Short-Term Results of Carotid Endarterectomy and Stenting After the Introduction of Carotid Magnetic Resonance Imaging: A Single-Institution Retrospective Study

Evaluation of ischemic lesions after carotid artery stenting with diffusion-weighted imaging

BACKGROUND

Almost 90% of cerebral thromboembolism cases are caused by atherosclerosis. Craniocervical atherosclerosis is often observed at the carotid bifurcation and is responsible for 20%-30% of all stroke cases. The course of atherosclerotic carotid artery stenosis varies depending on the grade of stenosis and characteristics of the plaque. Carotid artery stenting (CAS) can be used as a less invasive method in patients with symptomatic and asymptomatic high-grade carotid artery stenosis. Diffusion-weighted imaging (DWI) is an effective method for detection of silent or symptomatic acute ischemic lesions that may arise due to CAS or carotid endarterectomy. The number and volume of new ischemic lesions are determined using DWI.

AIM

To evaluate the number and volume of ischemic lesions and their cerebral parenchymal and vascular distribution after CAS using DWI.

METHODS

Forty-seven male (73.4%) and seventeen female (26.6%) patients (total, n = 64) aged 42-84 years (mean 67.96 ± 8.03 years) diagnosed with carotid stenosis between October 2006 and July 2012 were included in this retrospective study. Twelve of the cases (18.8%) were asymptomatic, while fifty-two (81.2%) were symptomatic. The area where the stenosis was highest was measured, and the stenosis rate was determined using the North American Symptomatic Carotid Endarterectomy Trial method. DWI of the cases was evaluated by two radiologists experienced in neuroradiology (B.A. with more than 15 years of experience, E.G. with more than 10 years of experience). Routine DWI examinations were carried out by a 1.5 T MR device 1 h before and after the operation. Since the ischemic lesions that developed in the first hour and in the follow-up period of 5-24 h were assumed to be due to CAS, all lesions within the first 24 h were considered as new ischemias.

RESULTS

In the present study, 39 new ischemic lesions were detected in 20 cases. The average number of new lesions after all CAS operations was 0.62. They were mostly located in the occipital lobes, followed by the frontal and parietal lobes. These new ischemic lesions were most common in the middle cerebral artery territory, followed by the posterior cerebral artery territory and middle cerebral artery-posterior cerebral artery watershed areas. New lesions were found in 31.2% (20/64) of patients, including 17 (26.5%) in ipsilateral and three (4.6%) in contralateral hemispheres. New bilateral lesions were detected in one case (1.5%). The average volume of the new ischemic lesions detected by the two observers was 1.10 cm³. The numbers of newly appearing ischemic lesions in DWI after CAS were significantly higher in cases where stenting was applied on the left side of the carotid artery and in cases where longer plaques (> 1 cm) were responsible for the narrowing in symptomatic patients. The stenosis rate was low in the group with ulcerated plaques.

CONCLUSION

New ischemic lesions due to CAS appear mostly in the main arterial territory but they may also occur in watershed areas.

Associations between carotid intraplaque hemorrhage and new ipsilateral ischemic lesions after carotid artery stenting: a quantitative study with conventional multi-contrast MRI

The risk of cerebral embolism after CAS in patients with carotid IPH is still controversial. This study was to further investigate the relationship between IPH and new ipsilateral ischemic lesion (NIIL) after CAS, and to perform a volumetric analysis of IPH for predicting the risk of NIIL following CAS. One hundred and seventeen patients with carotid stenosis undergoing CAS were prospectively enrolled. Preprocedural multi-contrast carotid MRI was performed. NIIL was evaluated by brain DWI before and after CAS. IPH volume, wall volume at the plaque (WV_plaque) and relative IPH volume were calculated. Associations between IPH and postprocedural NIIL were studied. NIILs were shown in 52 patients. IPH were identified in 53 patients. NIILs were found more frequently in IPH-positive (33/53, 62.3%) than in IPH-negative patients (19/64, 29.7%, p < 0.001). There was no significant difference of WV_plaque between NIIL-positive and NIIL-negative patients (1166.6 ± 432.0 mm³ vs 1124.6 ± 410.4 mm³, p = 0.592). The IPH volume from NIIL-positive group was significantly larger than that of NIIL-negative group (252.8 ± 264.9 mm³ vs 59.3 ± 131.1 mm³, p < 0.001), with also higher relative IPH volume (20.4 ± 19.1% vs 5.7 ± 12.2%, p < 0.001). ROC curve showed that 183.45 mm³ of the IPH volume was the most reliable cutoff value for predicting NIIL with a specificity of 92.3% and a positive predictive value of 86.1%. Larger IPH volume is associated with increased risk of NIIL after CAS procedure. Quantification of IPH volume may be useful for predicting cerebral ischemic events after CAS.