Malignant Hepatic Tumors Treated with Percutaneous Radio-frequency Ablation: Comparison between Contrast-enhanced Color Doppler Ultrasound and Spiral CT in Evaluating the Therapeutic Efficacy.

Yoon,  Jung Hee; Han,  Sang Suk; Cha,  Sung Sook

Journal of Korean Society of Medical Ultrasound 2002;21(4): 273-281.

Jung Hee Yoon, Sang Suk Han, Sung Sook Cha

Department of Radiology, College of Medicine, Inje University, Busan Paik Hospital, Korea. minkimom@yahoo.co.kr

Published online: December 1, 2002.

ABSTRACT

PURPOSE: To compare contrast-enhanced color Doppler ultrasound (CECDUS) with spiral CT in the evaluation of the therapeutic efficacy of malignant hepatic tumors after radio-frequency ablation (RFA). MATERIALS AND METHODS: During a recent 2-year period (April 1999 to March 2001), One hundred fifteen hepatic tumors (95 hepatocellular carcinomas and 20 metastases; mean diameter, 2.7cm) from 83 consecutive patients (60 men and 23 women; mean age, 57 years) that were treated with RFA were included in this study. Both CECDUS and two-or three-phase spiral CT were performed a day after RFA as the immediate follow-up study in most cases. Afterward, both imaging studies were alternatively performed on monthly basis, but when incomplete ablation was suspected on one follow-up imaging study, the other imaging study was performed within a week for comparison. For ultrasound contrast agent, a suspension of 2.5 g or 4.0 g Levovist (Schering AG, Berlin, Germany) with a concentration of 300 mg/mL was used. For evaluating the therapeutic efficacy, the presence of viable portion, either residual or recurrent, within the ablated tumor was determined on each imaging study. The criteria for viable portion were defined as focal or irregular enhancement at the periphery of the ablated tumor on the arterial or portal phase spiral CT images and intratumoral vascularities on CECDUS. The correspondence rate between both imaging studies was assessed to compare the diagnostic accuracy of both studies in evaluating a residual or recurrent tumor. In addition, their imaging findings were analyzed. RESULTS: Analyzing both imaging findings of 116 malignant hepatic tumors, the correspondence rate between CECDUS and CT obtained after 116 times of imaging studies was 91.4% (106/116). For the diagnosis of residual or recurrent tumors, the sensitivity, specificity and diagnostic accuracy of spiral CT were 71%, 99%, and 94%, respectively, while those of CECDUS were 87%, 99%, and 97%, respectively. As the immediate follow-up study, CECDUS seemed to be more accurate than spiral CT. CONCLUSION: Our results showed that the correspondence rate between CECDUS and spiral CT was substantially high in the evaluation of therapeutic efficacy of malignant hepatic tumors following RFA. Therefore, we believe that both imaging studies can complement each other for this purpose. Particularly, CECDUS is the preferred immediate follow-up imaging study.

Keywords: Radio-frequency (RF) ablation; Liver neoplasms, US; Ultrasound (US), color Doppler studies; Ultrasound (US), contrast media; Computed tomography (CT), helical