Objective:To investigate the application of contrast enhanced ultrasound(CEUS) in planning and guiding for radiofrequency ablation(RFA) for metastatic liver carcinoma(MLC).Methods:One hundred and thirty-five patients with clinically and pathologically diagnosed MLC(from gastrointestinal tumors) were included in the present study,and 104 of them had received CEUS prior to RFA to assess the number,size,shape,infiltration,location and enhancing features of the lesions.Among the 104 patients,21(20.1%) were excluded from RFA treatment due to too many lesions or large infiltrative range based on CEUS.The remaining 83 patients with 147 lesions underwent RFA(group A).During the same period,other 31 patients with 102 lesions serving as control group were treated based on findings of conventional ultrasound without contrast(group B).The patients underwent follow-up enhanced CT at the 1st month,and then every 3-6 months after RFA.The tumor was considered as early necrosis if no contrast enhancement was detected in the treated area on the CT scan at the 1st month.Results:In group A,72 of 147 MLC lesions(48.9%) showed increased sizes on CEUS.Among them,48 lesions(66.6%) appeared enlarged in arterial phase,and 24(33.3%) showed enlarged hypoechoic area in parenchymal phase.CEUS showed total 61 additional lesions in 35 patients(42.1%)(ranged from 8 to 15 mm) compared with conventional ultrasound(US),and 42(68.8%) of them were visualized in parenchymal phase only.There were total 208 lesions in group A underwent RFA with CEUS planning,and the tumor necrosis rate was 94.2%(196/208).In this group,local recurrence was found in 16 lesions(7.7%) during 3-42 months’ following up,and new metastases were seen in 30 cases(36.1%).For group B,the tumor necrosis rate was 86.3%(88/102),local recurrence in 17 lesions(16.7%),and new metastases in 13 cases(41.9%).Tumor early necrosis and recurrence rates were significantly different between the two groups(P=0.018,P=0.016,respectively).Conclusion: CEUS played an important role in RFA for liver metastases by candidate selecting and therapy planning, which helped to improve the outcome of the treatment. Objective: To investigate the application of contrast enhanced ultrasound (CEUS) in planning and guiding for radiofrequency ablation (RFA) for metastatic liver carcinoma (MLC). Methods: One hundred and thirty-five patients with clinically and pathologically diagnosed MLC (gastrointestinal tumors ) were included in the present study, and 104 of them had received CEUS prior to RFA to assess the number, size, shape, infiltration, location and enhancing features of the lesions. Among the 104 patients, 21 (20.1%) were excluded from RFA treatment due to too many lesions or large infiltrative range based on CEUS. Remaining 83 patients with 147 lesions underwent RFA (group A). ​​The same period, other 31 patients with 102 lesions serving as control group were treated based on findings of conventional ultrasound without contrast (group B). The patients underwent follow-up enhanced CT at the 1st month, and then every 3-6 months after RFA. tumor was considered as early necrosis if no contrast enhanceme A was found in the treated area on the CT scan at the 1st month. Results: In group A, 72 of 147 MLC lesions (48.9%) showed increased sizes on CEUS. Amm them, 48 lesions (66.6%) phase, and 24 (33.3%) showed enlarged hypoechoic area in parenchymal phase. CEUS showed total 61 additional lesions in 35 patients (42.1%) ranged from 8 to 15 mm compared with conventional ultrasound (US), and 42 ) of them were visualized in parenchymal phase only. There were total 208 lesions in group A underwent RFA with CEUS planning, and the tumor necrosis rate was 94.2% (196/208) .In this group, local recurrence was found in 16 lesions ( For group B, the tumor necrosis rate was 86.3% (88/102), local recurrence in 17 lesions (16.7%), ), and new metastases in 13 cases (41.9%). Tumor early necrosis and recurrence rates were significantly different between the two groups (P = 0.018, P = 0.016, respectively) .Conclusion: CEUS played an important role in RFA for liver metastases by candidate selecting and therapy planning, which helped to improve the outcome of the treatment.