Radiofrequency ablation for viable hepatocellular carcinoma around retained iodized oil after transcatheter arterial chemoembolization: usefulness of biplane fluoroscopy plus ultrasound guidance

Factors associated with increased risk of peritoneal seeding after radiofrequency ablation for hepatocellular carcinoma

PURPOSE

To evaluate the incidence, risk factors, and prognosis associated with peritoneal seeding after percutaneous radiofrequency ablation (RFA) for HCC, focusing on viable tumors after previous locoregional treatment, including TACE and RFA.

METHODS

Exactly 290 patients (mean age, 67.9 years ± 9.74; 223 men) with 383 HCCs (mean size, 15.9 mm ± 5.49) who underwent RFA between June 2012 and December 2019 were included in this retrospective study. Among them, 158 had history of previous treatment (mean number, 1.3 ± 1.8) with 109 viable HCCs. Cumulative seeding after RFA was estimated using the Kaplan-Meier method. Independent factors affecting seeding were investigated using multivariable Cox proportional hazards regression analysis.

RESULTS

Median follow-up was 1175 days (range: 28-4116). Seeding incidence was 4.1 (12/290) and 4.7% (17/383) per patient and tumor, respectively. The median time interval between RFA and detection of seeding was 785 days (range: 81-1961). Independent risk factors for seeding included subcapsular tumor location (hazard ratio [HR] 4.2; 95% confidence interval [CI] 1.4, 13.0; p = 0.012) and RFA for viable HCC after previous locoregional treatment (HR 4.5; 95% CI 1.7, 12.3; p = 0.003). Subgroup analysis for viable tumors, revealed no significant difference in cumulative seeding rates between the TACE and RFA groups (p = 0.078). Cumulative overall survival rates differed significantly between patients with and without seeding metastases (p < 0.001).

CONCLUSION

Peritoneal seeding after RFA is a rare, delayed complication. Subcapsular-located and viable HCC after previous locoregional treatment are potential risk factors for seeding. Seeding metastases could affect the prognosis of patients who cannot receive local therapy.

Whole tumor ablation of locally recurred hepatocellular carcinoma including retained iodized oil after transarterial chemoembolization improves progression-free survival

OBJECTIVES

To evaluate and compare clinical outcomes of two different radiofrequency ablation (RFA) methods for locally recurred hepatocellular carcinoma (LrHCC) after locoregional treatment.

METHODS

Our institutional review board approved this study with a waiver of informed consent. A total of 313 patients previously treated with transarterial chemoembolization (TACE) (n = 167) and RFA (n = 146) with a single LrHCC ≤ 3 cm was included from five tertiary referral hospitals. RFA was done for LrHCCs using either viable tumor alone ablation (VTA) method (VTA: n = 61 in the TACE group and n = 127 in the RFA group) or whole tumor ablation (WTA) method which includes both viable tumor and retained iodized oil or previously ablated zone (WTA: n = 106 in the TACE group and n = 19 in the RFA group). Local tumor progression (LTP)-free survival as well as progression-free survival (PFS) were estimated using the Kaplan-Meier method, and prognostic factors were evaluated using the Cox proportional hazards regression model.

RESULTS

In 167 patients with LrHCC who underwent TACE, the 5-year LTP-free survival after RFA was significantly higher with the VTA method than with the WTA method (26.9% vs. 87.8%; p < 0.001; hazard ratio (HR) = 8.53 [4.16-17.5]). The estimated 5-year PFS after RFA for LrHCC after TACE using the VTA method was 5.7%, which was significantly lower than that with the WTA method (26.4%) (p = 0.014; HR = 1.62 [1.10-2.38]). However, in 146 patients with LrHCC after initial RFA, there were no significant differences in cumulative incidence of LTP (p = 0.514) or PFS (p = 0.905) after RFA between the two ablation methods.

CONCLUSIONS

For RFA of LrHCC after TACE, the WTA method including both viable tumor and retained iodized oil could significantly lower LTP and improve PFS than VTA.

KEY POINTS

• Whole tumor ablation (WTA) could provide significantly better local tumor control for locally recurred HCC (LrHCC) after TACE than viable tumor alone ablation (VTA). • WTA for LrHCC after TACE could also provide significantly better progression-free survival than VTA. • Regarding LrHCC after RFA, VTA would provide a comparable clinical outcome to WTA.

Percutaneous Radiofrequency Ablation of Small (1-2 cm) Hepatocellular Carcinomas Inconspicuous on B-Mode Ultrasonographic Imaging: Usefulness of Combined Fusion Imaging with MRI and Contrast-Enhanced Ultrasonography

PURPOSE

To assess usefulness of adding contrast-enhanced ultrasonography (CEUS) to fusion imaging (FI) for percutaneous radiofrequency ablation (RFA) of hepatocellular carcinomas (HCCs) inconspicuous on FI alone. Therapeutic outcomes of RFA under CEUS-added FI guidance for HCCs inconspicuous on FI alone were also evaluated.

