Bone marrow magnetic resonance studies in childhood leukemia. Evaluation of osteonecrosis.

In 25 patients under treatment or during follow-up for acute lymphoblastic leukemia magnetic resonance imaging (MRI) of both knees was compared to history and physical examination to detect osteonecrosis. Results of MRI were classified as: O, normal bone marrow (BM); 1, diffuse decrease in signal intensity; 2, circumscript lesions. Patients clinically suspected of osteonecrosis had a statistically significant increased incidence of Type 2 lesions. Three patients with a BM relapse also showed Type 2 lesions. Circumscript lesions of the epiphyses were seen exclusively in the four patients with clinical suspicion of osteonecrosis during BM remission and this may be a MR finding strongly indicative of osteonecrosis. Patients with Type 2 lesions during BM remission had received systemic chemotherapy for a statistically significant longer period than the other patients. Using MRI findings we suspect that at least four patients suffered osteonecrosis due to chemotherapy. MRI is a promising means of detecting this disorder.