IN-VIVO OBSERVATION OF ANISOTROPIC MOTION OF BRAIN WATER USING H-2 DOUBLE-QUANTUM FILTERED NMR-SPECTROSCOPY

The H-2 DQF NMR spectra of deuterated water molecules were measured fo r the first time in in vivo rat brain. The observation of the DQF sign al indicates that there is a water population that exhibits anisotropi c motion. The characteristics of the DQF spectra premortem and postmor tem are very similar (lineshape and relaxation times). In the 1st h th ere is a 10-15% decrease in the signal intensity of the DQF spectra fo llowed by a gradual but a much slower decrease in the DQF signal inten sity that reaches 65-70% of its initial value after only 12 h. When th e brains were kept at 4 degrees C, a 40% decrease in the DQ signal int ensity was observed only after 7 days. Mechanical chopping of the brai n tissues causes an immediate loss of more that 91% of the DQ signals. The slow, temperature-sensitive decay of the signal, and its sensitiv ity to mechanical treatment point out that these signals originate fro m water molecules that interact with structural components in the brai n. The characteristics of the DQF spectra depend on the amount of bulk water as exemplified by increased residual quadrupolar interaction an d relaxation rates obtained when dehydrating the brain tissue.