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

Maybody, Majid; Soliman, Mohamed M; Hwang, Sinchun; Gonzalez-Aguirre, Adrian; Martin, Ernesto G Santos; Kaye, Elena; Hsu, Meier; Moskowitz, Chaya; Healey, John H; Fabbri, Nicola

Object To assess the impact of MRI findings on management of symptomatic patients following RFA of OO. Materials & Methods 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. Results 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). Conclusions MRI is recommended for symptomatic patients after ablation.