Percutaneous Radiofrequency Ablation of Hepatocellular Carcinomas Adjacent to the Gallbladder with Internally Cooled Electrodes: Assessment of Safety and Therapeutic Efficacy

The objective of this study was to evaluate the safety and therapeutic efficacy of percutaneous radiofrequency (RF) ablation for the treatment of hepatocellular carcinomas (HCCs) adjacent to the gallbladder with the use of internally cooled electrodes.  We retrospectively assessed 45 patients with 46 HCCs (mean size, 2.2 cm) adjacent to the gallbladder (≤1.0 cm) treated with RF ablation using an internally cooled electrode system. An electrode was inserted into the tumor either parallel (n = 38) or perpendicular (n = 8) to the gallbladder wall. The safety and therapeutic efficacy of the procedures were assessed with clinical and imaging follow-up examinations. Follow-up with the use of CT ranged from four to 45 months (mean, 19 months). The association between variables (electrode direction, electrode type, tumor size, tumor location, lobar location) and the presence of a residual tumor or local tumor progression was also analyzed.  There were no major complications and minor complications were noted in three patients (7%) including one case of vasovagal syncope and two cases of bilomas. Wall thickening of the gallbladder adjacent to the RF ablation zone was noted in 14 patients (41%) as determined on immediate follow-up CT imaging. Wall thickening showed complete disappearance on subsequent follow-up CT imaging. The primary technique effectiveness rate was 96% (44/46) based on one-month follow-up CT imaging. Local tumor progression was noted in six (14%) of 44 completely ablated tumors during the follow-up period. The direction of electrode insertion (perpendicular), tumor size (≥3 cm) and tumor location (a tumor that abutted the gallbladder) were associated with an increased risk of early incomplete treatment. No variable was significantly associated with local tumor progression.  Percutaneous RF ablation of HCCs adjacent to the gallbladder using an internally cooled electrode is a safe and effective treatment. Significant risk factors that lead to early incomplete treatment include tumor size, tumor location and electrode direction.

Related papers:

title: A randomized controlled trial of radiofrequency ablation with ethanol injection for small hepatocellular carcinoma.
abstract: Percutaneous radiofrequency ablation is a recently introduced treatment for hepatocellular carcinoma, whereas ethanol injection is now a standard therapy. We compared their long-term outcomes.



Two hundred thirty-two patients with hepatocellular carcinoma who had 3 or fewer lesions, each 3 cm or less in diameter, and liver function of Child-Pugh class A or B were entered onto a randomized controlled trial. The primary end point was survival, and the secondary end points were overall recurrence and local tumor progression.



One hundred eighteen patients were assigned to radiofrequency ablation and 114 to ethanol injection. The number of treatment sessions was smaller (2.1 times vs 6.4 times, respectively, P < .0001) and the length of hospitalization was shorter (10.8 days vs 26.1 days, respectively, P < .0001) in radiofrequency ablation than in ethanol injection. Four-year survival rate was 74% (95% CI: 65%-84%) in radiofrequency ablation and 57% (95% CI: 45%-71%) in ethanol injection. Radiofrequency ablation had a 46% smaller risk of death (adjusted relative risk, 0.54 [95% CI: 0.33-0.89], P = .02), a 43% smaller risk of overall recurrence (adjusted relative risk 0.57 [95% CI: 0.41-0.80], P = .0009), and an 88% smaller risk of local tumor progression (relative risk, 0.12 [95% CI: 0.03-0.55], P = .006) than ethanol injection. The incidence of adverse events was not different between the 2 therapies.



Judging from higher survival but similar adverse events, radiofrequency ablation is superior to ethanol injection for small hepatocellular carcinoma.

title: Small hepatocellular carcinoma in cirrhosis: randomized comparison of radio-frequency thermal ablation versus percutaneous ethanol injection.
abstract: To compare the effectiveness of radio-frequency (RF) thermal ablation with that of percutaneous ethanol injection (PEI) for the treatment of small hepatocellular carcinoma (HCC) in patients with cirrhosis.



A series of 102 patients with hepatic cirrhosis and either single HCC 5 cm in diameter or smaller or as many as three HCCs each 3 cm or smaller (overall number of lesions, 142) randomly received either RF ablation (n = 52) or PEI (n = 50) as the sole first-line anticancer treatment. Mean follow-up was 22.9 months +/- 9.4 (SD) in the RF group and 22.4 months +/- 8.6 in the PEI group. Prognostic value of treatment techniques was assessed with univariate and multivariate Cox proportional hazards regression models.



