Background Neuroblastoma (NB) is the most common tumour in children younger than 5 years old and notable for highly heterogeneous. Our aim was to quantify the intra-tumoural metabolic heterogeneity of primary tumour lesions by using 18F-FDG PET/CT and evaluate the prognostic value of intra-tumoural metabolic heterogeneity in NB patients. Methods We retrospectively enrolled 38 pretreatment NB patients in our study. 18F-FDG PET/CT images were reviewed and analyzed using 3D slicer software. The semi-quantitative metabolic parameters of primary tumour were measured, including the maximum standard uptake value (SUVmax), metabolic tumour volume (MTV), and total lesion glycolysis (TLG). The areas under the curve of cumulative SUV-volume histogram index (AUC-CSH index) was used to quantify intra-tumoural metabolic heterogeneity. The median follow-up was 21.3 months (range 3.6 - 33.4 months). The outcome endpoint was event-free survival (EFS), including progression-free survival and overall survival. Survival analysis was performed using Cox regression models and Kaplan Meier survival plots. Results In all 38 newly diagnosed NB patients, 2 patients died, and 17 patients experienced a relapse. The AUC-CSHtotal (r=0.630, P<0.001) showed moderate correlation with the AUC-CSH40%. In univariate analysis, chromosome 11q deletion (P=0.033), Children's Oncology Group (COG) risk grouping (P=0.009), bone marrow involvement (BMI, P=0.015), and AUC-CSHtotal (P=0.007) were associated with EFS. The AUC-CSHtotal (P=0.036) and BMI (P=0.045) remained significant in multivariate analysis. The Kaplan Meier survival analyses demonstrated that patients with higher intra-tumoural metabolic heterogeneity and BMI had worse outcomes (log-rank P=0.002). Conclusion The intra-tumoural metabolic heterogeneity of primary lesions in NB was an independent prognostic factor for EFS. The combined predictive effect of intra-tumoural metabolic heterogeneity and BMI provided prognostic survival information in NB patients.

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A 1-year-old girl presented with vomiting for 1 week. Abdominal ultrasound revealed a mass with increased blood flow in the left lower abdomen. A malignancy was suspected. 18F-FDG PET/CT showed multiple lesions in the left ventricular wall, the kidney, and the left lower abdomen. Biopsy of the left abdominal mass confirmed the diagnosis of myeloid sarcoma associated with acute myeloid leukemia. After 4 cycles of chemotherapy, follow-up PET/CT was performed for evaluating the therapy response, which showed complete resolution.

A 17-month-old girl underwent FDG PET/CT to evaluate a right adrenal lesion, which showed abnormal 18F-FDG avidity. In addition, an unexpected lesion with mild 18F-FDG uptake was noted in the right anterior thoracic wall. Pathology demonstrated adrenocortical carcinoma in the right adrenal and rhabdosarcoma in both the left forearm and right anterior thoracic wall. Gene analysis confirmed the diagnosis of Li-Fraumeni syndrome. The present case emphasized FDG PET/CT value of showing simultaneously multiple lesions in Li-Fraumeni syndrome, especially in the early stage without the gene analysis result.