Topology of diffusion changes in corpus callosum in Alzheimer's disease: An exploratory case-control study

Sumeet Kumar; Alberto De Luca; Alexander Leemans; Seyed Ehsan Saffari; Septian Hartono; Fatin Zahra Zailan; Kok Pin Ng; Nagaendran Kandiah

doi:10.3389/fneur.2022.1005406

Topology of diffusion changes in corpus callosum in Alzheimer's disease: An exploratory case-control study

Front Neurol. 2022 Nov 30:13:1005406. doi: 10.3389/fneur.2022.1005406. eCollection 2022.

Authors

Sumeet Kumar^{1

2}, Alberto De Luca³, Alexander Leemans³, Seyed Ehsan Saffari^{1

2}, Septian Hartono^{1

2}, Fatin Zahra Zailan⁴, Kok Pin Ng^{1

2}, Nagaendran Kandiah⁴

Affiliations

¹ National Neuroscience Institute, Singapore, Singapore.
² Duke-NUS Graduate Medical School, Singapore, Singapore.
³ Image Sciences Institute, UMC Utrecht, Utrecht, Netherlands.
⁴ Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.

Abstract

Aim: This study aims to assess the integrity of white matter in various segments of the corpus callosum in Alzheimer's disease (AD) by using metrics derived from diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI) and white matter tract integrity model (WMTI) and compare these findings to healthy controls (HC).

Methods: The study was approved by the institutional ethics board. 12 AD patients and 12 HC formed the study population. All AD patients were recruited from a tertiary neurology memory clinic. A standardized battery of neuropsychological assessments was administered to the study participants by a trained rater. MRI scans were performed with a Philips Ingenia 3.0T scanner equipped with a 32-channel head coil. The protocol included a T1-weighted sequence, FLAIR and a dMRI acquisition. The dMRI scan included a total of 71 volumes, 8 at b = 0 s/mm², 15 at b = 1,000 s/mm² and 48 at b = 2,000 s/mm². Diffusion data fit was performed using DKI REKINDLE and WMTI models.

Results and discussion: We detected changes suggesting demyelination and axonal degeneration throughout the corpus callosum of patients with AD, most prominent in the mid-anterior and mid-posterior segments of CC. Axial kurtosis was the most significantly altered metric, being reduced in AD patients in almost all segments of corpus callosum. Reduced axial kurtosis in the CC segments correlated with poor cognition scores in AD patients in the visuospatial, language and attention domains.

Keywords: Alzheimer's disease; axial kurtosis; corpus callosum; diffusion kurtosis imaging; diffusion tensor imaging; magnetic resonance imaging (MRI); white matter tract integrity.