A method and composition for hyperthermally diagnosing and monitoring treatment of cells in an animal with photoacoustic sound and nanoparticles. The heat (temperature) and photoacoustic sound wave production inside the target tissue is measured. The desired temperature is achieved using a laser and photoacoustic imaging technique. Hyperthermia treatment of tissue in a target site applies a heat source to kill cells without protein denaturation. The method introduces an encapsulated dye that is released at a selected temperature in the target site to indicate that a threshold temperature has been reached to hyperthermally treat the tissue. In one embodiment, the composition releases the dye at a temperature of 42° C. to 56° C., and preferably about 45° C. to 49° C. The composition which can be a liposome composition encapsulating the dye can be introduced to the bloodstream of the patient to flow through the target site.