METHODS

This prospective study was approved by the institutional review board and informed consent was obtained from all patients. Planning US was performed with FI for 126 patients with a single HCC (1-2 cm) to evaluate the feasibility of RFA by grading lesion conspicuity score using a four-point scale. RFA was performed under CEUS-added FI guidance for HCCs inconspicuous on FI alone. We evaluated how many HCCs initially inconspicuous on FI became conspicuous after adding CEUS. After CEUS-added FI-guided RFA, therapeutic outcomes including rates of technical success, primary technique efficacy, major complications, and local tumor progression were assessed.

RESULTS

After adding CEUS, 90.5% (19/21) of all tumors initially inconspicuous on FI became conspicuous, thus enabling direct targeting for RFA. Technical success and primary technique efficacy rates were 94.7% (18/19) and 100% (19/19), respectively. No major complications were observed after RFA. Cumulative local tumor progression rates after RFA were estimated to be 5.3%, 10.8%, and 10.8% at 1, 2, and 3 years, respectively.

CONCLUSION

Adding CEUS to FI is useful for improving the conspicuity of HCCs inconspicuous on FI alone, thus enabling successful percutaneous RFA with excellent therapeutic outcomes.

Real-time Monitoring of Contrast-enhanced Ultrasound for Radio Frequency Ablation

Background

This study compared the realtime monitoring effects of conventional ultrasound and contrast-enhanced ultrasound (CEUS) on evaluating radio frequency ablation (RFA) in a living swine liver model.

Methodology

Liver RFA was performed on 10 young swine. Conventional ultrasound and CEUS were performed immediately. After the animals were sacrificed, ablation lesions were removed to histopathologically examine the range of the lesions. Ablation completeness based on three methods were compared using histopathology as the gold standard.

Results

Forty-three ablation lesions were produced in the animals. The horizontal diameter, vertical diameter and ablation lesion area based on conventional ultrasound were all significantly smaller than those based on the gross sample, but no significant differences existed between the results of the CEUS and the gross sample. Histopathology showed that 30 lesions were incompletely ablated and 13 were completely ablated, while CEUS showed that 28 lesions were incompletely ablated and 15 were completely ablated. Compared with histopathology, CEUS had an accuracy of 81.4%, a sensitivity of 83.3%, and a specificity of 76.9%. No significant difference in ablation completeness judgment between CEUS and histopathology was observed.

Conclusion

CEUS provides a real-time radiological foundation for evaluating RFA lesion ranges and completeness in a living swine liver model.

Viable hepatocellular carcinoma around retained iodized oil after transarterial chemoembolization: radiofrequency ablation of viable tumor plus retained iodized oil versus viable tumor alone

OBJECTIVE

The objective of our study was to compare the effectiveness of radiofrequency ablation (RFA) for viable hepatocellular carcinoma (HCC) including areas of retained oil after transarterial chemoembolization (TACE) versus RFA treatment of viable HCC alone for ablation coverage.

MATERIALS AND METHODS

Eighty-five patients with 88 viable HCCs underwent RFA of residual viable HCCs around retained iodized oil after TACE. RFA of both viable HCC and retained iodized oil was performed on 47 viable tumors (group A), and RFA of viable HCC only was used to treat the remaining 41 viable tumors (group B).

RESULTS

After initial RFA, the endpoint of ablation was successfully achieved for 45 of 47 tumors in group A and for all 41 tumors in group B. Two residual viable tumors in group A were successfully treated by additional RFA. Major complications occurred after initial RFA treatment of one tumor each in group A (pleural effusion) and group B (collateral damage). During follow-up (mean, 37.1 months; range, 5-116.5 months), local tumor progression of treated lesions was found in 28% in group A and 59% in group B. The respective 1-, 3-, 5-, and 7-year local tumor progression rates were significantly lower in group A (15%, 32%, 32%, and 32%) than in group B (43%, 71%, 81%, and 81%) (p = 0.001).

CONCLUSION

In treatment of viable tumors after TACE in patients with HCC, RFA of both viable tumor and retained iodized oil may reduce rates of local tumor progression compared with RFA of viable tumor only.

Relationship between postoperative imaging findings and therapeutic effect in patients with unresectable hepatocellular carcinoma after ultrasound-guided percutaneous radiofrequency ablation

AIM: To investigate the relationship between postoperative imaging findings and therapeutic effect in patients with unresectable hepatocellular carcinoma after ultrasound-guided percutaneous radiofrequency ablation (PRFA).

METHODS: Thirty-six patients with unresectable hepatocellular carcinoma who undersent ultrasound-guided percutaneous radiofrequency ablation were selected. The levels of alanine aminotransferase (ALT), aspartate aminotrans-ferase (AST), total bilirubin (TBIL), albumin (ALB), and alpha fetal protein (AFP) as well as imaging findings were retrospectively analyzed (1 day before, 7, 14 and 28 d after PRFA).

