Traditional Posters: Miscellaneous

Electron Spin Resonance

Hall B Thursday 13:30-15:30

1034. Non-Invasive Demonstration of Instabilities in Tumor Oxygen Concentration Using Dynamic 3D EPR Oxygen Imaging

Hironobu Yasui^1,2, Shingo Matsumoto¹, Jeeva P. Munasinghe³, Nallathamby Devasahayam¹, Sankaran Subramanian¹, James B. Mitchell¹, Murali C. Krishna<sup>1

1</sup>National Cancer Institute, Bethesda, MD, United States; ²Hokkaido University, Hokkaido, Japan; ³National Institute of Neurological Disorder and Stroke

Structural and functional abnormality of blood vessels within malignant tumors influences delivery of oxygen, a key radio-sensitizer, resulting in two different types of hypoxia. Chronic hypoxia is attributed to large diffusion distances between tumor microvessels and longitudinal oxygen gradient, whereas acute hypoxia is though to be the result of transient vascular occlusion and fluctuation in red blood cell flux. Electron paramagnetic resonance (EPR) imaging is a sensitive method to non-invasively map tissue oxygenation distribution. To investigate the fluctuation of tumor oxygen concentration, dynamic 3D EPR oxygen imaging was applied to two different types of tumor bearing in mouse.

1035. Assessment of Rapamycin Effects on Tumor Oxygenation and Angiogenesis by Using EPRI and MRI

Keita Saito¹, Shingo Matsumoto¹, Nallathamby Devasahayam¹, Sankaran Subramanian¹, Jeeva P. Munasinghe², Vyomesh Patel³, Silvio Gutkind³, James B. Mitchell¹, Murali C. Krishna<sup>1

1</sup>National Cancer Institute, Bethesda, MD, United States; ²National Institute of Neurological Disorder and Stroke; ³National Institute of Dental and Craniofacial Research

Effects of anti-tumor drug rapamycin on tumor oxygenation and angiogenesis in tumor bearing mice were investigated by using pulsed electron spin resonance imaging and magnetic resonance imaging. Blood volume in tumor region was significantly decreased after 2 days from beginning of the rapamycin treatment. Tumor oxygenation did not drastically change by rapamycin treatments, but pO₂ level slightly increased and the ratio of hypoxic area to tumor region slightly decreased after 2 days rapamycin treatments. These results suggest that rapamycin can normalize blood volume and suppress depletion of oxygen in the tumor region.

1036. Spatial Distribution of Free Radicals in Dental Resins Using Electron Paramagnetic Resonance Imaging (EPRI)

Philippe Levêque¹, Julian Leprince^2,3, Ana Maria Dos Santos-Goncalvez², Gaëtane Leloup², Bernard Gallez<sup>1

1</sup>Biomedical magnetic resonance unit, Université catholique de Louvain, Brussels, Belgium; ²School of Dentistry and Stomatology, Université catholique de Louvain, Brussels, Belgium; ³Laboratory of Polymer Science, Université catholique de Louvain, Louvain-la-Neuve, Belgium

Methacrylate resins are highly popular in dentistry and are largely used in clinic for tooth restoration. Free radicals are created during the photopolymerization process and can be detected by EPR spectroscopy. EPR has been successfully used to study the mechanical properties of this material. This study focuses on the feasibility of EPRImaging using dental resins which exhibits complex signal. 2D imaging and 2D spectral spatial imaging were applied and give the unique possibility of non destructive characterization and mapping of free radicals in dentam resins and more generally in biomaterials and materials science.