Radio-frequency ablation of hepatic metastases: postprocedural assessment with a US microbubble contrast agent--early experience.
OBJECTIVE
To evaluate contrast agent-enhanced ultrasonography (US) in the detection of untreated tumor after radio-frequency (RF) ablation of hepatic metastases.


METHODS
Twenty patients with solitary colorectal liver metastases underwent percutaneous RF tumor ablation. Pre- and postablation imaging was performed with nonenhanced and enhanced color and power Doppler US and contrast-enhanced helical computed tomography (CT). Initial follow-up CT and US were performed 24 hours after ablation. The findings at US and CT were compared.


RESULTS
Nonenhanced US demonstrated intratumoral signal in 15 of 20 metastases before ablation. This signal increased after contrast agent administration. Contrast-enhanced US performed 24 hours after ablation demonstrated residual foci of enhancement in three tumors, whereas no US signals were seen in any tumor on nonenhanced scans. CT demonstrated small (< 3-mm) persistent foci of residual enhancement in these three tumors and in three additional lesions that were not seen at US (US sensitivity, 50%; specificity, 100%; diagnostic agreement with CT, 85%). All six patients with evidence of residual tumor underwent repeat RF ablation.


CONCLUSIONS
Contrast-enhanced US may depict residual tumor after RF application and thereby enable additional directed therapy. The potential reduction in treatment sessions and/or ancillary imaging procedures might increase the ease and practicality of percutaneous ablation of focal hepatic metastases.
Solbiati
L
L
Department of Radiology, Ospedale Generale, Busto Arsizio, Italy.
Goldberg
S N
SN
Ierace
T
T
Dellanoce
M
M
Livraghi
T
T
Gazelle
G S
GS
D000368:Aged; D017115:Catheter Ablation; D015179:Colorectal Neoplasms / Q000473:pathology; D003287:Contrast Media; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary* / Q000601:surgery; D008875:Middle Aged; D018365:Neoplasm, Residual / Q000000981:diagnostic imaging; D011134:Polysaccharides; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D018615:Ultrasonography, Doppler, Color; D018084:Ultrasonography, Interventional
D003287:Contrast Media; D011134:Polysaccharides; C059891:SHU 508