RESULTS: The levels of ALT and AST were significantly higher on day 7 after PRFA than on day 1 before PRFA (102.21 U/L ± 53.41 U/L vs 55.34 U/L ± 36.57 U/L, 90.58 U/L ± 37.22 U/L vs 65.77 U/L ± 40.29 U/L), and they decreased to preoperative levels on day 14. Patients with an AFP level decreased by ≥ 50% on day 28 showed complete ablation of the tumors on magnetic resonance imaging (MRI) and high echo area with liquefaction and no blood flow in the center of the lesions on ultrasound. Patients with elevated AFP values showed incomplete ablation of the tumors on MRI and incomplete high echo area with blood flow on ultrasound. The effective rate of PRFA was higher than 60% when the levels of AFP were used as evaluation criterion. The 3-year survival rate was 68%. The median survival time was 38.09 mo.

CONCLUSION: The imaging findings can well reflect the changes of serum markers and recurrence in patients with unresectable hepatocellular carcinoma after ultrasound-guided percutaneous radiofrequency ablation. Imaging examinations can be used as an effective approach for the detection of recurrence of hepatocellular carcinoma.

Computed tomographic-guided radiofrequency ablation of recurrent or residual hepatocellular carcinomas around retained iodized oil after transarterial chemoembolization

Objective

To assess the clinical efficacy, safety, and risk factors influencing local tumor progression, following CT-guided radiofrequency ablation (RFA) of recurrent or residual hepatocellular carcinoma (HCC), around iodized oil retention.

Materials and Methods

Sixty-four patients (M : F = 51 : 13, 65.0 ± 8.2 years old) with recurrent or residual HCC (75 index tumors, size = 14.0 ± 4.6 mm) had been treated by CT-guided RFA, using retained iodized oil as markers for targeting. The technical success, technique effectiveness rate and complications of RFA were then assessed. On pre-ablative and immediate follow-up CT after RFA, we evaluated the size of enhancing index tumors and iodized oil retention, presence of abutting vessels, completeness of ablation of iodized oil retention, and the presence of ablative margins greater than 5 mm. Also, the time interval between transarterial chemoembolization and RFA was assessed. The cumulative local tumor progression rate was calculated using the Kaplan-Meier method, and the Cox proportional hazards model was adopted, to clarify the independent factors affecting local tumor progression.

Results

The technical success and technique effectiveness rate was 100% and 98.7%, respectively. Major complications were observed in 5.6%. The cumulative rates of local tumor progression at 1 and 2 years were 17.5% and 37.5%, respectively. In multivariate analyses, partial ablation of the targeted iodized oil retention was the sole independent predictor of a higher local tumor progression rate.

Conclusion

CT-guided RFA of HCC around iodized oil retention was effective and safe. Local tumor progression can be minimized by complete ablation of not only index tumors, but targeted iodized oil deposits as well.

Dual switching monopolar radiofrequency ablation using a separable clustered electrode: comparison with consecutive and switching monopolar modes in ex vivo bovine livers

Objective

To compare the in-vitro efficiency of dual-switching monopolar (DSM) radiofrequency ablation (RFA) using a separable clustered electrode (Octopus® electrodes) with consecutive monopolar (CM) and switching monopolar (SM) RFA techniques to create an ablative zone in the explanted bovine liver.

Materials and Methods

For DSM-RFA, we used a prototype, three-channel, dual generator RFA Unit and Octopus® electrodes with three, 17 gauge internally cooled electrodes. The RFA Unit allowed simultaneous radiofrequency (RF) energy delivery to two electrodes of the Octopus® electrodes as well as automatic switching among the three electrode pairs according to the impedance changes. RF energy was sequentially applied to one of the three electrodes for 24 minutes (group A; CM mode, n = 10) or alternatively applied for 12 minutes (group B; SM mode, n = 10) or concurrently applied to a pair of electrodes for 12 minutes (group C; DSM mode, n = 10) in explanted bovine livers. Changes in the impedance and current during RFA as well as the dimensions of the thermal ablative zones were compared among the three groups.

Results

The mean, delivered RF energy amounts in groups A, B, and C were 63.15 ± 8.6 kJ, 72.13 ± 5.4 kJ, and 106.08 ± 13.4 kJ, respectively (p < 0.001). The DSM mode created a significantly larger ablation volume than did the other modes, i.e., 68.1 ± 10.2 cm³ (group A), 92.0 ± 19.9 cm³ (group B), and 115.1 ± 14.0 cm³ (group C) (p < 0.001). The circularity in groups A, B, and C were 0.84 ± 0.06, 0.87 ± 0.04 and 0.90 ± 0.03, respectively (p = 0.03).

Conclusion

DSM-RFA using Octopus® electrodes can help create large ablative zones within a relatively short time.