Myelin mapping in the living mouse brain using manganese-enhanced magnetization transfer MRI.
This work demonstrates manganese-enhanced magnetization transfer (MT) MRI to improve the contrast of myelinated structures in mouse brain in vivo. Systemic administration of manganese chloride led to a reduction of the MT ratio by 23% in white matter and 35% in gray matter. The effect increased their contrast-to-noise ratio by 48% and facilitated a mapping of myelin-rich white matter tissues. Relaxation time measurements revealed the manganese-induced shortening of T1 to be smaller in the corpus callosum (-42%) than in the cortex (-52%) or hippocampus (-60%). These findings are in line with the assumption that a high myelin and correspondingly low water content hinder the free diffusion and uptake of manganese ions. The resulting preferential accumulation of manganese in gray matter structures causes a stronger reduction of the MT saturation in gray matter than in white matter. Extending MRI assessments with conventional MT contrast, manganese-enhanced MT MRI at 76 x 80 x 160 microm(3) resolution and 2.35 T field strength allowed for a delineation of small myelinated structures such as the fornix, mammillothalamic tract, and fasciculus retroflexus in the living mouse brain.
Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, 37070 Göttingen, Germany. twatana@gwdg.de
Takashi
T
Watanabe
Jens
J
Frahm
Thomas
T
Michaelis
D000818:Animals; D001921:Brain / Q000033:anatomy & histology* / Q000378:metabolism; D001931:Brain Mapping / Q000379:methods*; D002712:Chlorides / Q000378:metabolism*; D003287:Contrast Media; D005260:Female; D008279:Magnetic Resonance Imaging / Q000379:methods*; D017895:Manganese Compounds / Q000378:metabolism*; D051379:Mice; D008815:Mice, Inbred Strains; D009186:Myelin Sheath; D013997:Time Factors
D002712:Chlorides; D003287:Contrast Media; D017895:Manganese Compounds; C025340:manganese chloride