Quantitative assessment of idiopathic normal pressure hydrocephalus and obstructive hydrocephalus based on glymphatic parameters.

BACKGROUND

To compare glymphatic system parameters (the Diffusion Tensor Imaging-Analysis of Lymphatic System [DTI-ALPS] index, perivascular space [PVS], choroid plexus volume [CPV]) between idiopathic normal pressure hydrocephalus (iNPH) patients and obstructive hydrocephalus (OBS) patients, and develop a diagnostic model for their differentiation based on parameter performance.

MATERIALS AND

METHODS

This retrospective study included 30 iNPH patients, 14 OBS patients, and 23 healthy controls undergoing 3.0T MRI with diffusion tensor imaging (DTI) and 3D T1-weighted sequences. Automated quantification of the ALPS index, basal ganglia PVS (BGPVS), and CPV was performed. Multivariate logistic regression analysis was used to build a diagnostic model.

RESULTS

iNPH and OBS patients showed significantly lower mean ALPS index scores compared with healthy controls (median [interquartile range] iNPH: 1.10 [0.92-1.48]; OBS: 1.17 [0.99-1.57]; HC: 1.57 [1.20-1.79], p < 0.001 for both comparisons with HC). BGPVS volume increased in iNPH and decreased in OBS compared with healthy controls (median [interquartile range] iNPH:56.27 [2.00-190.00]; OBS:23.57 [5.00-66.00]; HC:36.78 [4.00-99.00], iNPH vs. HC,p = 0.129,OBS vs. HC p = 0.524,iNPH vs. OBS p = 0.017). CPV was elevated in both groups. Multivariable logistic regression identified both age and BGPVS volume as independent predictors, which were subsequently incorporated into a diagnostic model for differentiating iNPH and OBS.( AUC 0.90 [95%CI:0.79-1.00]).

CONCLUSION

BGPVS may augment current diagnostic workflows for shunt-responsive iNPH. BGPVS volume discriminates iNPH from OBS [AUC = 0.90], warranting further validation.