Nuclear Magnetic Resonance Relaxation Parameters of Muscle in Malignant Hyperthermia-Susceptible Swine

Rationale and Objectives. The malignant hyperthermia (MH) syndrome involves characteristic changes in metabolism that have a significant effect on the postmortem properties of muscle tissue. We investigated the H-1 nuclear magnetic resonance (MR) relaxation parameters of muscle tissue from normal (MH-) and malignant hyperthermia-susceptible (MH+) swine 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 characterized by proton MR relaxation times (T1 and T2). The water content, pH, conducting, 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 distinguished from normal swine using nuclear MR relaxometry. The results of relaxation measurements and the multiexponential analysis of the T2 curves suggest a shift between the different water compartments during MH that might predict the increased water loss of muscle tissue after death.