Contrast-enhanced Doppler Ultrasound for Guiding Percutaneous Microwave Ablation of Hepatocellular Carcinoma: A Report of 32 Cases

Objective To evaluate the usefulness of contrast-enhanced Doppler ultrasound for percutaneous microwave ablation therapy (PMAT) of hepatocellular carcinoma (HCC). Methods A total of 51 hepatic tumors in 32 patients with HCC were treated using a microwave system with a frequency of 2,450 MHz. Before and after PMAT, color Doppler imaging with a bolus injection of Levovist® (Schering AG, Berlin, Germany), at a dose 5 mL at 400 mg/mL, was performed with an A 128 XP10/ART unit (Acuson, Mountain View, CA), with a probe frequency of 3.5 MHz. Results Immediately after PMAT, gray-scale ultrasound imaging of the treated tumor appeared as a hyperechoic area with an acoustic shadow around the electrode. Non-contrast-enhanced color flow signals were detected in all 51 nodules before treatment, while color flow signals disappeared in 49 (96.1%) nodules and were still present in two nodules after the treatment. Contrast-enhanced sonography with Levovist® demonstrated only 36 nodules without flow signals and 15 nodules still having flow signals, 30 days after PMAT. Based on contrast-enhanced ultrasound findings, the residual tumor regions with blood flow signals were treated again within 1 month. Twenty-one of 32 patients had follow-up within 18 months (65.6%). Conclusion Contrast-enhanced Doppler ultrasound is useful for evaluating ultrasound-guided PMAT for HCC.