FACTORS THAT AFFECT RADIOFREQUENCY HEAT LESION SIZE
Authors: Cosman E. Jr, Dolensky JR, and Hoffman RA.
Study type: Feasibility – Prospective, single center
Publication: Pain Medicine 2014; 15(12): 2020-36 (Link to PubMed)
Key Words: Sacroiliac Joint - Bipolar RF vs Cooled RF - Lesion Geometry
Figures are reproduced with permission from Copyright Clearance Center
- To compare RF heat lesion size across a broad range of active tip diameters, active tip lengths, set temperatures, set times, and modalities available for interventional pain management.
- To evaluate typical cannula and generator configurations, configurations that maximize lesion size, the RRE “Ray” electrode, cooled RF, and bipolar RF under controlled conditions.
Monopolar RF lesions were generated in bovine liver, using sharp cannulae with varying tip diameters (22-, 23-, 20-, 16-, and, 18-Gauge), tip lengths (5, 6, 10 and, 15 mm), set temperatures (60°, 70°, 80° and, 90°C) and set times (1, 1.5, 2, 3, 5, and, 10 minutes). For lesion size comparison, the following cannulas were used:
- All the factors (cannula diameters, active tip lengths, set temperatures, and set times) analyzed in the study, were found to significantly affect RF heat lesion size.
- Increasing temperature and/or time enables a thinner cannula to generate lesion dimensions similar to those produced by a thicker cannula at lower temperatures or shorter times.
- With proper selection of generator settings; monopolar RF using a standard 18-gauge or 16-gauge cannulae produces heat lesions similar to those generated by cooled RF for the treatment of SIJ pain
- Bipolar RF between parallel cannulae produces a rounded brick-shaped lesion of comparable shape to three sequential monopolar lesions generated using the same cannulae and generator settings.
Tip gauge, tip length, temperature, and time substantially affect RF lesion size.