Characterization of malignant kidney tumors in childhood by 18 F-FDG PET/CT

To evaluate the role of semiquantitative parameters derived from F-FDG PET/CT in characterizing pediatric malignant kidney tumors. 54 children with pathologically confirmed renal malignancies who underwent pretreatment F-FDG PET/CT were retrospectively reviewed. Association between PET-derived semiquantitative parameters, including maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG), and tumor histology, disease stage, and loss of heterozygosity were analyzed. Of the 54 patients, 43 had Wilms tumor (WT), 4 had clear cell sarcoma of the kidney (CCSK), 3 had rhabdoid tumor of kidney, 2 had renal cell carcinoma, and 2 had congenital mesoblastic nephroma. F-FDG PET/CT detected all primary renal tumors, with SUVmax ranging from 1.2 to 14.5. PET-derived parameters showed no significant differences among different tumor types, except for CCSK, which exhibited lower FDG uptake compared to WT (SUVmax 3.60 ± 1.02 vs. 6.10 ± 2.25, p = 0.034). Higher MTV, TLG, and lactate dehydrogenase were associated with stage IV disease. ROC analysis showed that TLG had the highest AUC (0.931) for predicting stage IV disease in the whole cohort, while SUVmax had the highest AUC (0.867) for predicting stage IV and V in WT. Furthermore, Children with 1q gain exhibited higher MTV in WT (447 ± 354 vs. 207 ± 189, p = 0.041). PET-derived semiquantitative parameters highly associated with disease stage both in the overall cohort of renal malignancies and specifically in the WT group. Additionally, volumetric metabolic indices might provide further insights into loss of heterozygosity in children with WT.