Methodology for Quantifying Interactions Between Perfusion Evaluated by DCE-US and Hypoxia Throughout Tumor Growth

Abstract 

The objective was to validate a combination of two new technologies to depict tumor physiology both temporally and spatially with dynamic contrast-enhanced sonography and an oximeter. Human cancer prostate tumors xenografted onto mice were followed for three weeks using dynamic contrast-enhanced ultrasonography (DCE-US) to detect tumor perfusion. Time intensity curves in linear data were quantified on four regions-of-interest (ROI, main tumor section and its anterior, central and posterior intra-tumoral areas) to extract three indices of perfusion. An oxygen sensor was guided by sonography to obtain accurate pO₂ measurements in the three predefined areas of tumors during their development. No impact on tumor growth of subsequent pO₂ probe insertion was detected. Among the four ROIs studied, the local central tumor showed significant perfusion and oxygenation variations throughout the experiment. A correlation was observed between local central tumor perfusion and pO₂, both of them decreasing through time (p = 0.0068; r = 0.66). The methodology which we developed demonstrated the potential of combining DCE-US with direct tissue pO₂ measurements, improving the description of complex intratumoral dynamic behavior. (E-mail: lassau@igr.fr)

Key Words: Ultrasound-power Doppler, Prostate, IV-contrast agents, Instrumentation, Oxygen partial pressure