title: Real-time optoacoustic monitoring of vascular damage during photodynamic therapy treatment of tumor.
abstract: The optoacoustic technique is a noninvasive imaging method with high spatial resolution. It potentially can be used to monitor anatomical and physiological changes. Photodynamic therapy (PDT)-induced vascular damage is one of the important mechanisms of tumor destruction, and real-time monitoring of vascular changes can have therapeutic significance. A unique optoacoustic system is developed for neovascular imaging during tumor phototherapy. In this system, a single-pulse laser beam is used as the light source for both PDT and for concurrently generating ultrasound signals for optoacoustic imaging. To demonstrate its feasibility, this system is used to observe vascular changes during PDT treatment of chicken chorioallantoic membrane (CAM) tumors. The photosensitizer used in this study is protoporphyrin IX (PpIX) and the laser wavelength is 532 nm. Neovascularization in tumor angiogenesis is visualized by a series of optoacoustic images at different stages of tumor growth. Damage of the vascular structures by PDT is imaged before, during, and after treatment. Rapid, real-time determination of the size of targeted tumor blood vessels is achieved, using the time difference of positive and negative ultrasound peaks during the PDT treatment. The vascular effects of different PDT doses are also studied. The experimental results show that a pulsed laser can be conveniently used to hybridize PDT treatment and optoacoustic imaging and that this integrated system is capable of quantitatively monitoring the structural change of blood vessels during PDT. This method could be potentially used to guide PDT and other phototherapies using vascular changes during treatment to optimize treatment protocols, by choosing appropriate types and doses of photosensitizers and doses of light.
authors.affiliation: South China Normal University, MOE Key Laboratory of Laser Life Science, Institute of Laser Life Science, Guangzhou 510631, China.
authors.forename: Liangzhong
authors.initials: L
authors.lastname: Xiang
authors.forename: Da
authors.initials: D
authors.lastname: Xing
authors.forename: Huaimin
authors.initials: H
authors.lastname: Gu
authors.forename: Diwu
authors.initials: D
authors.lastname: Yang
authors.forename: Sihua
authors.initials: S
authors.lastname: Yang
authors.forename: Lvming
authors.initials: L
authors.lastname: Zeng
authors.forename: Wei R
authors.initials: WR
authors.lastname: Chen
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002645:Chickens; D003199:Computer Systems; D004305:Dose-Response Relationship, Drug; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D008545:Melanoma / Q000098:blood supply* / Q000175:diagnosis / Q000188:drug therapy; D033401:Microscopy, Acoustic / Q000295:instrumentation* / Q000379:methods; D009389:Neovascularization, Pathologic / Q000000981:diagnostic imaging*; D010778:Photochemotherapy / Q000295:instrumentation* / Q000379:methods; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011379:Prognosis; D011524:Protoporphyrins / Q000494:pharmacology*; D016896:Treatment Outcome
chemical_list: D017319:Photosensitizing Agents; D011524:Protoporphyrins; C028025:protoporphyrin IX