Vascular Features of Gallbladder Lesions Using Microvascular Flow Imaging on Transabdominal Ultrasonography: A...

Background/Objectives: Transabdominal ultrasonography (TUS) is widely used for the detection of gallbladder lesions (GBLs), but differentiating malignant lesions from non-malignant lesions remains challenging. Microvascular flow imaging (MVFI), including superb microvascular imaging, detective flow imaging, and B-flow, enables visualization of low-flow vessels without contrast agents. This study aimed to characterize MVFI vascular features of GBLs and evaluate their reproducibility. Methods: We retrospectively analyzed 42 patients with GBLs who underwent TUS between March 2022 and December 2025. Two blinded readers independently assessed B-mode and MVFI findings. The evaluated MVFI findings included vascular flow detection, number of basal vessels, vessel shape, vessel thickness, and vessel irregularity. Interobserver agreement was assessed using Cohen's kappa coefficient, and imaging findings were compared between invasive malignant and non-malignant lesions. Results: Of the 42 lesions, 10 were invasive malignant and 32 were non-malignant. Vascular signals were detected in all invasive malignant lesions and in 21 of 32 non-malignant lesions. Multiple basal vessels and vessel dilation were more frequently observed in invasive malignant lesions. Interobserver agreement was excellent for the number of basal vessels (κ = 0.91) and good for vessel thickness (κ = 0.72), indicating that these findings were more reproducible than other MVFI features. Conclusions: MVFI enables visualization of intralesional vascular features in GBLs. Multiple basal vessels and vessel dilation were associated with invasive malignancy and showed favorable reproducibility. These findings may serve as candidate imaging markers for future prospective validation.