Assessment of real-time US-CT/MR-guided percutaneous gold fiducial marker implementation in malignant hepatic tumors for stereotactic body radiation therapy.

Backgrounds/aims: This study explored the initial institutional experience of using gold fiducial markers for stereotactic body radiotherapy (SBRT) in treating malignant hepatic tumors using real-time ultrasound-computed tomography (CT)/magnetic resonance (MR) imaging fusion-guided percutaneous placement.

Methods: From May 2021 to August 2023, 19 patients with 25 liver tumors that were invisible on pre-contrast CT received fiducial markers following these guidelines. Postprocedural scans were used to confirm their placement. We assessed technical and clinical success rates and monitored complications. The implantation of fiducial markers facilitating adequate treatment prior to SBRT, which was achieved in 96% of the cases (24 of 25 tumors), was considered technical success. Clinical success was the successful completion of SBRT without evidence of marker displacement and was achieved in 88% of cases (22 of 25 tumors). Complications included one major subcapsular hematoma and marker migration into the right atrium in two cases, which prevented SBRT.

Results: Among the treated tumors, 20 of 24 (83.3%) showed a complete response, three of 24 (12.5%) remained stable, and one of 24 (4.2%) progressed during an average 11.7-month follow-up (range, 2-32 months).

Conclusions: This study confirms that percutaneous gold fiducial marker placement using real-time CT/MR guidance is effective and safe for SBRT in hepatic tumors, but warns of marker migration risks, especially near the hepatic veins and in subcapsular locations. Using fewer markers than traditionally recommended-typically two per patient, the outcomes were still satisfactory, particularly given the increased risk of migration when markers were placed near major hepatic veins.