Enhancing Glaucoma Sensitivity: MK-Curve Corrected Diffusion Kurtosis Imaging of Optic Radiation
Poster No:
1289
Submission Type:
Abstract Submission
Authors:
Loxlan Kasa1, Samantha Holdsworth1, William Schierding2, Eryn Kwon1, Helen Danesh-Meyer3
Institutions:
1Mātai Medical Research Institute, Gisborne, New Zealand, 2Department of Ophthalmology, The University of Auckland, Auckland, New Zealand, 3Vision Research Foundation, Auckland, New Zealand
First Author:
Co-Author(s):
Introduction:
Recent studies have demonstrated that diffusion kurtosis imaging (DKI) can detect changes in the visual pathways, including the optic radiation (OR), providing insights into early glaucomatous biomarkers (Kang & Wan, 2022). However, DKI is more prone to noise, diminishing its sensitivity to identify true microstructural changes. To address this, we applied a newly developed noise correction method (MK-Curve) (Zhang et al., 2019) when analyzing the UK Biobank (UKBB) diffusion MRI dataset. This study evaluates the sensitivity of MK-Curve corrected DKI in detecting microstructural abnormalities along the OR in glaucoma patients.
Methods:
A cohort of 427 glaucoma patients and 427 age- and sex-matched healthy controls were selected from the UKBB database. Imaging was performed on a 3T Siemens Skyra scanner with a 32-channel receiver head coil. Structural images were acquired using the MPRAGE sequence (FOV=208x256mm², slice thickness=1mm). Diffusion MRI parameters included TR/TE=3600/92ms, FOV=104×104mm², 2mm³ voxels, and a multiband EPI sequence (acceleration factor=3). A total of 100 diffusion-weighted volumes were acquired in AP phase encoding directions at b=1000 and b=2000s/mm², along with 5 b=0s/mm² volumes, and 3 additional b=0s/mm² in PA phase encoding direction for EPI distortion correction (Miller et al., 2016). Preprocessing included motion and eddy current correction using FSL "eddy," followed by gradient distortion correction. Both MK-Curve corrected and uncorrected DKI mean kurtosis (MK), axial kurtosis (AK), and radial kurtosis (RK), including DTI mean diffusivity (MD), were generated using MATLAB R2024a. Anatomically constrained tractography was performed before extracting the OR with recoBundleX (Garyfallidis et al., 2018). The uncinate fasciculus (UF), used as the baseline, along with the inferior fronto-occipital fasciculus (IFOF), were also extracted. For tractometry analysis, we cluster the OR model bundle from the recoBundleX atlas into centroids with 100 points each using Quickbundles (Garyfallidis et al., 2012). Each point on a subject's OR streamline was assigned a disk (segments) number based on its proximity to the model centroid, using Euclidean distance. Both corrected and uncorrected DKI maps were sampled at each of the 100 OR segments. Linear mixed models (LMMs) were used for group-wise statistical analyses, treating each DKI map as the response variable, with group, age, and sex as fixed effects, and subjects as random effects. We also compared corrected and original MK-Curve data in repeated measures within subjects using LMMs. The same analysis was done for the IFOF and UF bundles.
Results:
Comparison of MK-Curve corrected and uncorrected DKI measurements from the left OR (Fig. 1) showed significant differences (p < 0.001) in MK, RK, and AK maps. The uncorrected MK-Curve data had the strongest negative impact on RK, followed by MK, and least on AK. A similar trend was observed for the right OR. Significant differences (p < 0.001) were found between glaucoma patients and controls at specific locations along both ORs for MK (Fig. 2) and RK. In non-visual pathways, significant differences (p < 0.001) were found in IFOF, but not in the baseline bundle (UF).
Conclusions:
Corrected DKI measurements showed a significant increase in MK and RK in the OR compared to uncorrected maps. This suggests that MK-Curve correction should be considered in DKI preprocessing to improve sensitivity to microstructural changes in glaucoma. Using corrected DKI and recoBundleX tractometry revealed significant microstructural changes in the OR and IFOF bundles, with increased MK and RK in specific regions suggesting higher microstructural complexity in glaucoma patients. These findings indicate that glaucoma-related damage extends beyond the visual pathway (Bagetta & Nucci, 2020). MK-Curve correction enhances DKI sensitivity and could aid in detecting subtle microstructural changes in the OR and related networks in glaucoma.
Disorders of the Nervous System:
Neurodegenerative/ Late Life (eg. Parkinson’s, Alzheimer’s) 2
Modeling and Analysis Methods:
Diffusion MRI Modeling and Analysis 1
Motion Correction and Preprocessing
Keywords:
Degenerative Disease
MRI
Vision
WHITE MATTER IMAGING - DTI, HARDI, DSI, ETC
Other - Glaucoma
1|2Indicates the priority used for review
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