A comprehensive study on the feasibility and diagnostic potential of fluctuation imaging in liver tumor assessment

Ultrasound (US) is a widely used technique for liver disease but has limitations in distinguishing tumors. This study evaluates the clinical efficacy of fluctuational imaging (FLI), a new US method that detects the fluttering sign in liver tumors. We conducted a prospective exploratory study with 120 participants diagnosed with liver tumors through histopathology or standard imaging. Both FLI and US were performed, capturing approximately 100 image frames within a 10-second breath-hold to create a color-coded FLI map. The fluttering sign, shown by yellow to red area in tumors, was primarily analyzed in the largest tumor in cases with multiple tumors. Eleven participants were excluded due to non-visibility of tumor in B-mode US (n = 3), not a hepatic tumor (n = 1) or motion artifact affecting FLI map creation (n = 7). The final cohort comprised 70 hemangiomas, 17 hepatocellular carcinomas, 7 cholangiocarcinomas, 11 metastases, 3 angiomyolipomas, and 1 cortical adenoma. The fluttering sign was observed in 57.1% (40/70) of hemangiomas, significantly higher than the 12.8% (5/39) in other tumor types (P < 0.001). Mixed or hypoechoic hemangiomas showed an 86.1% incidence (31/38) of the fluttering sign, significantly more than hyperechoic hemangiomas (28.1%, 9/32) (P < 0.001). FLI significantly detects the fluttering sign in hepatic hemangiomas, especially mixed or hypoechoic types, enhancing its diagnostic value.