title: Dendrimer-based macromolecular MRI contrast agents: characteristics and application.
abstract: Numerous macromolecular MRI contrast agents prepared employing relatively simple chemistry may be readily available that can provide sufficient enhancement for multiple applications. These agents operate using a approximately 100-fold lower concentration of gadolinium ions in comparison to the necessary concentration of iodine employed in CT imaging. Herein, we describe some of the general potential directions of macromolecular MRI contrast agents using our recently reported families of dendrimer-based agents as examples. Changes in molecular size altered the route of excretion. Smaller-sized contrast agents less than 60 kDa molecular weight were excreted through the kidney resulting in these agents being potentially suitable as functional renal contrast agents. Hydrophilic and larger-sized contrast agents were found better suited for use as blood pool contrast agents. Hydrophobic variants formed with polypropylenimine diaminobutane dendrimer cores created liver contrast agents. Larger hydrophilic agents are useful for lymphatic imaging. Finally, contrast agents conjugated with either monoclonal antibodies or with avidin are able to function as tumor-specific contrast agents, which also might be employed as therapeutic drugs for either gadolinium neutron capture therapy or in conjunction with radioimmunotherapy.
authors.affiliation: Center for Cancer Research, National Cancer Institute, National Institutes of Health, Building 10, Room 4N109, 10 Center Drive, Bethesda, MD 20892-1374, USA. Kobayash@mail.nih.gov
authors.forename: Hisataka
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Martin W
authors.initials: MW
authors.lastname: Brechbiel
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000737:chemistry / Q000493:pharmacokinetics; D007668:Kidney / Q000502:physiology; D008208:Lymphatic System / Q000033:anatomy & histology; D046911:Macromolecular Substances; D018810:Magnetic Resonance Angiography / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015394:Molecular Structure; D009369:Neoplasms / Q000175:diagnosis
chemical_list: D003287:Contrast Media; D046911:Macromolecular Substances