One- and 2-year survival rates were 100% and 98% in the RF group and 96% and 88% in the PEI group, respectively (univariate relative risk [RR] = 0.20; 95% CI: 0.02, 1.69; P =.138). One- and 2-year local recurrence-free survival rates were 98% and 96% in the RF group and 83% and 62% in the PEI group, respectively (univariate RR = 0.17; 95% CI: 0.06, 0.51; P =.002). One- and 2-year event-free survival rates were 86% and 64% for the RF group and 77% and 43% for the PEI group, respectively (univariate RR = 0.48; 95% CI: 0.27, 0.85; P =.012). RF treatment was confirmed as an independent prognostic factor for local recurrence-free survival rates with multivariate analysis (adjusted RR = 0.20; 95% CI: 0.05, 0.73; P =.015).



RF ablation is superior to PEI with respect to local recurrence-free survival rates.

title: Small hepatocellular carcinoma: comparison of radio-frequency ablation and percutaneous microwave coagulation therapy.
abstract: To evaluate the effectiveness of radio-frequency (RF) ablation and percutaneous microwave coagulation (PMC) for treatment of hepatocellular carcinoma (HCC).



Seventy-two patients with 94 HCC nodules were randomly assigned to RF ablation and PMC groups. Thirty-six patients with 48 nodules were treated with RF ablation, and 36 patients with 46 nodules were treated with PMC. Therapeutic effect, residual foci of untreated disease, and complications of RF ablation and PMC were prospectively evaluated with statistical analyses.



The number of treatment sessions per nodule was significantly lower in the RF ablation group than in the PMC group (1.1 vs 2.4; P <.001). Complete therapeutic effect was achieved in 46 (96%) of 48 nodules treated with RF ablation and in 41 (89%) of 46 nodules treated with PMC (P =.26). Major complications occurred in one patient treated with RF ablation and in four patients treated with PMC (P =.36). During follow-up (range, 6-27 months), residual foci of untreated disease were seen in four of 48 nodules treated with RF ablation and in eight of 46 nodules treated with PMC. No significant difference in rates of residual foci of untreated disease was noted (P =.20, log-rank test).



RF ablation and PMC thus far have had equivalent therapeutic effects, complication rates, and rates of residual foci of untreated disease. However, RF tumor ablation can be achieved with fewer sessions.

title: Multiphase helical CT findings after percutaneous ablation procedures for hepatocellular carcinoma
abstract: Multiple-phase helical computed tomography (CT) has been regarded as the method of choice in the evaluation of patients with hepatocellular carcinoma (HCC) treated by nonsurgical procedures. The aim of this article was to report our experience in the assessment of nodular and parenchymal changes recognizable after various percutaneous ablation therapies.
 Methods: We reviewed the studies of 116 consecutive patients with HCC treated with multisession percutaneous ethanol injection (56 patients, 98 nodules), single-session percutaneous ethanol injection (14 patients, 31 nodules), radiofrequency thermal ablation (32 patients, 48 nodules), and interstitial laser photocoagulation (14 patients, 25 nodules). CT had been performed 3–28 days after the last session (mean = 18 days) with unenhanced helical acquisition and with contrast-enhanced double- or triple-phase helical acquisition.
  Persisting neoplastic tissue was identified within 54.5% of the nodules. It was located centrally in 4.5% of these nodules, peripherally in 11%, and eccentrically in 84.5%, and its shape was crescent in 58%, globular in 24.5%, and other in 16%. On arterial phase scans, viable tumor was hyperdense in 97% of the lesions and isodense in 3%; on portal phase scans, the tumor was hyperdense in 20%, isodense in 28%, and hypodense in 52%; on delayed phase scans, the tumor was consistently hypodense. Tumor necrosis was always hypodense on contrast-enhanced scans. On unenhanced images, 7.4% of the nodules were undetectable. Nodule diameter appeared as unchanged in 53% of the nodules and as larger in 47%; its shape was unchanged in 54% and modified in 46%; its margins were unchanged in 36% and modified in 64%. A rim of granulation tissue was detected around 15% of the nodules, and a perilesional transient attenuation difference was detected in 21%. Perihepatic effusion was seen in 13% of the patients, segmental biliary duct dilation and local atrophy each in 9%, arterioportal fistula in 6%, portal vein thrombosis, subcapsular collection and pleural effusion each in 7%, hepatic infarction in 5%, and inferior vena cava thrombosis in 2%.
  Percutaneous ablation of HCC may cause several changes. Knowledge of their CT appearance is mandatory to correctly assess and manage this tumor. RID="" ID="" Correspondence to: O. Catalano

title: Radiofrequency ablation and percutaneous ethanol injection in patients with small hepatocellular carcinoma: a comparative study.
abstract: Radiofrequency ablation (RFA) is a novel thermal ablation technique to achieve coagulative necrosis of hepatocellular carcinoma. A study was conducted to compare the antitumor effect and adverse effect of RFA with those of percutaneous ethanol injection (PEI) in patients with solitary small hepatocellular carcinoma.



