# Electromagnetic Navigation System with a Marker Option for Computed Tomography-Guided Microwave Ablation of Undetectable or Inconspicuous Hepatic Tumors in Non-Enhanced Scans: A Feasibility Study

## TL;DR

A new electromagnetic navigation system helps guide microwave ablation for hard-to-see liver tumors in CT scans, showing promising results in a small study.

## Contribution

Introduces an electromagnetic navigation system with a marker option to improve microwave ablation for inconspicuous liver tumors.

## Key findings

- 100% local tumor progression-free survival was achieved in 16 treated lesions over 23 months.
- The system enabled accurate needle placement with a median deviation of 1 mm and no complications.
- Primary efficacy rate was 94%, rising to 100% with re-ablation in one case.

## Abstract

The aim of the present study is to report the feasibility and efficacy of percutaneous ablation of hepatic malignant tumors that are undetectable or inconspicuous in non-enhanced CT scans using an electromagnetic navigation system with a marker software. Overall, 15 patients with 16 tumors were treated in 16 sessions. Over a median follow-up duration of 23 months, no records of local tumor progression were identified among the treated lesions (100% local tumor progression free survival). The results of the current study support utilization of an electromagnetic navigation system with a marker software for tumors that are undetectable or inconspicuous in non-enhanced CT scans.

Objectives: Primary objective was to report the feasibility, safety and efficacy of percutaneous ablation of hepatic malignant tumors that are undetectable or inconspicuous in non-enhanced computed tomography (CT) scans using an electromagnetic navigation system with a marker option. Secondary objectives included the evaluation of technical parameters including the accuracy of needle placement, the number of control CT acquisitions, and procedural duration. Methods: This prospective study (performed from 1 March 2022 until 30 November 2024) included all patients with hepatic tumors (not visible or poorly defined on non-enhanced CT) who underwent percutaneous microwave ablation (MWA). Technical efficacy was assessed with contrast-enhanced CT immediately post-ablation, and oncologic outcomes (overall and progression-free survival) were evaluated with MRI at 1, 3, and 6 months. Results: Fifteen patients (12 males, 3 females; mean age of 66 years) with 16 tumors (median diameter of 15 mm) were treated in 16 sessions. Tumor types included hepatocellular carcinoma (n = 7), colorectal metastasis (n = 4), ocular melanoma (n = 1), neuroendocrine tumor (n = 1), intrahepatic cholangiocarcinoma (n = 1), and breast cancer metastasis (n = 1). Median procedure time was 53 min, scans number was nine, needle length was 12 cm, and median deviation was 1 mm. No complications were reported. Primary efficacy rate was 94% (15/16), rising to a secondary (assisted) technique efficacy of 100% after re-ablation (one session). During median follow-up of 23 months, local tumor progression-free survival was 100%; distant progression-free survival was 80%, and two patients (13.3%) died, one being cancer-related. Conclusions: Electromagnetic navigation with a marker option enables safe, accurate, and effective MWA of inconspicuous hepatic tumors, achieving excellent local control with favorable oncologic outcomes.