Magnetic resonance imaging of inflammatory reaction in osteoid osteoma.

Between 1988 and 1993, 16 cases of osteoid osteoma were examined by magnetic resonance imaging (MRI). MRI clearly visualized the extent of inflammation in the bone marrow and soft parts that is difficult to observe with other diagnostic techniques. The degree of inflammation varied among the patients. This might be associated with the anatomical relationship between the nidus and the cortex. The high sensitivity of MRI, unfortunately, may lead to an erroneous interpretation in lesions accompanied by inflammatory responses of the bone marrow or soft parts, such as osteoid osteoma. However, these reactions on MRI may offer a key to the pathogenesis of osteoid osteoma, a unique bone neoplasm.