Prospective study of differential diagnosis of hepatic tumors by pattern-based classification of contrast-enhanced sonography

Figure 1 Diagram showing enhancement patterns of hepatic tumors in the arterial phase. A: Intratumoral vessels in the early arterial phase (a) with homogeneous enhancement in the late arterial phase (b) (pattern A1); B: Intratumoral vessels in the early arterial phase (a) with heterogeneous enhancement in the late arterial phase (b) (pattern A1); C: Intratumoral vessels without homogeneous or heterogeneous enhancement (pattern A2); D: Peritumoral vessels alone (pattern A3); E: Peripheral nodular enhancement without tumor vessels (pattern A4); F: No enhancement and no tumor vessels (pattern A5).