Original Article SMJ
Percutaneous Radiofrequency Ablation Treatment
of Hepatocellular Carcinoma in Caudate Lobe
Using Expandable Electrodes
Somrach Tamtorawat, M.D.*, Torpong Claimon, M.D.**, Satit Rojwatcharapibarn, M.D.*, Pradesh Ghimire,
M.D.*, Trongtum Tongdee, M.D.*, Jirawadee Yodying, M.D. * Walailak Chaiyasoot, M.D.*
*Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Tailand, **Department of Radiology, Faculty
of Medicine Vajira Hospital, Navamindradhiraj University, Bangkok 10300, Tailand.
ABSTRACT
Objective: To evaluate the outcome of radiofrequency (RF) ablation using expandable electrodes in the treatment
of hepatocellular carcinoma (HCC) located in the caudate lobe.
Materials and Methods: Between January 2011 and April 2017, 29 consecutive patients with HCC at the caudate
lobe were treated with RF ablation using expandable electrodes. Te electrodes were placed on the targeted tumor
under combined ultrasound and computed tomography (CT) guidance for each tumor in all the patients. Out
of the 29 cases, 19 (65.5%) were accessed via the lef hepatic lobe. Te technical success, primary efficacy, local
tumor progression, secondary efficacy, overall survival, and complications were evaluated. Univariate analysis was
performed of the various prognostic factors for technical success, primary efficacy, and local tumor progression.
Results: Te technical success rate was 86.2%, primary efficacy was 89.7%, and secondary efficacy was 82.8%. Te
local tumor progression (LTP) rate was 12.3% at one year and 31.5% at two years. Te median time of LTP was
6.9 months. Te overall survival rate was 85.8% at one year and 57.1% at two years. Ten patients died during the
follow-up period (mean 22.5 months; with a range of 3.6-53.2 months). A minor complication of asymptomatic
biloma was found in one patient (3.5%). Small-sized tumors (≤2 cm) and Spiegel’s lobe location had significantly
better treatment outcomes (p = 0.007 and 0.045, respectively).
Conclusion: Radiofrequency ablation using expandable electrodes is feasible and safe in treating HCCs located in
the caudate lobe, especially for small-sized tumors (≤2 cm).
Keywords: Caudate lobe; Expandable electrodes; Hepatocellular carcinoma; Radiofrequency ablation (Siriraj Med
J 2021; 73: 541-548)
INTRODUCTION
(directly to the IVC), and the complex biliary drainage,
Treatment of hepatocellular carcinoma (HCC) in
either by surgical resection, or through percutaneous
the caudate lobe, to date, is challenging due to the deep
ablation, or via transarterial treatment.1-4
location; proximity to the IVC and main portal vein; the
With regard to the surgical resection of HCC in the
unique anatomy of the caudate lobe, including the arterial
caudate lobe, Tanaka et al.’s study in 20 patients showed
feeder, the portal venous supply, and the draining vein a relatively poor prognosis compared to procedures
Corresponding author: Satit Rojwatcharapibarn
E-mail: satit.roj@mahidol.ac.th
Received 1 March 2021 Revised 9 July 2021 Accepted 10 July 2021
Volume 73, No.8: 2021 Siriraj Medical Journal
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Thamtorawat et al.
performed at other locations, owing to the intraoperative
studies used a non-expandable RF ablation electrode, the
blood loss, longer duration of operation, higher chances
purpose of this study was to evaluate the outcome of RF
of post-operative complications, and more frequent
ablation using an expandable electrode in the treatment
intrahepatic recurrent rate, and a significantly poor
of HCC located in the caudate lobe in experienced hands.
survival rate.3
Tere are a limited number of studies on percutaneous
MATERIALS AND METHODS
RF ablation of HCC in the caudate lobe. Seror et al. studied
Tis is a retrospective study performed over the
10 cases that underwent percutaneous RF ablation in the
period January 2011 to April 2017. Afer approval from
caudate lobe, with 8 cases being HCC. All the procedures
the institutional review board, with protocol number (Si
were performed using single straight needle electrode.
