Bio-Distribution, Imaging Protocols and Diagnostic Accuracy of PET with Tracers of Lipogenesis in Imaging Prostate Cancer: a Comparison between 11C-Choline, 18FFluoroethylcholine and 18F-Methylcholine.

Abstract

PET/CT with choline is a diagnostic tool useful for imaging prostate cancer patients. The overall published papers in this field are referred to three variants of the same radiopharmaceutical: 11C-Choline, 18FMethylcholine and 18F-Ethylcholine. As no data has been reported on the theoretical differences between these three variants of radiolabeled choline, this study aims to explore the knowledge on the physiological distribution of these three tracers, to compare data of imaging acquisition protocols and to verify the theoretical equivalence in terms of diagnostic accuracy and potential false positive cases that can occur in clinical practice. A literature research about published papers was conducted regarding the physiological distribution, imaging acquisition protocols and diagnostic performance of 11C-choline, 18F-methylcholine and 18F-ethylcholine PET/CT. Minimal differences of the "in vivo" bio-distribution of the variants of radiolabeled choline were registered. Several imaging acquisition protocols were utilized, considering the different half-decay of 11C and 18F and the early urinary excretion of 18F-FECH. The diagnostic accuracy resulted similar for all the tracers, despite an insignificant amount of data for 18F-FECH; however, some pitfalls were documented for all the variants, related to the intrinsic properties of choline as a non-tumour specific tracer. Finally, our clinical experience with the two fluorinated kinds of choline has also been reported describing the "in vivo" bio-distribution with semi-quantitative measurement of Standardised Uptake Value in target organs. The literature suggests these three variants of choline equally useful to be considered for prostate cancer imaging. A standardisation of acquisition protocols for fluorinated choline PET/CT has also been proposed.