Utility of real-time image fusion technology in ultrasonography-guided fiducial marker implantation for stereotactic body radiation therapy for liver tumors

Fiducial marker migration following computed tomography-guided placement in the liver: a case report

Radiation therapy for liver tumors has been shown to provide a local control and overall survival benefit in patients with primary or oligometastatic liver tumors. However, accurate delineation of the target volume in intraabdominal tumors can be limited by diaphragmatic motion. In addition to image guidance during radiation therapy, computed tomography (CT)-guided fiducial marker placement can improve the accuracy of radiation treatment and optimize tumor control. Fiducial marker placement is often indicated in stereotactic body radiation therapy (SBRT) due to the ablative doses used as well as in proton therapy given that these markers are clearly visible on orthogonal kV image guidance and studies have suggested that their placement in liver tumors offers improved local control. However, fiducial marker migration is a rare risk associated with fiducial placement for which literature remains scarce. We report two separate cases of fiducial marker migrations from the liver into the inferior vena cava and right atrium which occurred following CT-guided placement without any resultant toxicity. Imaging using contrast-enhanced or volume navigation ultrasound techniques during fiducial marker deployment may mitigate the risk of fiducial marker migration and potential end-organ injury. Alternative techniques for motion management such as inspiratory or expiratory breath hold or use of residual lipiodol on imaging in patients who have undergone transarterial chemoembolization (TACE) should be considered as well to avoid potential complications from fiducial marker placement.