Christopher H. Sotak1,2, Alan P. Koretsky3
1Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA, United States; 2Radiology, University of Massachusetts Medical School, Worcester, MA, United States; 3NINDS/LFMI, National Institutes of Health, Bethesda, MD, United States
Convection-enhanced delivery (CED) of manganese(III)-transferrin (Mn(III)-Tf) into the rat brain was used to investigate its properties as an in vivo MRI contrast agent. The spatio-temporal evolution of MEMRI signal enhancement and calculated T1 relaxation times following Mn(III)-Tf infusion was comparable to that observed following CED of Mn2+ alone. Furthermore, Mn2+ released following intrastriatal Mn(III)-Tf infusion was transported along the striatonigral pathway and the temporal dynamics were in excellent agreement with the neuronal tract tracing studies that employ Mn2+ alone. The results of this study are consistent with the release and subsequent transport of Mn2+ following receptor-mediated endocytosis of Mn(III)-Tf.