109/2017 (EC2)), the electronic records in the radiological
Te results showed that percutaneous RF ablation had a
information system (RIS) were searched for patients
high technical success rate (about 90%), without major
with HCC in the caudate lobe who had underwent RF
complications. However, the local recurrence rate was
ablation.
relatively high, compared to other locations, possibly due
Out of a total of 1,292 ablation procedures in the
to the heat sink effect from the adjacent large vessels,
liver, including 1,251 RF ablations, 19 IRE (irreversible
which made it hard to achieve an adequate ablation
electroporation), and 22 microwave ablations, the records
margin.5
of 29 patients with HCC at the caudate lobe treated with
In Yamakado et al.’s study, percutaneous RF ablation
RF ablation by an expandable electrode were obtained.
was performed in 6 cases of HCC in the caudate lobe, also,
Te patients included 21 males and 8 females with mean
using a single straight needle electrode.6 Te difference
age of 65.4 ± 10.8 years old. All the patients had liver
was in the use of CT scan as imaging guidance in all the
cirrhosis, mostly with an etiology of hepatitis B (n =
cases. Te results showed not only a higher technical
13) (Table 1). Child-Pugh classifications A and B were
success rate of 100%, but also had the ability to achieve
obtained in 24 patients and 5 patients, respectively.
local tumor control in all the cases, with a mean follow-
Serum alpha-fetoprotein (AFP) levels with the mean
up period of 10 months.
and median values of 109.0 and 5.69 ng/ml, respectively,
Nishigaki et al.’s study in 2012 performed percutaneous
(range, 1.0-2,444.0 ng/ml) were noted.
RF ablation in 20 patients with HCC in the caudate lobe,
which also showed similar results, with a 100% technical
Tumor characteristics
success rate without major complications. In these cases,
The diagnosis of HCC at the caudate lobe was
however, the local recurrence rate was relatively high
based on either the imaging criteria or the pathological
(22.3%) compared to at the other locations (4.5%).7
results. Te mean size of the tumor was 1.78 ± 0.80
With regard to an alternative treatment of HCC in
cm (range 0.7 - 4.0 cm). Tumor size was classified into
the caudate lobe with transarterial chemoembolization
two categories (size ≤2 cm; n = 18, and >2 cm; n = 11).
(TACE), Kim et al. showed that the key to achieving
Location of the tumor was classified according to three
treatment efficacy was a successful super-selection of
sub-segments of the caudate lobe: Spiegel’s lobe (48.3%),
the caudate artery. However, local tumor progression
paracaval portion (41.4%), and caudate process (10.3%)
(LTP) was still relatively high (about 64%).8
(Table 1). Tere were 7 lesions (24.1%) that underwent
In terms of combined treatment using TACE and RF
TACE before the ablation treatment.
ablation for treating HCC in the caudate lobe, Fujimori
et al. (2012) and Hyun et al. (2016) also used a single
RF ablation procedure
straight electrode needle in both studies.9,10 Similar results
Percutaneous RF ablation procedures were performed
were noted, without significant difference in the results
by one of the five interventional radiologists in our
between RF ablation used alone and in combined treatment
institution, who had at least three years’ experience. Te
regarding the local tumor control. However, with regard
procedures were performed under intravenous sedation,
to the survival rate, the combined treatment was seen to
using expandable RF electrodes (Leveen needle electrode;
be better.11,12 For some small HCCs, combined treatment
Boston Scientific, Marlborough, Massachusetts, USA).
is effective that are not visible in unenhanced CT and
All the procedures were performed under combined
ultrasound.13
ultrasound (iU22; Philips Healthcare, Amsterdam, the
Since relatively fewer studies have been reported
Netherlands) and CT (Optima CT660; GE Healthcare,
regarding the use of percutaneous RF ablation for the
Chicago, Illinois, USA) guidance, as the standard protocol
treatment of HCC in the caudate lobe, and all the prior
in the institution. Depending on the tumor size and
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TABLE 1. Patient demographics and tumor characteristics.
Patients’ characteristics
Age (years)
65.4 ± 10.8 (range, 34-84)
Sex (male: female)
21:8
Etiology of liver cirrhosis
Chronic hepatitis B
13 (44.8%)
Chronic hepatitis C
7 (24.1%)
Cryptogenic cirrhosis
6 (20.7%)
NASH
2 (6.9%)
Alcoholic cirrhosis
1 (3.5%)
Child-Pugh classification
A
24 (82.8%)
B
5 (17.2%)
AFP Median
5.69 ng/ml
(range, 1.0-2,444.0)
Tumor characteristics
Mean tumor size (cm)
1.78 ± 0.80 (range, 0.7-4.0)
Size classified
≤ 2 cm
18 (62.1%)
> 2 cm
11 (37.9%)
Tumor location
Spiegel’s lobe
14 (48.3%)
Paracaval portion
12 (41.4%)
Caudate process
3 (10.3%)
Prior TACE treatment of the lesion
7 (24.1%)
Subcapsular location
18 (64.3%)
Perivascular location
16 (57.1%)
Abbreviations: NASH, Non-alcoholic steatohepatitis; AFP, Alpha-fetoprotein; TACE, Transarterial chemoembolization
the depth from the skin, the diameter and the length of
on the real-time ultrasonography.
