Neurofluid fluctuation analysis using dynamical network biomarker MRI in idiopathic normal pressure hydrocephalus

Area of Science:

• Neuroimaging
• Biomarker Discovery
• Neurology

Background:

• Idiopathic normal pressure hydrocephalus (iNPH) is a neurological condition characterized by abnormal cerebrospinal fluid dynamics.
• Current diagnostic methods for iNPH may not fully capture the dynamic changes in intracranial fluid.
• Dynamical network biomarker (DNB) theory offers a framework for detecting early signs of system transition.

Purpose of the Study:

• To adapt dynamical network biomarker (DNB) theory for diffusion MRI (dMRI).
• To develop a novel diffusion MRI-derived DNB (dMRI-DNB) index.
• To evaluate the utility of the dMRI-DNB index for assessing neurofluid fluctuation in iNPH.

Main Methods:

• Seventeen iNPH patients and ten controls underwent electrocardiogram-triggered diffusion echo-planar imaging.
• Fast and slow diffusion coefficients (Df and Ds) were calculated for each cardiac phase.
• The dMRI-DNB index was computed as the product of the mean coefficient of variation (CVmean) and correlation coefficient (CC) of Df and Ds in the frontal white matter.

Main Results:

• The dMRI-DNB index was significantly higher in the iNPH group (10.3 ± 3.1) compared to controls (6.5 ± 1.9).
• Both CVmean (15.3% ± 3.8% vs. 11.1% ± 2.9%) and CC (0.661 ± 0.090 vs. 0.576 ± 0.055) were significantly elevated in iNPH patients.
• No significant correlation was found between CVmean and CC within either group.

Conclusions:

• The dMRI-DNB index, integrating neurofluid fluctuation amplitude and correlation, is elevated in iNPH.
• This index represents a novel approach for evaluating intracranial conditions.
• dMRI-DNB may serve as a sensitive biomarker for detecting alterations in neurofluid dynamics.