Breast tumor vascular oxygenation and blood volume assessed by near-infrared spectroscopy and magnetic resonance

Abstract

The goal of this study is to evaluate the feasibility of Near Infrared Spectroscopy (NIRS) as an in vivo monitoring tool for rat breast tumor oxygenation and vascular blood volume by comparison with the established modalities, magnetic resonance imaging/spectroscopy (MRI/MRS). The changes in oxygenated hemoglobin concentration and total hemoglobin concentration (Δ[HbO 2 ], Δ[Hb] total ) with respect to hyperoxic gas interventions were monitored by NIRS. Changes in deoxygenated hemoglobin, a blood oxygenation level dependent (BOLD) contrast, and blood volume on breast tumors were monitored by BOLD MRI and 19 F MRS of PFOB, respectively. Results showed strong consistency among the two pairs: Δ[HbO 2 ] versus BOLD signal, Δ[Hb] total versus tumor blood volume. These consistent results demonstrated the ability of NIRS as a valid in-vivo real time monitoring tool for studying the dynamic responses of Δ[HbO 2 ] and Δ[Hb] total to therapeutic interventions applied to rat breast tumors. Furthermore, the results suggested that NIRS and MRS are complimentary with each other in terms of temporal and spatial resolutions.