Multivalent Gd-DOTA Decorated Oligopeptide as Sensitive MRI Molecular Probes for In Vivo Imaging of Brain Connectivity.

One of the most important goals of brain imaging is to define the anatomical connections within the brain. In addition to revealing normal circuitry, studies of neural connections and neuronal transport can show rewiring and degeneration following brain injury and diseases. In this work, a highly sensitive magnetic resonance imaging (MRI)-visible neural tracer that can be used to visualize brain connectivity in vivo is developed. It is based on an oligopeptide with gadolinium chelates appended to the peptide backbone. This peptide construct is a sensitive MRI contrast agent that was conjugated to the classical neurotracer, Cholera-toxin Subunit-B. Injection of this probe enabled it to be used to trace neural connections in vivo. This complements other MRI tracing techniques such as diffusion tensor imaging and manganese-enhanced MRI for neural tracing.