Brain diffusion changes in unilateral carotid artery stenosis with non-shunt endarterectomy: Correlation with white matter lesions.

OBJECTIVE: Carotid stenosis is associated with hemodynamic cerebral ischemia. Diffusion-weighted MR imaging allows for the assessment of changes related to alterations in tissue integrity. The aim of this study was to investigate (a) whether white matter lesions (WML) and apparent diffusion coefficient (ADC) values differ between ipsilateral and contralateral hemispheres, (b) whether ADC values are related to WMLs and common vascular risk factors, and (c) whether ADC values differ after carotid endarterectomy (CEA) without a shunt in patients with unilateral internal carotid artery stenosis (ICAS). METHODS: Twenty-five patients (16 men, 9 women; mean age of 68 years) with unilateral ICAS (≥ 70% carotid stenosis) were assessed with brain MRI before and after CEA, prospectively. Two experienced radiologists scored the WMLs. Bilateral ADC values in anterior and posterior periventricular WM, occipital WM, and thalamus were evaluated on preoperative and postoperative MRI. Differences in ADC values and WML scores between the two hemispheres were assessed and associations between ADC values, WML scores, and explanatory variables (e.g., age, sex, vascular risk factors) were analyzed. RESULTS: WMLs were significantly greater and ADC values were elevated in the ipsilateral cerebral WM. After CEA, ADC values rapidly decreased but remained higher than within the contralateral hemisphere. Ipsilateral hemispheric ADC values were associated with basal ganglia WMLs. No association between ADC values and vascular risk factors was found. CONCLUSION: ICAS is associated with increased diffusion in normal-appearing WM in comparison to more prominent chronic ischemic lesions. CEA has a partial effect on diffusion. These cerebral changes may be related to chronic low-grade ischemic damage that is induced by ICAS.