Targeted radiofrequency ablation (t-RFA) prior to cement augmentation of symptomatic malignant spine lesions: clinical evaluation

Purpose: We are reporting early clinical outcome of t-RFA followed by cement augmentation in painful malignant lesions of the spine using a novel bipolar RF ablation system, purpose built for minimally invasive procedures in the axial skeleton. Materials and Methods: 51 spinal lytic lesions in 34 patients with different malignant etiologies were included after IRB approval. Primary diagnosis includes; myeloma (n1⁄411), breast cancer (n1⁄49), lung cancer (n1⁄46), lymphomas (n1⁄45) and pancreatic (n1⁄41), renal (n1⁄41) and neuroendocrine tumor (n-1). The STAR Tumor Ablation System is a bipolar device that contain two thermocouples (TC) positioned at 10 and 20 mm from center of the ablation zone to permit real-time monitoring of the ablation zone. RF warmed cement augmentation via the same guiding cannula was performed after lesion ablation. Results: All procedures were performed safely with no complications or thermal injury. Ablation time ranged from 1.5-6 minutes. Maximum recorded temperature was 651C at the distal TC and 501C at the proximal TC (10 and 20 mm from the center of the ablation zone, respectively). TCs on the electrode were used to confirm re-establishment of core temperature prior to cement augmentation. Post procedure CT showed no significant cement leakage. Average VAS scores dropped from 7.8 pre-procedure to 3.6, 2-4 weeks post-procedure. Average ODQ scores improved from 26.5 to 15.7, 2-4 weeks postprocedure. Decreased tumor volume and decreased metabolic activity was confirmed by MRI and PET scan, respectively. Conclusion: Targeted RF Ablation followed by RF warmed high viscosity cement augmentation was performed successfully in this series of malignant spinal lesions. Improvement in pain and functional status was noted in all patients. The articulating ability of the STAR Tumor Ablation System permitted minimally invasive access to all lesions, regardless of location. Proximal and distal TCs allowed accurate monitoring of the temperature inside the vertebral body to avoid complications of nearby vital structures. Targeted delivery of high viscosity cement following ablation via the same guiding cannula provided vertebral stability.