TIME AND TEMPERATURE-DEPENDENCE OF MR PARAMETERS DURING THERMAL COAGULATION OF EX-VIVO RABBIT MUSCLE

Detailed measurements of the T-1,-weighted, T-2,-weighted, and MT-weig hted signal were performed for ex vivo muscle samples heated to variou s temperatures for different times, Consistent, monotonic increases in signal intensity were observed with progressive thermal coagulation, corresponding to an increase in T-2 ,relaxation time and an increase i n MT-weighted signal for temperatures above 60 degrees C., The relatio nship for T-1, relaxation was more complex, showing a decrease in T-1, relaxation from 40 to 60 degrees C and an increase above 60 degrees C ., These techniques provide a more direct measure of tissue thermal co agulation than that provided by MR thermometry and suggest MR imaging strategies for the optimization and monitoring of thermal coagulation therapy protocols that create thermal damage in target tissues.