Evaluation of Glymphatic System Using Diffusion MR Technique in T2DM Cases

Abstract

Objective: We aimed to evaluate the activity of the human glymphatic system in type 2 diabetes mellitus (T2DM) using diffusion tensor image analysis along with the perivascular space (DTI-ALPS). Methods: Diffusion tensor images were acquired to calculate the diffusivities in the direction of the x-axis (right-to-left; Dx), y-axis (anterior-to-posterior; Dy), and z-axis (inferior-to-superior; Dz) of the plane of the lateral ventricle body in 20 patients with type 2 diabetes and 10 people in a control group. We evaluated the diffusivity along with the perivascular spaces, as well as the projection fibers and association fibers, separately. The analysis along the perivascular space (ALPS-index) was defined as the mean (Dxpro, Dypro)/mean (Dypro, Dzasc), where the Dxpro and Dxasc were the Dx values in the projection and association fiber areas, respectively. Results: There were significant differences in diffusivity along the projection fibers and the association fibers among the groups. The significant differences among the groups along the perivascular spaces, shown as the ALPS-index and medical history of T2DM, indicating lower water diffusivity along the perivascular space concerning type 2 diabetes severity, was also observed. Conclusion: Lower diffusivity along the perivascular space on DTI-APLS can reflect impairment of the glymphatic system in T2DM. This study showed that the activity of the glymphatic system could be evaluated by diffusion tensor image analysis.

The Influence of Demographics and Vascular Risk Factors on Glymphatic Function Measured by Diffusion Along Perivascular Space

“…This was possibly due to the low number of diabetic subjects, and that most subjects had relatively good sleep conditions. While a recent study ( Yang et al, 2020 ) suggests that patients with type 2 diabetes mellitus had reduced ALPS, their sample size was also very small. Future studies should investigate the influence of these factors in more dedicated large samples.…”

Reproducibility of diffusion tensor image analysis along the perivascular space (DTI-ALPS) for evaluating interstitial fluid diffusivity and glymphatic function: CHanges in Alps index on Multiple conditiON acquIsition eXperiment (CHAMONIX) study

“…The DTI-ALPS method is used for evaluating the glymphatic system's function or the interstitial fluid dynamics, and this method has been adopted in several studies evaluating the alteration of the glymphatic system or interstitial fluid dynamics in various pathologies [21][22][23][24][25][26][27][28]. One of the report showed that results of ALPS method were significantly related to glymphatic clearance function calculated on MRI by intrathecal administration of GBCA [28].…”

“…The DTI-ALPS method provides ALPS index, which is a ratio of the diffusivity in the direction of the perivascular space and the diffusivity in the direction perpendicular to both major fiber tract and perivascular space, based on a special spatial relationship in the fiber tracts and the perivascular space in the axial imaging plane at the corona radiata [19,20]. Recently, the DTI-ALPS method has been adopted in several studies evaluating the alteration of the glymphatic system or interstitial fluid dynamics in various pathologies [21][22][23][24][25][26][27][28]. These reports indicated that the ALPS-index is a useful biomarker to evaluate the interstitial fluid dynamics or glymphatic function.…”

Factors Associated With Dysfunction of Glymphatic System in Patients With Glioma

“…Although this method is based on a deductive model, it is frequently used to investigate human glymphatic function. Its potential to serve as an imaging marker of glymphatic activity has been reported in many clinical conditions such as Alzheimer’s disease ( 10 , 30 ), normal pressure hydrocephalus ( 31 , 32 ), Parkinson disease ( 33 , 34 ), age-related iron deposition ( 15 ), diabetic cognitive impairment ( 35 ), and meningioma-associated brain edema ( 17 ). However, there are limitations to this method and, consequently, our study.…”