Assess FDG-PET/CT performance in characterization of renal lesions and its impact on patient management.

Objectives Assess clinical significance of renal lesions detected on FDG-PET/CT during oncologic imaging for staging and Restaging work-up for a variety of malignancies.

Methods This is retrospective analysis of the significance of Solid/semisolid renal lesions detected from January 1, 2014- December 1, 2015 during oncologic FDG-PET/CT imaging at University of Rochester medical center. Patients with suspicious solid/semisolid renal lesions demonstrating wide range of FDG avidity were included with the diagnosis confirmed by CECT/US, histology, and/or clinical follow-up including response to targeted therapies. Simple renal cysts and congenital renal anomalies were excluded from further analysis. Solid/semisolid lesions regardless of the degree of FDG avidity were considered suspicious for renal cell carcinoma(RCC) and more intensely hypermetabolic single or multiple renal cortical lesions as metastatic.

Results 30 patients met the inclusion criteria, of which 28 were malignant (12 primary RCC, 8 metastatic, 5 lymphoma, 3 RCC recurrence) and 2 false positive. A majority (90%) RCC masses were solid/semisolid, had low-grade uptake equal to the renal parenchyma, could be easily missed if not recognized on the CT portion of the PET/CT. The metastatic lesions were metabolically more intense and often multiple. CECT showed enhancing tumors corresponding to PET/CT identified suspicious RCC, subsequently resected and confirmed on histology. Lymphoma lesions were intensely hypermetabolic, focal or diffuse, and demonstrated complete metabolic response to targeted chemotherapy. Recurrent RCC and distant metastases from RCC, contrary to the common belief were more intensely hypermetabolic.

Conclusions FDG-PET/CT can play a key role in the early detection of RCC and potentially improve patient outcome with a positive predictive value of 90% (p-value <.01). Similarly detecting renal metastases (which may be the only metastatic site), and detection of RCC recurrence can influence staging/management decisions. RESEARCH SUPPORT: None