Increased interstitial fluid in periventricular and deep white matter hyperintensities in patients with suspected idiopathic normal pressure hydrocephalus

Abstract

Periventricular white matter changes are common in patients with idiopathic normal pressure hydrocephalus (iNPH) and considered to represent focally elevated interstitial fluid. We compared diffusion measures in periventricular hyperintensities in patients with imaging features of iNPH to patients without. The hypothesis is that periventricular hyperintensities in patients with presumed iNPH show higher water content than in patients without imaging features of iNPH. 21 patients with iNPH Radscale 7–12 (“high probability of iNPH”) and 10 patients with iNPH Radscale 2–4 (“low probability of iNPH”) were examined with a neurodegeneration imaging protocol including a diffusion microstructure imaging sequence. Periventricular hyperintensities and deep white matter hyperintensities were segmented and diffusion measures were compared. In patients with imaging features of iNPH, the free water content in periventricular hyperintensities was significantly higher compared to the control group (p = 0.005). This effect was also detectable in deep white matter hyperintensities (p = 0.024). Total brain volumes and total gray or white matter volumes did not differ between the groups. Periventricular cap free water fraction was highly discriminative regarding patients with presumed iNPH and controls with an ROC AUC of 0.933. Quantitative diffusion microstructure imaging shows elevated water content in periventricular hyperintensities in patients with imaging features of iNPH, which could be the imaging correlate for pathologic fluid accumulation and may be used as an imaging biomarker in the future.

New insights in addressing cerebral small vessel disease: Associated with extracellular fluid in white matter

“…Although the petrophysical mechanism of WMH remains unclear, a hyperintensity on T2 Flair image, WMH, often indicated an increased water volume, according to the principle of MRI. This finding corroborates similar findings from previous studies ( Rau et al, 2021 ). However, all CSVD MR markers were only lesions in white matter.…”

Deep Medullary Vein Score is Associated with Burden of White Matter Hyperintensities

“…This long-term uctuation gradually increases the pressure in the DMVs, resulting in collagen deposition in the venous wall [19]. The long-term increase in venous pressure can also lead to disordered venous re ux with a subsequent decrease in cerebral blood ow and eventually chronic hypoperfusion injury of the white matter [20][21].Moreover, increasing venous pressure leads to increased vascular permeability, which causes blood components to leak into the extravascular white matter, aggravating white matter injury [22][23]. Excessive extracellular uid accumulation will also lead to abnormal remodeling of microveins [24], thus increasing the pressure of the venous circulation and further aggravating white matter injury.…”

Diffusion Microstructure Imaging to Analyze Perilesional T2 Signal Changes in Brain Metastases and Glioblastomas

“…From this, DMI derives a standard model for white matter consisting of the intra-axonal volume fraction (V-intra) with nearly one-dimensional molecular diffusion due to the narrow membrane boundaries, and the extra-axonal volume fraction (V-extra) corresponding to the extra-axonal cellular compartment and the extracellular matrix and characterized by restricted diffusion and the free water/CSF fraction (V-CSF). DMI has recently been used in clinical research to study normal pressure hydrocephalus (NPH) [ 18 ] and temporal lobe epilepsy [ 19 ] and is a promising diffusion imaging technique that could find application in numerous white matter pathologies.…”