Diagnostic utility of superb microvascular imaging in depiction of corkscrew collaterals in Buerger's disease

Abstract Purpose To evaluate the corkscrew collaterals in Buerger's disease by superb microvascular imaging (SMI) and power Doppler ultrasonography (PDU). Methods We evaluated with SMI and PDU 14 patients with Buerger's disease in whom corkscrew collaterals had been identified on digital subtraction angiography (DSA). Corkscrew collaterals were classified on DSA and PDU based on their size and morphology. Results A total of 17 vascular regions of collateral vessel formation were assessed. Based on DSA classification, there were three cases of type I collaterals (arterial diameter of >2 mm with large helical pattern), seven cases of type III collaterals (arterial diameter of 1‐1.5 mm with small helical pattern), and seven cases of type IV collaterals (arterial diameter of <1 mm with tiny helical pattern). On PDU, all type I collaterals on DSA appeared as “large snake” images, all type III collaterals on DSA appeared as “small snake” images, and all type IV collaterals on DSA appeared as dots. SMI imaging, both in color and monochrome mode, provided superior demonstration of the continuity of the vessel of large or small “snake” images. In cases appearing as dot pattern on PDU, color SMI was able to show continuity of the flow signal as a helical pattern. Discussion SMI is a promising new Doppler imaging technique that is superior to conventional power Doppler imaging in depiction and identification of corkscrew collaterals in Buerger's disease.