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Delta relaxation enhanced MR: Improving activation‐specificity of molecular probes through R 1 dispersion imaging
Author(s) -
Alford Jamu K.,
Rutt Brian K.,
Scholl Timothy J.,
Handler William B.,
Chronik Blaine A.
Publication year - 2009
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21933
Subject(s) - gadolinium , chemistry , albumin , bovine serum albumin , nuclear magnetic resonance , in vivo , serum albumin , molecular probe , relaxation (psychology) , dispersion (optics) , analytical chemistry (journal) , chromatography , biochemistry , optics , dna , social psychology , psychology , physics , microbiology and biotechnology , organic chemistry , biology
MR molecular imaging enables high‐resolution, in vivo study of molecular processes frequently utilizing gadolinium‐based probes that specifically bind to a particular biological molecule or tissue. While some MR probes are inactive when unbound and produce enhancement only after binding, the majority are less specific and cause enhancement in either state. Accumulation processes are then required to increase probe concentration in regions of the target molecule/tissue. Herein, a method is described for creating specificity for traditionally nonspecific probes. This method utilizes MR field‐cycling methods to produce MRI contrast related to the dependence of R 1 upon magnetic field. It is shown that the partial derivative of R 1 with respect to magnetic field strength, R 1 ′, can be used as an unambiguous measure of probe binding. T 1 ‐weighted images and R 1 ′ images were produced for samples of albumin and buffer both enhanced with the albumin‐binding agent Vasovist. For T 1 images, samples with low concentrations of Vasovist in an albumin solution could not be differentiated from samples with higher concentrations of Vasovist in buffer. Conversely, the R 1 ′ images showed high specificity to albumin. Albumin samples with a 10‐μM concentration of Vasovist were enhanced over buffer samples containing up to 16 times more Vasovist. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.