To investigate the utility of prostate-specific membrane antigen (PSMA)-targeted [18F]DCFPyL positron emission tomography (PET)/X-ray computed tomography (CT) imaging for the detection of sites of disease in patients with metastatic non-clear cell renal cell carcinoma (RCC).
Eight patients with metastatic non-clear cell RCC underwent imaging with PSMA-targeted [18F]DCFPyL PET/CT. Imaged RCC histologic subtypes included papillary RCC (n = 3), chromophobe RCC (n = 2), unclassified RCC (n = 2), and Xp11 translocation RCC (n = 1). Using comparison to conventional CT and/or magnetic resonance imaging as reference, two radiologists with expertise in nuclear medicine identified putative sites of disease on [18F]DCFPyL PET/CT and classified each lesion as having no radiotracer uptake, equivocal uptake, or definitive uptake.
In total, 73 metastatic sites and 3 primary tumors compatible with sites of non-clear cell RCC were identified on conventional imaging. Metastatic sites of disease included lymph nodes (n = 40), venous thrombi (n = 3), pulmonary nodules (n = 10), bone lesions (n = 15), brain lesions (n = 3), and retroperitoneal masses (n = 2). Only 10 of the 73 lesions (13.7 %) were classified as having definitive radiotracer uptake (median SUVmax = 3.25, range = 1.2-9.5), 14 lesions (19.2 %) had equivocal uptake (median SUVmax = 2.85, range = 0.5-6.5), and 49 lesions (67.1 %) had no definitive uptake above background (median SUVmax = 1.7, range = 0.2-3.0). The three primary renal tumors demonstrated lower radiotracer avidity relative to surrounding normal renal parenchyma.
A small proportion of sites of non-clear cell RCC showed uptake of the PSMA-targeted radiotracer [18F]DCFPyL. Unlike for clear cell RCC, the results of this study indicate that PSMA-based PET is not appropriate for imaging other RCC subtypes.
Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging. 2018 Sep 14 [Epub ahead of print]
Yafu Yin, Scott P Campbell, Mark C Markowski, Philip M Pierorazio, Martin G Pomper, Mohamad E Allaf, Steven P Rowe, Michael A Gorin
The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA., The James Buchanan Brady Urological Institute and Department of Urology, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Park 213, Baltimore, MD, 21287, USA., Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA., The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA. .