Evaluation of Microvascular Flow Characteristics of Hepatic Hemangiomas: A Prospective Comparison of Ultra‐Micro Angiography With Conventional Doppler and the Effects of Lesion Depth, Size, and Steatosis

OBJECTIVES: To compare ultra-micro angiography (UMA) modalities-color (cUMA), power (pUMA), and subtraction UMA (sUMA)-with conventional color Doppler (CD) and power Doppler (PD) in hepatic hemangiomas, and to identify factors limiting flow detectability, including lesion depth, size, and steatosis. METHODS: In this prospective single-center study, hemangiomas confirmed by contrast-enhanced computed tomography or magnetic resonance imaging underwent B-mode ultrasound, CD, PD, and 3 UMA modes. Vascularity was graded with the Adler scale (0-3), and the vascular index measured for each modality. Steatosis was graded visually and quantified by ultrasound attenuation (USAT). Groups with and without flow were compared with the Mann-Whitney U test; predictors of detectability were assessed by logistic regression and receiver operating characteristic (ROC) analysis. RESULTS: Of 138 hemangiomas in 81 patients, 124 were analyzed; flow was detected in 89 (71.8%). Flow-positive hemangiomas were shallower (44.67 versus 87.06 mm) and larger (29.53 versus 17.89 mm; p < .001 for both). Depth was the strongest predictor (area under the ROC curve 0.904; cutoff 59 mm), followed by size (0.710) and USAT (0.612); moderate and severe steatosis (grades 2 and 3) independently reduced detection (p ≤ .045). Adler grade 2 or higher was present in 65-73% of hemangiomas on UMA versus 21-24% on conventional Doppler (p < .001). Strip rim (30.3%) and peripheral dot-like (23.6%) patterns predominated; interobserver agreement was good (κ = 0.748). CONCLUSIONS: UMA outperforms conventional Doppler in hepatic hemangiomas; depth, small size, and moderate-to-severe steatosis limit signal detection, and peripheral microvascular patterns parallel the globular enhancement on computed tomography (CT) and magnetic resonance imaging (MRI).