Multi-stage semi-supervised learning enhances white matter hyperintensity segmentation.

Introduction: White matter hyperintensities (WMHs) are frequently observed on magnetic resonance (MR) images in older adults, commonly appearing as areas of high signal intensity on fluid-attenuated inversion recovery (FLAIR) MR scans. Elevated WMH volumes are associated with a greater risk of dementia and stroke, even after accounting for vascular risk factors. Manual segmentation, while considered the ground truth, is both labor-intensive and time-consuming, limiting the generation of annotated WMH datasets.

Enhancing Cognitive Performance Prediction through White Matter Hyperintensity Connectivity Assessment: A Multicenter Lesion Network Mapping Analysis of 3,485 Memory Clinic Patients.

Introduction: White matter hyperintensities of presumed vascular origin (WMH) are associated with cognitive impairment and are a key imaging marker in evaluating cognitive health. However, WMH volume alone does not fully account for the extent of cognitive deficits and the mechanisms linking WMH to these deficits remain unclear. We propose that lesion network mapping (LNM), enables to infer if brain networks are connected to lesions, and could be a promising technique for enhancing our understanding of the role of WMH in cognitive disorders.

Quantifying cerebral microbleeds using quantitative susceptibility mapping from magnetization-prepared rapid gradient-echo.

T1-weighted magnetization-prepared rapid gradient-echo (MPRAGE) is commonly included in brain studies for structural imaging using magnitude images; however, its phase images can provide an opportunity to assess microbleed burden using quantitative susceptibility mapping (QSM). This potential application for MPRAGE-based QSM was evaluated using in vivo and simulated measurements. Possible factors affecting image quality were also explored.

Spatial distributions of white matter hyperintensities on brain MRI: A pooled analysis of individual participant data from 11 memory clinic cohorts.

Introduction: The spatial distribution of white matter hyperintensities (WMH) on MRI is often considered in the diagnostic evaluation of patients with cognitive problems. In some patients, clinicians may classify WMH patterns as "unusual", but this is largely based on expert opinion, because detailed quantitative information about WMH distribution frequencies in a memory clinic setting is lacking. Here we report voxel wise 3D WMH distribution frequencies in a large multicenter dataset and also aimed to identify individuals with unusual WMH patterns.

Brain iron content in cerebral amyloid angiopathy using quantitative susceptibility mapping.

Introduction: Cerebral amyloid angiopathy (CAA) is a small vessel disease that causes covert and symptomatic brain hemorrhaging. We hypothesized that persons with CAA would have increased brain iron content detectable by quantitative susceptibility mapping (QSM) on magnetic resonance imaging (MRI), and that higher iron content would be associated with worse cognition.

Methods: Participants with CAA ( = 21), mild Alzheimer's disease with dementia (AD-dementia; = 14), and normal controls (NC; = 83) underwent 3T MRI.

Subcortical volumes in cerebral amyloid angiopathy compared with Alzheimer's disease and controls.

Background: Previous reports have suggested that patients with cerebral amyloid angiopathy (CAA) may harbor smaller white matter, basal ganglia, and cerebellar volumes compared to age-matched healthy controls (HC) or patients with Alzheimer's disease (AD). We investigated whether CAA is associated with subcortical atrophy.

Methods: The study was based on the multi-site Functional Assessment of Vascular Reactivity cohort and included 78 probable CAA (diagnosed according to the Boston criteria v2.

Gait and falls in cerebral small vessel disease: a systematic review and meta-analysis.

Background: Gait impairment contributes to falls and frailty. Some studies suggest that cerebral small vessel disease (CSVD) is associated with gait impairment in the general population. We systematically reviewed and meta-analysed the literature on associations of CSVD with gait impairment and falls.

Strategic white matter hyperintensity locations for cognitive impairment: A multicenter lesion-symptom mapping study in 3525 memory clinic patients.

Introduction: Impact of white matter hyperintensities (WMH) on cognition likely depends on lesion location, but a comprehensive map of strategic locations is lacking. We aimed to identify these locations in a large multicenter study.

Methods: Individual patient data (n = 3525) from 11 memory clinic cohorts were harmonized.

Gait in Cerebral Amyloid Angiopathy.

Background Gait is a complex task requiring coordinated efforts of multiple brain networks. To date, there is little evidence on whether gait is altered in cerebral amyloid angiopathy (CAA). We aimed to identify impairments in gait performance and associations between gait impairment and neuroimaging markers of CAA, cognition, and falls.

Short-term repeatability and long-term reproducibility of quantitative MR imaging biomarkers in a single centre longitudinal study.

Quantitative imaging biomarkers (QIBs) can be defined as objective measures that are sensitive and specific to changes in tissue physiology. Provided the acquired QIBs are not affected by scanner changes, they could play an important role in disease diagnosis, prognosis, management, and treatment monitoring. The precision of selected QIBs was assessed from data collected on a 3-T scanner in four healthy participants over a 5-year period.

Lifespan Volume Trajectories From Non-harmonized T1-Weighted MRI Do Not Differ After Site Correction Based on Traveling Human Phantoms.

Multi-site imaging consortiums strive to increase participant numbers by pooling data across sites, but scanner related differences can bias results. This study combines data from three research MRI centers, including three different scanner models from two vendors, to examine non-harmonized T1-weighted brain imaging protocols in two cohorts. First, 23 human traveling phantoms were scanned twice each at all three sites (six scans per person; 138 scans total) to quantify within-participant variability of brain volumes (total brain, white matter, gray matter, lateral ventricles, thalamus, caudate, putamen and globus pallidus), and to calculate site-specific correction factors for each structure.

