Inter-reader agreement and diagnostic accuracy of early postoperative magnetic resonance imaging for detecting macroscopic residual disease in neuroblastic tumors.

BACKGROUND

Accurate detection of macroscopic residual disease after neuroblastoma resection is essential for postoperative treatment decisions, including radiotherapy. Standard imaging follow-up is often performed at a time point when postoperative and therapy-related changes may hamper reliable differentiation between residual disease and reactive findings.

OBJECTIVE

To assess inter-reader agreement and the diagnostic accuracy of early postoperative magnetic resonance imaging (MRI) for detecting residual disease after neuroblastoma surgery.

METHODS

This retrospective single-center study included patients with histologically confirmed neuroblastic tumors who underwent surgical resection at a reference center and received standardized early postoperative MRI with adequate preoperative imaging. Two independent pediatric radiologists, blinded to all clinical data, assessed all examinations. A hierarchical multimodal reference standard was established based on surgical reports including expert consensus between a senior pediatric radiologist and a pediatric surgeon, and follow-up imaging (median follow-up 33 months).

RESULTS

Thirty-nine patients (median age 46 months), predominantly with International Neuroblastoma Staging System (INSS) stage 4 neuroblastoma, were included; all patients had at least one image-defined risk factor. MRI was performed at a mean of 8±5 days after surgery. Residual disease was identified in 14 patients and confirmed by the reference standard. Five residual diseases were expected by the surgeons (median volume 8 ml), whereas nine were unexpected and small (median volume 1 ml). Diagnostic accuracy were 95% and 90% for the two readers, respectively, with substantial inter-reader agreement (Cohen's κ=0.76). Early postoperative MRI findings led to clinically relevant management adaptations in selected cases.

CONCLUSION

Early postoperative MRI demonstrates high diagnostic accuracy and substantial inter-reader agreement in detecting macroscopic residual disease, providing a robust baseline for further assessment.