Radiofrequency Ablation and Microwave Ablation in Liver Tumors: An Update

Abstract

This article provides an overview of radiofrequency ablation (RFA) and microwave ablation (MWA) for treatment of primary liver tumors and hepatic metastasis. Only studies reporting RFA and MWA safety and efficacy on liver were retained. We found 40 clinical studies that satisfied the inclusion criteria. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive to treat hepatic tumors. According to the literature, the overall survival, local recurrence, complication rates, disease-free survival, and mortality in patients with hepatocellular carcinoma (HCC) treated with RFA vary between 53.2 ± 3.0 months and 66 months, between 59.8% and 63.1%, between 2% and 10.5%, between 22.0 ± 2.6 months and 39 months, and between 0% and 1.2%, respectively. According to the literature, overall survival, local recurrence, complication rates, disease-free survival, and mortality in patients with HCC treated with MWA (compared with RFA) vary between 22 months for focal lesion >3 cm (vs. 21 months) and 50 months for focal lesion ≤3 cm (vs. 27 months), between 5% (vs. 46.6%) and 17.8% (vs. 18.2%), between 2.2% (vs. 0%) and 61.5% (vs. 45.4%), between 14 months (vs. 10.5 months) and 22 months (vs. no data reported), and between 0% (vs. 0%) and 15% (vs. 36%), respectively. According to the literature, the overall survival, local recurrence, complication rates, and mortality in liver metastases patients treated with RFA (vs. MWA) are not statistically different for both the survival times from primary tumor diagnosis and survival times from ablation, between 10% (vs. 6%) and 35.7% (vs. 39.6), between 1.1% (vs. 3.1%) and 24% (vs. 27%), and between 0% (vs. 0%) and 2% (vs. 0.3%). MWA should be considered the technique of choice in selected patients, when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size. IMPLICATIONS FOR PRACTICE: Although technical features of the radiofrequency ablation (RFA) and microwave ablation (MWA) are similar, the differences arise from the physical phenomenon used to generate heat. RFA has become an established treatment modality because of its efficacy, reproducibility, low complication rates, and availability. MWA has several advantages over RFA, which may make it more attractive than RFA to treat hepatic tumors. The benefits of MWA are an improved convection profile, higher constant intratumoral temperatures, faster ablation times, and the ability to use multiple probes to treat multiple lesions simultaneously. MWA should be considered the technique of choice when the tumor is ≥3 cm in diameter or is close to large vessels, independent of its size.

Keywords: Efficacy; Hepatocellular carcinoma; Liver metastasis; Microwave ablation; Radiofrequency ablation.

Figure 1.

Study flow diagram showing the included and excluded studies in the systematic review.

Figure 2.

A 53‐year‐old man with hepatocellular carcinoma on IV hepatic segment near the gallbladder. In the axial plan (A) and (B) the multiplanar reconstruction in the coronal plan, multidetector CT scan before microwave ablation (MWA) treatment during arterial phase of contrast study; the lesion shows hyperenhancement. After MWA treatment (C and D), the lesion appears without enhancement (arrow). No biliary complications are evident.

Figure 3.

A 62‐year‐old man with hepatocellular carcinoma on VIII hepatic segment. Post‐ microwave ablation (MWA) treatment Multidetector CT scan [(A) arterial phase of contrast study] and magnetic resonance imaging study [(B) volume‐interpolated breath‐hold examination T1 weigthed fat sat during arterial phase of contrast study]. The lesion shows no contrast enhancement, with hypodense (A) and hypointense signal compared with surrounding liver parenchymal (arrow).

Figure 4.

A 48‐year‐old woman with colorectal liver metastasis on VI hepatic segment treated with radiofrequency ablation. In (A) (Multiplanar reconstruction in coronal plane) and (B) (Multidetector CT in axial plane during portal phase of contrast study), incomplete ablation with residual disease (arrow) that shows less hypodense feature compared with ablated zone.

Figure 5.

A 51‐year‐old man with colorectal liver metastasis. Magnetic resonance imaging [(A) VIBE T1‐W FS during portal phase of contrast study and (B) Multiplanar reconstruction in coronal plane] and multidetector CT [(C) portal phase of contrast study on axial plane and (D) MPR in coronal plane] studies show lesion without enhancement, with regular enhancement of portal branch near to the treated area. The time between the MDCT examination and MR scan is 7–10 days.

Figure 6.

A 72‐year‐old woman with peribiliary colorectal liver metastasis treated with microwave ablation. Magnetic resonance imaging [(A) half‐Fourier acquired single‐shot turbo spineEcho T2 weighted coronal plane; (B) T1‐W in of phase in axial plane; (C) T1‐W out of phase in axial plane; (D) volume‐interpolated breath‐hold examination T1 weigthed fat sat during arterial phase of contrast study; (E) VIBE T1‐W FS during portal phase of contrast study] study shows the lesion with hypointense signal on T2‐W, hypointense signal on T1‐W (B and C), without contrast enhancement (D and E) and with biliary injury (dilation of a biliary branch; arrows).

Figure 7.

A 72‐year‐old man with microwave ablated colorectal liver metastasis (CRLM) on VIII‐VII hepatic segment. Magnetic resonance imaging [(A) volume‐interpolated breath‐hold examination T1 weigthed fat sat during arterial phase of contrast study in axial plane; (B) volume‐interpolated breath‐hold examination T1 weigthed fat sat during portal phase of contrast study in axial plane; (C) volume‐interpolated breath‐hold examination T1 weigthed fat sat during portal phase of contrast study in coronal plane] study shows no residual disease and no diaphragm injury and pneumothorax. In (D) Multidetector CT scan during portal phase of contrast study follow‐up at 1 years post a new microwave ablation treatment for another CRLM: no residual disease and no diaphragm injury and pneumothorax.

Figure 8.

Multidetector CT scan without contrast medium during emergency setting (A and B) for hemoperitoneum post‐radiofrequency ablation treatment. The bleeding is hyperdense (arrow).