Proton nuclear magnetic resonance spectroscopy of normal and edematous brain tissue in vitro: changes in relaxation during tissue storage.

Proton nuclear magnetic resonance relaxation times, T1 and T2, of water in unfixed gray and white matter from normal and edematous rabbit brain tissues were measured in vitro at 23 degrees C and 100 MHz to evaluate the effects of the temperature (-25 degrees C to 37 degrees C) and duration (0 to 96 h) of tissue storage on relaxation times. T1 and T2 tended to decrease during storage, probably from slow dehydration of the tissue. This effect was greatest in tissues stored at 37 degrees C and least in those stored at 4 and -25 degrees C; decreases in T1 and T2 were greater in white matter than in gray matter. Freezing brain tissue to -25 degrees C caused a sudden decrease in the T2 of normal white matter. Relaxation times were constant for 5 h in tissues stored at 23 degrees C and for 40 h at 4 degrees C. These results correlated well with corresponding tissue water loss.