Quantitative Activity Measurements of Brown Adipose Tissue at 7 T Magnetic Resonance Imaging After Application of Triglyceride-Rich Lipoprotein 59Fe-Superparamagnetic Iron Oxide Nanoparticle: Intravenous Versus Intraperitoneal Approach.

Objectives: The aim of this study was to determine metabolic activity of brown adipose tissue (BAT) with in vivo magnetic resonance imaging (MRI) after intravenous (IV) and intraperitoneal (IP) injection of radioactively labeled superparamagnetic iron oxide nanoparticles (SPIOs) embedded into a lipoprotein layer.

Materials And Methods: Fe-labeled SPIOs were either polymer-coated or embedded into the lipid core of triglyceride-rich lipoproteins (TRL-Fe-SPIOs). First biodistribution and blood half time analysis in thermoneutral mice after IP injection of either TRL-Fe-SPIOs or polymer-coated Fe-SPIOs (n = 3) were performed.