Bone marrow metastasis of neuroblastoma analyzed by MRI and its influence on prognosis.

Bone marrow metastases (BM mets) of neuroblastoma were analyzed by magnetic resonance imaging (MRI). BM mets were demonstrated in 45 femurs of 23 patients with neuroblastoma by MRI. They were classified into two patterns, nodular (N) type and diffuse (D) type, on MRI, with an incidence of 16% (7/45) and 84% (38/45), respectively. No bone metastases (B mets) were accompanied by N type BM mets, whereas all of them were accompanied by D type BM mets. The rate of disappearance of N type BM mets after chemotherapy was 100% (7/7) and was significantly higher than that (26%, 10/38) of D type BM mets. The rate of disappearance (58%, 11/19) of BM mets in bones without associated B mets was also significantly higher than that (23%, 6/26) of BM mets in bones with associated B mets. BM mets present in bones with B mets tended to persist after chemotherapy. The survival rate of patients with residual BM mets after chemotherapy was significantly lower than that of patients without residual BM mets. This suggests that powerful systematic chemotherapy and additional targeted therapy to lesions remaining after chemotherapy are needed to improve the cure rate of patients with advanced neuroblastoma.