A Method for generating a biomarker includes acquiring an image using an MRI system; processing the MRI image to generate a three-dimensional image of the lung; generating a first function corresponding to the distribution of the different signal intensity values; automatically calculating a filtering threshold of the first function from a second signal intensity value distribution function; segmenting a lung volume comprising: a main volume; a filtered volume of a volume of voxels quantified by the first function and filtered by at least the calculated filtering threshold, normalizing the values of the three-dimensional image of the lung volume; generating a biomarker indicating a normalized segmented volume ratio.