Assessment of transient ischemic attack with diffusion- and perfusion-weighted imaging

Abstract

Background: Diagnosing TIA can be difficult, since evidence of brain ischemia is habitually lacking on CT and conventional MR imaging. It has been suggested that patients with acute brain infarction on neuroimaging should be considered stroke cases instead of TIA, regardless of duration of symptoms, implying that optimal diagnostic methods need to be utilized. We therefore postulated that perfusion-weighted MR imaging (PW imaging) would be useful in the diagnosis of TIA.

Methods: Retrospective analysis of 22 patients with reversible neurologic symptoms lasting less than 24 hours, assessed with DW and PW imaging.

Results: MR imaging was abnormal in 15 patients (68%): 12 had abnormal DW imaging, four had both DW and PW imaging defects (all with a mismatch) and three had an isolated PW imaging abnormality. There were no differences in symptom duration, stroke etiology or cardiovascular risk factors between patients with abnormal MR imaging and those with unremarkable scan. Patients with mismatch were more likely to need conventional angiography or other cerebrovascular procedures.

Conclusion: The combined use of DW imaging and PW imaging provided evidence of brain ischemia in most patients with clinical diagnosis of TIA. Prospective studies using follow-up MR imaging are required to determine the outcome of affected tissue, as well as the clinical implications of DW-PW imaging abnormalities.

Fig 1.

Brain MR imaging of case 1. Left, Initial images show faint DW imaging hyperintensities in the right temporal lobe (top) and frontoparietal junction (bottom). Right, Follow-up images obtained 6 days later show slight expansion of the DW imaging abnormalities but complete resolution of the PW imaging defects.

Fig 2.

Brain MR imaging of case 2. Top, upper cut images; bottom, lower cut images.

Fig 3.

Brain MR imaging of case 3. The MRA shows severe stenosis of the left intracranial ICA (arrow) and tandem stenosis involving both A1 and A2 segments of the ACAs (arrowheads).