There is a growing interest to use non-invasive optical imaging methods to study central nervous system diseases. The application of a myelin-binding fluorescent dye, 3,3-diethylthiatricarbocyanine iodide (DBT) was recently described for in vivo optical imaging of demyelination in the mouse. In the present study we aimed at adapting the method to our optical imaging systems, the IVIS Lumina II to measure epifluorescence and the fluorescent molecular tomograph (FMT) for 3-dimensional quantification of the fluorophore. Epifluorescent imaging was performed 5-30 min after DBT injection which was followed by FMT imaging at 40 min. Two mice also underwent micro-CT imaging in the FMT cassette for the purpose of FMT-CT co-registration. Ex vivo imaging of the brain and other tissues of the head and neck was carried out 1 h after injection. Both the FMT-CT co-registration and the ex vivo imaging of organs proved that DBT poorly crossed the blood-brain barrier. The dye did not accumulate in the myelin sheath of the sciatic nerve. In contrast, there was an intense accumulation in the pituitary and salivary glands. The FMT-CT co-registration unequivocally demonstrated that the signal localized to the head did not originate from beyond the blood-brain barrier. No myelin binding was demonstrated by the ex vivo imaging either. In conclusion, DBT is unsuitable for in vivo imaging of myelination due to its poor BBB penetration, accumulation in other structures of the head and neck region and lack of selective binding towards myelin in vivo.

中文翻译：

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荧光染料 3,3'-diethylthiatriccarbocyanine iodide 不适用于小鼠髓鞘形成的体内成像。

使用非侵入性光学成像方法研究中枢神经系统疾病的兴趣越来越大。最近描述了髓磷脂结合荧光染料 3,3-二乙基硫代碳菁碘化物 (DBT) 的应用，用于小鼠脱髓鞘的体内光学成像。在本研究中，我们旨在使该方法适用于我们的光学成像系统、IVIS Lumina II 以测量落射荧光和荧光分子断层扫描仪 (FMT) 以对荧光团进行 3 维量化。在 DBT 注射后 5-30 分钟进行荧光成像，然后在 40 分钟进行 FMT 成像。为了 FMT-CT 联合注册，两只小鼠还在 FMT 盒中进行了微 CT 成像。注射后 1 小时进行脑和头颈部其他组织的离体成像。FMT-CT 联合配准和器官的离体成像都证明 DBT 很难穿过血脑屏障。染料没有积聚在坐骨神经的髓鞘中。相比之下，脑垂体和唾液腺中有大量积聚。FMT-CT 联合配准明确表明，定位于头部的信号并非来自血脑屏障之外。离体成像也没有证明髓磷脂结合。总之，DBT 不适用于髓鞘形成的体内成像，因为其 BBB 渗透性差，在头颈部其他结构中积累，并且在体内缺乏对髓鞘的选择性结合。染料没有积聚在坐骨神经的髓鞘中。相比之下，脑垂体和唾液腺中有大量积聚。FMT-CT 联合配准明确表明，定位于头部的信号并非来自血脑屏障之外。离体成像也没有证明髓磷脂结合。总之，DBT 不适用于髓鞘形成的体内成像，因为其 BBB 渗透性差，在头颈部其他结构中积累，并且在体内缺乏对髓鞘的选择性结合。染料没有积聚在坐骨神经的髓鞘中。相比之下，脑垂体和唾液腺中有大量积聚。FMT-CT 联合配准明确表明，定位于头部的信号并非来自血脑屏障之外。离体成像也没有证明髓磷脂结合。总之，DBT 不适用于髓鞘形成的体内成像，因为其 BBB 渗透性差，在头颈部其他结构中积累，并且在体内缺乏对髓鞘的选择性结合。离体成像也没有证明髓磷脂结合。总之，DBT 不适用于髓鞘形成的体内成像，因为其 BBB 渗透性差，在头颈部其他结构中积累，并且在体内缺乏对髓鞘的选择性结合。离体成像也没有证明髓磷脂结合。总之，DBT 不适用于髓鞘形成的体内成像，因为其 BBB 渗透性差，在头颈部其他结构中积累，并且在体内缺乏对髓鞘的选择性结合。