Use of real-time magnetic resonance guidance to assist bone biopsy in pediatric malignancy.

Magnetic resonance (MR) imaging (MRI) has the advantage of demonstrating lesions not visualized by other radiologic modalities. We present a case involving pediatric malignancy where MR-guided bone biopsy confirmed correct histologic diagnosis and was used to plan additional treatment. A 2-year, 9-month-old boy had a history of spontaneous regression of stage 4S neuroblastoma. (123)I-metaiodobenzylguanidine scintigraphy showed a hot spot at his right lower leg; however, neither plain radiograph (99m)Tc diphosphonate bone scan was positive. Only MRI depicted a lesion at the distal third of his right tibia, and a subsequent MR-guided bone biopsy was diagnostic of bone marrow metastasis. After 6 courses of intensive chemotherapy, he has been in complete remission. MR-guided biopsy technique is likely to be particularly useful for the resection of invisible metastatic lesions, especially those that are only visible using MRI.