Diffusion kurtosis imaging suggests sex‐specific alteration of white matter in mild cognitively impaired participants: Neuroimaging / New imaging methods. (7th December 2020)

• Record Type: Journal Article
• Authors: Mishra, Virendra R; Ritter, Aaron; Cordes, Dietmar; Caldwell, Jessica ZK
• Is Part Of: Alzheimer's & dementia. Volume 16(2020)Supplement 4
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-12-07
• Subjects: Alzheimer's disease -- Periodicals; Alzheimer Disease -- Periodicals; Dementia -- Periodicals; Démence; Maladie d'Alzheimer; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 616.83
• DOI: 10.1002/alz.046130
• Languages: English
• ISSNs: 1552-5260

Abstract

Abstract: Background: Sex differences in Alzheimer's disease (AD)‐dementia is well documented. However, whether sex differences in white‐matter (WM) microstructural integrity could serve as potential biomarker to identify sex‐specific participants progressing to AD‐dementia is currently unexplored. Method: 78 participants were recruited at our center, of which 38 were diagnosed with MCI based on expert consensus, using results of a neuropsychological test battery and the Clinical Dementia Rating (CDR) interview (Table.1). Isotropic 1.5mm 3 multi‐shell dMRI (b‐values=500s/mm 2, 1000s/mm 2, and 2500s/mm 2 ) each with 71 directions was acquired for each participant. Diffusion kurtosis (DKI) model was fitted from every participant along with conventional single‐tensor (ST) diffusion tensor imaging (DTI) model. DKI metrics such as axonal water fraction (AWF), axonal kurtosis (AK), radial kurtosis (RK), and mean kurtosis (MK) was estimated at every voxel. Tract‐based Spatial Statistics (TBSS) was used to extract the WM skeleton from ST‐fractional anisotropy (FA), and various DKI‐derived metrics were mapped to a common space using the registration parameters from ST‐FA. Nonparametric statistical comparisons were conducted between each group to test for mean difference in these metrics. Significance was established at familywise error corrected (FWE) p<0.05. Result: Male‐HC showed a significantly higher AK as compared to female‐HC in the WM regions encompassing corpus‐callosum, cingulum, inferior longitudinal fasciculus, and thalamic and cerebellar WM fibers. However male‐MCI only showed a higher AK in the thalamic and cerebellar WM fibers (Fig.1). There were also significant differences in other metrics such as MK and RK, both within (male vs female HC and MCI) and between groups of HC and MCI (Fig.1). Significantly lower AWF was observed in male‐HC as compared to female‐HC, and in male‐MCI as compared to female‐HC in the entire WM skeleton but selectively sparring the corpus callosum (Fig.1). DTI metrics showed no significant sex‐specific differences within groups in our cohort. Conclusion: Multi‐shell dMRI imaging is a promising avenue to explore sex‐specific alterations in the WM microstructural integrity in MCI participants, and could be utilized to identify the most promising imaging biomarker to predict AD‐dementia which is sex‐specific. Similar analysis with other complex models such as free‐water corrected DTI and NODDI models are currently underway.