MRI of aseptic osteonecrosis in children with acute lymphoblastic leukemia

Purpose: To evaluate the incidence, localisation, and course of symptomatic aseptic osteonecrosis (AON) in children undergoing treatment for acute lym phoblastic leukemia (ALL). Methods: 72 MRI examinations obtained from 26 ch ildren with bone pain selected from a group of 121 children with ALL were e valuated retrospectively. The area of the AON was determined by computer as sisted planimetry. Follow-up examinations after 2 - 5 years were considered . Results: 10/121 (8.3 %) of the children had symptomatic AON, the number o f lesions varied between 1 and 24 per child. 62/66 lesions were localized w ithin the lower extremities. 58% of the AON were positioned in the epiphysi s and 42% in the meta- and diaphysis. The mean area of AON was 7.6 cm(2) wi th a range of 0.5 to 50 cm(2). Follow-up examinations revealed a regression in 19 AON, no change in 43 and a progression in 4 lesions. AON within the epiphysis with joint involvement or lesions greater than 9 cm(2) more frequ ently showed a progression of AON with final joint destruction. An elevated risk for AON was seen in children older than 10 ears and in children with intensified chemotherapy due to high-risk ALL. Conclusion: AON is a common complication in ALL-children under chemotherapy. Most frequently, the cours e is benign but large AON with joint involvement have an elevated risk for progression of AON with final joint destruction.