the RF electrode were determined by the performing
Te imaging assessment protocol at this institution
physicians. Tree types of access route were used: supine
includes multiphase CT of the liver or MRI of the liver
approach through the lef lobe, right anterior approach,
with a hepatocyte specific agent; performed at 1, 3,
and right posterior approach (Fig 1). Te aim of the
6, 9, and 12 months afer the ablation, and thereafer
ablation treatment was to cover the visualized tumor
every 3-6 months. Te treatment response definitions
area and to generate a sufficient ablation zone of at least
were based on the Society of Interventional Radiology
5 mm margin, which was could be as an echogenic cloud
Standardization of Terminology and Reporting.14
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Thamtorawat et al.
Statistical analysis
Analysis of the data was done by using the chi-square
test to determine whether technical success, primary
efficacy, secondary efficacy, and local tumor progression
were related to the size of the tumor (classified as ≤2 cm
and >2 cm), access route, and location of the tumor, prior
to TACE treatment, and the Child-Pugh classification.
Kaplan-Meier analysis was used to assess the survival
rate and local tumor progression rate.
All the statistical analyses were performed using
IBM SPSS Statistics for Windows version 23.0 (IBM
Corporation, Armonk, New York). A difference with
p < 0.05 was considered to be statistically significant.
Fig 1. Schematic diagram showing three access sites for the caudate
RESULTS
lobe approach;
Primary efficacy and technical success rate
A. - lef lobe approach
B. - right anterior approach
Among the 29 patients treated by RF ablation using
C. - right posterior approach
expandable electrodes, four lesions demonstrated residual
disease upon imaging at one month afer ablation. Te
technical success rate of the first session was 86.2%. One
Treatment response assessment
lesion had another RF ablation session and achieved complete
Technical success was determined as complete ablation
tumor ablation within three months (Fig 2). Two lesions
of a targeted tumor at one month imaging follow-up.
had re-ablation but the follow-up imaging still showed
Primary efficacy was achieved if there was disappearance
residual disease. In one lesion, re-ablation treatment was
of the tumor at the ablation site without evidence of a
not performed because of multiple intrahepatic distant
residual viable tumor at three months imaging follow-up.
recurrence; hence TACE was performed instead. Te
Local tumor progression (LTP) was determined as any
primary efficacy rate was 89.7%, as 26 of the 29 tumors
imaging follow-up afer three months showing evidence
had complete tumor control at three months follow-up
of a recurrent tumor. Secondary efficacy was defined as
imaging.
successful local tumor control by re-ablation of the LTP
Univariate analysis (Table 2) showed better technical
using RF ablation.
success (p = 0.014) and primary efficacy (p = 0.045)
Follow-up concluded at the time of death, liver
in the smaller tumor group (≤2 cm), as compared to
transplantation, or the last clinical follow-up evaluation.
the larger tumor group (>2 cm). With regard to the
Te primary endpoints of the study were LTP and control
location (Table 3), the technical success was statistically
of the tumor growth. Te secondary endpoint of the
significant in the tumor located at Spiegel’s lobe and
study was the overall survival rate.
in the caudate process (100% technical success; p =
Complications were analyzed by imaging findings,
0.042). In terms of the access site (Table 3), the primary
clinical symptoms, and laboratory examinations afer
efficacy was significantly better in the lef lobe approach
treatment and were ranked according to the SIR standard
(100% primary efficacy; p = 0.033) compared to the right
classification.15
anterior or right posterior approach. Te rest of the
various tumor-related prognostic factors, such as the
Risk factors analyzed
patient’s age and sex, Child-Pugh score, prior TACE
Risk factors related to LTP include the tumor size,
treatment of the lesions, perivascular or subcapsular
location of the tumor, proximity to the large vessels, and
location, vessel in ligamentum venosum, and the depth
proximity from the liver capsule and the adjoining critical
from the skin, showed no statistically significant results
organs that might be injured during ablation. Perivascular
in both technical success and primary efficacy.
location was established as the tumor abutting vessels >3
mm in diameter. Subcapsular location was defined as a
Local tumor progression rate and secondary efficacy rate
tumor located less than 10 mm from the liver capsule.
