Wang Y, et al. – The utility of ¹⁸–fluorodeoxyglucose (FDG) positron emission tomography/computerized tomography (PET/CT) was examined in the diagnosis and organ involvement evaluation of idiopathic retroperitoneal fibrosis (iRPF). The experts illustrated that ¹⁸F–FDG PET/CT could aid in differentiating iRPF from retroperitoneal malignancy, to detect high–FDG–uptake RPF lesions despite normal inflammatory markers and to determine the overlap between iRPF and IgG4–RD.