Endovascular Fiducial Placement in Splenic Metastatic Disease as a Novel Option for Radiotherapy: A Case Report

Splenic metastases are rare but difficult-to-treat entities, especially if they recur after initial surgery or ablation. They are particularly difficult to treat with radiation therapy due to their subdiaphragmatic location and the presence of respiratory excursions. This report describes a case in which an endovascular fiducial placement approach was used to mark the splenic metastasis prior to radiation therapy. We present a 77-year-old male with an extensive history of colorectal metastatic disease. After hemicolectomy, the patient showed metastases - first in the spleen and then in the liver. These were treated with locoregional therapy, including radiofrequency ablation (RFA) for the spleen metastasis and RFA and microwave ablation (MWA) for the liver metastases. Contrast-enhanced computed tomography (CT) imaging, eight years after initial therapy, showed two new liver metastases and a recurrent metastasis in the spleen. Percutaneous ablation of the splenic metastasis was deemed too dangerous because of the subdiaphragmatic location of the spleen and the presence of respiratory motion, and the multidisciplinary tumor board, therefore, opted for radiotherapy. To guide radiotherapy, the interventional radiologist chose to place three microcoil fiducial markers (FMs) around the splenic lesion via an endovascular transradial approach. Radiotherapy was successful, and no recurrence of splenic metastasis has been observed during follow-up. In summary, transradial endovascular FM placement in splenic metastatic disease is technically possible from both an interventional radiological and a radiotherapy standpoint.