The study population consisted of 119 consecutive patients with solitary hepatocellular carcinoma smaller than 3 cm in diameter. Among these, 23 patients were treated with RFA and the remaining 96 patients were treated with PEI. The antitumor effects of both treatments were assessed by contrast-enhanced computed tomography 1 month after treatment.



Complete tumor necrosis was achieved in 23 patients (100%) of the RFA group and 90 patients (94%) of the PEI group (p = 0.48) and local recurrence rates at 1 year were 15% in the RFA group and 14% in the PEI group (p = 0.80). RFA required an average of 1.5 sessions to achieve complete necrosis, whereas PEI required an average of 4.0 sessions. As a consequence, the hospital stay in the RFA group (median 10 days) was significantly shorter than that in the PEI group (median 17 days). There were no serious adverse effects or complications except for one case of cholangitis in the PEI group, although deterioration of serum transaminase after RFA was significantly more severe than that after PEI.



RFA achieved complete tumor necrosis for small hepatocellular carcinoma with fewer treatment sessions compared with PEI. There were no serious complications.

title: A Prospective Randomized Trial Comparing Percutaneous Local Ablative Therapy and Partial Hepatectomy for Small Hepatocellular Carcinoma
abstract: To compare the results of percutaneous local ablative therapy (PLAT) with surgical resection in the treatment of solitary and small hepatocellular carcinoma (HCC). PLAT is effective in small HCC. Whether it is as effective as surgical resection in the long-term survivals remains unknown. We conducted a prospective randomized trial on 180 patients with a solitary HCC ≦5 cm to receive either PLAT or surgical resection. The patients were regularly followed up after treatment with physical examination, blood, and radiologic tests. Of the 90 patients who were randomized to PLAT, only 71 received PLAT because 19 withdrew their consent. Of the 90 patients who were randomized to surgical resection, a single Couinaud liver segment resection was carried out in 69 patients, 2 segments in 16 patients, and 3 or more segments in 3 patients. Ethanol injection was given during open surgery in 2 patients. Only 1 patient died after surgical resection within the same hospital admission. Posttreatment complications were more often and severe after surgery than PLAT. The 1-, 2-, 3-, and 4-year overall survival rates after PLAT and surgery were 95.8%, 82.1%, 71.4%, 67.9% and 93.3%, 82.3%, 73.4%, 64.0%, respectively. The corresponding disease-free survival rates were 85.9%, 69.3%, 64.1%, 46.4% and 86.6%, 76.8%, 69%, 51.6%, respectively. Statistically, there was no difference between these 2 treatments. PLAT was as effective as surgical resection in the treatment of solitary and small HCC. PLAT had the advantage over surgical resection in being less invasive.

title: Comparing the Outcomes of Radiofrequency Ablation and Surgery in Patients With a Single Small Hepatocellular Carcinoma and Well-Preserved Hepatic Function
abstract: Goals: To compare the efficacy of radiofrequency ablation (RFA) and surgical resection in a group of patients with a Child-Pugh score of 5 and a single HCC less than 4 cm in diameter.  Radiofrequency ablation (RFA) has become a popular method for treatment of hepatocellular carcinoma (HCC) and has been applied as an alternative primary therapy to surgical resection.  We compared outcomes for 148 patients treated with RFA (n = 55) and those treated surgically (n = 93).  The rate of local recurrence among patients in the RFA group was significantly higher than in the surgery group (P = 0.005), while the incidence of remote recurrence was similar between the two groups (P = 0.30). The cumulative 1- and 3-year overall survival rates (P = 0.24) and the cumulative 1- and 3-year recurrence-free survival rates (P = 0.54) were not significantly different between the two groups.  Despite a higher rate of local recurrence, RFA was found to be as effective as surgical resection for the treatment of single small HCC in patients with well-preserved liver function, in terms of the incidence of remote recurrence and the patients' likelihood of achieving overall and/or recurrence-free survival.

title: Radiofrequency ablation of porcine liver in vivo: effects of blood flow and treatment time on lesion size.
abstract: To determine, in vivo, the effect of radiofrequency ablation (RFA) treatment time and tissue blood flow on the size and shape of the resulting necrotic lesion in porcine liver.



