Spatial and temporal control of hyperthermia using real time thermal strain imaging with motion compensation

Ultrasound mild hyperthermia has been employed to induce physiological changes that can directly treat cancer and enhance local drug delivery. For mild hyperthermia, temperature monitoring is essential to avoid undesirable biological effects. In previous work by our group, control of mild hyperthermia was achieved using a proportional-integral-derivative (PID) controller based on thermocouple measurements [1]. Despite good temporal control of heating, this method was limited by the fact that temperature was measured only at the thermocouple position. Ultrasound thermometry techniques based on exploiting the thermal dependence of the longitudinal wave speed can be extended to create thermal maps and allow accurate monitoring of temperature with good spatial resolution. However, in vivo applications of this technique have not been fully developed due to the high sensitivity to tissue motion. Here, we address translational and compressional motion compensation and demonstrate effective thermometry in the presence of physiological-scale motion.