Arterial Spin Labeled Cerebral Blood Flow to Diagnose Normal-Pressure Hydrocephalus: A Pilot Study

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Normal-pressure hydrocephalus (NPH) diagnosis is challenging due to limited objective measures post-cerebrospinal fluid (CSF) drainage.
• Arterial Spin Labeled Magnetic Resonance Imaging (ASL-MRI) offers a novel, non-invasive, and radiation-free method to assess cerebral blood flow (CBF).

Purpose of the Study:

• To evaluate the utility of ASL-MRI in measuring global CBF changes before and after large-volume lumbar puncture (LVLP) in patients with suspected NPH.
• To correlate CBF changes with clinical improvements in gait, balance, cognition, and urinary incontinence.

Main Methods:

• ASL-MRI was used to measure baseline CBF in 20 NPH-suspected patients.
• CBF was re-measured after LVLP (20-53 mL CSF drainage) under fluoroscopy.
• Regional CBF was analyzed, and correlations with clinical outcomes were assessed.

Main Results:

• Global CBF significantly increased post-LVLP (mean 39 to 45 mL/100g/min, p <0.01).
• CBF enhancement was observed in gray matter, thalamus, and periventricular white matter.
• A dose-response relationship was noted, with greater CSF drainage (≥50 mL) yielding higher CBF increases.

Conclusions:

• ASL-MRI confirmed global cerebral hypoperfusion in NPH, which is a constant feature.
• Cerebral perfusion consistently enhanced post-lumbar puncture across all evaluated regions.
• Improved CBF correlated positively with gait speed and balance, suggesting ASL-MRI can simplify NPH diagnosis.