Chemical tumor ablation with use of a novel multiple-tine infusion system in a canine sarcoma model

To determine whether larger confluent zones of ablation can be achieved in chemical ablation with use of a multiple-tine infusion device compared with standard needle infusion in a solid tumor model.

Multiple canine venereal sarcomas (N=42) were implanted in nine mildly immunosuppressed dogs (treated with 10 mg/kg cyclosporin A twice daily). Tumors incubated for 8-12 weeks grew to a diameter of 5.4 cm+/-1.0. With ultrasound guidance, 8-56 mL of 100% ethanol or 15% acetic acid (diluted in saturated saline solution) were injected in aliquots (2-8 mL) at multiple distances (radius of 0-2 cm) from the needle axis with use of a multiple-tine infusion device. Presence of fluid reflux at the needle puncture site and resultant coagulation diameters were measured within 1 hour and compared with the results of infusion with a standard 18-gauge needle.

Multiple-tine infusion enabled greater fluid infusion (15 mL+/-3 to 53 mL+/-3 depending on protocol) than standard needle injection (8 mL+/-1) before reflux was observed at the puncture site (P<.01). Additionally, progressive gains in contiguous tumor coagulation were achieved because acetic acid was infused as far as 2 cm from the needle axis with the multiple-tine device (P<.01; R(2)=0.59; y=0.5x+2.9). Optimal coagulation was achieved with the infusion of 4-mL aliquots at 0.5 cm and 1.0 cm from the needle, followed by three 4-mL or 8-mL aliquots (40 degrees rotation between infusions) at 1.5 cm and 2.0 cm from the needle (32 mL+/-0 and 53 mL+/-3 total, respectively). This yielded confluent short-axis coagulation diameters of 4.9 cm+/-1.0 and 5.4 cm+/-1.0, respectively, which were significantly greater than the measurement of 3.1 cm+/-0.4 achieved with standard needle infusion (P<.01). Smaller and noncontiguous foci of coagulation foci (1.7 cm+- 0.5) were seen with the use of ethanol for standard needle and multiple-tine infusions.

Chemical ablation with 15% acetic acid with use of a multiple-tine infusion device resulted in larger diameters of contiguous tumor coagulation and enabled greater volumes of infusion than standard needle infusion or ethanol ablation. This suggests that chemical ablation with acetic acid infused with use of a multiple-tine device may overcome some of the difficulties seen with the use of conventional needle chemical ablation injection alone, such as irregular ablation and fluid reflux up the needle tract.