Molecular Imaging II

Volume 185/2 of the series Handbook of Experimental Pharmacology pp 37-57

Environment-sensitive and Enzyme-sensitive MR Contrast Agents

  • Manuel QuerolAffiliated withS2-808 Department of Radiology, UMASS Medical School
  • , Alexei BogdanovJr.Affiliated withS2-808 Department of Radiology, UMASS Medical School Email author 

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The majority of approved MR contrast agents belong to the class of paramagnetic chelates. These small molecules are uniquely suited to respond to changes in the microenvironment in vivo. These contrast agents can also function as substrates for several classes of enzymes. In both cases, the chelates can be designed in a way that the relaxivity — i.e., the ability of chelated paramagnetic metal cations to shorten the relaxation times of water — is directly affected by changes in the microenvironment. This chapter summarizes a variety of MR contrast agent designs that enable “sensing” of metal cations, pH and enzymatic activity.