Radiofrequency ablation is an electrosurgical technique that uses a high frequency alternating current to heat tissues to the point of desiccation (thermal coagulation). Radiofrequency ablation is well established as the treatment of choice for many symptomatic cardiac arrhythmias because of its ability to create localized necrotic lesions in the cardiac conducting system. Until recently, a major limitation of RFA was the small lesion size created by this technique. Development of bipolar and multiple-electrode RFA probes has enabled the creation of larger lesions and therefore has expanded the potential clinical applications of RFA, which includes the treatment of liver tumors. A basic understanding of factors that influence RFA lesion size in vivo is critical to the success of this treatment modality. The optimal RFA technique, which maximizes liver lesion size, has yet to be determined. Theoretically, lesion size varies directly with time of application of the RF current, and inversely with blood flow, but these relationships have not been previously studied in the liver.



Six animals underwent hepatic RFA (460 kHz), for 5, 7.5, 10, 12.5, 15, and 20 minutes. Identical, predetermined anatomic areas of the liver were ablated in each animal. Two additional animals underwent 12 RFA treatments -- 6 with vascular inflow occlusion (Pringle maneuver) and 6 with uninterrupted hepatic blood flow. Animals were euthanized and the livers were removed for gross pathologic examination. All lesions were measured in three dimensions and photographed. Tissues were examined by routine histology and by histochemistry to determine viability.



Increasing duration of RFA application from 5 through 20 minutes did not create lesions of larger diameter, but this time increase did predict deeper lesion production (beta = 0.34, p = 0.04). A range of lesion shapes were created from four separate ovals (corresponding to each electrode), to larger ovals intersecting to form a cross, to spheroid lesions. The number of blood vessels in close proximity to the probe tip (within a 1-cm radius from the center of the lesion) strongly predicted minimum lesion diameter (beta = -0.61, p = 0.0001) and lesion volume (beta = -0.56, p = 0.0004). This negative effect of blood flow on lesion size was confirmed experimentally. Radiofrequency ablation lesions created during a Pringle maneuver were significantly larger in all three dimensions than lesions created without a Pringle maneuver: minimum diameter was 3.0 cm (with Pringle) versus 1.2 cm (p = 0.002), maximum diameter was 4.5 cm (with Pringle) versus 3.1 cm (p = 0.002), depth was 4.8 cm (with Pringle) versus 3.1 cm (p < 0.001), and lesion volume was 35.0 cm3 (with Pringle) versus 6.5 cm3 (p < 0.001).



Blood flow is a strong predictor of all RFA lesion dimensions in porcine liver in vivo, whereas a change of treatment time from 5 to 20 minutes is predictive only of lesion depth, but not diameter or volume.

title: Small hepatocellular carcinoma: treatment with radio-frequency ablation versus ethanol injection.
abstract: To compare the effectiveness of radio-frequency (RF) ablation with that of percutaneous ethanol injection in the treatment of small hepatocellular carcinoma (HCC).



Eighty-six patients with 112 small (< or = 3-cm-diameter) HCCs underwent RF ablation (42 patients with 52 tumors) or percutaneous ethanol injection (44 patients with 60 tumors). Therapeutic efficacy was evaluated with dual-phase spiral computed tomography performed at least 4 months after treatment.



Complete necrosis was achieved in 47 of 52 tumors with RF ablation (90%) and in 48 of 60 tumors with percutaneous ethanol injection (80%). These results were obtained with an average of 1.2 sessions per tumor with RF ablation and 4.8 sessions per tumor with percutaneous ethanol injection. One major complication (hemothorax that required drainage) and four minor complications (intraperitoneal bleeding, hemobilia, pleural effusion, cholecystitis) occurred in patients treated with RF ablation; no complications occurred in patients treated with percutaneous ethanol injection.



RF ablation results in a higher rate of complete necrosis and requires fewer treatment sessions than percutaneous ethanol injection. However, the complication rate is higher with RF ablation than with percutaneous ethanol injection. RF ablation is the treatment of choice for most patients with HCC.

title: Complications of percutaneous radiofrequency ablation for hepato-cellular carcinoma: imaging spectrum and management.
abstract: Percutaneous radiofrequency (RF) ablation is feasible for the treatment of unresectable hepatocellular carcinoma, and experience at the authors' institution during 5 years indicates that percutaneous RF ablation can be performed safely in most cases. However, early or late complications related to mechanical or thermal damage may be observed at follow-up examination. Complications may be classified in three groups: vascular (eg, portal vein thrombosis, hepatic vein thrombosis with partial hepatic congestion, hepatic infarction, and subcapsular hematoma), biliary (eg, bile duct stenosis and biloma, abscess, and hemobilia), and extrahepatic (eg, injury to the gastrointestinal tract, injury to the gallbladder, pneumothorax and hemothorax, and tumor seeding). Most complications can be managed with conservative treatment, percutaneous or endoscopic drainage, or surgical repair. Because an early and accurate diagnosis is necessary for proper management, radiologists should be familiar with the imaging features of each type of complication.

title: Treatment strategy to optimize radiofrequency ablation for liver malignancies.
abstract: The purposes of this study were to investigate a treatment strategy to increase liver tumor necrosis and minimize complications with ultrasound-guided percutaneous radiofrequency (RF) ablation and to evaluate its therapeutic efficacy.



