Magnetic resonance imaging (MRI) provides both functional and structural information with high spatial resolution of soft tissue. Molecular imaging is a broad term that refers to imaging applications that detect specific molecules or molecular signals. MRI is a powerful and widely used non-invasive imaging tool but the primary limitation in molecular imaging applications is a large background signal that makes MRI relatively insensitive to targeted molecular imaging agents compared to other imaging modalities. In this work, I present two complimentary approaches to addressing sensitivity issues in MRI. First, by taking advantage of non-linear field spin dynamics, contrast-to-noise ratios (CNR) between tissues with small differences in magnetic susceptibility (i.e. gray matter and white matter, healthy and tumorous tissues) are improved. This work explores the advantages of non-linear field spin dynamics in imaging applications and employs an external electronic device built by Lin group members to amplify the non-linear field strength. Second, in collaboration with a materials science group, a novel supramolecular nanoparticle with enhanced relaxation effects was developed and demonstrated potential in dynamic lymphatic drainage studies. By taking advantage of the flexible and modular synthetic approach of the SNP, we are able to investigate the enhancement mechanism with relaxation theory simulations as well as to optimize the material characteristics for application as a T₁ MRI contrast agent.