Detection of clinically silent infarcts after carotid endarterectomy by use of diffusion-weighted imaging

BACKGROUND AND PURPOSE: Intraprocedural transcranial Doppler sonography has identified multiple microembolic events during and immediately after carot id endarterectomy (CEA) or angioplasty, yet the rate of clinically evident stroke is small. To determine the significance of the transcranial Doppler sonography findings, we examined patients by use of diffusion-weighted imag ing and fluid-attenuated inversion recovery MR imaging before and immediate ly after CEA for evidence of clinically silent ischemic events. METHODS: Twenty-five patients with atherosclerotic disease of the carotid a rteries underwent diffusion-weighted imaging and fluid-attenuated inversion recovery MR imaging performed, on average, 3 days before and 12 hours afte r CEA, Diffusion-weighted images were acquired in three orthogonal directio ns at b = 900, Pre- and postoperative neurologic examinations mere performe d by the same physician. RESULTS: After endarterectomy, 4.0% of the patients (one of 25 patients) sh owed a single, cortical focus of restricted diffusion and new fluid-attenua ted inversion recovery hyperintensity, measuring <1 cm in diameter, ipsilat eral to the CEA, The postoperative neurologic examination showed no change in status from the preoperative baseline state. This patient had an intraop erative course complicated by the development of a large luminal thrombus, necessitating thrombectomy, CONCLUSION: The use of diffusion-weighted imaging may serve to improve cons picuity of clinically silent infarcts after CEA, An important next step is to determine the risk factors that predispose to detectable parenchymal isc hemic events.