Does the evidence suggest that brain imagingstudies should be ordered for this patient?

Yes. The 2009 American Heart Association/American Stroke Association (AHA/ASA) guidelines recommend patients with suspected TIA undergo imaging within 24 hours of symptom onset.1 The goals of neuroimaging in the evaluation of TIA are to obtain evidence of a vascular origin (acute infarct/hypoperfusion), to exclude a nonischemic origin, and to help determine underlying mechanism of the event (e. g., large-vessel atherothrombotic, small-vessel/lacunar, and cardioembolic), which helps guide therapy. MRI with diffusion-weighted imaging (DWI) is the preferred imaging modality.1 If MRI is unavailable, computer tomography (CT) with contrast is a reasonable alternative.1 MRI is superior to CT in the very early stages of acute infarction.1 Approximately 90% of patients with ischemic stroke will show MRI changes within 24 hours.4

Pooled data from 19 studies show that DWI provides a more precise evaluation of ischemic insult in TIA patients compared with standard CT and MRI.1 Unfortunately, the use of MRI is associated with several drawbacks including high cost and limited availability. As a result, contrast head CT is considered to be a good alternative to MRI. For diagnosis of acute intracranial hemorrhage, MRI had a sensitivity of 81% and a specificity of 100% (98%-100%), whereas noncontrast CT has a sensitivity and specificity of 89% and 100%, respectively.5

Bottom line: All patients suspected of having a TIA should undergo imaging of the brain. Although diffusion weighted MRI is ideal, a noncontrast CT performed early can effectively rule out an intracranial bleed whereas a contrast CT performed the next day can effectively detect an acute infarct.

  • Contact
  • Category: Heart and vessels