Molecular and cellular imaging is a relatively young field that is rapidly changing our approach towards understanding and solving problems in in vivo diagnoses with innovative solutions. The development of high sensitive, targeting and responsive agents is a major challenge to enhance the role of MRI in the field of Molecular Imaging applications. Understanding the relationships between structure and dynamics of Lanthanide(III) chelates has been fundamental for the development of high sensitive Gd(III) based agents. From targeting Human Serum Albumin for the development of angiographic agents, our research efforts are now addressing the visualization of molecules (characterizing diseased states) that are present at much lower concentration(1). The need of targeting molecules that are present at very low concentration requires the development of a novel class of contrast agents characterized by higher contrasting ability and improved targeting capabilities.Efficient targeting procedures for cellular labeling and recognition of epitopes characterizing important pathologies have been set up (2). Furthermore, interesting insights on nano-sized structure containing Gd(III) ions have been gained to suggest that innovative approaches to high relaxivity agents may also be possible. As far as the delivery of a large number of Gd-complexes at the targeting sites is concerned, several systems are currently under intense scrutiny, including dendrimers, liposomes and other form of lipophilic aggregates. Finally, much attention is currently devoted to CEST agents that represent an emerging class of MRI contrast media of huge potential. They act as negative agents by reducing the signal intensity of water protons through a saturation transfer mediated by chemical exchange. The great potential of CEST agents lies on the possibility of switching on and off the contrast at will, making possible the detection of more agents, each uniquely characterized by specific frequency of their mobile protons. Marked sensitivity improvements have been obtained by using as source of mobile protons the water molecules contained in the inner cavity of liposomes, properly shifted by the addition of a shift reagent.