The brain responds dynamically to transient episodes of ischemic insult. Standard brain imaging techniques, computed tomography (CT) and conventional magnetic resonance imaging (MRI) are insensitive to dynamic and regionally varying neural parenchymal responses to tissue ischemia. MR spectroscopy is an interesting new application of MRI for the study of patients with transient ischemic attack (TIA). In an UCLA study, among TIA patients with early DWI abnormalities who had follow-up imaging, approximately one-half exhibited late CT or MRI evidence of established infarction. Both UCLA and Duke Series found a strong statistical correlation between duration of TIA symptoms and presence of a lesion on DWI. MR imaging studies have demonstrated the untenability of any definition of TIA based solely on clinical manifestations and an arbitrarily assigned time window, rather than tissue changes and physiologic processes. MRI has fundamentally altered our understanding of the pathophysiology of transient ischemic attack.