Percutaneous Radiofrequency Ablation of Liver Tumors Using Multiple Saline-Perfused Electrodes

Quantitative Volumetric Assessment of Ablative Margins in Hepatocellular Carcinoma: Predicting Local Tumor Progression Using Nonrigid Registration Software

Purpose

After radiofrequency ablation (RFA) of hepatocellular carcinoma (HCC), pre- and postinterventional contrast-enhanced CT (CECT) images are usually qualitatively interpreted to determine technical success, by eyeballing. The objective of this study was to evaluate the feasibility of quantitative assessment, using a nonrigid CT-CT coregistration algorithm.

Materials and Methods

25 patients treated with RFA for HCC between 2009 and 2014 were retrospectively included. Semiautomated coregistration of pre- and posttreatment CECT was performed independently by two radiologists. In scans with a reliable registration, the tumor and ablation area were delineated to identify the side and size of narrowest RFA margin. In addition, qualitative assessment was performed independently by two other radiologists to determine technical success and the anatomical side and size of narrowest margin. Interobserver agreement rates were determined for both methods, and the outcomes were compared with occurrence of local tumor progression (LTP).

Results

CT-CT coregistration was technically feasible in 18/25 patients with almost perfect interobserver agreement for quantitative analysis (κ = 0.88). The interobserver agreement for qualitative RFA margin analysis was κ = 0.64. Using quantitative assessment, negative ablative margins were found in 12/18 patients, with LTP occurring in 8 of these patients. In the remaining 6 patients, quantitative analysis demonstrated complete tumor ablation and no LTP occurred.

Conclusion

Feasibility of quantitative RFA margin assessment using nonrigid coregistration of pre- and postablation CT is limited, but appears to be a valuable tool in predicting LTP in HCC patients (p=0.013).

Prognostic factors after ultrasound-guided percutaneous ablation of colorectal liver metastases: A systematic review

Introduction

Liver metastases from colorectal cancer are common and ablation therapy is a favourable treatment option for selected patients not suited for surgical resection. This study aimed to systematically review the literature and present prognostic factors associated with survival and local recurrence after percutaneous ultrasound-guided ablation treatment.

Materials and methods

This review is reported according to the PRISMA. PubMed, Embase and Scopus were searched and records were independently screened by two authors, initially on title and abstract and subsequently on full-text basis. The quality of the studies was assessed using the Newcastle-Ottawa quality assessment scale.

Results

Of 2.882 records screened, 18 studies were included. The median survival was 23 months. One-year survival was median 95% and 3-year survival was median 58%. Complete ablation response and adjuvant chemotherapy produce considerably improved survival and low local recurrence rate outcomes.

Conclusion

Percutaneous ultrasound-guided ablation technique for colorectal liver metastases provides impressive survival rates for patients not suited for surgical resection. However, there are some factors related to poorer prognosis, which may be considered when selecting patients.

Percutaneous cryoablation of hepatic tumors: long-term experience of a large U.S. series

PURPOSE

To report our long-term experience with percutaneous cryotherapy for primary and metastatic liver tumors, including historical perspectives on complications over time and local recurrence rates.

MATERIALS AND METHODS

Following IRB approval under HIPAA compliance, 342 CT fluoroscopic-guided, percutaneous cryotherapy procedures were performed for 443 masses in 212 outpatients with hepatocellular carcinoma (HCC; N = 36), or metastatic disease (N = 176), grouped as colorectal carcinoma (CRC) and non-CRC metastases. Tumor and ablation sizes were noted in relation to adjacent vasculature. All complications were graded according to standardized criteria. Patients were followed by CT and/or MRI at 1, 3, 6, 12, 18, 24 months and yearly thereafter. Local recurrences were defined as either "procedural" within the ice ablation zone, or "satellite" within 1 cm of the ablation rim to evaluate recurrence patterns.

RESULTS

Average tumor diameter of 2.8 cm was treated by average cryoprobe number of 4.5, which produced CT-visible ice ablation zone diameters averaging 5.2 cm. Grade >3 complications were primarily hematologic [N = 20/342; (5.8%)], and appeared related to pre-procedural anemia/thrombocytopenia, carcinoid tumor type, and large ablation volumes. No significant central biliary leak, strictures, or bilomas were noted. At a mean follow-up of 1.8 years, local tumor recurrences were 5.5%, 11.1%, and 9.4% for HCC, CRC, and non-CRC metastases, respectively, consisting mainly of satellite foci. No significant difference was noted for local recurrences near major blood vessels or tumors >3 cm diameter.

