Utility of carotid ultrasound using microvascular flow imaging for detecting in-stent plaque protrusion after carotid artery stenting.

BACKGROUND

In-stent plaque protrusion (ISP) refers to the extrusion of unstable plaque material through the stent struts, potentially leading to ischemic complications. It often occurs after carotid artery stenting (CAS) and requires additional treatment. However, ISP is difficult to evaluate by conventional imaging modalities. Microvascular flow imaging (MVFI) is a novel Doppler ultrasound technique for assessing vessels with low-velocity flow. MVFI markedly increases the echogenicity of vessels, and clear contrast between the ISP and the in-stent vessels can be obtained. In this study, whether MVFI is useful for detecting ISP compared with computed tomography angiography (CTA) was investigated.

METHODS

This study investigated 26 patients (22 men; mean age, 72.4 years). Preoperative plaque evaluation was performed by magnetic resonance imaging, ultrasonography, and carotid angiography. The mean stenosis rate according to North American Symptomatic Carotid Endarterectomy Trial methods was 76.2 %. Follow-up ultrasonography and CTA were performed in all patients 4-7 days after CAS. Whether MVFI was useful for detecting ISP compared with results of CTA was investigated.

RESULTS

ISP was observed in 4 patients (15.4 %) on MVFI and in 3 patients (11.5 %) on CTA. Compared with the results of CTA for detecting ISP, MVFI offered sensitivity of 100.0 % and specificity of 95.7 %.

CONCLUSIONS

For detecting ISP, carotid ultrasound using MVFI may deliver a comparable result to CTA.