Grayscale median analysis of primary stenosis and restenosis after carotid endarterectomy

BackgroundSeveral studies have reported that echolucent carotid lesions, as determined by grayscale median (GSM) analysis, are associated with increased perioperative embolic complications during carotid artery stenting (CAS). However, there is limited research of the predictive value of GSM analysis comparing values for primary atherosclerotic lesions in the carotid artery with those for recurrent lesions after carotid endarterectomy (CEA).MethodsRetrospective data were collected and analyzed from all patients undergoing CAS from November 2005 to August 2010. Available preoperative images amenable to GSM analysis were processed in Adobe Photoshop (version CS4; San Jose, Calif). Statistical analysis included t-test, Fischer exact test, and generation of a receiver operating characteristic curve.ResultsWith at least 29 days of follow-up, 212 patients underwent 228 CAS procedures. There were 189 stents placed for primary lesions (CAS for primary stenosis group) and 39 stents placed for restenosis after CEA (CAS for restenosis group). GSM analysis was feasible for 47 patients, and the mean GSM was 45.6 (n = 34; 95% confidence interval, ± 8.3) for the primary stenosis group and 20.5 (n = 13; 95% confidence interval, ±9.6) for the restenosis group (P < .01). The mean time from CEA to CAS intervention for the restenosis group was 8.6 years. There was no statistical difference in procedural individual and combined complications of ipsilateral stroke, 30-day stroke, or 30-day mortality between the CAS for primary stenosis group and the CAS for restenosis group. In the primary stenosis group, the mean GSM was lower in those with procedural complications compared with those without complications (15 ± 22 vs 49 ± 8; P = .02).ConclusionsA low GSM value was associated with increased perioperative risk when CAS was performed for native carotid lesions, but a low GSM value was not associated with higher procedural risk when carotid stenting was performed for carotid stenosis after CEA (restenosis). GSM analysis for restenosis may be altered by the time interval from CEA to restenosis.