Non-invasive thermography of laser-induced hyperthermia using magnetic resonance

Saher M. Maswadi, Randolph D. Glickman, Stephen J. Dodd, Jia Hong Gao

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The possibility to induce selective hyperthermia in a target tissue or organ is of great interest for the treatment of cancer and other diseases. An emerging application of thermotherapy is for choroidal neovascularization, a complication of age-related macular degeneration. The therapy is currently limited because the temperature required for optimal tissue response is unknown. We report here an investigation of near infrared laser-induced heating in an ocular phantom. Magnetic resonance thermography (MRT) was used as a non-invasive method to determine the temperature distribution inside the phantom during exposure to a continuous wave diode laser at 806 nm wavelength with 1 watt maximum output. The laser beam had a quasi-Gaussian profile, with a radius of 0.8-2.4 mm at the target. High quality temperature images were obtained from temperature-dependent phase shifts in the proton resonance frequency with a resolution of 1deg C or better, using a 2T magnet. A phantom with a layer of bovine RPE melanin of 1.5 mm thickness was used to determine the spatial resolution of the MRT measurements. Three dimensional temperature maps were also constructed showing a spatial resolution of 0.25 mm in all direction. The heat distribution depended on the laser parameters, as well as the orientation of the melanin layer with respect to the incident laser beam. The temperature profiles determined by MRT closely followed predictions of a heat diffusion model, based on the optical properties of infrared light in melanin. These results support the use of MRT to optimize laser-induced hyperthermia in a small organ such as the eye.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsS.L. Jacques, W.P. Roach
Number of pages12
StatePublished - 2004
EventProgress in Biomedical Optics and Imaging - Laser Interaction with Tissue and Cells XV - San Jose, CA, United States
Duration: Jan 26 2004Jan 28 2004


OtherProgress in Biomedical Optics and Imaging - Laser Interaction with Tissue and Cells XV
Country/TerritoryUnited States
CitySan Jose, CA


  • Infrared, magnetic resonance
  • Laser
  • Ocular phantom
  • Thermal model
  • Thermography
  • Transpupillary thermotherapy

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics


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