title: Magnetic resonance imaging guidance for laser photothermal therapy.
abstract: Temperature distribution is a crucial factor in determining the outcome of laser phototherapy in cancer treatment. Magnetic resonance imaging (MRI) is an ideal method for 3-D noninvasive temperature measurement. A 7.1-T MRI was used to determine laser-induced high thermal gradient temperature distribution of target tissue with high spatial resolution. Using a proton density phase shift method, thermal mapping is validated for in vivo thermal measurement with light-absorbing enhancement dye. Tissue-simulating phantom gels, biological tissues, and tumor-bearing animals were used in the experiments. An 805-nm laser was used to irradiate the samples, with laser power in the range of 1 to 3 W. A clear temperature distribution matrix within the target and surrounding tissue was obtained with a specially developed processing algorithm. The temperature mapping showed that the selective laser photothermal effect could result in temperature elevation in a range of 10 to 45 degrees C. The temperature resolution of the measurement was about 0.37 degrees C with 0.4-mm spatial resolution. The results of this study provide in vivo thermal information and future reference for optimizing laser dosage and dye concentration in cancer treatment.
authors.affiliation: University of Central Oklahoma, College of Mathematics and Science, Department of Engineering and Physics, 100 North University Drive, Edmond, OK 73034, USA.
authors.forename: Yichao
authors.initials: Y
authors.lastname: Chen
authors.forename: Surya C
authors.initials: SC
authors.lastname: Gnyawali
authors.forename: Feng
authors.initials: F
authors.lastname: Wu
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.forename: Yasvir A
authors.initials: YA
authors.lastname: Tesiram
authors.forename: Andrew
authors.initials: A
authors.lastname: Abbott
authors.forename: Rheal A
authors.initials: RA
authors.lastname: Towner
authors.forename: Wei R
authors.initials: WR
authors.lastname: Chen
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology* / Q000628:therapy*; D005260:Female; D006979:Hyperthermia, Induced / Q000379:methods*; D053685:Laser Therapy / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D025321:Surgery, Computer-Assisted / Q000379:methods*; D016896:Treatment Outcome