Uncooled microwave ablation of osteoid osteoma: New approaches to an old problem.

Objective: This study aims to evaluate the technical and clinical success of uncooled microwave ablation (MWA) in the treatment of osteoid osteoma with two-dimensional fluoroscopy guidance in the operating room.

Methods: The clinical and imaging data of 9 patients were retrospectively evaluated. Mean patient age was 14.55 years. The mean size and volume of the lesions were 17.2 × 10.8 × 8.0 mm and the mean nidus size was 6.86±2.05 mm on computed tomography. MWA was performed with uncooled probe in operating room and in sterile conditions. Numerical pain score was recorded before the procedure, the day after, and at 1, 3 months after the procedure.

Results: Clinical and technical success was achieved in 100% of patients. The mean volume of MWA-induced necrosis was 20.8 × 12.8 × 10.7 mm, peripheral scar thickness was 3.5±0.75 mm, and none of the patients had nidus enhancement on first month follow-up magnetic resonance imaging. Fluoroscopic guidance was conducted under digital c-arm. Patients received four to 12 spot films (mean: 6.6 kVp, 2.66 mAs) over the lower extremity. Mean radiation exposure to the skin due to imaging was 0.02 mGy per patient per procedure. The dose area product-the total amount of radiation deliverable to the patient was 0.75±0.32 Gy.cm.

Conclusion: This study demonstrated the effectiveness and the safety of the uncooled MWA in osteoid osteoma. The technique may effectively be used in operating room under c-arm fluoroscopy. Such hybrid approach may ensure sterility, anesthetic safety, and lower radiation dose to patients.