Diffusion weighted MRI imaging and MES detection in the assessment of stroke origin

OBJECTIVES: This study compares the additional benefit of diffusion-weighted MRI (DWI) and microembolus detection by transcranial Doppler ultrasonography (TCD) in the assessment of stroke etiology. METHODS: Fifty-five acute anterior circulation stroke or TIA patients were investigated by both cranial DWI and bilateral TCD of the middle cerebral arteries (1 hour). RESULTS: In one of the 13 patients without acute ischemic lesions visualized on DWI, microembolic signal (MES) detection was positive. However, in 33 out of 44 patients without MES, DWI revealed at least one lesion. In two patients with unilateral territorial infarction and otherwise normal cardiovascular work-up, bilateral MES were found thus localizing the embolic source into the aortic arch or the heart. In a further patient with a dissection, the occurrence of contralateral MES raised doubts on a dissection to be the cause of the infarct. DISCUSSION: There is a contribution of both techniques to the understanding of stroke etiology. The impact of DWI is, however, superior to that of MES detection. Longer TCD recording times may diminish this discrepancy.