<p>Frequency analysis of the photoacoustic radiofrequency signals and <a href="https://www-sciencedirect-com.ezproxy.lib.ryerson.ca/topics/medicine-and-dentistry/oxygen-saturation" target="_blank">oxygen saturation</a> estimates were used to monitor the in-vivo response of a novel, thermosensitive <a href="https://www-sciencedirect-com.ezproxy.lib.ryerson.ca/topics/medicine-and-dentistry/liposome" target="_blank">liposome</a> treatment. The liposome encapsulated <a

more »

... t-com.ezproxy.lib.ryerson.ca/topics/medicine-and-dentistry/doxorubicin" target="_blank">doxorubicin</a> (HaT-DOX) releasing it rapidly (<20 s) when the tumor was exposed to mild hyperthermia (43 °C). <a href="https://www-sciencedirect-com.ezproxy.lib.ryerson.ca/topics/medicine-and-dentistry/photoacoustic-imaging" target="_blank">Photoacoustic imaging</a> (VevoLAZR, 750/850 nm, 40 MHz) of EMT-6 breast cancer tumors was performed 30 min pre- and post-treatment and up to 7 days post-treatment (at 2/5/24 h timepoints). HaT-DOX-treatment <a href="https://www-sciencedirect-com.ezproxy.lib.ryerson.ca/topics/physics-and-astronomy/transponders" target="_blank">responders</a> exhibited on average a 22% drop in oxygen saturation 2 h post-treatment and a decrease (45% at 750 nm and 73% at 850 nm) in the slope of the normalized PA frequency spectra. The spectral slope parameter correlated with treatment-induced hemorrhaging which increased the optical absorber effective size via <a href="https://www-sciencedirect-com.ezproxy.lib.ryerson.ca/topics/physics-and-astronomy/interstitials" target="_blank">interstitial</a> red blood cell leakage. Combining frequency analysis and oxygen saturation estimates differentiated treatment responders from non-responders/control animals by probing the treatment-induced structural changes of blood vessel. </p>