Assessing white matter microstructural changes in idiopathic normal pressure hydrocephalus using voxel-based R2*...

Area of Science:

• Neuroimaging
• Neuroscience
• Medical Physics

Background:

• Idiopathic normal-pressure hydrocephalus (iNPH) is a neurological disorder characterized by gait disturbance, cognitive impairment, and urinary incontinence.
• Distinguishing white matter microstructural changes from iron deposition is crucial for understanding iNPH pathophysiology.
• R2* relaxometry and quantitative susceptibility mapping (QSM) offer complementary approaches for in vivo tissue characterization.

Purpose of the Study:

• To investigate white matter microstructural alterations in iNPH patients using R2* relaxometry and QSM.
• To explore the association between these microstructural changes and clinical symptoms, specifically cognitive impairment and gait disturbance.

Main Methods:

• 16 patients with possible or probable iNPH and 18 age- and sex-matched healthy controls (HC) were evaluated.
• R2* relaxometry and QSM data were analyzed using voxel-wise and atlas-based methods.
• Partial correlation analyses assessed the relationship between R2* values and clinical scores.

Main Results:

• R2* values were lower in the bilateral superior longitudinal fascicle (SLF) and sagittal stratum (SS) in the iNPH group compared to HC.
• QSM revealed no significant differences between groups, indicating no clear iron deposition.
• Positive correlations were found between R2* and cognitive scores (left SLF, right SS), and negative correlations between R2* and gait disturbance scores (left SS).

Conclusions:

• Microstructural changes, not iron deposition, are present in the SLF and SS in iNPH.
• These white matter alterations are associated with cognitive impairment and gait disturbances in iNPH patients.
• Combined R2* relaxometry and QSM can elucidate the underlying pathophysiology of iNPH.