CTA follow up of patients with carotid stent

Standart imaging protocol has not been yet established for patients undergoing CAS. The aim of this study to determine whether CTA is a feasible modality for assessing stented carotid arteries. In a total of 62 consecutive patients ( 48 male, 14 female patient; median age 66, range 50-81) 64 succesfully stented carotid arteries (39 Wallstent, 25 nitinol stent) were examined by CTA and vascular US. CTA and US images were compared with respect to assessability and patency. Both visual estimation (?50% or not) and the ?NASCET? method were used to determine percent stenosis in CTA images for two different kernels. For US, a determination of ?50% stenosis was based on PSV (?200 cm/s) and an ICA to CCA ratio (?2.5). Percent stenosis values by CTA were also compared to value (n=9, 15% ) determined by catheter angiography. Measurements of intimal thickening in CTA for different kernels and US (B-flow imaging) were compared by ROC analysis. CTA and US images were ?excellent, assessable? in 36 (56.3% ) ve 34 (53.1% ), ?poor, non-assessable? in 0 (0% ) and 3 (4.7% ) respectively. Assessability of CTA images was equal to or better than that of US images in 53 (83% ). The percent stenoses by CTA and US were comparable in all cases. CTA found ?50% stenoses using the ?NASCET? method in 14 of 64 stents; 7 of these showed ? 50% stenosis by spectral Doppler US. Compared with catheter angiography percent stenosis of CTA and US (PSV) were correlated in 5 stent patients. İntimal thickening predominantly were found in middle stent region and on the posterior surface. Measurements of the intimal thickening made using CTA were significantly correlated with those of US (B-flow imaging, p<0,001). However, the coefficient between CTA ( both filter filter) and B-flow imaging for ?nitinol stent? group was higher than that ?wallstent? group (standart filter r=0.965, bone filter r=0.946). In the assessment of intimal thickening, minimum intimal thickness measurement of 0.75 mm was determined as the optimal threshold value for standart filter. The sensitivity, specifity were 88.9% and 90% , respectively. The bone filter threshold value was 0.65 mm and sensitivity, specifity were 64.8% and 90% , respectively. Mean effective radiation dose for CTA helical (head and neck) was calculated as 2.09 mSv and as 0.42 mSv for CT axial examinations performed to evaluate stented carotid segments. In conclusion, CTA provides better image quality for stented carotid arteries than US, but percent stenosis might be higher than US. Therefore, CTA is likely to be an alternative to US in cases of non-assessability. A large scale study including more restenosis cases is warranted to reveal which modality is more reliable.