Safety and efficacy of MRI-fluoroscopic guided microwave ablation of small subdiaphragmatic and pericardial liver tumors

<h2>Abstract</h2><h3>Purpose</h3> Evaluating safety and efficacy of magnetic resonance-guided microwave ablation (MRgMWA) for small subdiaphragmatic and pericardial hepatic malignancies (HM). <h3>Methods</h3> This single-center study retrospectively reviewed MRgMWA for lesions ≤ 2cm within 1cm of the diaphragm from 02/2017 to 05/2025. Complications were classified according to "Cardiovascular and Interventional Radiological Society of Europe" guidelines. Technical efficacy, local tumor progression (LTP), local tumor recurrence (LTR), non-target progression (NTP), and time to progression were assessed. Data is presented as mean ± standard deviation. <h3>Results</h3> Twenty-three patients (64.8 ± 10.2 years; 15 males, 8 females) with 25 HM (17 hepatocellular carcinoma, 1 cholangiocarcinoma, 7 metastases) were treated. Lesion size was 13.1 ± 4.4mm, with proximity to diaphragm of 3.1 ± 3.2mm. Total procedure duration was 2h 14min ± 51min. The complication rate was 33.3%, including pain (N = 3), fever (N = 2), hematoma (N = 1), bilioma (N = 1), and reactive cholecystitis (N = 1). All complications resolved - two with pain medication and one with antibiotics. Technical efficacy was 100%. No tumor recurrence was observed at ablation sites (LTP and LTR=0%) at 32.5 ± 29.0 months, but one seeding metastasis occurred. NTP occurred in 14 patients (60.9%) at 13.6 ± 10.8 months. Three patients died 7, 32 and 48 months post-ablation. One patient underwent liver transplantation post-ablation. <h3>Conclusions</h3> MRgMWA for small subdiaphragmatic and pericardial HM may be safe and effective, demonstrating no LTR at 32.5 ± 29.0 months follow-up. <h3>Synopsis</h3> This study highlights the potential of MR-guided microwave ablation as minimally-invasive treatment option for small subdiaphragmatic (N = 20) or pericardial (N = 5) liver tumors. Complications seem relatively low compared to existing studies with excellent local tumor control.