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.