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Interstitial photodynamic therapy and glioblastoma: Light fractionation study on a preclinical model: Preliminary results

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review


Original languageEnglish
Title of host publicationOptical Techniques in Neurosurgery, Neurophotonics, and Optogenetics II
ISBN (Electronic)9781628413953
Publication statusPublished - 2015
Publication typeA4 Article in a conference publication
EventOptical Techniques in Neurosurgery, Neurophotonics, and Optogenetics II - San Francisco, United States
Duration: 7 Feb 201510 Feb 2015


ConferenceOptical Techniques in Neurosurgery, Neurophotonics, and Optogenetics II
CountryUnited States
CitySan Francisco


Background: Glioblastoma is a high-grade cerebral tumor with local recurrence and poor outcome. Photodynamic therapy (PDT) is a local treatment based on the light activation of a photosensitizer (PS) in the presence of oxygen to form cytotoxic species. Fractionation of light delivery may enhance treatment efficiency by restoring tissue oxygenation. Objectives: To evaluate the efficiency of light fractionation using MRI imaging, including diffusion and perfusion, compared to histological data. Materials and Methods: Thirty-nine "Nude" rats were grafted with human U87 cells into the right putamen. After PS precursor intake (5-ALA), an optic fiber was introduced into the tumor. The rats were randomized in three groups: without illumination, with monofractionated illumination and the third one with multifractionated light. Treatment effects were assessed with early MRI including diffusion and perfusion sequences. The animals were eventually sacrificed to perform brain histology. Results: On MRI, we observed elevated diffusion values in the center of the tumor among treated animals, especially in multifractionated group. Perfusion decreased around the treatment site, all the more in the multifractionated group. Histology confirmed our MRI findings, with a more extensive necrosis and associated with a rarified angiogenic network in the treatment area, after multifractionated PDT. However, we observed more surrounding edema and neovascularization in the peripheral ring after multifractionated PDT. Conclusion: Fractionated interstitial PDT induced specific tumoral lesions. The multifractionated scheme was more efficient, inducing increased tumoral necrosis, but it also caused significant peripheral edema and neovascularization. Diffusion and perfusion MRI imaging were able to predict the histological lesions.