Table 1 Investigation of the glymphatic system: different imaging techniques with their advantages and disadvantages
Investigation tool | Technique | Pros | Cons | |
|---|---|---|---|---|
Imaging | Optical imaging | Two-photon microscopy | Tracking tracers with high spatial and temporal resolution | Limited field of view Invasive technique |
MRI | FLAIR | Facilitates the visualization of perivascular spaces and the assessment of glymphatic function | Low specificity | |
CE-MRI and DCE-MRI | Noninvasive technique Whole brain images 3D visualization | Low spatial and temporal resolution Movement artifacts | ||
DTI-ALPS | Quantify the diffusion of water molecules within the brain's interstitial space, providing valuable insights into glymphatic function | Low specificity | ||
Arterial spin labeling, chemical exchange saturation transfer, intravoxel incoherent motion | Blood brain barrier permeability, assess of solutes concentration at two order of magnitude lower than traditional MRI, diffusion/perfusion effect evaluation of blood motion | Indirect measurements of the glymphatic system function Need of integration with other techniques | ||
ULTRA-HIGH MRI | Better detection of PVS abnormalities | Movement artifacts, dishomogeneity in magnetic field, difficulty to identify subcortical PVS, radiofrequency absorption rate and lower compatibility of medical devices | ||
Positron emission tomography | Use of radiolabeled tracers | Whole brain images Quantify the glymphatic system clearence | Low spatial resolution Movement artifacts | |
Ultrasound Imaging | Transcranial Doppler ultrasound | Study glymphatic pulsations and CSF dynamics in humans | Low specificity | |