A total of 332 patients with 503 liver malignancies underwent RF ablation according to a mathematical protocol with adjunctive measures. In the 332 patients, 205 had 308 hepatocellular carcinomas (HCCs) with a mean largest diameter of 4.1 cm and 127 had 195 metastatic liver carcinomas (MLCs) with a mean largest diameter of 3.9 cm. In patients with HCC, 60 (29.3%) had stage I/II disease and 145 (70.7%) had stage III/IV disease. Depending on tumor size, shape, and location, a defined treatment strategy was adopted that consisted of a mathematical protocol, an individualized protocol, and adjunctive measures. The mathematical protocol was followed for tumors larger than 3.5 cm. The individualized protocol was used for tumors located adjacent to the diaphragm, gastrointestinal tract, or gallbladder. Some adjunctive measures such as supplementary fine needle localization, local saline solution injection, and feeding vessel ablation were used to deal with different features of these liver tumors. Patients were followed regularly to assess treatment efficiency, and the tumor was considered to have early complete necrosis if no viability was found on enhanced computed tomography 1 month after RF ablation.



In this series, the early necrosis rates were 95.8% for HCC (295 of 308 tumors), 94.9% for MLC (185 of 195 tumors), 91.3% for tumors larger than 3.5 cm (189 of 207 tumors), 90.7% for tumors near the gastrointestinal tract (49 of 54 tumors), 91.5% for tumors near the diaphragm (86 of 94 tumors), and 90.6% for tumors near the gallbladder (48 of 53 tumors). The local recurrence rates were 10.7% for HCC (33 of 308 tumors) and 14.9% for MLC (29 of 195 tumors). The 1-, 2-, and 3-year overall survival rates were 89.6%, 69.4%, and 59.6%, respectively, for HCC and 80.3%, 52.8%, and 30.9%, respectively, for MLC. The 1-, 2-, and 3-year survival rates in 60 patients with stage I/II HCC were 93.7%, 87.1%, and 76.2%, respectively. The incidence of major complications was 1.4% (eight of 574 sessions), which included of three hemorrhages, four injuries to adjacent structures, and one case of needle tract seeding.



In RF ablation of hepatic tumors, application of a proper protocol and adjunctive measures play important roles in improving tumor necrosis rate and minimizing potential complications.

title: Radiofrequency ablation of problematically located hepatocellular carcinoma: tailored approach
abstract: BackgroundThe challenge for radiofrequency ablation (RFA) of hepatocellular carcinomas (HCC) in problematic locations is that the outcome is limited due to insufficient ablation or injury of nearby structures. This study aimed to evaluate effective strategy and treatment results of RFA in these cases.MethodsUltrasound guided percutaneous RFA was performed in 326 HCC patients. Among them, 249 tumors in 215 patients located at liver periphery, including 54 adjacent to GI tract, 110 close to the diaphragm, 49 close to the gallbladder, and 36 tumors close to liver surface. The sizes of the tumors ranged 1.2–7.0 cm (average 3.7 ± 1.3 cm). Individualized treatment strategy was established for tumors in various locations, including “artificial ascites”, “lift-expand” electrode placement, “draw-expand” electrode placement, “Supplementary ablation”, and “accumulative multiple ablations” techniques. Treatment outcome was compared with another 64 central-located tumors (control group) in the same patients. One-month post-RFA contrast CT was used to evaluate early necrosis rate of the treated tumors.ResultsEarly tumor necrosis were obtained in 91.6% (228/249) of the problematically located HCC, including 90.7% (49/54) of the tumors adjacent to GI tract, 90.9% (100/110) near the diaphragm, 91.8% (45/49) by the gallbladder, and 94.4% (34/36) close to liver surface. The necrosis rate of control group was 98.4% (63/64), which was higher than the tumors close to diaphragm (P = 0.049). Local tumor recurrence was 8.4% (21/249), comparing with 3.1% (2/64) of the control group (P > 0.05). The 1-, 2- and 3-year survival rate of this group were 81.6%, 63.8%, and 53.6%, respectively. Major complications occurred in 3.2% (11/343) of the treatment sessions, including hemorrhage in two, nearby structure injury in five, and needle tract seeding in four patients.ConclusionsIndividualized treatment strategy for problematically located HCC is helpful in improving RFA outcome and expanding the application range of the therapy.

title: Radiofrequency ablation of hepatic tumors adjacent to the gallbladder: feasibility and safety.
abstract: This study was performed to assess the feasibility and safety of radiofrequency ablation of hepatic tumors adjacent to the gallbladder.



