[Magnetic resonance imaging for bone marrow metastases of neuroblastoma]

From March 1985 to February 1987, 41 patients (pts) presenting with a neuroblastoma underwent 52 MRI to detect bone marrow metastases. Mean age was 4 years (R: 6 m, 13 y). Acquisitions were done with a 1.5 t unit. Images were obtained in coronal (legs and pelvis) and sagittal (dorso-lumbar spine) sections. Nine out of 52 examinations were excluded because of artifacts or technical failure. In 13 cases, MRI was performed for initial staging, in 30 during follow-up. Out of 24 anatomically proven medullary involvement (18 pts), MRI showed focal abnormal signals in 23 (17 pts): foci of hypersignal in T2 weighted images, compared to the normal value of bone marrow and fat tissue, were more often detected in lower limbs than dorso-lumbar vertebral body or iliac bone. In our series, the sensitivity of MRI to detect BM metastases is 84% and the specificity is 88%. In comparison to the medullograms and bone marrow biopsy, MRI explores distinct sites, especially lower limbs which are often involved.