Percutaneous Microwave Ablation of Liver Lesions: Differences on the Sphericity Index of the Ablation Zone between Cirrhotic and Healthy Liver Parenchyma.

Athanasios Tsochatzis,Argyro Mazioti,Nikolaos Kelekis,Alexis Kelekis,Georgios Velonakis,Dimitrios Filippiadis,Georgios Iliadis,Evgenia Efthymiou

doi:10.3390/diagnostics11040655

Athanasios Tsochatzis, Argyro Mazioti + Show 6 more

Open Access

https://doi.org/10.3390/diagnostics11040655

Copy DOI

Abstract

To compare different parameters of the sphericity index of the ablation zone following microwave ablation (MWA) on cirrhotic- and healthy-liver parenchyma in a series of patients treated with the same MWA system. Institutional database research identified 46 patients (77 lesions) who underwent MWA. “Cirrhotic liver group” (CLG) included 35 hepatocellular carcinoma lesions; “healthy liver group” (HLG) included 42 metastatic lesions. The long axis (LAD), short axis 1 (SAD-1) and 2 (SAD-2), the mean SAD-1 and SAD-2 (mSAD) diameter (in mm) and the mean sphericity (mSPH) index of the ablation zones were evaluated for each treated lesion in both groups from baseline to follow-up. A mixed model analysis of variance reported significant main effect of group on SAD-1 (p = 0.023), SAD-2 (p = 0.010) and mSAD (p = 0.010), with HLG showing lower values compared to CLG. No differences were detected on the LAD (pFDR = 0.089; d = 0.45), and mSPH (pFDR = 0.148, d = 0.40) between the two groups. However, a significant main effect of time was found on LAD (p < 0.001), SAD-1 (p < 0.001), SAD-2 (p < 0.001) and mSAD (p < 0.001), with decreased values in all indices at follow-up compared to baseline. A significant group by time interaction was observed on mSPH (p = 0.044); HLG had significantly lower mSPH at follow-up where CLG did not show any significant change. Our findings indicate that although in cirrhotic liver short axis diameter of the MWA zone seems to be significantly longer, this has no effect on the sphericity index which showed no significant difference between cirrhotic vs. healthy liver lesions. On the contrary, on one month follow-up ablation zones tend to become significant more ellipsoid in healthy whilst remains stable in cirrhotic liver.

Highlights

Percutaneous imaging-guided microwave ablation (MWA) is an increasingly applied technique for the treatment of malignant liver tumors, achieving high local tumor control rates in both primary and secondary lesions irrespective of the target’s histology [1,2,3]
In addition the “oven effect” theory proposed by Liu et al supports that the increased heating efficacy for tumors surrounded by a cirrhotic liver is attributed to the fibrotic changes that cause the liver to act as a refractive tissue which condensates energy [10]
[cirrhotic liver group (CLG)] and those with hepatic metastases developed on a healthy liver [healthy liver group (HLG)] based on medical record and imaging findings on computed tomography (CT)

Summary

Introduction

Percutaneous imaging-guided MWA is an increasingly applied technique for the treatment of malignant liver tumors, achieving high local tumor control rates in both primary and secondary lesions irrespective of the target’s histology [1,2,3]. Advantages of the MWA systems include the aptitude to reach higher temperatures and greater ablation zones in less time, with less heat sink effect when compared to RF ablation [4,5,6]. When compared to other heat based ablation techniques, microwaves are more effective in tissues with high blood circulation or near vascular structures with resultant ablation zones being relatively unvarying in shape and size and more predictable in extension [7,8]. In addition the “oven effect” theory proposed by Liu et al supports that the increased heating efficacy for tumors surrounded by a cirrhotic liver is attributed to the fibrotic changes that cause the liver to act as a refractive tissue which condensates energy [10]

Objectives

Methods

Results

Conclusion