Evaluation of in-stent restenosis after carotid artery stenting with superb microvascular imaging: initial findings

BackgroundCarotid artery stenting (CAS) is an interventional management in preventing ischemic stroke caused by carotid artery stenosis. After the treatment with CAS, in-stent restenosis caused by neointimal hyperplasia may develop.PurposeThis study aims to obtain a better determination of neointimal hyperplasia using superb microvascular imaging (SMI), which provides a high-quality visualization of the endoluminal lesions, and to compare these results with B-mode and Doppler ultrasound (US).Material and MethodsA total of 106 patients who underwent CAS in our interventional radiology unit between 2018 and 2020 were retrospectively analyzed. In total, 44 patients whose procedure images and post-procedural follow-up Doppler US and SMI data could be accessed were included.ResultsThere were nine patients who had in-stent restenosis. One patient had no velocity increase; however, on SMI the measurements showed in-stent restenosis both in area and diameter. The other eight patients had a stenosis degree in the range of 50%-79% on Doppler US. Five patients had in-stent restenosis, both in Doppler US and SMI, by area and diameter measurements. Two patients underwent digital subtraction angiography (DSA).ConclusionWe suggest that using SMI with duplex sonography improves detecting neointimal hyperplasia and in-stent restenosis. With SMI, better visualization of the stent lumen may improve the patient selection for DSA.