title: Photoacoustic monitoring of tumor and normal tissue response to radiation.
abstract: Hypoxia is a recognized characteristic of tumors that influences efficacy of radiotherapy (RT). Photoacoustic imaging (PAI) is a relatively new imaging technique that exploits the optical characteristics of hemoglobin to provide information on tissue oxygenation. In the present study, PAI based measures of tumor oxygen saturation (%sO2) were compared to oxygen-enhanced magnetic resonance imaging (MRI) measurements of longitudinal relaxation rate (R1 = 1/T1) and ex-vivo histology in patient derived xenograft (PDX) models of head and neck cancer. PAI was utilized to assess early changes (24 h) in %sO2 following RT and chemoRT (CRT) and to assess changes in salivary gland hemodynamics following radiation. A significant increase in tumor %sO2 and R1 was observed following oxygen inhalation. Good spatial correlation was observed between PAI, MRI and histology. An early increase in %sO2 after RT and CRT detected by PAI was associated with significant tumor growth inhibition. Twenty four hours after RT, PAI also detected loss of hemodynamic response to gustatory stimulation in murine salivary gland tissue suggestive of radiation-induced vascular damage. Our observations illustrate the utility of PAI in detecting tumor and normal tissue hemodynamic response to radiation in head and neck cancers.
authors.affiliation: Departments of Molecular and Cellular Biophysics and Biochemistry, Roswell Park Cancer Institute, Buffalo, NY 14263.|Departments of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263.
authors.forename: Laurie J
authors.initials: LJ
authors.lastname: Rich
authors.affiliation: Departments of Molecular and Cellular Biophysics and Biochemistry, Roswell Park Cancer Institute, Buffalo, NY 14263.|Departments of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263.|Oral Medicine/Head and Neck Surgery, Roswell Park Cancer Institute, Buffalo, NY 14263.
authors.forename: Mukund
authors.initials: M
authors.lastname: Seshadri
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D006258:Head and Neck Neoplasms / Q000175:diagnosis / Q000532:radiotherapy; D006439:Hemodynamics; D064593:Heterografts; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods; D051379:Mice; D009369:Neoplasms / Q000175:diagnosis* / Q000188:drug therapy / Q000378:metabolism / Q000532:radiotherapy; D009389:Neovascularization, Pathologic / Q000175:diagnosis; D010101:Oxygen Consumption; D061088:Photoacoustic Techniques; D016896:Treatment Outcome