A method of directing energy to tissue includes the initial steps of determining target tissue location and/or target tissue margins, positioning an ablation device for delivery of energy to target tissue, and introducing a material having a shape into a tissue region to be monitored. The material is adapted to change echogenic properties in response to heat. The method also includes the steps of applying energy to the ablation device, monitoring the material on a monitor, determining an echogenic response of the material, and terminating ablation if it is determined that the echogenic response of the material is outside a predetermined target tissue threshold.
