Silent ischemia after neuroprotected percutaneous carotid stenting: a diffusion-weighted MRI study

Abstract

Background and purpose: To assess by diffusion-weighted MR imaging (DWI) the efficacy of cerebral protection devices in avoiding embolization and new ischemic lesions in patients with severe internal carotid artery (ICA) stenosis undergoing carotid artery stent placement (CAS).

Methods: One hundred sixty-two CASs in the extracranial ICA were performed with the use of distal filters. Mean age of the patients was 68.5 years (range, 33-86) and 122 patients (75.3%) were symptomatic. MR imaging was performed in all patients during the 3-day period before CAS, and DWI was obtained within 24 hours after the procedure. Ninety-five patients (58.6%) were monitored by transcranial Doppler ultrasonography for microemboli detection in the territory of the middle cerebral artery (MCA), ipsilateral to the vessel being treated.

Results: Twenty-eight patients (17.3%) showed 58 new ischemic foci in DWI, and 13 patients (46.4%) had multiple foci. Location of new lesions was mainly in the vascular territory supplied by the treated vessel (19 patients; 67.9%), but also in the contralateral MCA (1 patient; 3.6%), and the posterior fossa (4 patients; 14.3%). A significant relationship (P < .03) was found between occurrence of transient ischemic attack (TIA) and appearance of new lesions. Microembolic signals (MES) were detected in 88 patients (92.6%), with no relationship between number of MES and the appearance of new ischemic foci.

Conclusion: New ischemic foci were observed in 17.3% of the patients undergoing neuroprotected CAS. Appearance of new ischemic lesions were only significantly related to the occurrence of TIA but not to the number of MES registered or other variables. Despite the encouraging results, the incidence of new ischemic lesions should promote research for safer techniques and devices.

Fig. 1.

A, MR angiography of the right common carotid artery before carotid artery stent (CAS) placement, showing a severe stenosis of the proximal internal carotid artery. B, Diffusion-weighted image (DWI) obtained at the same time shows no abnormalities. C, DWI after CAS with a new ipsilateral lesion in the deep territory of the ipsilateral middle cerebral artery.

Fig. 2.

A–D, Normal axial diffusion-weighted image (DWI). E–K, Post-carotid artery stent placement DWI (axial, sagittal, and coronal) with multiple and bilateral cortical new ischemic lesions in the territory of both middle cerebral artery and contralateral anterior and posterior arteries.

Fig. 3.

A, MR angiography of the right common carotid artery before carotid artery stent placement (CAS) with a tandem lesion in the proximal internal carotid artery. B and C, Diffusion-weighted image before (B) and after CAS (C), showing a new lesion <5 mm in the superficial territory of the contralateral middle cerebral artery.

Fig. 4.

A, Right common carotid artery MR angiography before carotid artery stent placement (CAS). Ulcerated stenosis of the proximal internal carotid artery (ICA). B–D, Axial diffusion-weighted images (B and C) and apparent diffusion coefficient map (D). Before CAS, ischemic focal lesion >10 mm in the left caudate nucleus, contralateral to the treated ICA. E and F, After CAS, a new lesion is shown in the contralateral posterior fossa.

Fig. 5.

A, Normal diffusion-weighted image before carotid artery stent placement. B, After a successful procedure, a new ischemic cortical lesion >10 mm is seen in the contralateral posterior artery territory.