Manganese protoporphyrin IX. A potential intravenous paramagnetic NMR contrast agent: preliminary communication.

An endogenous, biological chelating substance--protoporphyrin--has been studied in vitro and in vivo for potential usefulness as an MRI contrast agent. In vitro data show that manganese protoporphyrin IX (Mn PP) maintains strong paramagnetic properties. Limited in vivo studies suggest that Mn PP causes marked reduction of T1 in the liver, with less pronounced effects on other body tissues.