Thermal dosimetry of spinal cord heating in the mouse

Abstract

Three systems for the localized heating of the spinal cord of the mouse have been evaluated by measuring the temperatures in the spinal canal (T_sp); at a reference location dorsal to the spine (T_do), and by numerically calculating temperature distributions throughout two-dimensional transverse cross-sections through the middle of the heated region. The systems assessed were water bath heating alone, water bath-rf combination and rf heating alone with oblique, dorsally located electrodes. It has been established that (1) for all systems ΔT (where ΔT–T_sp) decreased throughout a 1 h heating period–this was attributed to changes in blood flow; (2) there existed a considerable variation in the experimental value of ΔT, particularly for rf heating. The resulting error in the estimation of T_sp from a measured value of T_do can be reduced by making use of the observed correlation between ΔT and the slope of a temperature decay curve measured at the beginning of the heating period; (3) rf alone best spares adjacent visceral and superficial tissues from significant elevation of temperature.

Key Words:

• Hyperthermia
• spinal cord
• thermal dosimetry
• blood perfusion