Risk stratification and tumour characterization of pheochromocytoma and paraganglioma using [18F]FDOPA PET/CT

[ 18 F]FDOPA is a non-invasive imaging modality for pheochromocytomas and paragangliomas (PPGLs). However, its role in risk stratification and tumour characterization remains unclear. We aimed to evaluate the potential of visual and quantitative parameters of preoperative [ 18 F]FDOPA PET/CT in PPGLs by investigating the associations between tumour characteristics (angioinvasion, differentiation) and biochemical marker levels. A total of 121 PPGL patients with 133 lesions were included (mean age 54 years, 60 [49.6%] male). All PPGL lesions demonstrated discernible uptake and mostly heterogenous uptake, however, visual parameters were not significantly associated with tumour angioinvasion and differentiation. Quantitative parameters were maximum and peak standardized uptake values (SUVmax and SUVpeak), lesion-to-background ratio (LBR), metabolic tumour volume (MTV), total lesion uptake (TLU), and lesion size. The associations of parameters with tumour angioinvasion, differentiation status (as a surrogate for malignant potential) according to the Grading system for Adrenal Pheochromocytoma and Paraganglioma (GAPP) score, and catecholamine metabolites (plasma and 24 h urine metanephrine and normetanephrine) levels were assessed. MTV and TLU differed significantly by angioinvasion status (All P = 0.016) and GAPP-based differentiation category ( P = 0.015 and 0.002, respectively). In addition, MTV was significantly correlated with all measured plasma and urinary catecholamine metabolites levels ( P < 0.001–0.005). Among visual and quantitative parameters of [ 18 F]FDOPA PET/CT, volumetric parameters, especially MTV, confirmed significant difference by angioinvasion status and differentiation category. MTV also validated significant correlations with studied catecholamine metabolites. This supports that [ 18 F]FDOPA PET/CT may provide complementary, non-invasive information relevant to risk stratification and tumour characterization of PPGL.