Impact of Magnetic Resonance Imaging (MRI) Findings on Management of Symptomatic Patients Following Radiofrequency Ablation (RFA) of Osteoid Osteoma (OO)

The purpose of this study is to assess the impact of MRI findings on management of symptomatic patients following RFA of OO. Retrospective review of 43 patients with RFA for OO between June 2010 and June 2017 was performed. Patient, nidus, and ablation data were reviewed. Pre- and 6–8 weeks post-procedural MRI (n = 32) were compared for coverage of nidus by ablation zone, bone marrow edema, nidus hyperintensity, and other findings. Baseline pain levels and analgesic use were compared with post-procedural follow-up visit at 6–8 weeks. Three groups of clinical and MRI outcomes of complete (CR), partial (PR), and no response (NR) were defined. A weighted kappa statistic was used to assess for agreement. Clinical responses were CR in 34/43 (79.1%, 95% CI: 64.0–90.0%), PR in 8/43 (18.6%), and NR in 1/43 (2.3%) patients. All 19/32 patients with MRI CR experienced clinical CR. One patient with MRI NR had clinical NR. All 7/32 patients with clinical PR had MRI PR. All 4/43 complications were in MRI PR or NR groups. Substantial agreement was observed between MRI and clinical outcomes (kappa: 0.69, 95% CI: 0.45–0.95). MRI helped determine etiologies in all symptomatic patients and their management (n = 8). MRI is recommended for symptomatic patients after ablation.