Of the 83 patients who underwent radiofrequency ablation of hepatic tumors at our institution between December 1997 and August 2000, we identified eight patients--four men and four women who were 42-85 years old (mean age, 67 years)--who had tumors adjacent to the gallbladder. All ablations were performed with curative intent. We reviewed the patients' preablation imaging, radiofrequency ablation parameters, and course after ablation. Follow-up ranged from 3 to 22 months (mean, 8 months).



Six patients with colorectal carcinoma and two with hepatocellular carcinoma had a total of 14 tumors adjacent to the gallbladder. Of the 14 tumors, nine (64%) were metastases and five (36%) were hepatocellular carcinoma. Eleven tumors (79%) were located directly adjacent to the gallbladder and three (21%) were located within 1 cm of the gallbladder. Tumor size ranged from 0.9 to 4.5 cm (mean, 3.6 cm). The number of radiofrequency ablations performed on each tumor ranged between one and six (mean, three ablations). Right upper quadrant pain developed in the immediate postablation period (within 7 days after the ablation) in six patients (75%) and ranged in duration from 5 to 21 days (mean, 7 days). Fever developed in four patients (50%), with a mean duration of 5 days. Arthralgia and right shoulder pain developed in one patient (12%). No deaths were noted in the immediate period after ablation. Complete ablation of all tumors visible on CT was achieved in seven patients. Of these, one patient (14%) had local tumor recurrence after 11 months.



Radiofrequency ablation of tumors adjacent to the gallbladder is feasible and appears to be safe. Self-limited morbidity after ablation is noted in most patients and is probably related to a mild iatrogenic cholecystitis.

title: Radiofrequency ablation for hepatocellular carcinoma in so‐called high‐risk locations
abstract: We evaluated the efficacy and safety of radiofrequency (RF) ablation for hepatocellular carcinoma (HCC) in presumably high‐risk locations. Between February 1999 and December 2001, we performed RF ablation on 1,419 nodules in 636 consecutive HCC patients, of which 231 nodules in 207 patients were in high‐risk locations, defined as less than 5 mm from a large vessel or an extrahepatic organ. Eighty‐one patients had a nodule adjacent to a large vessel, 145 patients had a nodule adjacent to an extrahepatic organ, of whom 19 also had one adjacent to a large vessel. Early complications and local tumor progression were analyzed with regard to the location of each nodule. The mean nodule diameter and average number per patient were 27 mm and 2.3, respectively. Early complications, within 30 days after ablation, occurred in 12 of 207 patients (5.8 %) with a nodule in a high‐risk location and in 15 of 429 patients (3.5 %) without (P = .1776). There was no significant difference in local tumor progression rate between nodules in high‐risk locations (1 year: 2.1%, 2 years: 3.1%, 3 years: 3.1%) and those elsewhere (1 year: 0.6%, 2 years: 1.7%, 3 years: 2.5%) (P = .2745). In conclusion, HCC nodules adjacent to a large vessel or extrahepatic organ were treated with RF ablation without compromising the efficacy of the procedure. However, even though without significant difference, some complications occurred at risky locations and need to be carefully considered. (HEPATOLOGY 2006;43:1101–1108.

title: Porcine liver: morphologic characteristics and cell viability at experimental radiofrequency ablation with internally cooled electrodes.
abstract: To evaluate morphologic characteristics and cell viability of radiofrequency ablation zones in porcine liver.



Approval of the study protocol was obtained from the Ethics Committee on Use of Live Animals for Teaching and Research at University of Hong Kong. Internally cooled electrodes were used to produce 120 ablated zones ex vivo and 60 ablated zones in vivo with single electrodes (1-, 2-, and 3-cm exposed lengths) or clustered electrodes (1.0-, 2.0-, and 2.5-cm exposed lengths) at 4, 8, 12, and 16 minutes of ablation (ex vivo) and 8 and 12 minutes of ablation (in vivo). Morphologic measurements of each ablated zone were performed. Cell viability in each ablated zone was assessed qualitatively with histochemical staining and quantitatively with measurement of intracellular adenosine 5'-triphosphate (ATP) concentration.



