Variability of Normal Pressure Hydrocephalus Imaging Biomarkers with Respect to Section Plane Angulation: How Wrong a...

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Idiopathic normal pressure hydrocephalus (iNPH) diagnosis relies on imaging biomarkers.
• Variability of these biomarkers due to imaging angulation is not well-documented.

Purpose of the Study:

• To assess the angulation-related variability of iNPH imaging biomarkers.
• To determine the impact of imaging plane angulation on biomarker reliability.

Main Methods:

• Prospective 3T brain MR imaging of 80 subjects (35 iNPH, 45 controls).
• Two readers assessed 12 iNPH biomarkers on sections with varying angulations.
• Sections were aligned relative to bicallosal, bicommissural, hypophysis-fastigium, and brain stem vertical lines.

Main Results:

• Five biomarkers showed no significant angulation-related differences.
• Seven biomarkers, including Evans Index and callosal angle, exhibited significant variability across section planes.
• Brain stem vertical line-aligned sections yielded the most deviating results.

Conclusions:

• Angulation significantly affects 7 of 12 iNPH biomarkers, including commonly used ones like the Evans Index and callosal angle.
• Strict adherence to standardized measurement methodology is essential for accurate iNPH diagnosis.
• Biomarkers like z-Evans Index, frontal horn diameter, and disproportionately enlarged subarachnoid space hydrocephalus show low variability and warrant further attention.