THE EFFECT OF MAGNETIC-FIELD INHOMOGENEITY ON THE TRANSVERSE RELAXATION OF QUADRUPOLAR NUCLEI MEASURED BY MULTIPLE-QUANTUM FILTERED NMR

The effects of magnetic fields B-0 and B-1 inhomogeneities on techniqu es which are commonly used for the measurements of triple-quantum-filt ered (TQF) NMR spectroscopy of Na-23 in biological tissues are analyze d, The results of measurements by pulse sequences with and without ref ocusing of B-0 inhomogeneities are compared, It is shown that without refocusing the errors in the measurement of the transverse relaxation times by TQF NMR spectroscopy may be as large as 100%, and thus, refoc using of magnetic field inhomogeneity is mandatory, Theoretical calcul ations demonstrate that without refocusing B-0 inhomogeneities the spe ctral width and phase depend on the interpulse time intervals, thus, l eading to errors in the measured relaxation times, It is shown that pu lse sequences that were used for the refocusing of the magnetic held ( B-0) inhomogeneity also reduce the sensitivity of the experimental res ults to radiofrequency (B-1) magnetic field inhomogeneity. (C) 1997 Ac ademic Press.