In vivo imaging of central nervous system fluid spaces using synchrotron radiation-based micro computed tomography

Area of Science:

• Neuroscience
• Medical Imaging
• Biophysics

Background:

• Current intravital imaging techniques for the mouse central nervous system (CNS) lack the necessary resolution, coverage, and speed for comprehensive in vivo fluid dynamics studies.
• Existing methods create a gap between optical microscopy and MRI, hindering detailed analysis of organ-wide CNS processes.

Purpose of the Study:

• To introduce and validate intravital synchrotron radiation-based hard X-ray micro computed tomography (SRµCT) for dynamic, whole-brain imaging of mouse CNS fluid spaces.
• To overcome the limitations of current techniques by providing simultaneous micrometer spatial resolution, whole-brain coverage, and sub-minute temporal resolution.

Main Methods:

• Intravital SRµCT was performed on mouse CNS fluid spaces across three synchrotron radiation facilities.
• Imaging included both anesthetized free-breathing and mechanically ventilated animals, with and without cardiac gating.
• Achieved voxel sizes down to 6.3 µm and effective spatial resolution better than 20 µm, with temporal resolution up to 23 seconds.

Main Results:

• SRµCT enabled dynamic, whole-brain imaging of mouse CNS fluid spaces with micrometer-scale resolution.
• The technique allowed time-resolved visualization of cerebrospinal fluid (CSF) contrast distribution.
• Quantitative analysis of tissue motion across the entire brain was achieved in vivo.

Conclusions:

• SRµCT bridges the methodological gap between optical microscopy and MRI for CNS fluid dynamics research.
• This technique provides unprecedented spatiotemporal information for studying CSF dynamics and solute transport at the whole-brain scale.
• Establishes a framework for integrating mechanistic models with dynamic, high-resolution in vivo imaging data.