Which MRI sequence of the spine best reveals bone-marrow metastases of neuroblastoma?

Background: MRI is an effective tool in evaluating bone marrow metastases. However, no study has defined which MRI sequences or image characteristics best correlate with bone-marrow metastases in neuroblastoma. Objective: To identify and refine MRI criteria and sequence selection for the diagnosis of bone-marrow metastases in children with neuroblastoma. Materials and methods: Ninety-one children (mean age: 3.2 years; standard deviation: 2.8 years) enrolled in the RDOG IV study participated in our study. Forty-five children had bone metastases determined by bone-marrow aspiration or biopsy (n =4), radionuclide imaging (n =2), or both (n =39). Spine lesions were characterized using coronal T1-weighted (T1W) sagittal short tau inversion recovery (STIR) and coronal gadolinium-enhanced T1-weighted (GAD) MR sequences. Contingency table analysis was performed to determine which MRI sequences and characteristics were associated with metastases. The MRI criteria for metastatic disease were then developed for each imaging sequence. The sensitivity, specificity, predictive values, and accuracy of these criteria were determined for the whole group, children younger than 12 months old, and children 12 months and older. Results: The MR characteristics that had significant (P < 0.05) associations with metastases were homogeneous low T1-signal intensity, homogeneous high STIR-signal intensity, and heterogeneous pattern on T1, STIR, or GAD. Homogeneous low T1-signal had the highest sensitivity (88%), but a specificity of 62% for detecting metastases. A heterogeneous pattern on GAD was highly specific (97%), but relatively insensitive (65%) for detecting metastases. These MR characteristics were most accurate in children 12 months and older. Conclusion: The combination of non-contrast-enhanced T1W and GAD sequences can be used to determine the presence of spinal metastases in children with neuroblastoma, particularly those children who are 1 year and older.