Recent diffusion-weighted imaging (DWI) studies describe a relevant ischemic lesion in almost half of all patients with transient ischemic attack (TIA). We report 3 cases of TIA in which the ischemic lesions were recognized on DWI at a later date ("late-imaged TIA"). Three men (average age, 72.7 years) were admitted to our hospital on complains of monoparesis or sensory disturbance in their right arms. On admission, no apparent ischemic lesion was detected by DWI
however, spotty lesions were apparent in the left precentral or postcentral gyrus on hospital days 2-5. The neurological symptoms resolved within 24 hours, and all the cases were clinically diagnosed as TIA. Carotid MRI revealed low-grade stenosis of the left internal carotid artery with atherosclerotic plaque, characterized as so-called "vulnerable plaque". These findings suggest that the carotid atherosclerotic plaque lead to artery-to-artery embolism. Carotid MRI is considered useful as an adjunct to other imaging modalities in the diagnosis of late-imaged TIA.