Analysis of changes in MR properties of tissues after heat treatment

To characterize changes in the MR parameters of tissues due to thermal coagulation, a series of T₁, T₂, diffusion, and magnetization transfer measurements were performed on a variety of ex vivo tissues: murine slow twitch skeletal muscle, murine cardiac muscle, murine cerebral hemisphere, bovine white matter, murine liver tissue, bovine retroperitoneal adipose tissue, hen egg white, human prostate and human blood. Standardized heat treatments were performed for each tissue type, over the temperature range from 37°C to 90°C. For all tissues, changes in each MR measurement resulting from thermal coagulation were observed above a threshold temperature of approximately 60°C. These changes are explained based on biophysical knowledge of thermal damage mechanisms and the MR properties of normal tissues, and are particularly relevant for interpreting the changes in image contrast that are observed when MRI is used to guide and monitor thermal coagulation therapy procedures. Magn Reson Med 42:1061–1071, 1999. © 1999 Wiley-Liss, Inc.