CONCLUSIONS

Percutaneous hepatic cryotherapy is a well-visualized, safe procedure that produces very low local recurrence rates, even for tumors near vasculature and diameters over 3 cm. Cryoablation deserves to be in the armamentarium of percutaneous hepatic ablation, especially with careful patient selection for tumors <4 cm and patients with platelet counts >100,000. Percutaneous hepatic cryoablation represents a highly flexible technique with particular benefits near central biliary structures and/or adjacent crucial structures.

Switching bipolar hepatic radiofrequency ablation using internally cooled wet electrodes: comparison with consecutive monopolar and switching monopolar modes

OBJECTIVE

To evaluate whether switching bipolar radiofrequency ablation (SB-RFA) using three internally cooled wet (ICW) electrodes can induce coagulations >5 cm in porcine livers with better efficiency than consecutive monopolar (CM) or switching monopolar (SM) modes.

METHODS

A total of 60 coagulations were made in 15 in vivo porcine livers using three 17-gauge ICW electrodes and a multichannel radiofrequency (RF) generator. RF energy (approximately 200 W) was applied in CM mode (Group A, n = 20) for 24 min, SM mode for 12 min (Group B, n = 20) or switching bipolar (SB) mode for 12 min (Group C, n = 20) in in vivo porcine livers. Thereafter, the delivered RFA energy, as well as the shape and dimension of coagulations were compared among the groups.

RESULTS

Spherical- or oval-shaped ablations were created in 30% (6/20), 85% (17/20) and 90% (18/20) of coagulations in the CM, SM and SB groups, respectively (p = 0.003). SB-RFA created ablations >5 cm in minimum diameter (Dmin) in 65% (13/20) of porcine livers, whereas SM- or CM-RFA created ablations >5 cm in only 25% (5/20) and 20% (4/20) of porcine livers, respectively (p = 0.03). The mean Dmin of coagulations was significantly larger in Group C than in Groups A and B (5.1 ± 0.9, 3.9 ± 1.2 and 4.4 ± 1.0 cm, respectively, p = 0.002) at a lower delivered RF energy level (76.8 ± 14.3, 120.9 ± 24.5 and 114.2 ± 18.3 kJ, respectively, p < 0.001).

CONCLUSION

SB-RFA using three ICW electrodes can create coagulations >5 cm in diameter with better efficiency than do SM- or CM-RFA.

ADVANCES IN KNOWLEDGE

SB-RFA can create large, regular ablation zones with better time-energy efficiency than do CM- or SM-RFA.

Small- and medium-sized hepatocellular carcinomas: monopolar radiofrequency ablation with a multiple-electrode switching system-mid-term results

PURPOSE

To prospectively assess the safety and mid-term therapeutic effectiveness of monopolar radiofrequency (RF) ablation with a multiple-electrode switching system for treating small- and medium-sized (≤ 5 cm) hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

The institutional review board approved this prospective study, and all patients gave informed consent. From February 2009 to January 2010, 166 patients (110 men and 56 women; age range, 38-86 years; mean age, 62 years ± 10 [standard deviation]) with 166 HCCs less than or equal to 5 cm in diameter were treated with monopolar RF ablation with a multiple-electrode switching system. One of three experienced radiologists performed the RF ablation. Technique effectiveness, ablation volume and time, and major complications were evaluated by means of computed tomography (CT) immediately after RF ablation and at follow-up CT examinations at 1 month and then every 3 months after the procedure. The overall survival, disease-free survival, and local tumor progression-free survival rates were evaluated by using the Kaplan-Meier method.

RESULTS

The technique effectiveness rate determined 1 month after RF ablation was 99.4%. Mean ablation parameters were as follows: volume, 85 cm(3) ± 54; maximum diameter, 61 mm ± 13; and minimum diameter, 43 mm ± 11. The major complication rate was 4.8%. The 6-month and 1-, 2-, and 3-year local tumor progression rates were 2%, 6%, 10%, and 11%, respectively. The overall survival rates at 1, 2, and 3 years after RF ablation were 99%, 97%, and 96%, and corresponding local tumor progression-free survival rates were 94%, 90%, and 89%, respectively. The disease-free survival rates at 1, 2, and 3 years after RF ablation were 75%, 60%, and 54%, respectively.

