Colorectal liver metastases: Correlations of contrast-enhanced ultrasound features with tumor clinicopathological factors and clinical outcomes following conversion therapy.

OBJECTIVE: To explore the prognostic impact of contrast-enhanced ultrasound (CEUS) features for initially unresectable colorectal liver metastases (CLMs) in a clinical setting of conversion therapy. METHODS: Between March 2015 and November 2020, consecutive patients with CLMs who received conversion treatment were prospectively enrolled. All participants underwent liver CEUS at baseline. The primary endpoint was conversion resection rate (R0 and overall resection). Secondary endpoints were objective response rate (ORR), overall survival (OS), and progression-free survival (PFS). RESULTS: 104 participants who completed conversion treatment were included. CEUS enhancement pattern was correlated with index lesion (size and echogenicity), primary (site, differentiation, perineural invasion, and RAS genotype) and serum (CA19-9 level) characteristics (P = <0.001-0.016). CEUS enhancement pattern was significantly associated with R0 resection rate, ORR, PFS, and OS (P = 0.001-0.049), whereas enhancement degree was associated with PFS and OS (P = 0.043 and 0.045). Multivariate analysis showed that heterogeneous enhancement independently predicted R0 and overall resection (P = 0.028 and 0.024) while rim-like enhancement independently predicted ORR and OS (P = 0.009 and 0.026). CONCLUSION: CEUS enhancement pattern was significantly associated with tumor characteristics and clinical outcomes following conversion therapy, and thus might be of prognosis impact for initially unresectable CLMs.