Superb microvascular imaging for evaluation of microvascularity in breast nodules compared with conventional Doppler imaging

Background: Neovascularity visualization in breast nodules is challenging due to the limitations of conventional Doppler imaging methods. This study aims to assess the performance of superb microvascular imaging (SMI) in evaluating the microvascularity of breast nodules (diameter ≤2 cm). The comparison of performances of SMI with color Doppler flow imaging (CDFI) and power Doppler imaging (PDI) was made by using a three-factor scoring system of vascularity. This study also investigated the common features of microvascularity in small malignant nodules on SMI for early differentiating from benign nodules. Methods: Ninety-one female patients (with 125 breast nodules) were enrolled in this retrospective study. All the breast nodules were examined by grayscale ultrasonography (US), CDFI, PDI, and SMI. The number, morphologic features, and distribution of blood vessels were scored to evaluate the nodular vascularity in light of the three-factor scoring system. The diagnostic value of SMI for microvascularity in breast nodules was analyzed and compared with CDFI and PDI. Results: Histological analysis showed 53 malignant and 72 benign nodules. The vascularity grades detected by SMI were significantly different from those of CDFI and PDI (P<0.05). SMI detected 47 grade-IV nodules of the total 125 nodules (37.6%), which was more than those detected by CDFI (10.4%, 13/125) and PDI (12.8%, 16/125), while more grade-I nodules were detected by CDFI (42.4%, 53/125) and PDI (36.8%, 46/125) compared with SMI (21.6%, 27/125). Differences in the vessel number, morphologic features, and distribution between benign and malignant breast nodules were significant on SMI (P<0.05). The vessel number ≥6, penetrating vessels, and a mixed distribution of vessels in peripheral and central nodular tissues were the common features of microvascularity in the grade-IV malignant nodules on SMI, whereas the blood vessels in the benign nodules were straight and branching and peripherally distributed. Conclusions: In comparison with CDFI and PDI, SMI enhances microvascularity detection, depicts the microvascular architecture in breast nodules and has potential in the differential diagnosis of malignant nodules from benign nodules.