Objective:

To investigate the value of ultrasound (US) and contrast-enhanced ultrasound (CEUS) using highfrequency linear probe in the characterization of small colorectal liver metastases (CRLMs).

Methods:

A total of 85 patients with final diagnosis of CRLMs were included in this study. A total of 156 small CRLMs [(7.401.90) mm in diameter

]

were investigated. Logiq E9 (GE Healthcare

USA) equipped with a convex probe (C1-5) and a linear probe (9L) was used. The co

nvex and linear probes were used for US and CEUS

respectively. Senior and junior radiologists separately reviewed all the images and made the final diagnosis.

Results:

The diagnostic value of US and CEUS using high-frequency linear probe were slightly superior to those using convex probe. Senior radiologists diagnostic ability was better than junior radiologist

especially when using convex probe (

P

0.05). High-frequency US and CEUS helped to improve the observe agreement in lesion boundary

halo sign

enhancement level and pattern (boundary Kappa: 0.928 vs. 0.860; halo sign Kappa: 0.909

vs

. 0.816; enhancement level Kappa: 0.714

vs

. 0.572; enhancement pattern Kappa: 0.893

vs

. 0.600). High-frequency linear probe helped to improve the diagnostic consistency of two radiologists (US Kappa: 0.628

vs

. 0.479; CEUS Kappa: 0.658

vs

. 0.363).

Conclusion:

US and CEUS using high-frequency linear probe could depict thesmall CRLMs in high spatial resolution and high contrast

which may help to improve the characterization of small CRLMs and the diagnostic consistency of radiologists with different levels of experience.