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. Author manuscript; available in PMC: 2016 Sep 1.
Published in final edited form as: Wiley Interdiscip Rev Nanomed Nanobiotechnol. 2015 Feb 13;7(5):722–735. doi: 10.1002/wnan.1336

FIGURE 2.

FIGURE 2

There are several targets for optimizing the relaxivity of a T1 contrast agent. DTPA-Gd is shown with a single water molecule in the binding position. Factors that affect relaxivity are the number of water molecules that can bind to the Gd ion (q), the exchange lifetime of the water molecule or molecules bound to the Gd (τM), and the rotational correlation time of the Gd complex (τR). The parameters q and τM are difficult to change for a given Gd-chelator complex leaving τR particle loading as optimization targets. (Reprinted with permission from Ref 9. Copyright 2009 American Chemical Society)