Osteoid osteoma is a painful, benign, osteoblastic lesion that occurs in younger patients and affects the extremities or the axial skeleton. While plain film findings may suggest the diagnosis, in complex anatomical regions such as the spine, pelvis, wrist and foot advanced imaging modalities are often required. A typical nidus surrounded by
sclerosis or cortical thickening characterizes
osteoid osteoma on plain radiography and CT. MR is the cross-sectional imaging modality of choice for most musculoskeletal disorders. Unfortunately, extensive accompanying bone marrow oedema, soft-tissue alterations, difficulty detecting the nidus, and lesion locations close to a joint (with
reactive arthritis) may make a confident diagnosis of
osteoid osteoma by MR imaging difficult. Hybrid imaging with bone-seeking tracers such as SPECT/CT with 99mTc-labelled
bisphosphonates or PET/CT with 18F-labelled
sodium fluoride (18F-NaF) combines high
radionuclide uptake with morphological details and provides accurate diagnosis of
osteoid osteoma and additional information for treatment planning. FDG is not the recommended PET tracer because
osteoid osteoma is normally FDG-negative, although some
osteoid osteomas may show increased FDG uptake.
Osteoblastoma, Brodie's
abscess and
stress fractures may mimic
osteoid osteoma on imaging and clinical presentation. Once identified as the
pain generator, destruction of the
osteoid osteoma nidus by ablation or resection techniques usually leads to complete healing. Image-guided drill excision and
radiofrequency ablation are widely used interventions. We review the presentation of
osteoid osteoma across all imaging modalities, with special focus on hybrid imaging techniques.