Abstract: Objective The purpose of this study was to summarize the enhancement pattern of liver metastases (LM) in contrast-enhanced ultrasonography (CEUS). Methods A total of 76 patients with LM were encountered in our hospital between January 2016 and January 2019, and all of them underwent CEUS and CT scan. The diagnosis of LM was proven by post-operational or liver biopsy with typical pre-operational MRI and / or CT scan. According to the enhancement feature of the lesions in hepatic arterial phase of CT scan, the lesions were divided into poor blood supply (hypovascular, low density in hepatic arterial phase) and rich blood supply (hypervascular, high or equal density). Results The primary foci of liver metastases in our series included colon cancer in 65.8%, breast cancer in 9.2%, lung cancer in 6.6%, gastric cancer in 6.6%), pancreatic cancer in 5.3%, pancreatic neuroendocrine tumors in 3.9% and ovarian cancer in 2.6%; the hypovascular group of LM arisen from colon cancer, lung cancer, gastric cancer, pancreatic cancer and ovarian cancer, and the hypervascular group were from neuroendocrine tumors and breast cancer; the CEUS arterial phase imaging showed homogeneous hyperenhancement, rim-like hyperenhancement, heterogeneous hyperenhancement and isoenhancement; at arterial phase, the incidences of focal homogeneous hyperenhancement, rim-like hyperenhancement, isoenhancement and heterogeneous hyperenhancement in 108 foci in hypovascular group were 52.8%, 35.2%, 3.7% and 8.3%, significantly different as compared to 87.5%, 12.5%, 0.0% and 0.0%, respectively (P<0.05) in 24 hypervascular foci; at portal phase, the incidences of hypoenhancement and isoenhancement in foci with poor blood supply were 99.1% and 0.9%, and at delayed phase, the incidences of hypoenhancement and isoenhancement were 99.1% and 0.9%, significantly different as compared to 70.8%, 29.2%, 79.2% and 20.8%, respectively (P<0.05) in rich blood supply; the initial time of enhancement and the enhancement time to peak in hypovascular group were (17.6±3.8)s and (23.0±4.8)s, much longer than in hypervascular group, while the washout time was(41.1±23.4)s, significantly shorter than in hypervascular group. Conclusion The common LM is poor blood supply foci, with homogeneous CEUS hyperenhancement and quick clearance, and the demonstration of primary foci is helpful for the diagnosis of LM in clinical practice.

Key words: Liver metastases, Contrast-enhanced ultrasonography, Enhancement pattern, Enhancement time to peak, Diagnosis