Associations Among Diffusion Tensor Image Along the Perivascular Space (DTI-ALPS), Enlarged Perivascular Space (ePVS), and Cognitive Functions in Asymptomatic Patients With Carotid Plaque

Background and Aim: Carotid atherosclerosis (CAS) is a common pathogenesis of cerebrovascular disease closely related to stroke and silent cerebrovascular disease (SCD), while the insufficient brain perfusion mechanism cannot quite explain the mechanism. The purpose of this study was to utilize diffusion tensor image analysis along the perivascular space (DTI-ALPS) to evaluate the glymphatic system activity and correlated DTI-ALPS with enlarged perivascular spaces (ePVS), carotid intima-media thickening (CIMT), mini-mental state examination (MMSE), and serological indicator in individuals with carotid plaque.Methods: Routine MRI and diffusion tensor images scan of the brain, carotid ultrasound, and blood examination were conducted on 74 individuals (52 carotid plaque subjects, 22 non-carotid plaque subjects), whose demographic and clinical characteristics were also recorded. DTI-ALPS index between patients with carotid plaque and normal controls were acquired and the correlations with other variables were analyzed.Results: The values of ALPS-index in the carotid plaque group was significantly lower compared to normal controls (2.12 ± 0.39, 1.95 ± 0.28, respectively, p = 0.034). The ALPS-index was negatively correlated with the basal ganglia (BG)-ePVS score (r = −0.242, p = 0.038) while there was no significant difference in the centrum semiovale (CSO)-ePVS score. Further analysis showed that there are more high-grade ePVS in the BG compared to the carotid plaque group than in the non-carotid plaque group (84.6% vs. 40.9%, p = 0.001).Conclusions: ALPS-index reflects the glymphatic system of the brain, which is associated with early high-risk cerebrovascular diseases. There may be damage in the function of the glymphatic system which induces the expansion of the perivascular space (PVS) in the BG in individuals with carotid plaque.

Associations among Cognitive Functions, Plasma DNA, and Diffusion Tensor Image along the Perivascular Space (DTI-ALPS) in Patients with Parkinson’s Disease

Background. Parkinson’s disease (PD) is a common neurodegenerative disease associated with accumulation of misfolding proteins and increased neuroinflammation, which may further impair the glymphatic system. The purpose of this study was to utilize diffusion tensor image analysis along the perivascular space (DTI-ALPS) to evaluate glymphatic system activity and its relationship with systemic oxidative stress status in PD patients. Methods. Magnetic resonance imaging and neuropsychological tests were conducted on 25 PD patients with normal cognition (PDN), 25 PD patients with mild cognitive impairment (PD-MCI), 38 PD patients with dementia (PDD), and 47 normal controls (NC). Oxidative stress status was assessed by plasma DNA level. Differences in ALPS-index among the subgroups were assessed and further correlated with cognitive functions and plasma DNA levels. Results. The PD-MCI and PDD groups showed significantly lower ALPS-index compared to normal controls. The ALPS-index was inversely correlated with plasma nuclear DNA, mitochondrial DNA levels, and cognitive scores. Conclusions. Lower diffusivity along the perivascular space, represented by lower ALPS-index, indicates impairment of the glymphatic system in PD patients. The correlation between elevated plasma nuclear DNA levels and lower ALPS-index supports the notion that PD patients may exhibit increased oxidative stress associated with glymphatic system microstructural alterations.

Associations among Cognitive Functions, Plasma DNA, and Diffusion tensor image along the perivascular space (DTI-ALPS) in Patients with Parkinson's Disease

Background Parkinson’s disease (PD) is a common neurodegenerative disease associated with accumulation of misfolding proteins and increased neuroinflammation. The purpose of this study was to utilize diffusion tensor image analysis along the perivascular space (DTI-ALPS) to evaluate glymphatic system activity, and its relationship with systemic oxidative stress status in PD patients. Methods Magnetic resonance imaging and neuropsychological tests were conducted on 25 PD patients with normal cognition (PDN), 25 PD patients with mild cognitive impairment (PD-MCI), 38 PD patients with dementia (PDD), and 47 normal controls (NC). Oxidative stress status was assessed by plasma DNA level. Differences in ALPS-index among the subgroups were assessed and further correlated with cognitive functions and plasma DNA levels. Results The PD-MCI and PDD groups showed significantly lower ALPS-index compared to normal controls. The lower ALPS-index was correlated with higher plasma nuclear DNA, mitochondrial DNA levels, and lower cognitive scores. Conclusions Lower diffusivity along the perivascular space, represented by lower ALPS-index, indicates impairment of the glymphatic system in PD patients. The correlation between elevated plasma nuclear DNA levels and lower ALPS-index support the notion that PD patients may exhibit increased oxidative stress associated with glymphatic system microstructural alterations.

Understanding gamma ventral capsulotomy: Potential implications of diffusion tensor image tractography on target selectivity

Background: The role of tractography in gamma ventral capsulotomy (GVC) planning is still unclear. This paper aims to describe the spatial distribution of medial orbitofrontal cortex (OFC) and lateral OFC fibers passing through the anterior limb of the internal capsule (ALIC) and analyze quantitative tractography parameters that differentiate obsessive-compulsive disorder (OCD) individuals from other neurosurgery functional patients (morbid obesity and Parkinson’s disease [PD]). Methods: Twenty patients undergoing functional stereotactic procedures, between 2013 and 2016, were included in this study. OCD patients underwent GVC (single shot 150 Gy and 4-mm collimators). PD and morbid obesity patients were submitted to deep brain stimulation implants. Diffusion tensor image tractography was reconstructed using Brainlab Elements software (Brainlab AG, Munich, Germany). Results: Nine PD, six morbid obesity, and five OCD patients were included with a mean age of 65.4 ± 9.1, 41.0 ± 8.2, and 31.2 ± 5.5, respectively, which are statistically different from each other (P < 0.001). Fourteen patients (70%) were men. A total of 40 cerebral hemispheres were analyzed. Medial OFC fibers are localized more inferior in the ALIC than the lateral OFC fibers in all hemispheres, but the level of intersection and exact topography of fiber bundles are variable among individuals. Both medial and lateral OFC fiber tracts of PD and morbid obesity patients have lower volume than, respectively, medial and lateral counterparts of OCD patients (P < 0.001). Conclusions: Medial and lateral OFC tract fibers have a general standard distribution in the anterior internal capsule (lateral OFC higher than medial OFC fibers). There are differences between obesity, Parkinson, and OCD patients regarding fiber tract statistics.