Association between perivascular spaces, DTI-derived Indices, and choroid plexus with ventriculomegaly and white matter hyperintensity in idiopathic normal pressure hydrocephalus

This study aimed to investigate perivascular spaces (PVS), Diffusion tensor imaging (DTI)-derived indices, and choroid plexus in patients with iNPH and to assess potential associations between these MRI indices and ventriculomegaly and WMH. This single-center, cross-sectional retrospective study included healthy controls (HCs) and patients with iNPH who underwent 3.0T MRI measurements including MRI-visible PVS volume fraction (PVSVF), fractional volume of free water in white matter (FW-WM), the diffusion tensor image analysis along the perivascular space (DTI-ALPS), and choroid plexus volume fraction (CPVF). Among them, FW-WM and DTI-ALPS are DTI-derived indices. MRI measurements were compared and correlated with ventricular parameters and WMH in both groups using general linear univariate model and partial Spearman rank correlation tests. Fifty-six patients with iNPH (71.5 ± 7.7 years; 34 males) and 47 HCs (69.1 ± 6.3 years; 26 males) were analyzed. Patients with iNPH had significantly higher PVSVF, FW-WM, and CPVF, and a lower DTI-ALPS index than HCs (all p < 0.001). Lower DTI-ALPS (iNPH group: r = -0.625; HCs group r = -0.629; all p corrected for false discovery rate (FDR) < 0.001) and higher CPVF (iNPH group: r = 0.462, pFDR < 0.001; HCs group r = 0.444, pFDR = 0.027) were correlated with a larger relative ventricular volume. Lower DTI-ALPS (r = 0.390, pFDR = 0.030) and higher CPVF (r = -0.385, pFDR = 0.023) correlated with lower relative extra-ventricular CSF volume only in the iNPH group. iNPH exhibited higher PVS, FW-WM, and CPVS and lower DTI-ALPS. Lower DTI-ALPS and higher CPVS may play important roles in ventriculomegaly and alterations in CSF distribution in iNPH.