Abstract
Introduction
Osteoid osteomas (OOs) are benign bone lesions that predominantly affect young individuals
and are characterized by persistent, nocturnally exacerbated pain, which typically
responds to nonsteroidal anti-inflammatory drugs (NSAIDs). While traditional surgical
excision was once the standard treatment, percutaneous CT-guided radiofrequency ablation
(RFA) has emerged over the past decades as the preferred minimally invasive approach.
Objectives
This article explores the technical aspects of RFA in OO treatment, with a particular
focus on the challenges posed by elevated impedance during the procedure and strategies
for optimization.
Materials and Methods
The RFA procedure involves precise CT-guided placement of an RF electrode within the
nidus, followed by thermal ablation at 90°C for 5 to 6 minutes. Procedural technical
success is determined by achieving effective coagulation necrosis, indicated by stable
impedance values (350–400 ohms) and the occurrence of a “roll-off” effect, as set
by the manufacturer. However, abnormally high impedance can hinder energy delivery,
compromising treatment efficacy.
Results
Elevated impedance commonly arises due to electrode misplacement, contact with cortical
bone or the sclerotic rim of the OO, or tissue charring around the electrode tip.
Strategies to mitigate these issues include meticulous electrode positioning, incremental
energy delivery, continuous temperature monitoring, and techniques such as repositioning
the electrode, cleaning or replacing the radiofrequency system, “overdrilling,” or
saline injection to enhance conductivity.
Conclusion
Managing impedance variations is crucial for optimizing technical RFA outcomes in
OO treatment. By understanding and addressing impedance-related challenges, interventional
radiologists can improve procedural success, minimize complications, and enhance patient
outcomes in this minimally invasive approach.
Keywords
osteoid osteoma - radiofrequency ablation - impedance
