Oxygen-enhanced MRI can accurately identify, quantify and map tumour hypoxia in preclinical models

Abstract

Aim There is need for non-invasive methods to identify, quantify and map tumour hypoxia. In this study we used an emerging technology – R1 oxygen enhanced MRI (OEMRI) – to distinguish those tumour sub-regions that respond to hyperoxic gas challenge from refractory subregions. We hypothesised that the proportion of refractory tumour tissue (Oxy-R) would be a robust biomarker of tumour hypoxia across multiple models with different vascular and hypoxic phenotypes. Methods: OE-MRI signal precision, stability and relationship to tissue pO2 were evaluated in well vascularised renal cancer 786-O xenografts. Dynamic sensitivity of proportional Oxy-R to acute changes in hypoxia was evaluated using hydralazine challenge. Relationship of proportional Oxy-R to tissue immunohistochemistry and gadolinium DCE-MRI were explored in parental and drug-resistant 786-O models and in SW620 xenografts.