Ex vivo imaging of mouse brain using micro-CT with non-ionic iodinated contrast agent: a comparison with myelin staining.
OBJECTIVE
We investigated the use of micro-CT with contrast agent for the non-invasive characterisation of fixed mouse brain tissue specimens as a means to differentiate between grey and white matter.


METHODS
Nine mice were divided into two groups for micro-CT (n=6) and myelin staining (n=3) experiments. Six mice underwent in vivo micro-CT and were then prepared for brain specimens by transcardiac perfusion with paraformaldehyde. The six mouse brains were soaked in two different concentrations of non-ionic iodinated contrast agents (60 and 150 mg ml(-1)). Immersion times used for each concentration of iodine were for 3, 7 and 14 days. Three-dimensional ex vivo micro-CT images were acquired with a resolution of 39 μm(3) to create isotropic images. The other three mice were stained for evaluation of the myelin structure.


RESULTS
Soaking the brains in non-ionic iodinated contrast agent resulted in clear differences in signal between the grey matter, the white matter and the ventricular spaces. The 150 mg ml(-1) contrast agent solution yielded images with better contrast-to-noise ratio (CNR) than 60 mg ml(-1) iodine contrast agent solution. 14 days of soaking yielded images with better CNR than 3 and 7 days. The CT contrast of grey and white matter derived from the iodine-soaked fixed brains was strongly related to tissue myelin.


CONCLUSIONS
The present study demonstrated that micro-CT can be used to detect the mouse brain myelin structure at 3, 7 and 14 days after fixation using a CT contrast agent.
Department of Medical Physics and Engineering, Division of Medical Technology and Science, Faculty of Health Science, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan. saito@sahs.med.osaka-u.ac.jp
S
S
Saito
K
K
Murase
D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000648:ultrastructure; D004396:Coloring Agents; D003287:Contrast Media; D007455:Iodine; D051379:Mice; D008810:Mice, Inbred C57BL; D009186:Myelin Sheath / Q000648:ultrastructure*; D055114:X-Ray Microtomography / Q000379:methods*
D004396:Coloring Agents; D003287:Contrast Media; D007455:Iodine