Abstract

Simple SummaryLiver tumors like hepatocellular carcinoma (HCC) can be treated minimally invasive, e.g., by Irreversible Electroporation (IRE), which destroys the cancer. As it is possible that the tumor re-grows due to single tumor cells inadvertently not covered by the treatment, follow-up imaging of the liver is important for early detection of local tumor progression. As ablation leaves scarred tissue, recurrent tumor after IRE can appear vastly different than before treatment and thus can be hard to detect on MRI via classical imaging features. We here examined cases of local tumor progression after IRE of HCC and found distinct MR-imaging features helpful for the identification of re-grown viable tumor, namely T2 BLADE and diffusion weighted images (DWI) at the ablation zone border and T1 portal-venous and delayed phase post-contrast images in the center of the ablation zone. This knowledge will help in early detection and re-treatment of HCC for a prolonged survival.This single-center retrospective study was conducted to improve the early detection of local tumor progression (LTP) after irreversible electroporation (IRE) of a hepatocellular carcinoma (HCC) using gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-based 3T MR imaging and to identify helpful signal characteristics by comparing 23 patients with and 60 patients without LTP. To identify the differences in the sensitivity of MRI sequences, the specificity, positive prediction value, negative prediction value (NPV) and diagnostic odds ratio were calculated. A chi-squared test, two-tailed student’s t-test and binary logistic regression model were used to detect distinct patient characteristics and variables for the prediction of LTP. LTP was mostly detected in the peripheral ablation zone (82.6%) within the first six months (87.0%). The central LTP ablation area presented more hypointensities in T1 p.v. (sensitivity: 95.0%; NPV: 90.0%) and in T1 d.p. (sensitivity: 100.0%; NPV: 100.0) while its peripheral part showed more hyperintensities in T2 BLADE (sensitivity: 95.5%; NPV: 80.0%) and in diffusion sequences (sensitivity: 90.0%). Liver cirrhosis seems to be an unfavorable prognosticator for LTP (p = 0.039). In conclusion, LTP mostly occurs in the peripheral ablation zone within six months after IRE. Despite often exhibiting atypical Gd-EOB-DTPA MR signal characteristics, T2 BLADE and diffusion sequences were helpful for their detection in the peripheral zone while T1 p.v. and T1 d.p. had the highest sensitivity in the central zone.

Highlights

  • Surgical resection plays a significant role in the therapy of a hepatocellular carcinoma, many patients do not qualify for surgery because of the cancer spread, localization near or infiltration of critical structures or certain comorbidities [1]

  • While thermal ablation techniques mostly entail the risk of damaging adjacent structures [3,4], several studies have proven that irreversible electroporation (IRE) protects the architecture of hepatic structures such as large vessels and bile ducts in close proximity to the IRE ablation area [1,5,6,7,8]

  • The aim of this study was to find imaging characteristics that help to improve the detection of a local tumor relapse after IRE of an hepatocellular carcinoma (HCC), which is the hallmark for initiation of early and successful treatment; a small tumor size and early treatment are two of the most important factors influencing survival in almost all types of cancer including

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Summary

Introduction

Surgical resection plays a significant role in the therapy of a hepatocellular carcinoma, many patients do not qualify for surgery because of the cancer spread, localization near or infiltration of critical structures or certain comorbidities [1]. In this patient group, percutaneous ablation methods have increasingly been implemented in the clinical routine in recent years. By causing cell death through the repeated application of high-voltage electrical impulses, which generate irreversible damage to the membranes of tumor cells [2], IRE offers significant benefits over thermal-based ablative methods especially concerning safety. IRE is of interest for clinical use because of its safety characteristics and its high efficacy [9,10]

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