Mn-metalloporphyrin conjugated with Gd-DTPA (Gd-ATN10): tumor enhancement agent for magnetic resonance imaging.

A conjugate of manganese-metalloporphyrin and gadolinium (Gd)-diethylenetriaminepenta-acetic acid (Gd-ATN10) was developed as a tumor-specific enhancement agent for magnetic resonance (MR) imaging. Gd-ATN10 was evaluated in an experimental 9L gliosarcoma rat tumor model. T1-weighted MR imaging showed enhancement of the tumor which persisted for up to 24 hours. Gd concentration measurement by inductively coupled plasma atomic emission spectroscopy revealed the peak Gd concentration was reached after 30 minutes and Gd was retained in the blood and tumor up to 24 hours. There was no uptake of Gd in the normal brain and little in the skin. Gd-porphyrin derivatives are potentially useful agents for tumor diagnosis on MR imaging and for neutron capture therapy.