CONCLUSION

Monopolar RF ablation with a multiple-electrode switching system in small- and medium-sized HCCs was safe and efficient, and it provided successful local tumor control and high local tumor progression-free survival rates because an adequate ablation volume was obtained.

Ablative zone size created by radiofrequency ablation with and without chemoembolization in small hepatocellular carcinomas

PURPOSE

We retrospectively evaluated whether combined use of chemoembolization expands ablative zone sizes created by radiofrequency (RF) ablation in patients with small hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

Fifty-seven patients treated with single RF ablation for solitary HCC measuring ≤2 cm were assessed. RF ablation alone was done in nine patients and in 48 patients following chemoembolization, with an interval of 0 days in 6, 1-14 days in 27, 15-28 days in 6, and ≥4 weeks in 9. Ablative zone sizes, disappearance of tumor enhancement, and creation of sufficient ablative margins (>5 mm) were evaluated on contrast-enhanced computed tomography (CT) images.

RESULTS

Both mean long-axis (4.2-4.7 vs. 3.6 ± 0.4 cm, p < 0.04) and short-axis (3.3-3.8 vs. 2.3 ± 0.5 cm, p < 0.03) diameters were expanded significantly when RF ablation was done until 4 weeks after chemoembolization than with RF ablation alone. Tumor enhancement disappeared in all patients. Frequency of achieving sufficient ablative margins was significantly higher when RF ablation was done until 4 weeks after chemoembolization than with RF ablation alone (74.0-83.3 vs. 22.2 %, p < 0.05).

CONCLUSION

Ablative zones created by RF ablation with chemoembolization become larger than RF ablation alone, leading to secure ablative margins.

Microwave coagulation using a perfusion microwave electrode: Preliminary experimental study using ex vivo and in vivo liver

To assess the coagulation capability of a perfusion microwave electrode (PME) as a key component of microwave coagulation therapy, a preliminary experimental study was performed using ex vivo and in vivo livers. For a microwave electrode, a PME was employed. Using a PME, saline was passed through the electrode and injected continuously into the target tissue. Using an ex vivo bovine liver, the range of tissue coagulation was measured for various volumes of infused saline and microwave outputs. Using an in vivo porcine liver, the efficiency of coagulation by a PME was compared with that of radiofrequency ablation (RFA) using a cool-tip needle. In an ex vivo bovine liver, the range of tissue coagulation increased as the flow rate of saline increased. In the in vivo porcine liver, the range of coagulation was similar to that found in the ex vivo bovine liver. With a PME under conditions of a microwave output of 80 W, a flow rate of 3 ml/min and irradiation time of 5 min, the range of coagulation was 44.8±2.8 mm [maximum vertical diameter: (a)] x 31.2±2.4 mm [maximum transverse diameter: (b)]. The range of RFA (cool-tip needle) at 12 min was 46.0±2.0 mm (a) x 30.2±2.0 mm (b). With only 5 min of microwave irradiation, the use of a PME enabled induction of the same range of coagulation that was obtainable by RFA for 12 min. In comparison with microwave coagulation without saline infusion, the use of a PME made it possible to extend the range of tissue coagulation to a range equal to that of RFA in a short time. Microwave coagulation using a PME may be one of the suitable tissue coagulation systems for local ablation treatment.

Preinjected fluids do not benefit microwave ablation as those in radiofrequency ablation

RATIONALE AND OBJECTIVES

To detect whether the efficacy of microwave ablation (MWA) could be improved by preinjected fluids in an ex vivo porcine liver model.

MATERIALS AND METHODS

Ablations were performed for 12 minutes using energy output of impedance-based (power output gradually rose to 200W, maintained until increases in tissue impedance of 20 Ω, reduced to 10W, and switched on again 15 seconds later) in radiofrequency ablation (RFA) or 80 W in MWA. Before ablation, 5 mL of ethanol, distilled water, 0.9% NaCl solution, or 10% NaCl solution (n = 6 each) was injected into the targeted liver tissue. Ablations without fluid injection served as control. The ablation diameter, volume, shape index, and temperature were recorded and compared.

