Evaluation of Interstitial Fluid Volume and Diffusivity in Patients With Idiopathic Normal Pressure Hydrocephalus...

Area of Science:

• Neuroimaging
• Fluid dynamics
• Neurology

Background:

• Interstitial fluid (ISF) dynamics may play a role in idiopathic normal pressure hydrocephalus (iNPH).
• Spectral diffusion analysis offers surrogate markers for ISF volume (F_int) and diffusivity (D_int).

Purpose of the Study:

• To compare ISF volume (F_int) and diffusivity (D_int) between iNPH patients and healthy controls (HCs).

Main Methods:

• Retrospective analysis of 34 iNPH patients and 132 HCs using 3.0 T MRI.
• Spectral diffusion analysis to compute F_int and D_int in eight brain regions.
• Statistical comparison using Kruskal-Wallis and Dunn's tests, with Spearman correlation for age effects.

Main Results:

• In iNPH patients with periventricular hyperintensity (PVH) regions (iNPH_PVH), F_int and D_int were significantly higher in the centrum semiovale (CSO) and frontal white matter (FWM) compared to controls and non-PVH iNPH groups.
• F_int in the lenticular nucleus (LN) showed a positive correlation with age in both iNPH and control groups.
• ISF dynamics outside PVH regions did not show significant differences between iNPH patients and HCs.

Conclusions:

• Spectral diffusion analysis reveals increased ISF volume and diffusivity in PVH regions of the CSO and FWM in iNPH.
• ISF dynamics in non-PVH regions may not be significantly altered in iNPH compared to HCs.
• These findings highlight region-specific ISF alterations in iNPH.