A magnetic resonance (MR) imaging system (600) for generating information indicative of an MR response to an oxygen breathing challenge, the MRI (600) system comprising at least one controller (610) which is configured to define a reference region (302) within a region of interest (ROI) (300 A) of reconstructed MR image information (300) including a plurality of voxels, the reference region (302) comprising a plurality of reference voxels selected from the plurality of voxels, each of the plurality of voxels having associated ΔR2* and ΔR1 values; select a cluster of voxels comprising voxels from at least the reference voxels from a multiparametric ΔR2* and ΔR1 mapping of the plurality of voxels; determine AR2* and AR\ limit points based upon at least minimum ΔR2* and ΔR1 values of voxels of the cluster of voxels; and determine outlier voxels (115) based upon a comparison of ΔR2* and ΔR1 of at least one of the plurality of voxels with respective values of the ΔR2* and ΔR1 limit points.