Application of percutaneous ultrasound-guided treatment for ultrasonically invisible hypervascular hepatocellular carcinoma using microbubble contrast agent

Aim: To evaluate the efficacy of contrast-enhanced ultrasound for the localization of ultrasonically invisible hypervascular lesions in the liver to facilitate percutaneous ultrasound-guided treatment. Materials and methods: Forty patients with 47 ultrasonically invisible hypervascular lesions (5-20 mm) diagnosed on contrast-enhanced computed tomography were enrolled in the retrospective study. Contrast-enhanced ultrasound (CEUS) with Levovist was performed to localize the lesions both in the early phase and liver-specific phase. Diagnosis of was confirmed by percutaneous needle biopsy where feasible, and on the basis of on treatment outcomes or changes in computed tomography findings in those not amenable to biopsy. Results: Thirty-two lesions were diagnosed as hepatocellular carcinoma (HCC). Contrast-enhanced ultrasound localized hepatocellular carcinoma in 24/32 (75%) lesions, the mean diameter (15.1 ± 4.9 mm), as measured using computed tomography, being significantly larger than that of the remaining eight lesions (10.5 ± 2.1 mm). Ultrasound-guided treatment was performed in 19 of the 24 lesions, and transarterial chemoembolization (TACE) was applied for the other five lesions because of difficult percutaneous access. Five of the eight non-visualised lesions were treated by transarterial chemoembolization, and the other three by surgical resection. The beneficial effect of CEUS was significantly greater when the reason for poor initial visualisation was the coarse liver architecture (17/17) than when it was due to adverse location (seven of 15, p < 0.005). Fifteen of the CT-detected hypervascular lesions were considered to represent false positives for HCC, based on their behaviour during follow-up. Conclusion: Contrast-enhanced ultrasound with Levovist facilitates the application of percutaneous ultrasound-guided treatment by improving localization of ultrasonically invisible hypervascular hepatocellular carcinomas in the liver