Additional value of superb microvascular imaging of ultrasound examinations to evaluate focal liver lesions

Purpose: To evaluate the additional value of superb microvascular imaging (SMI) to characterize focal liver lesions (FLLs). Method: Between July 2020 and December 2020, 70 patients (39 men and 31 women; mean age [+/- standard deviation], 61.1 +/- 10.1 years) with FLLs were prospectively enrolled and underwent B-mode ultrasound (US), color Doppler imaging (CDI), power Doppler imaging (PDI), and SMI examinations on the same day. All the malignant FLLs were confirmed by histological diagnosis, while the benign FLLs were confirmed by typical imaging features at contrast-enhanced CT and/or MRI. Tumor vascularity scores in CDI, PDI, and SMI were graded using a 5-point scale. For tumors in which vascularity was detected on SMI, tumor vascular pattern on SMI was assessed in each lesion. The diagnostic performance of a combination of B-mode US and SMI, based on vascular pattern on SMI, was compared to B-mode US alone to diagnose malignant lesions; and hemangiomas. Results: Seventy FLLs (34 benign [31 hemangiomas, 3 focal nodular hyperplasias] and 36 malignant tumors [16 hepatocellular carcinomas, 10 cholangiocarcinomas, 10 metastases]) were enrolled. Tumor vascularity score in SMI was significantly higher than those in CDI and PDI (P < 0.001). Using a combination of B-mode US and SMI, the diagnostic performance was improved from 0.867 and 0.834 to 0.945 and 0.921 (P = 0.035 and 0.112) to diagnose malignant tumors and from 0.896 and 0.853 to 0.975 and 0.987 (P = 0.027 and 0.006) to diagnose hemangiomas by reviewers 1 and 2, respectively. Conclusions: SMI provides higher sensitivity than CDI and PDI to detect tumor vascularity, and a combination of B-mode US and SMI can improve the characterization of FLLs when vascular pattern of tumor is considered.