Utility of computed tomography fusion imaging for the evaluation of the ablative margin of radiofrequency ablation for hepatocellular carcinoma and the correlation to local tumor progression.
OBJECTIVE
To demonstrate the usefulness of the computed tomography (CT) fusion imaging for the evaluation of treatment effect of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC).


METHODS
Eighty-five patients with 94 HCC with complete ablation judged on conventional side-by-side interpretation of pre-RFA and post-RFA CT at the time of RFA were included in this retrospective study. CT data was retrospectively used to create fusion images of pre-RFA and post-RFA CT using automatic rigid registration and manual correction referring to intrahepatic structures and hepatic contours around a tumor. Clinical factors including a minimal ablative margin (MAM) measured on fusion images were examined to prove risk factors for local tumor progression (LTP).


RESULTS
LTP was observed in 13 (13.8%) tumors with a median follow up of 21.0 months (range, 2-75). The mean MAM on the fusion image was 1.4 ± 3.1 mm and 23 tumors (24.5%) were judged to be protruding from the ablation zone. Multivariate analysis revealed that protruding from the ablation zone was the only significant factor for LTP (hazard ratio, 7.09; 95% confidential interval, 2.26-22.3; P < 0.001).


CONCLUSIONS
Some HCC were assessed as incomplete ablation on the CT fusion images, although considered completely ablated on side-by-side images at the time of treatment, and incomplete ablation was revealed to be the only independent risk factor for LTP. The CT fusion imaging enables quantitative and accurate evaluation of treatment effect of RFA.
Department of Gastroenterology, Ikeda Municipal Hospital, Ikeda.
Yuki
Y
Makino
Yasuharu
Y
Imai
Takumi
T
Igura
Masatoshi
M
Hori
Kazuto
K
Fukuda
Yoshiyuki
Y
Sawai
Sachiyo
S
Kogita
Hideko
H
Ohama
Yasushi
Y
Matsumoto
Masanori
M
Nakahara
Shinichiro
S
Zushi
Masanori
M
Kurokawa
Keisuke
K
Isotani
Manabu
M
Takamura
Norihiko
N
Fujita
Takamichi
T
Murakami
ablative margin; computed tomography fusion imaging; hepatocellular carcinoma; local tumor progression; radiofrequency ablation