RESULTS

Preinjection of 0.9% or 10% NaCl solution resulted in larger coagulation volumes than that of the control group in RFA experiments (28.1 ± 2.9 cm(3), 45.3 ± 6.3 cm(3), 20.0 ± 2.5 cm(3), respectively; P < .05). Ethanol and distilled water had no impact on coagulation volumes in RFA. Preinjection of ethanol or 10% NaCl solution created smaller coagulation volumes than that of the control group in MWA experiments (34.3 ± 2.0 cm(3), 33.9 ± 4.1 cm(3), 58.0 ± 6.6 cm(3), respectively; P < .001). 0.9% NaCl solution and distilled water had no impact on coagulation volumes in MWA.

CONCLUSION

In an ex vivo porcine liver, preinjected fluids do not benefit microwave ablation as those in radiofrequency ablation.

Radiofrequency ablation of hepatocellular carcinoma: Current status

Ablation therapy is one of the best curative treatment options for malignant liver tumors, and can be an alternative to resection. Radiofrequency ablation (RFA) of primary and secondary liver cancers can be performed safely using percutaneous, laparoscopic, or open surgical techniques, and RFA has markedly changed the treatment strategy for small hepatocellular carcinoma (HCC). Percutaneous RFA can achieve the same overall and disease-free survival as surgical resection for patients with small HCC. The use of a laparoscopic or open approach allows repeated placements of RFA electrodes at multiple sites to ablate larger tumors. RFA combined with transcatheter arterial chemoembolization will make the treatment of larger tumors a clinically viable treatment alternative. However, an accurate evaluation of treatment response is very important to secure successful RFA therapy. Since a sufficient safety margin (at least 0.5 cm) can prevent local tumor recurrences, an accurate evaluation of treatment response is very important to secure successful RFA therapy. To minimize complications of RFA, clinicians should be familiar with the imaging features of each type of complication. Appropriate management of complications is essential for successful RFA treatment.

Radiofrequency ablation of hepatocellular carcinoma: a literature review

Radiofrequency ablation (RFA) of liver cancers can be performed safely using percutaneous, laparoscopic, or open surgical techniques, and much of the impetus for the use of RFA has come from cohort series that have provided an evidence base for this technique. Here, we give an overview of the current status of radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC), including its physical properties, to assess the characteristics that make this technique applicable in clinical practice. We review the technical development of probe design and summarize current indications and outcomes of reported clinical use. An accurate evaluation of treatment response is very important to secure successful RFA therapy since a sufficient safety margin (at least 0.5 cm) can prevent local tumor recurrences. We also provide a profile of side effects and information on the integration of this technique into the general management of patients with HCC. To minimize complications of RFA, physicians should be familiar with each feature of complication. Appropriate management of complications is essential for successful RFA treatment. Moreover, adjuvant therapy, such as molecular targeted therapies following curative therapy, is expected to further improve survival after RFA.

Radiofrequency ablation of hepatocellular carcinoma: Current status

Ablation therapy is one of the best curative treatment options for malignant liver tumors, and can be an alternative to resection. Radiofrequency ablation (RFA) of primary and secondary liver cancers can be performed safely using percutaneous, laparoscopic, or open surgical techniques, and RFA has markedly changed the treatment strategy for small hepatocellular carcinoma (HCC). Percutaneous RFA can achieve the same overall and disease-free survival as surgical resection for patients with small HCC. The use of a laparoscopic or open approach allows repeated placements of RFA electrodes at multiple sites to ablate larger tumors. RFA combined with transcatheter arterial chemoembolization will make the treatment of larger tumors a clinically viable treatment alternative. However, an accurate evaluation of treatment response is very important to secure successful RFA therapy. Since a sufficient safety margin (at least 0.5 cm) can prevent local tumor recurrences, an accurate evaluation of treatment response is very important to secure successful RFA therapy. To minimize complications of RFA, clinicians should be familiar with the imaging features of each type of complication. Appropriate management of complications is essential for successful RFA treatment.

MR monitoring of NaCl-enhanced radiofrequency ablations: observations on low- and high-field-strength MR images with pathologic correlation

PURPOSE

To test the hypothesis that magnetic resonance (MR) imaging can be used to monitor both intraparenchymal injection of NaCl solution and subsequent radiofrequency ablation (RFA) within tissues pretreated with NaCl, report the low- and high-field-strength MR appearance of NaCl-enhanced RFAs, and compare MR findings with pathologic findings.

