Poster Sessions

IMAG -6

Shingo Matsumoto

S. Matsumoto, F. Hyodo, S. Subramanian, N. Devasahayam, J. Munasinghe, E. Hyodo, C. Gadisetti, J. Cook, J. Mitchell, M. Krishna

Low Field Para-Magnetic Resonance Imaging of Tumor Oxygenation and Glycolytic Activity

Non-invasive capabilities to assess the metabolic and physiologic status of tumors can be valuable for diagnostic and therapeutic purposes. A priori knowledge of spatial and temporal changes in oxygenation in solid tumors, a key prognostic factor in cancer treatment outcome, could greatly improve treatment planning in radiotherapy and chemotherapy. A novel methodology has been developed that can provide quantitative three-dimensional maps of tissue oxygenation (pO2) using pulsed Electron Paramagnetic Resonance Imaging (EPRI) in living objects. The pO2 images can be overlaid with anatomic and corresponding physiologic images from conventional Magnetic Resonance Imaging (MRI) on a unified platform. The pulsed EPRI demands instrumentation with nanosecond time resolution to monitor the spin dynamics of paramagnetic oxygen tracers, compared to millisecond-second order in MRI. However, once accomplished, tissue pO2 maps can be generated readily. This study shows that: 1) Using EPRI and air/Carbogen(r) breathing cycle, perfusion limited hypoxia in tumors can be visualized; 2) The relationship between tumor blood perfusion and pO2 status can be examined, where significant hypoxia exists even in regions exhibiting flow; 3) High levels of lactate even in normoxic tumor regions were identified using sequential EPRI and Magnetic Resonance Spectroscopy, suggesting the predominance of aerobic glycolysis in tumor.