The PERFORM MRI Project was an ancillary study of the PERFORM trial. Its aim was to investigate the potential effects of terutroban in patients with atherothrombotic disorders, in comparison to aspirin, on the evolution of magnetic resonance imaging (MRI) lesions after a recent ischemic stroke or transient ischemic attack (TIA). The change in both hypointense and hyperintense lesions on the fluid attenuated inversion recovery (FLAIR) sequence, in the total brain volume and in the hippocampal volume from baseline (M1) to the final visit (M24) was assessed as well as the number of emergent microbleeds. A total of 748 patients had their MRI examination validated both at M1 and M24 during the study. At baseline, the volume of hypointense and hyperintense lesions on FLAIR images, the total brain volume, the hippocampal volume and the number of patients with microbleeds did not differ between the two groups. During follow-up, the mean volumetric increase of lesions hypointense or hyperintense on FLAIR images (from 5 to 8 %), the mean reduction of total brain volume (−0.4 %) and of hippocampal volume (−4 %), did not differ between the two treatment arms. The same parameters analysed ipsilateral to the ischaemic lesion did not differ either between the two groups. In the terutroban group, 16.3 % of patients presented with emergent microbleeds, 10.7 % in the aspirin group; this difference was not significant. In the PERFORM study, the progression of FLAIR lesions, of cerebral or hippocampal atrophy and of microbleeds did not differ between patients treated by terutroban and those treated by aspirin.