MATERIALS AND METHODS

Ten ex vivo calf liver specimens were injected with saturated NaCl (seven were mixed with methylene blue during MR fluoroscopic monitoring) and reexamined with fast imaging with steady-state progression (FISP), true FISP, reversed FISP (PSIF), and fast spin-echo T2-weighted MR sequences. The NaCl-to-liver contrast-to-noise ratio (CNR) was calculated for various sequences, and CNRs were compared with the Student t test. Distribution on MR images was compared with the results of pathologic analysis. Forty additional in vivo monopolar RFAs were performed in paraspinal muscles of seven minipigs after animal care committee approval (10 standard control ablations, 30 were preceded by direct injection of saturated NaCl at various volumes [3-9 mL] and rates [1 or 6mL/min]). Postablation low-field-strength (n = 20) and high-field-strength (n = 20) MR examinations consisted of T2-weighted imaging, short inversion time inversion-recovery (STIR) imaging, and contrast material-enhanced T1-weighted imaging. Ablation shape, conspicuity, volume, and signal intensity were compared between the two groups and with the results of pathologic analysis. The difference in volumes with and without NaCl injection was evaluated by using two-way analysis of variance.

RESULTS

Mean CNR was highest on fast spin-echo T2-weighted images and was significantly higher for PSIF than for FISP (P < .0001) or true FISP (P = .003). NaCl distribution on MR images corresponded with the results of pathologic analysis in ex vivo livers. Interactive in vivo monitoring of NaCl injection and electrode placement was feasible. NaCl-enhanced ablations had irregular shapes, a higher CNR, and significantly larger volumes (F = 22.0; df = 1, 90; P < .00001). All ablations had intermediate or low signal intensity with high-signal-intensity rims on all images. Fluid signals overlaid NaCl-enhanced ablations on fast spin-echo T2-weighted and STIR images, particularly on high-field-strength MR images.

CONCLUSION

MR imaging can be used to reliably monitor the distribution of injected NaCl solution in tissues. Interventional MR imaging techniques can be used to guide and monitor RFAs within NaCl pretreated tissues, with good correlation with pathologic results.

Radiofrequency ablation of hepatic tumours: effect of post-ablation margin on local tumour progression

PURPOSE

The purpose of this study was to retrospectively evaluate the relationship between post-ablation margins and local tumour progression following radiofrequency ablation (RFA) of hepatocellular carcinomas and colorectal liver metastases.

METHODS

Eighty-three patients with 107 hepatic tumours who underwent RFA were divided into two groups: the hepatocellular carcinoma (HCC) group (55 patients with 69 lesions) and the colorectal liver metastases group (28 patients with 38 lesions). Post-ablation margins were calculated on 1-month follow-up contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) studies. Efficacy was evaluated at 1-month post-ablation, then at 3-month intervals for the first year and biannually thereafter.

RESULTS

The results of the log-rank test showed that the minimum threshold post-ablation margin of 0.4 cm (P = 0.020) and tumour size smaller than 2.5 cm (P = 0.001) significantly correlated with local control for the HCC group. In the colorectal liver metastases group, the results of the log-rank test showed that the minimum threshold post-ablation margin of 0.4 cm (P = 0.345) and tumour size smaller than 2.5 cm (P = 0.168) did not correlate with local control.

CONCLUSION

Percutaneous RFA is more effective in achieving local control in patients with HCCs than with colorectal liver metastases.

Laser ablation of liver metastases from colorectal cancer with MR thermometry: 5-year survival

PURPOSE

To determine technical success, technique effectiveness, complications, and survival after laser ablation of liver metastases from colorectal cancer.

MATERIALS AND METHODS

Eighty-seven consecutive patients (65 men and 22 women; mean age, 62.8 years) with 180 liver metastases from colorectal carcinoma were included between 1998 and 2005. They underwent laser ablation with magnetic resonance (MR) thermometry in 170 sessions. Indications for laser ablation were locally unresectable tumors (16.1%), metastases in both liver lobes (34.5%), and refusal of surgery and/or general contraindications to surgery (49.4%). Technical success, technique effectiveness, and complication and survival rates were evaluated retrospectively.

