title: Compartment-specific enhancement of white matter and nerve ex vivo using chromium.
abstract: 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.
authors.affiliation: Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Dortch
authors.forename: Greg A
authors.initials: GA
authors.lastname: Apker
authors.forename: William M
authors.initials: WM
authors.lastname: Valentine
authors.forename: Barry
authors.initials: B
authors.lastname: Lai
authors.forename: Mark D
authors.initials: MD
authors.lastname: Does
mesh_terms: D000818:Animals; D002857:Chromium; D003287:Contrast Media; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D009413:Nerve Fibers, Myelinated / Q000737:chemistry* / Q000648:ultrastructure*; D009900:Optic Nerve / Q000033:anatomy & histology* / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014982:Xenopus laevis
chemical_list: D003287:Contrast Media; D002857:Chromium
references.citation: J Magn Reson B. 1996 Nov;113(2):136-44
references.pmid: 8954899
references.citation: Magn Reson Med. 2002 Feb;47(2):239-45
references.pmid: 11810666
references.citation: Magn Reson Imaging. 1995;13(4):575-80
references.pmid: 7674853
references.citation: Toxicology. 2000 Sep 7;150(1-3):137-46
references.pmid: 10996670
references.citation: Mol Cell Biochem. 2002 May-Jun;234-235(1-2):293-300
references.pmid: 12162446
references.citation: Magn Reson Med. 1995 Apr;33(4):490-6
references.pmid: 7776879
references.citation: Magn Reson Med. 1998 Sep;40(3):405-10
references.pmid: 9727943
references.citation: Nature. 1984 Aug 23-29;310(5979):681-3
references.pmid: 6472448
references.citation: Magn Reson Med. 1996 Feb;35(2):207-13
references.pmid: 8622585
references.citation: Experientia. 1978 Nov 15;34(11):1443-4
references.pmid: 309823
references.citation: Mol Cell Biochem. 2001 Jun;222(1-2):41-7
references.pmid: 11678610
references.citation: Magn Reson Med. 2002 Feb;47(2):274-83
references.pmid: 11810670
references.citation: Magn Reson Imaging. 1998 Dec;16(10):1201-10
references.pmid: 9858277
references.citation: Magn Reson Med. 2006 Jul;56(1):1-6
references.pmid: 16767764
references.citation: Magn Reson Imaging. 1998 Nov;16(9):1033-41
references.pmid: 9839987
references.citation: Magn Reson Med. 1999 Nov;42(5):911-8
references.pmid: 10542350
references.citation: Magn Reson Med. 1992 Dec;28(2):264-74
references.pmid: 1281258
references.citation: J Neurosci. 1983 Aug;3(8):1554-64
references.pmid: 6875656
references.citation: Neuroimage. 2007 Aug 1;37(1):82-9
references.pmid: 17574443
references.citation: Magn Reson Med. 1994 Jun;31(6):673-7
references.pmid: 8057820
references.citation: J Comp Neurol. 1996 Feb 05;365(2):232-55
references.pmid: 8822167
references.citation: Magn Reson Med. 2007 Feb;57(2):437-41
references.pmid: 17260381
references.citation: Magn Reson Med. 1991 Dec;22(2):425-34
references.pmid: 1812377
references.citation: J Neuropathol Exp Neurol. 1985 Jan;44(1):60-72
references.pmid: 3965625
references.citation: Magn Reson Med. 1999 Dec;42(6):1128-36
references.pmid: 10571935
references.citation: J Magn Reson. 2005 Feb;172(2):306-11
references.pmid: 15649757
references.citation: J Magn Reson Imaging. 1992 Sep-Oct;2(5):541-53
references.pmid: 1392247
references.citation: Magn Reson Med. 2005 Sep;54(3):743-7
references.pmid: 16088884
references.citation: Magn Reson Med. 1993 Jun;29(6):767-75
references.pmid: 8350719
references.citation: Magn Reson Med. 2006 Oct;56(4):927-31
references.pmid: 16941621
references.citation: NMR Biomed. 2007 Apr;20(2):113-20
references.pmid: 16998953