Spatially selective excitation sequence CARVE (completely arbitrary regional volume excitation) excites signal from an arbitrarily shaped profile (I. Sersa, S. Macura: Magn. Reson. Med. 37, 920-931, 1997) by an interleaved sequence of precalculated small tip angle radio-frequency pulses and gradient pulses. Here we propose a spatially selective observation method based on the CARVE principles which is insensitive to the relaxation and the off-resonance effects. The method, CARVE-D (CARVE detection), excites spins uniformly across the sample and across the spectrum but achieves spatial selectivity by weighted coaddition of the signals after the data acquisition. CARVE-D is suitable for spatially selective high-resolution nuclear magnetic resonance spectroscopy in chemically and geometrically complex systems. The method is analyzed theoretically and demonstrated experimentally on model systems.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics