NUCLEAR-MAGNETIC-RESONANCE RELAXATION PARAMETERS OF MUSCLE IN MALIGNANT HYPERTHERMIA-SUSCEPTIBLE SWINE

Rationale and Objectives. The malignant hyperthermia (MH) syndrome inv olves characteristic changes in metabolism that have a significant eff ect on the postmortem properties of muscle tissue. We investigated the H-1 nuclear magnetic resonance (MR) relaxation parameters of muscle t issue from normal (MH-) and malignant hyperthermia-susceptible (MH+) s wine taken before their death to identify whether postmortem metabolic differences would be accompanied by changes in relaxation parameters. Methods. Muscle samples from 63 MH-susceptible swine were characteriz ed by proton MR relaxation times (T1 and T2). The water content, pH, c onducting, and the ''subjective meat'' quality were assessed in order to differentiate the meat into one of three groups: normal, pale-soft- exudative, and dark-firm-dry. Results. The T2 relaxation of MH- and MH + muscles was significantly different, but no significant changes were detected in the water content and corresponding T1 relaxation times. Conclusion. These data suggest that MH-susceptible swine can be distin guished from normal swine using nuclear MR relaxometry. The results of relaxation measurements and the multiexponential analysis of the T2 c urves suggest a shift between the different water compartments during MH that might predict tile increased water loss of muscle tissue after death.