Hypoxia-specific MRI contrast agents

Introduction: Hypoxia or decreased availability of oxygen in tumours is of significant interest in oncology as it is known to increase radiotherapy and chemotherapy resistance, and promote tumour progression [1, 2]. For better prognosis of solid tumours, it is vital to be able to identify and quantify the extent of hypoxia in the different regions of a tumour. MRI provides a non-invasive and safe (i.e., without using any ionising radiation) means of visualising tumours [3, 4]. Paramagnetic contrast agents, often injected intravenously in the patients before an MRI scan, enhance image contrast to assist in the delineation of the tumours [5]. However, as none of the current commercially available MRI contrast agents is hypoxia-specific, it is difficult to visualise hypoxic regions of tumour directly using contrast enhanced MRI. This presentation reports on the development and characterisation of a nanoparticle-based MRI contrast agent system with the ability to actively target hypoxic cells.