Clinical MRI studies correlate decreases in molecular diffusion to abnormal regions within brain tissue. As a result, diffusion weighed MRI is exquisitely sensitive to brain pathologies such as stroke.
The aim of this proposal is to elucidate determinants of molecular diffusion in the extracellular space of brain and to clarify the factors important for comparing diffusion measurements derived from different experimental techniques. The two primary methods that generate diffusion measurements in brain tissue are iontophoresis and magnetic resonance (MR) spectroscopy. Although both methods have been extensively used by multiple research groups to generate quantitative measurements in normal brain and in many pathological brain states, comparisons between the two bodies of research are complicated by the unknown effects of differences in the experimental methodologies. This proposal outlines a strategy for calibrating the two methods. The fundamental experimental involves measuring diffusion of the same molecule with both techniques. After initial comparisons are made, the MR diffusion measurements will be altered so that they are sensitive to motions over a mean distance that approaches the distance between the electrodes used for the iontophoresis measurements. Finally, the change in the observed diffusion rates will be assessed under ischemic conditions to assess the degree to which both diffusion measurements respond to the same anatomical changes at the onset of ischemia.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
5F32NS043010-02
Application #
6622322
Study Section
Special Emphasis Panel (ZRG1-DMG (33))
Program Officer
Michel, Mary E
Project Start
2002-01-01
Project End
Budget Start
2003-01-01
Budget End
2003-12-31
Support Year
2
Fiscal Year
2003
Total Cost
$46,420
Indirect Cost
Name
Washington University
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
068552207
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
Kroenke, Christopher D; Van Essen, David C; Inder, Terrie E et al. (2007) Microstructural changes of the baboon cerebral cortex during gestational development reflected in magnetic resonance imaging diffusion anisotropy. J Neurosci 27:12506-15
Kroenke, Christopher D; Bretthorst, G Larry; Inder, Terrie E et al. (2006) Modeling water diffusion anisotropy within fixed newborn primate brain using Bayesian probability theory. Magn Reson Med 55:187-97
Kroenke, Christopher D; Bretthorst, G Larry; Inder, Terrie E et al. (2005) Diffusion MR imaging characteristics of the developing primate brain. Neuroimage 25:1205-13
Kroenke, Christopher D; Ackerman, Joseph J H; Yablonskiy, Dmitriy A (2004) On the nature of the NAA diffusion attenuated MR signal in the central nervous system. Magn Reson Med 52:1052-9
Kroenke, Christopher D; Ackerman, Joseph J H; Neil, Jeffrey J (2003) Magnetic resonance measurement of tetramethylammonium diffusion in rat brain: Comparison of magnetic resonance and ionophoresis in vivo diffusion measurements. Magn Reson Med 50:717-26