Early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma: utility of gray scale harmonic ultrasonography with a microbubble contrast agent.
OBJECTIVE
To evaluate the utility of gray scale harmonic ultrasonography with a microbubble contrast agent in the early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma.


METHODS
Seventy-five patients with 81 nodular hepatocellular carcinomas (1.3-4.8 cm) treated with percutaneous radio frequency ablation were evaluated with contrast-enhanced gray scale harmonic ultrasonography after intravenous bolus injection of a galactose-based microbubble contrast agent. The vascularity within the ablation zones was evaluated with a continuous scan for 3 to 5 seconds between 15 and 30 seconds after initiation of contrast agent injection. To evaluate the perfusion of the ablation zones, intermittent stimulated acoustic emission imaging was performed with a rapid sweeping technique from the end of the continuous scan. All patients underwent follow-up 3-phase helical computed tomography at 1 month after radio frequency ablation and were followed for at least 1 year. The results of contrast-enhanced ultrasonography were compared with those of follow-up computed tomography in terms of the presence or absence of residual unablated tumors.


RESULTS
In 10 (12%) of the 81 treated hepatocellular carcinomas, contrast-enhanced ultrasonography showed either nodular or crescentic enhancing foci at the margins of ablation zones, suggesting residual unablated tumors. Contrast-enhanced computed tomography obtained 1 month after radio frequency ablation confirmed the residual unablated tumors in the same 10 lesions. Diagnostic agreement between 1-month follow-up computed tomography and contrast-enhanced ultrasonography was achieved in all 81 cases (100%).


CONCLUSIONS
Contrast-enhanced gray scale harmonic ultrasonography can be a reliable alternative to contrast-enhanced computed tomography in the early assessment of the therapeutic response to radio frequency ablation for hepatocellular carcinoma.
Choi
Dongil
D
Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
Lim
Hyo K
HK
Lee
Won Jae
WJ
Kim
Seung Hoon
SH
Kim
Young Han
YH
Kim
Seong Hyun
SH
Lim
Jae Hoon
JH
D000328:Adult; D000368:Aged; D006528:Carcinoma, Hepatocellular / Q000000981:diagnostic imaging* / Q000601:surgery*; D017115:Catheter Ablation; D003287:Contrast Media; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008863:Microspheres; D008875:Middle Aged; D011134:Polysaccharides; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014463:Ultrasonography / Q000379:methods*
D003287:Contrast Media; D011134:Polysaccharides; C059891:SHU 508