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Compartment‐specific enhancement of white matter and nerve ex vivo using chromium
Author(s) -
Dortch Richard D.,
Apker Greg A.,
Valentine William M.,
Lai Barry,
Does Mark D.
Publication year - 2010
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.22460
Subject(s) - potassium dichromate , sciatic nerve , chromium , myelin , chemistry , ex vivo , white matter , anatomy , in vivo , nuclear magnetic resonance , biophysics , central nervous system , magnetic resonance imaging , neuroscience , biology , biochemistry , medicine , in vitro , physics , inorganic chemistry , organic chemistry , radiology , microbiology and biotechnology
Chromium—Cr(VI) in the form of potassium dichromate—has been shown to specifically enhance white matter signal. The proposed mechanism for this enhancement is reduction of diamagnetic Cr(VI) to paramagnetic chromium species by oxidizable myelin lipids. The purpose of the study herein was to better understand the microanatomical basis of this enhancement (i.e., the relative enhancement of myelin, intra‐axonal, and extra‐axonal water). Toward this end, integrated T 1 ‐ T 2 measurements were performed in potassium dichromate loaded (hereafter referred to as chromated) rat brains, rat optic nerve samples, and frog sciatic nerve samples ex vivo. In control optic nerve and white matter, two T 1 ‐ T 2 components were resolved, representing myelin and nonmyelin water (intra‐ and extra‐axonal water). Following chromation, three T 1 ‐ T 2 components were resolved in these same tissues. Results from similar measurements in sciatic nerve—all three components are resolvable in control and chromated samples—and quantitative histologic analysis suggest that this additional T 1 ‐ T 2 component is due to a splitting of the nonmyelin water component into intra‐ and extra‐axonal water components. This compartment‐specific enhancement may provide unique contrast for MR histology, as well as allow one to probe the compartmental basis of various contrast mechanisms in neural tissue. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.