557 - Selective Intra Arterial Lipiodol Staining Enhances CT Guided Thermal Ablation of Poorly Visualized Malignant Liver Tumors: A Prospective Single Arm Study

Purpose: A prospective single‑arm study evaluated whether selective intra‑arterial delivery of lipiodol can improve visualization and technical success during CT‑guided thermal ablation of malignant liver tumors.

Materials and Methods: Electronic medical records from 2024–2025 were retrospectively reviewed for patients with hepatocellular carcinoma or metastatic liver tumors who underwent image‑guided thermal ablation (TA). Patients were included if they had previously unsuccessful TA, tumors that were difficult to visualize on unenhanced computed tomography (CT) or ultrasound, or lesions that were technically challenging to access percutaneously because of size or location. Pre-ablation selective hepatic arteriogram was performed during the same treatment session and intra‑arterial lipiodol was delivered into the selected hepatic artery to stain target lesions before ablation. Subsequentially, tumor ablation was performed under CT guidance.

Results: We identified 34 patients (mean age 64.5 ± 12.9 years; 26 men) with 43 malignant liver tumors (mean tumor size 2 ± 1 cm; range 0.5 to 5.5 cm)) treated by TA (42 with microwave ablation and one with cryoablation). Mean follow‑up was 21.7 ± 16.6 weeks. Three patients (4 tumors) lacked adequate post‑procedure follow‑up, leaving 31 patients and 39 tumors for final analysis. Primary technique efficacy, defined as complete ablation after the initial session, was achieved in 90 % of tumors (35/39). One patient required a second ablation session, resulting in a secondary technique efficacy of 92 % (36/39). Lipiodol staining enabled microwave ablation in two patients whose tumors had not been visible during prior attempts. One patient developed a small self‑limited pneumothorax that did not require chest tube placement. No major adverse events were observed (Table 1).

Conclusion: Pre‑ablation selective intra‑arterial lipiodol staining is a safe and effective method to enhance lesion visualization and improve technical success when performing thermal ablation of malignant liver tumors that are poorly visualized on unenhanced CT.