Local tumor progression (LTP) occurred in five of
Adjoining critical organs at risk were contemplated if
the 29 tumors. Two tumors were successfully treated
located <10 mm from the tumor.
by additional RF ablation with a secondary efficacy
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Fig 2. A 71 year-old man with
a 1 cm HCC in Spiegel portion
of caudate lobe (arrow in a, b)
RF ablation was performed via
anterior lef lobe approach (c).
CT afer ablation showed
complete ablation (d). At two
years follow up, MRI showed
local tumor progression
(arrowhead in e). Second RF
ablation was performed by using
the same technique and complete
ablation was achieved (arrowhead
in f).
TABLE 2. Univariate analysis of the tumor characteristics and results between tumor size.
Variables
Tumor size
Tumor size
P-value
≤2 cm
>2 cm
No. tumors
18
11
Age (years)
68.6 ± 9.2
60.1 ± 11.6
.291
Sex
Male
13 (72.2%)
8 (72.7%)
.976
Female
5 (27.8%)
3 (27.3%)
Child-Pugh score
A
13 (72.2%)
11 (100%)
.126
B
5 (27.8%)
0 (0%)
Prior TACE treatment
2 (28.6%)
5 (71.4%)
.071
Location of tumor
Spiegel lobe
11 (61.1%)
3 (27.3%)
Paracaval portion
4 (22.2%)
8 (72.7%)
.024
Caudate process
3 (16.7%)
0 (0%)
Perivascular
7 (41.2%)
9 (81.8%)
.054
Subcapsular
10 (58.8%)
8 (72.7%)
.689
Vessel in ligamentum venosum
2 (11.1%)
3 (27.3%)
.339
Access site
Left lobe
14 (77.8%)
5 (45.5%)
Right anterior
2 (11.1%)
3 (27.3%)
.267
Right posterior
2 (11.1%)
3 (27.3%)
Results
Technical success
18 (100%)
7 (63.6%)
.014
Primary efficacy
18 (100%)
8 (72.7%)
.045
LTP
3 (16.7%)
3 (37.5%)
.330
Secondary efficacy
17 (94.4%)
7 (63.6%)
.054
Abbreviations: TACE, Transarterial chemoembolization; LTP, Local tumor progression
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Thamtorawat et al.
TABLE 3. Univariate analysis of the prognostic factors for technical success, primary efficacy, and local tumor
progression.
Variable
Technical success
Primary efficacy
Local tumor progression
(LTP)
(%)
(P-value)
(%)
(P-value)
No LTP (%)
(P-value)
Prior TACE treatment
Present
71.4%
0.238
85.7%
1.000
2 (33.3%)
0.596
Absent
90.9%
90.9%
4 (20.0%)
Location of tumor
Spiegel’s lobe
100%
100%
4 (28.6%)
Paracaval portion
66.7%
0.042
75%
0.136
2 (22.2%)
0.829
Caudate process
100%
100%
0 (0%)
Vessel in ligamentum venosum
Present
80%
0.553
80%
0.446
2 (50%)
0.218
Absent
87.5%
91.7%
4 (18.2%)
Perivascular
Present
75%
0.113
81.3%
0.238
5 (29.4%)
0.624
Absent
100%
100%
1 (12.5%)
Subcapsular
Present
88.9%
0.601
94.4%
0.284
3 (23.1%)
1.000
Absent
80%
80%
3 (25%)
Access site
Left lobe
94.7%
100%
5 (26.3%)
Right anterior
60%
0.105
60%
0.033
0 (0%)
1.000
Right posterior
80%
80%
1 (25%)
Abbreviation: TACE, Transarterial chemoembolization
rate of 82.8%. Tree patients with LTP had no further
Follow-up period and overall survival rate
ablation treatment due to disease progression. One
Te mean follow-up period was 22.5 ± 14.3 months
developed pulmonary metastasis, another had concomitant
(range, 3.6-53.2 months). Ten patients died during
cholangiocarcinoma proven by tissue biopsy and both
the follow-up period. One patient underwent liver
were subjected to systemic chemotherapy. Another patient
transplantation. Te overall survival rate was computed
had deterioration of liver function and was treated with
by using Kaplan-Meier analysis, which showed survival
palliative care. Kaplan-Meier analysis showed LTP rates
rates of 85.8% at one year and 57.1% at two years
of 12.3% at one year and 31.5% at two years. Te median
(Fig 3B).
time of LTP was 6.9 months (Fig 3A).
Univariate analysis also showed a high LTP rate
Complications
and low secondary efficacy in the larger tumor group
Tere were no major complications encountered.