Exposed length of electrode (coefficient = 0.79, standard error = 0.04, P < .001), duration of ablation (coefficient = 0.14, standard error = 0.01, P < .001), and clustered electrode design (coefficient = 1.21, standard error = 0.05, P < .001) were independent factors that affected minimal transverse diameter and volume of ablated zone in ex vivo study. Similar morphologic characteristics existed among ablated zones in in vivo study. Mean distance of ablation beyond the electrode tip remained constant (ex vivo, 1.0 cm +/- 0.08 [standard deviation]; in vivo, 0.5 cm +/- 0.05) regardless of different ablation conditions. Histochemical staining revealed no viable hepatocytes from center to margins of white zone in each ablated area. Mean intracellular ATP concentration in margins of white zone (9.5 x 10(-12) mol/microg DNA +/- 1.43) was lower than that in red zone (4088 x 10(-12) mol/microg DNA +/- 65.97, P < .001) and in adjacent normal liver (4528 x 10(-12) mol/microg DNA +/- 52.74, P < .001).



Distance of ablation beyond the tip of the electrode remained constant (ex vivo, 1.0 cm; in vivo, 0.5 cm) with different conditions of ablation. Complete and uniform cellular destruction was achieved in the white zone of ablated area.

title: Radiofrequency Thermal Ablation of Hepatocellular Carcinomas
abstract: Although surgical resection remains the best option as potentially curative therapy for hepatocellular carcinoma, radiofrequency thermal ablation has begun to receive much attention as an effective minimally invasive technique for the local control of unresectable malignant hepatic tumors. Most recent radiofrequency devices equipped with a powerful generator and larger needle electrode permit larger thermal lesions, up to 5 cm in diameter, with a single ablation. In this article, the author reviews the technical developments and early clinical results obtained with radiofrequency ablation techniques.

title: Hepatocellular carcinoma treated with percutaneous radio-frequency ablation: evaluation with follow-up multiphase helical CT.
abstract: To determine serial changes in hepatocellular carcinomas (HCCs) treated with percutaneous radio-frequency (RF) ablation at long-term follow-up multiphase helical computed tomography (CT).



There were 43 nodular HCCs in 40 patients at follow-up CT performed not less than 12 months after RF ablation. All patients underwent follow-up multiphase helical CT immediately, 1 month, and then every 3 months after percutaneous RF ablation. The serial changes in attenuation, enhancement pattern, shape, other findings, and volume of the ablated lesions were analyzed at follow-up CT.



Thirty-eight (88%) of 43 ablated lesions were of low attenuation, with absence of contrast material enhancement at immediate and 1-month follow-up CT, which is suggestive of successful treatment. The remaining five lesions (12%) showed peripheral nodular enhancement, suggesting residual viable tumor. Compared with volume changes at immediate follow-up CT, the mean percentages of volume change at 1, 4, 10, 16, and 19 months were 79%, 50%, 27%, 11%, and 6%, respectively. Of 43 ablated lesions, 24 (56%) were mostly round at immediate CT and remained unchanged at subsequent follow-up CT. Peripheral rim enhancement was seen in 34 (79%) of 43 lesions at immediate CT but resolved in all 34 lesions at 1-month follow-up CT. Other associated findings included iatrogenic arteriovenous shunt in 10 patients, perihepatic hemorrhage in three, and pneumothorax in one.



Follow-up multiphase helical CT of HCCs treated with percutaneous RF ablation showed variable findings in the treated lesions and surrounding liver parenchyma.

title: Therapeutic efficacy and safety of percutaneous radiofrequency ablation of hepatocellular carcinoma abutting the gastrointestinal tract.
abstract: The purpose of this study was to evaluate the therapeutic efficacy and safety of percutaneous radiofrequency ablation in the treatment of hepatocellular carcinomas abutting the gastrointestinal tract.



Forty-one patients with hepatocellular carcinomas abutting the gastrointestinal tract underwent sonographically guided percutaneous radiofrequency ablation. Forty-one tumors (1.2-4.3 cm in maximum diameter) had parts 5 mm or greater (or at least one quarter of their circumferences) abutting the stomach in 23 patients and the colon in 18 patients. Thirty tumors were ablated with internally cooled electrodes and 11 with multitined expandable electrodes. All patients were followed up for at least 1 year after ablation. Therapeutic efficacy and safety were evaluated with follow-up sonography and multiphase helical CT.



