The invention relates to a device and a method for quantifying a variation of oxygenation in a tissue by using a magnetic resonance imaging technique. The variation of oxygenation in a tissue can be quantified from a measured variation of a proton longitudinal relaxation rate ΔR1 and from calibration data. The method of the invention is characterized in that the variation of proton longitudinal relaxation rate ΔR1 that is used is a variation of proton longitudinal relaxation rate of lipids rather than a variation of proton longitudinal relaxation rate of water molecules.
