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26 February 2008 Monitoring Pc 4-mediated photodynamic therapy of U87 tumors with dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) in the athymic nude rat
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Abstract
Post-operative verification of the specificity and sensitivity of photodynamic therapy (PDT) is most pressing for deeply placed lesions such as brain tumors. We wish to determine whether Dynamic Contrast Enhanced-Magnetic Resonance Imaging (DCE-MRI) can provide a non-invasive and unambiguous quantitative measure of the specificity and sensitivity of brain tumor PDT. Methods: 2.5 x 105 U87 cells were injected into the brains of six athymic nude rats. After 5-6 days, the animals received 0.5 mg/kg b.w. of the phthalocyanine photosensitizer Pc 4 via tail-vein injection. On day 7 peri-tumor DCE-MRI images were acquired on a 7T microMRI scanner before and after tail-vein administration of 100 μL gadolinium and 400 μL saline. After this scan the animals received a 30 J/cm2 dose of 672-nm light from a diode laser (i.e., PDT). The DCE-MRI scan protocol was repeated on day 13. Next, the animals were euthanized and their brains were explanted for Hematoxylin and Eosin (H&E) histology. Results: No tumor was found in one animal. The DCE-MRI images of the other five animals demonstrated significant tumor enhancement increase (p < 0.053 two-sided t-test and p < 0.026 one-sided t-test) following PDT. H&E histology presented moderate to severe tumor necrosis. Discussion: The change in signal detected by DCE-MRI appears to be due to PDT-induced tumor necrosis. This DCE-MRI signal appears to provide a quantitative, non-invasive measure of the outcome of PDT in this animal model and may be useful for determining the safety and effectiveness of PDT in deeply placed tumors (e.g., glioma).
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Davood Varghai M.D., Kelly Covey, Rahul Sharma, Nathan Cross, Denise K. Feyes, Nancy L. Oleinick, Chris A. Flask, and David Dean "Monitoring Pc 4-mediated photodynamic therapy of U87 tumors with dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) in the athymic nude rat", Proc. SPIE 6842, Photonic Therapeutics and Diagnostics IV, 68422P (26 February 2008); https://doi.org/10.1117/12.763983
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