At 1-month follow-up CT, three (7%) of the 41 tumors showed residual unablated tumor in the ablation zone. Of the remaining 38 hepatocellular carcinomas (93%) with no evidence of residual unablated tumor, four (11%) showed local tumor progression in the ablation zones on subsequent follow-up CT. We observed one major complication-a small perihepatic abscess-that needed specific treatment.



Percutaneous radiofrequency ablation is an effective and safe technique for treating hepatocellular carcinomas abutting the gastrointestinal tract.

title: Image-guided tumor ablation: standardization of terminology and reporting criteria.
abstract: The field of interventional oncology with use of image-guided tumor ablation requires standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison between treatments that use different technologies, such as chemical (ethanol or acetic acid) ablation, and thermal therapies, such as radiofrequency (RF), laser, microwave, ultrasound, and cryoablation. This document provides a framework that will hopefully facilitate the clearest communication between investigators and will provide the greatest flexibility in comparison between the many new, exciting, and emerging technologies. An appropriate vehicle for reporting the various aspects of image-guided ablation therapy, including classification of therapies and procedure terms, appropriate descriptors of imaging guidance, and terminology to define imaging and pathologic findings, are outlined. Methods for standardizing the reporting of follow-up findings and complications and other important aspects that require attention when reporting clinical results are addressed. It is the group's intention that adherence to the recommendations will facilitate achievement of the group's main objective: improved precision and communication in this field that lead to more accurate comparison of technologies and results and, ultimately, to improved patient outcomes. The intent of this standardization of terminology is to provide an appropriate vehicle for reporting the various aspects of image-guided ablation therapy.

title: Major complications after radio-frequency thermal ablation of hepatic tumors: spectrum of imaging findings.
abstract: Although radio-frequency (RF) ablation has been accepted as a promising and safe technique for treatment of unresectable hepatic tumors, investigation of its complications has been limited. According to the multicenter (1,139 patients in 11 institutions) survey data of the Korean Study Group of Radiofrequency Ablation, a spectrum of complications occurred after RF ablation of hepatic tumors. The prevalence of major complications was 2.43%. The most common complications were hepatic abscess (0.66%), peritoneal hemorrhage (0.46%), biloma (0.20%), ground pad burn (0.20%), pneumothorax (0.20%), and vasovagal reflex (0.13%). Other complications were biliary stricture, diaphragmatic injury, gastric ulcer, hemothorax, hepatic failure, hepatic infarction, renal infarction, sepsis, and transient ischemic attack. One procedure-related death (0.09%) occurred (due to peritoneal hemorrhage). Three important strategies for decreasing the rate of complications are prevention, early detection, and proper management. A physician who performs RF ablation of hepatic malignancies should be aware of the broad spectrum of major complications so that these strategies can be used.

title: Radiofrequency ablation of liver adjacent to body of gallbladder: histopathologic changes of gallbladder wall in a pig model.
abstract: The purpose of our study was to evaluate the histopathologic changes of gallbladder wall surrounding radiofrequency ablation zones in pig livers and to assess the risk factors for thermal injury of gallbladder wall in terms of distance of the electrode, electrode direction in relation to the gallbladder wall, and time of sacrifice of the animal.



The study was performed in 15 pigs using an internally cooled single electrode with a 1-cm electrically active tip under sonographic guidance. Twenty-three hepatic ablation zones abutting the gallbladder were analyzed in three phases on the basis of the distance of the electrode (group A, 0.5 cm; group B, 1.0 cm), electrode direction (perpendicular or parallel), and time of sacrifice (immediate or delayed [7 days after radiofrequency ablation]). We evaluated the gross changes, the depth of thermal injury, and the grade of abnormal microscopic changes in the gallbladder wall. Data analysis was performed on the basis of the Fisher's exact test.



Discoloration and perforation were more frequent in group A (60%, 6/10, and 20%, 2/10, respectively) than in group B (25%, 2/8, and 0%, respectively, p > 0.05). Perforation was more frequent in the parallel direction and delayed phase (33.3%, 1/3, and 40%, 2/5, respectively) compared with the perpendicular direction and immediate phase (14.3%, 1/7, and 0%, respectively, p > 0.05). Depth of thermal injury showed a significant difference between group A and group B for full-thickness involvement (53.8%, 7/13, versus 0%, respectively, p < 0.05). Abnormal microscopic changes showed that parallel direction and immediate phase were more frequent with full-thickness involvement (71.4%, 5/7, and 71.4%, 5/7, respectively) compared with perpendicular direction and delayed phase (33.3%, 2/6, and 33.3%, 2/6, respectively, p > 0.05).



Hepatic radiofrequency ablation abutting the gallbladder can produce substantial thermal injury of the gallbladder wall, including perforation, especially when performed without a safe distance.