Evaluation of the Vascular Architecture of Focal Liver Lesions Using Micro Flow Imaging

Objectives: To identify the vascular architecture of focal liver lesions using micro flow imaging and compare it with characteristics on contrast harmonic imaging during the arterial phase.

Methods: Micro flow imaging and contrast harmonic imaging were performed in 118 patients with various focal liver lesions: hepatocellular carcinoma (n = 70), metastasis(n = 19), intrahepatic cholangiocarcinoma (n = 3), lymphoma (n = 1), hemangioma (n = 17), and focal nodular hyperplasia (n = 8). The vascular architecture of the lesions on micro flow imaging was evaluated by 2 investigators independently to reveal 6 patterns (types IVI). Enhancement characteristics on contrast harmonic imaging were also evaluated.

Results: Inter-reader agreement for delineating the vascular architecture was higher on contrast harmonic imaging (κ= 0.856) than micro flow imaging (κ= 0.613). On micro flow imaging, the vascular patterns of hepatocellular carcinomas were types I (28.6%), II (65.7%), and III (5.7%). On contrast harmonic imaging, 44 of 70 (62.9%) hepatocellular carcinomas showed chaotic vessels, of which 40 were type II and 4 were type II. The vascular patterns of metastases were types IV (78.9%), I (10.5%), and II (10.5%). Typical rim enhancement was identified in 57.9% of metastases on contrast harmonic imaging, and all were type IV. The vascular patterns of focal nodular hyperplasia were types VI (87.5%) and I (12.5%). Typical spoked wheel arteries were identified on contrast harmonic imaging in 2 focal nodular hyperplasia cases. The vascular patterns of hemangiomas were types V (94.1%) and II (5.9%). Typical peripheral nodular enhancement was identified in 88.2% of hemangiomas on contrast harmonic imaging, and all were type V. The χ(2) test revealed that differences in vascular architecture between the lesions were significant on micro flow imaging (P < .001).

Conclusions: Micro flow imaging permitted detailed delineation of the vascular architecture of focal liver lesions. Hepatocellular carcinoma, metastasis, focal nodular hyperplasia, and hemangioma showed characteristic vascular architecture.