In this study, PET imaging studies of two structurally related 18F-hydroxyphenethylguanidines, 4-[18F]fluoro-meta-hydroxyphenethylguanidine ([18F]4F-MHPG) and 3-[18F]fluoro-para-hydroxyphenethylguanidine ([18F]3F-PHPG) will be performed. All studies will be performed in normal healthy volunteers.~PET stands for Positron Emission Tomography which is a type of imaging that uses a radioactive tracer. This is also called a radiotracer which is a compound linked to a radioactive element. Most compounds are short-lived, meaning that the radioactivity breaks down quickly or is excreted from the body.~In the first stage of the study, dynamic PET imaging for 90 min will be done with [18F]4F-MHPG (n = 4) and [18F]3F-PHPG (n = 4).~Data from these studies will assess each radiotracer's imaging properties, pharmacokinetics and metabolic breakdown in plasma. Application of tracer kinetic analysis methods to the kinetics of each tracer in heart and plasma will be studied to see if these methods can provide accurate measurements of regional nerve sympathetic nerve density in the hearts of human subjects. Results from these initial studies will be used to select the lead compound for further studies in patient populations.~In the second stage of the study, whole-body PET imaging studies (n = 4) with the selected lead radiotracer will be performed to acquire data necessary for generating more accurate human radiation absorbed dose estimates.
The purpose of this study is to perform first-in-human PET imaging studies of two new cardiac sympathetic nerve imaging agents, 4-[18F]fluoro-meta-hydroxyphenethylguanidine ([18F]4F-MHPG) and 3-[18F]fluoro-para-hydroxyphenethylguanidine ([18F]3F-PHPG).