A novel approach to the metabolic characterisation of brain tumours: edema-corrected OEF. A hybrid MR-PET study.

Motivation: Characterize hypoxia and water content in metabolically active brain tumour tissue and edema. Goal(s): Investigate tumour oxygenation without the confounding effect of edema, defined as increased free water content. Compare corrected values to 18F-FET PET as a marker of tumour malignancy. Approach: A single mGRE acquisition measures water content, T2*, OEF, venous blood volume and venous blood-corrected parameters χtissue and R2*tissue. Multicomponent relaxometry separates free and tissue water enabling edema correction Results: OEF and PET values are uncorrelated before and after edema correction and can be used to characterise different aspects of tumour respiration and malignancy Impact: A simple and fast acquisition method enables quantitative and metabolic characterisation of brain tumours and can be implemented in large and multicentre patient studies. Applying edema correction makes the properties of underlying tissue accessible, potentially enabling more precise tumour characterisation.