Table 2.

Malignant potential with intratumoral blood flow in the arterial phase or the portal phase of contrast-enhanced ultrasonography.

Study	n	Inclusion Criteria of Tumor	Treatment	Evaluation	Results
Maruyama et al. [32]	54	Solitary and ≤5 cm ≤3 tumors and ≤3 cm	RFA	Outcome (Recurrence)	Intensity differences at the early arterial time is one of the independent factors for intrahepatic distant recurrence (HR, 2.7; 95% CI, 1.2–5.8; p = 0.014).
Han et al. [33]	125	Solitary and 5 cm or less ≤3 tumors and ≤3 cm	RFA	Outcome (Recurrence)	Tumor peak intensity was a significant independent risk factor for intrahepatic recurrence after RFA (HR, 0.3; 95% CI, 0.1–0.9).
Feng et al. [34]	271	Early stage	LR	Differentiation	Washout before 120 s from contrast injection group had poorly differentiation. Sensitivity, 98.0%; specificity, 77.8%; positive predictive value, 96.0%; negative predictive value, 48.8%
Yao et al. [35]	211	Early stage	LR	Microvascular invasion	Washout time (<90 s) (OR: 2.755, 95% CI: 1.227–6.187) was one of the independent predictors of microvascular invasion.

CI: confidence interval; HR: hazard ratio; LR: liver resection; RFA: radiofrequency ablation; OR: odds ratio; SN: simple nodular.