Treatment-related alterations of imaging findings in osteoid osteoma after percutaneous radiofrequency ablation

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

“…Addition of intravenous contrast does not increase its prognostic value. Studies have shown that CT imaging of OO after ablation cannot identify the activity of nidus and the morphology and calcification of nidus as well as cortical thickening do not correlate with the clinical outcome [4][5][6].…”

“…Magnetic Resonance Imaging MRI is the most sensitive imaging tool in evaluating the nidus, bone marrow, and soft tissues. However, most studies have design flaws including poor definition of clinical outcomes, lack of consideration of other causes of symptoms like non-target tissue inflammation or complications, binary definition of MR findings without recognition of intermediate steps, poor timing of initial or further follow-up studies, complexity of the method of evaluation of imaging findings, and uniformity of clinical outcomes [4][5][6][7][8].…”

“…Multiple image-guided ablative modalities have been utilized for the treatment of OO, including RFA, laser, cryoablation, microwave, and high intensity focused ultrasound (HIFU). Excellent technical success, pain resolution, and low recurrence rates have been reported following ablation for OO [3][4][5][6][7][8].…”

Osteoid osteoma of the hip: imaging features

“…Using sequences repeated every 30 s after the administration of gadolinium, Liu et al showed that OOs exhibit a peak in signal enhancement during the arterial phase in 82% of the cases [44]. Several subsequent studies confirmed that this enhancement pattern was present in 82 to 100% of OOs using temporal resolutions that varied between 12 and 30 s [28,[45][46][47][48]. Some authors used a higher temporal resolution (sequences repeated every 3 s) and demonstrated that an enhancement delay of less than 6 s between the lesion and an adjacent artery was also a typical characteristic of OO ( Fig.…”

“…Response evaluation to percutaneous ablation is not straightforward. On CT, a persistent nidus on CT does not necessarily indicate treatment failure since successfully treated OOs remain unchanged or variably ossified [48,64]. On conventional MRI, bone marrow edema and signal enhancement after injection of gadolinium may persist after successful thermal ablation [64].…”