RESULTS

Technical success was achieved in 178 of 180 sessions (99%). Follow-up after 24-48 hours demonstrated an effectiveness rate of 85.6%. Local tumor progression rate was 10% after 6 months. Major complications included large pleural effusion, large subcapsular hematoma, abscess, large pneumothorax, pleuritis with fever, intrahepatic hemorrhage, and biloma. Mean survival from the time of diagnosis of the primary tumor was 50.6 months for all patients treated (95% CI, 44.9-56.3 months). Median survival time was 54 months and survival rates were 95.7% at 1 year, 86.2% at 2 years, 72.4% at 3 years, 50.1% at 4 years, and 33.4% at 5 years. The mean survival time after the first treatment was 31.1 months (95% CI, 26.9-35.3 months).

CONCLUSIONS

Laser ablation of liver metastases of colorectal cancer with MR thermometry appears safe and efficacious. Although the results are encouraging, direct comparison with other ablative modalities in a prospective clinical trial would be necessary to definitely show one modality is superior.

Magnetic thermal ablation using ferrofluids: influence of administration mode on biological effect in different porcine tissues

The purpose of this study was to compare the effects of magnetic thermal ablation in different porcine tissues using either a singular injection or a continuous infusion of superparamagnetic iron oxide nanoparticles. In the first setting samples of three ferrofluids containing different amounts of iron (1:171, 2:192, and 3:214 mg/ml) were singularly interstitially injected into specimens of porcine liver, kidney, and muscle (n = 5). Then the specimens were exposed to an alternating magnetic field (2.86 kA/m, 190 kHz) generated by a circular coil for 5 min. In the second experimental setup ferrofluid samples were continuously interstitially infused into the tissue specimens during the exposure to the magnetic field. To measure the temperature increase two fiber-optic temperature probes with a fixed distance of 0.5 cm were inserted into the specimens along the puncture tract of the injection needle and the temperature was measured every 15 s. Finally, the specimens were dissected, the diameters of the created thermal lesions were measured, and the volumes were calculated and compared. Compared to continuous infusion, a single injection of ferrofluids resulted in smaller coagulation volumes in all tissues. Significant differences regarding coagulation volume were found in kidney and muscle specimens. The continuous infusion technique led to more elliptically shaped coagulation volumes due to larger diameters along the puncture tract. Our data show the feasibility of magnetic thermal ablation using either a single interstitial injection or continuous infusion for therapy of lesions in muscle, kidney, and liver. Continuous infusion of ferrofluids results in larger zones of necrosis compared to a single injection technique.

Mid-term outcome of positron emission tomography/computed tomography-assisted radiofrequency ablation in primary and secondary liver tumours--a single-centre experience

AIMS

To determine the mid-term results of percutaneous radiofrequency ablation (RFA) of malignant liver tumours when using FDG-positron emission tomography (FDG-PET)/computed tomography for tumour evaluation and follow-up.

MATERIALS AND METHODS

Between January 2002 and June 2006, 55 patients (mean age 63 years) with 78 liver lesions (39 colorectal metastases, 39 hepatocellular carcinoma [HCC] nodules) were treated with RFA. All patients received PET/computed tomography before intervention. RFA was performed under computed tomography guidance with conscious sedation. Post-interventional PET/computed tomography was carried out in PET-positive patients 24h after the ablation and was repeated at 1, 3 and 6 months and every 6 months after the intervention. PET-negative patients received contrast-enhanced computed tomography at the same time points. The rate of local tumour progression (LTP) and survival rates were assessed for the whole patient population.

RESULTS

The 78 lesions (mean size 2.3 cm, range 0.8-5 cm) were treated with 101 consecutive ablation procedures resulting in a technical success rate of 96%. The mean time of follow-up was 25+/-12 months. Thirty-five of 78 tumours (45%) developed LTP. At the end of follow-up, LTP was found in 22 patients (40%), with intra- and extrahepatic recurrence in 11 patients. Twenty-two patients remained free of hepatic tumours. The 1-, 2- and 3-year survival rates were 85, 74 and 58%, respectively. Tumour entity, lesion size and localisation were significant risk factors for LTP.

CONCLUSIONS

Computed tomography-guided RFA of malignant liver tumours is effective, but shows a high rate of LTP. PET/computed tomography supports RFA by early identification of residual tumour or LTP.