Magnetic resonance microimaging of intraaxonal water diffusion in live excised lamprey spinal cord

• DOI: 10.1073/pnas.252249999
• Publication Date: 2002-12-10T17:42:57Z
• Authors: Masaya Takahashi; David B. Hackney; Guixin Zhang; Suzanne L. Wehrli; Alex C. Wright; William T. O'Brien; Hidemasa Uematsu; Felix W. Wehrli; Michael E. Selzer
• Keywords: Diffusion; 03 medical and health sciences; 0302 clinical medicine; Body Water; Spinal Cord; Cell Membrane; Animals; Lampreys; Magnetic Resonance Imaging; Axons

Anisotropy of water diffusion in axon tracts, as determined by diffusion-weighted MRI, has been assumed to reflect the restriction across membranes. Reduction this anisotropy interpreted degeneration axons. These interpretations are based primarily on a priori reasoning that had little empirical validation. We used experimental advantages sea lamprey spinal cord, which contains several very large axons, determine whether intraaxonal is isotropic and attributable mobility surface Through application magnetic resonance microimaging, we were able measure purely characteristics giant reticulospinal axons (20-40 microm diameter). The apparent coefficients parallel (longitudinal ADC, l-ADC) perpendicular (transverse t-ADC) long axis 0.98 +/- 0.06 (10(-3) mm2 sec) 0.97 0.11 sec), respectively. In white matter regions included multiple l-ADCs almost identical regardless density sampled tract. By comparison, t-ADCs reduced varied inversely with number (and thus axolemmas) fixed cross-sectional area. Thus, was found be when measured entirely within single anisotropic findings support hypothesis cell membrane primary source fiber tracts central nervous system.