Review ArticlesMolecular MR Contrast AgentsShuvaev, Sergey PhD; Akam, Eman PhD; Caravan, Peter PhDAuthor Information From the Institute for Innovation in Imaging, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA. Received for publication July 14, 2020; and accepted for publication, after revision, September 10, 2020. Conflicts of interest and sources of funding: Conflicts of interest and sources of funding: P.C. has equity in Reveal Pharmaceuticals that holds the patent rights to Mn-PyC3A, has equity in Factor 1A LLC that holds the patent rights to EP-2104R, and has equity in and receives consulting income from Collagen Medical LLC that holds the patent rights to EP-3533 and CM-101. P.C. has research support from Takeda, Janssen, and Pliant Therapeutics. S.S. and E.A. have no conflicts to declare. S.S. and E.A. contributed equally to this article. Correspondence to: Peter Caravan, PhD, Institute for Innovation in Imaging, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, 149 Thirteenth St, Suite 2301, Charlestown, MA 02129. E-mail: [email protected]. Investigative Radiology: January 2021 - Volume 56 - Issue 1 - p 20-34 doi: 10.1097/RLI.0000000000000731 Buy Metrics Abstract Molecular magnetic resonance (MR) imaging utilizes molecular probes to provide added biochemical or cellular information to what can already be achieved with anatomical and functional MR imaging. This review provides an overview of molecular MR and focuses specifically on molecular MR contrast agents that provide contrast by shortening the T1 time. We describe the requirements for a successful molecular MR contrast agent and the challenges for clinical translation. The review highlights work from the last 5 years and places an emphasis on new contrast agents that have been validated in multiple preclinical models. Applications of molecular MR include imaging of inflammation, fibrosis, fibrogenesis, thromboembolic disease, and cancers. Molecular MR is positioned to move beyond detection of disease to the quantitative staging of disease and measurement of treatment response. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.