Semi-automated assessment of the principal diffusion direction in the corpus callosum: differentiation of idiopathic normal pressure hydrocephalus from neurodegenerative diseases

• Published in: Journal of neurology Vol. 269; no. 4; pp. 1978 - 1988
• Main Authors: Caligiuri, Maria Eugenia, Quattrone, Andrea, Mechelli, Alessandro, La Torre, Domenico, Quattrone, Aldo
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2022; Springer Nature B.V
• Subjects: Alzheimer's disease; Anisotropy; Automation; Corpus callosum; Corpus Callosum - diagnostic imaging; Diffusion Tensor Imaging - methods; Humans; Hydrocephalus; Hydrocephalus, Normal Pressure - diagnostic imaging; Magnetic Resonance Imaging; Medicine; Medicine & Public Health; Neurodegenerative diseases; Neurodegenerative Diseases - diagnostic imaging; Neurology; Neuroradiology; Neurosciences; Original Communication; Paralysis; Patients; Progressive supranuclear palsy; Spatial distribution; Principal diffusion direction; Alzheimer’s disease; Progressive supranuclear palsy; Corpus callosum; Diffusion tensor imaging; Idiopathic normal pressure hydrocephalus
• ISSN: 0340-5354; 1432-1459; 1432-1459
• DOI: 10.1007/s00415-021-10762-9

Background Idiopathic normal pressure hydrocephalus (iNPH) shares clinical and radiological features with progressive supranuclear palsy (PSP) and Alzheimer’s disease (AD). Corpus callosum (CC) involvement in these disorders is well established on structural MRI and diffusion tensor imaging (DTI), but alterations overlap and lack specificity to underlying tissue changes. Objective We propose a semi-automated approach to assess CC integrity in iNPH based on the spatial distribution of DTI-derived principal diffusion direction orientation (V1). Methods We processed DTI data from 121 subjects (Site1: iNPH = 23, PSP = 27, controls = 14; ADNI: AD = 35, controls = 22) to obtain V1, fractional anisotropy (FA) and mean diffusivity (MD) maps. To increase the estimation accuracy of DTI metrics, analyses were restricted to the midsagittal CC portion (± 6 slices from midsagittal plane). Group-wise comparison of normalized altered voxel count in midsagittal CC was performed using Kruskal–Wallis tests, followed by post hoc comparisons (Bonferroni-corrected p  < 0.05). ROC analysis was used to evaluate the diagnostic power of DTI alterations compared to callosal volume. Results We found specific changes of V1 distribution in CC splenium of iNPH compared to AD and PSP, while MD and FA showed patterns of alterations common to all disorders. ROC curves showed that, compared to splenial volume, V1 represented the most accurate marker of iNPH diagnosis versus AD and PSP. Conclusions Our results provide evidence that V1 is a powerful biomarker for distinguishing patients with iNPH from patients with AD or PSP. Indeed, our findings also provide more specific insight into the pathophysiological mechanisms that underlie tissue damage across iNPH and its mimics.