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Abstract:
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Photothermal cancer therapy is a potential alternative to surgery and involves selective tissue destruction using thermal energy . Targeted photoabsorbers , used in conjunction with matching a continuous wave laser , make photothermal therapy both noninvasive and tumor -specific . However , to become clinically relevant , there is a need to develop an imaging technique to identify tissue composition and to detect the presence of photoabsorbers in the tumor volume before therapy ; to monitor the temperature rise during therapy ; and to assess the tumor damage after therapy . In this study , a combined ultrasound and photoacoustic imaging system was designed to assist photothermal therapy . The imaging system was tested on tissue mimicking phantoms , ex -vivo porcine tissue samples , ex -vivo mice and in -vivo mice . First , ultrasound imaging was utilized to differentiate between water -based and lipidbearing tissue . A combined ultrasound and photoacoustic imaging system was then assembled to identify the presence and spatial location of gold nanoparticles . Multiwavelength photoacoustic imaging was used to further confirm the presence of nanoparticles . Temperature monitoring algorithms , using both temperature -dependent time shifts in ultrasound signals and amplitude changes in photoacoustic signals , were developed . Finally , photothermal therapy was carried out on tumor -bearing nude mice using in -vivo ultrasound and photoacoustic imaging to identify the tumor boundary , detect the nanoparticles and monitor the temperature elevation . The results of the studies show that ultrasound and photoacoustic imaging provide complementary and clinically relevant information . Overall , there is potential of using the ultrasound and photoacoustic imaging system to plan , guide and monitor photothermal therapy . |