(>2 cm), but not significant statistically (p = 0.054).
No procedure-related death occurred. Only one case
(Table 2).
developed a minor complication of asymptomatic biloma
(3.5%), which resolved spontaneously.
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3A
3B
Fig 3. Kaplan-Meier analysis; (A) Local tumor progression rate (B) Overall survival rate
DISCUSSION
margins, difficulty of needle repositioning in the limited
For the curative treatment of HCC, RF ablation is
space of the caudate lobe, and the heat sink effect due
an alternative to surgical resection. Nevertheless, the
to the proximity to the large vessels, including the IVC
treatment of HCC located in the caudate lobe is still
and the main portal vein.
challenging to date due to the complex anatomy and
Regarding the access route of the RF electrode, this
deep location.1-4
study mainly involved the use of the lef lobe approach
Tis study showed an 86.2% technical success rate
(65.5%), which was probably due to the majority of the
and 89.6% primary efficacy rate, which are comparable
tumors being located in the Spiegel’s lobe (48.3%), which
with the prior study by Seror et al. (2005), where treatment
could be accessed by using this approach. Te technical
was done by RF ablation alone using non-expandable
success rate of the lef lobe approach also was the highest
electrodes.5 Tis study also used a combination of ultrasound
(94.7%) as long as the primary efficacy was 100%, also
and CT guidance for the needle electrode placement in
showing statistical significance (p = 0.033). Tis might
all cases, which may have been a major key in achieving
be due to the tumors in the Spiegel’s lobe seemingly able
the technical success of the RF ablation in the tumors
to be well-visualized in the ultrasonography, probably
deeply situated in the caudate lobe. Te advantage of
as the depth from the skin was mostly shorter compared
the expandable electrode seems to be allowing a more
to the other locations. Also there is likely less heat sink
precise estimation of the ablation zone, which can be
effect for tumors in the Spiegel’s lobe because of the
visualized in the image guidance from the reconstructed
greater distance to the large vessels.
non-contrast CT scan. However, a disadvantage is the
Te lef lobe approach may increase the risk of
difficulty to deploy the expandable electrode in the limited
bleeding, due to the needle piercing the liver capsule
space of the caudate lobe.
twice and also penetrating the ligamentum venosum,
Tis study demonstrated the advantage of the RF
in which an accessory/replaced lef hepatic artery or
ablation of tumors in the caudate lobe using expandable
accessory lef gastric artery may be present.5 A variant
electrodes in the smaller tumor group (≤2 cm), which
artery in ligamentum venosum causing a limitation for
showed better results with statistical significance for
the lef lobe approach was observed in five patients;
technical success (p = 0.014) and the primary efficacy
comprising accessory lef hepatic artery in four patients
(p = 0.045) compared to the larger tumor group (>2
and accessory lef gastric artery in one patient. Four of
cm). Similar results were reported by Hyun et al. using
these were accessed by using the lef lobe approach. Tere
combined transarterial treatment with RF ablation.10
was no evidence of bleeding, but we need to be catious
Te LTP rate of the present study (12.3% at one year
in this matter.
and 31.5% at two years) showed a higher rate compared
Limitations of this study include its retrospective
to RF ablation done in other locations.5-7 Tese could
design, non-randomized control, and small number of
be due to multifactorial causes, like inadequate ablation
patients, which may have caused some selection bias
Volume 73, No.8: 2021 Siriraj Medical Journal
547
Thamtorawat et al.
et al. Efficacy and safety of radiofrequency ablation for
and a difference in the results. Multivariate analysis also
hepatocellular carcinoma in the caudate lobe of the liver.
itself has inherent limitations that need to be taken into
Hepatol Res. 2013;43:467-74.
account. A longer follow-up period should be achieved
8.
Kim HC, Chung JW, Jae HJ, Yoon J-H, Lee J-H, Kim YJ, et al.
for a better evaluation of the overall survival and LTP.
Caudate Lobe Hepatocellular Carcinoma Treated with Selective
In conclusion, radiofrequency ablation using
Chemoembolization. Radiology. 2010;257:278-87.
expandable electrodes is feasible and safe in treating
9.
Fujimori M, Takaki H, Nakatsuka A, Uraki J, Yamanaka T,
Hasegawa T, et al. Combination therapy of chemoembolization
HCCs located in the caudate lobe, especially for small-
and radiofrequency ablation for the treatment of hepatocellular
sized tumors (≤2 cm).
carcinoma in the caudate lobe. J Vasc Interv Radiol. 2012;23:
1622-8.
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