[Imaging of osteoid osteoma by MR tomography]

We report the demonstration of eight osteoid osteomas by means of magnetic resonance imaging (MRI). The nidus could be depicted showing intermediate signal intensity in T1-weighted and intermediate or increased signal intensity in T2-weighted sequences. It was embedded in thickened bone cortex, which demonstrated a signal-free zone. A different pattern was found in a subchondral osteoid osteoma of the talar dome, in which neither nidus nor sclerotic margin could be delineated. MRI is a valuable diagnostic tool in osteoid osteomas and may provide important information in addition to conventional imaging methods.