Flash-echo contrast sonography in the evaluation of response of small hepatocellular carcinoma to percutaneous ablation

Purpose. To evaluate the use of flash-echo contrast sonography (FECS) in subtraction mode in assessing small hepatocellular carcinoma (HCC) after percutaneous local ablation therapy. Methods. Between March 2000 and February 2002, we prospectively assessed small HCCs after percutaneous local ablation therapy using FECS in subtraction mode. Thirty-three patients (22 men, 11 women) with 35 tumors ranging in size from 1.1 to 3.0 cm (mean ± SD, 2.0 ± 0.5) were enrolled. Twenty-one tumors received percutaneous ethanol injection only, 13 tumors received percutaneous microwave ablation therapy only, and the remaining tumor received both treatments. CT, hepatic angiography, and follow-up were used as gold standards in analyzing the accuracy of FECS in detecting residual tumors. Results. The agreements between FECS and CT, FECS and hepatic angiography, and all 3 imaging modalities were 80% (28/35), 85.7% (30/35), and 77.1% (27/35), respectively. Twenty-one patients with 23 completely ablated tumors were followed up for 5 to 39 months (mean ± SD, 20.2 ±11.2). Recurrent disease was detected in 11 (52.4%) patients; local tumor recurrence occurred in 4 (17.4%) patients. The sensitivity, specificity, accuracy, and positive and negative predictive value of FECS in detecting viable tumors were 53.8% (7/13), 90.9% (20/22), 77.1% (27/35), 77.8% (7/9), and 76.9% (20/26), respectively. Conclusions. FECS in subtraction mode shows good agreement with hepatic angiography and CT in the assessment of small HCC after percutaneous local ablation therapy. The sensitivity of FECS in detecting residual tumors is suboptimal.