Diffusion-tensor neuronal fiber tractography and manganese-enhanced MR imaging of primate visual pathway in the common marmoset: preliminary results.
OBJECTIVE
To investigate whether diffusion-tensor tractography (DTT) of neuronal fibers is useful for delineating the configuration of the neuronal fiber trajectories in the primate visual pathway, including the well-developed optic chiasm, in comparison with tract tracing at manganese-enhanced magnetic resonance (MR) imaging.


METHODS
The handling methods used for all the animals in this study were approved by the institutional committee for animal experiments. Diffusion-tensor MR imaging was performed in four healthy common marmosets, and in two of these animals, manganese-enhanced MR imaging tract tracing was performed by using a 7.0-T MR imaging unit. The visual pathways were quantitatively investigated in terms of the manganese distribution observed on the manganese-enhanced MR images. The images obtained with DTT and manganese-enhanced MR imaging tract tracing were qualitatively compared, and the features of the visual pathway were verified through fusion of the reconstructed images obtained by using these two modalities.


RESULTS
DTT provided information regarding the neuroanatomic features of the marmoset visual pathway and revealed the bilateral branching patterns of the typical primate retinogeniculate pathways, although several incorrectly tracked fibers were noted. The distribution of manganese on the manganese-enhanced MR images revealed bilateral innervation of the retinal projections and depicted the layered internal structure of the lateral geniculate nuclei bilaterally, depending on the ocularity of each layer. These morphologic findings were consistent with those of previous histopathologic studies.


CONCLUSIONS
The findings of this preliminary study raise the possibility that DTT is useful for visualizing the neuronal fiber trajectories in primate visual pathways.


BACKGROUND
http://radiology.rsnajnls.org/cgi/content/full/249/3/855/DC1.
Yamada
Masayuki
M
Central Institute for Experimental Animals, Collaborating Institute for Graduate School of Medicine, Keio University, Tokyo, Japan. kiyusamaya@mac.com
Momoshima
Suketaka
S
Masutani
Yoshitaka
Y
Fujiyoshi
Kanehiro
K
Abe
Osamu
O
Nakamura
Masaya
M
Aoki
Shigeki
S
Tamaoki
Norikazu
N
Okano
Hideyuki
H
D000818:Animals; D002144:Callithrix; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008345:Manganese / Q000494:pharmacology*; D009412:Nerve Fibers; D009897:Optic Chiasm / Q000033:anatomy & histology; D014795:Visual Pathways / Q000033:anatomy & histology*
D008345:Manganese