DiI-CT-A bimodal neural tracer for X-ray and fluorescence imaging

Here, we present an X-ray-visible neural tracer, referred to as DiI-CT, which is based on the well-established lipophilic indocarbocyanine dye DiI, to which we conjugated two iodine atoms. The tracer is visible with mi-crofocus computed tomography (microCT) imaging and shares the excellent fluorescent tracing properties of DiI. We document the discovery potential of DiI-CT by analyzing the vibrissa follicle-sinus complex, a struc-ture where visual access is poor and 3D tissue structure matters and reveal innervation patterns of the intact follicle in unprecedented detail. In the brain, DiI-CT tracing holds promise for verification evaluation of indirect connectivity measures, such as diffusion tensor imaging. We conclude that the bimodal dye DiI-CT opens new avenues for neuroanatomy.

Automated summary

Here, we introduce a X-ray-visible neural tracer called DiI-CT, which combines the well-known lipophilic indocarbocyanine dye DiI with two iodine atoms. This tracer is visible under microfocus computed tomography (microCT) imaging and retains the excellent tracing properties of DiI. We demonstrate the potential of DiI-CT in studying the vibrissa follicle-sinus complex, a structure with limited visual access and where 3D tissue structure is important, by revealing detailed innervation patterns. In the brain, DiI-CT tracing holds promise for validating indirect connectivity measures such as diffusion tensor imaging. In conclusion, the bimodal dye DiI-CT opens up new opportunities in neuroanatomy.