Assessment of interstitial fluid dynamics in patients with idiopathic normal pressure hydrocephalus using spectral diffusion analysis

Motivation: Spectral diffusion analysis provides a parameter (Fint) that represents interstitial fluid (ISF) volume. Goal(s): We aimed to clarify the ISF dynamics in patients with idiopathic normal pressure hydrocephalus (iNPH). Approach: We compared Fint values between patients with iNPH and healthy controls (HCs) and evaluated the age dependency of Fint. Results: Significant increases in Fint were observed only in the periventricular hyperintensity (PVH) regions of patients with iNPH, indicating that ISF dynamics may not differ significantly between patients with iNPH and HCs in regions other than the PVH. Additionally, age-dependent changes in ISF volume were observed only in the pons. Impact: The interstitial fluid (ISF) dynamics between patients with idiopathic normal pressure hydrocephalus and healthy controls may not be significantly different in regions other than the periventricular hyperintensity. Additionally, age-dependent changes in ISF volume were observed only in the pons.