A detailed analysis of the spatial selectivity of these sequences both on- and off-resonance suggests that the problem of combining good spatial resolution with adequate bandwidth has yet to be fully resolved. These and related problems, such as the shape of the sensitive volume and its dependence on resonance offset, are likely to limit the use of depth pulses, particularly where alternative methods of spatial selection are available.