Mediators of cognitive impairment in cerebral amyloid angiopathy.

Background: Cerebral amyloid angiopathy (CAA) is associated with cognitive decline. CAA has diverse impacts on brain structure and function; however, the brain lesions that mediate the association of CAA with cognition are not understood well.

Aims: To determine the degree to which CAA neuroimaging biomarkers mediate the association of CAA with cognitive dysfunction.

Diffusion tensor tractography of the fornix in cerebral amyloid angiopathy, mild cognitive impairment and Alzheimer's disease.

Purpose: Cerebral amyloid angiopathy (CAA) is a common neuropathological finding and clinical entity that occurs independently and with co-existent Alzheimer's disease (AD) and small vessel disease. We compared diffusion tensor imaging (DTI) metrics of the fornix, the primary efferent tract of the hippocampus between CAA, AD and Mild Cognitive Impairment (MCI) and healthy controls.

Methods: Sixty-eight healthy controls, 32 CAA, 21 AD, and 26 MCI patients were recruited at two centers.

Cerebrovascular Reactivity Across the Entire Brain in Cerebral Amyloid Angiopathy.

Background And Objectives: Reduced cerebrovascular reactivity is proposed to be a feature of cerebral amyloid angiopathy (CAA) but has not been measured directly. Employing a global vasodilatory stimulus (hypercapnia), this study assessed the relationships between cerebrovascular reactivity and MRI markers of CAA and cognitive function.

Methods: In a cross-sectional study, individuals with probable CAA, mild cognitive impairment, or dementia due to Alzheimer disease and healthy controls underwent neuropsychological testing and an MRI that included a 5% carbon dioxide challenge.

Cerebral Amyloid Angiopathy Is Associated With Emotional Dysregulation, Impulse Dyscontrol, and Apathy.

Background Cerebral amyloid angiopathy (CAA) causes cognitive decline, but it is not known whether it is associated with neuropsychiatric symptoms (NPS). Methods and Results Participants with CAA, mild cognitive impairment, mild dementia due to Alzheimer's disease, and normal cognition were recruited from stroke and dementia clinics and community advertising. NPS were captured using the Neuropsychiatric Inventory Questionnaire short form.

Effect of Cognitive Reserve on the Association of Vascular Brain Injury With Cognition: Analysis of the PURE and CAHHM Studies.

Background And Objectives: To determine whether cognitive reserve attenuates the association of vascular brain injury with cognition.

Methods: Cross-sectional data were analyzed from 2 harmonized studies: the Canadian Alliance for Healthy Hearts and Healthy Minds (CAHHM) and the Prospective Urban and Rural Epidemiology (PURE) study. Markers of cognitive reserve were education, involvement in social activities, marital status, height, and leisure physical activity, which were combined into a composite score.

Cortical Thickness and Its Association with Clinical Cognitive and Neuroimaging Markers in Cerebral Amyloid Angiopathy.

Background: Cerebral amyloid angiopathy (CAA) contributes to brain neurodegeneration and cognitive decline, but the relationship between these two processes is incompletely understood.

Objective: The purpose of this study is to examine cortical thickness and its association with cognition and neurodegenerative biomarkers in CAA.

Methods: Data were collected from the Functional Assessment of Vascular Reactivity study and the Calgary Normative Study.

Vascular Contributions to Neurodegeneration: Protocol of the COMPASS-ND Study.

Objective: To describe the neuroimaging and other methods for assessing vascular contributions to neurodegeneration in the Comprehensive Assessment of Neurodegeneration and Dementia (COMPASS-ND) study, a Canadian multi-center, prospective longitudinal cohort study, including reliability and feasibility in the first 200 participants.

Methods: COMPASS-ND includes persons with Alzheimer's disease (AD; n = 150), Parkinson's disease (PD) and Lewy body dementias (LBDs) (200), mixed dementia (200), mild cognitive impairment (MCI; 400), subcortical ischemic vascular MCI (V-MCI; 200), subjective cognitive impairment (SCI; 300), and cognitively intact elderly controls (660). Magnetic resonance imaging (MRI) was acquired according to the validated Canadian Dementia Imaging Protocol and visually reviewed by either of two experienced readers blinded to clinical characteristics.

Trial of remote ischaemic preconditioning in vascular cognitive impairment (TRIC-VCI): protocol.

Introduction: Cerebral small vessel disease (cSVD) accounts for 20%-25% of strokes and is the most common cause of vascular cognitive impairment (VCI). In an animal VCI model, inducing brief periods of limb ischaemia-reperfusion reduces subsequent ischaemic brain injury with remote and local protective effects, with hindlimb remote ischaemic conditioning (RIC) improving cerebral blood flow, decreasing white-matter injury and improving cognition. Small human trials suggest RIC is safe and may prevent recurrent strokes.

Age-related differences in cerebral blood flow and cortical thickness with an application to age prediction.

Cerebral cortex thinning and cerebral blood flow (CBF) reduction are typically observed during normal healthy aging. However, imaging-based age prediction models have primarily used morphological features of the brain. Complementary physiological CBF information might result in an improvement in age estimation.

Calgary Normative Study: design of a prospective longitudinal study to characterise potential quantitative MR biomarkers of neurodegeneration over the adult lifespan.

Introduction: A number of MRI methods have been proposed to be useful, quantitative biomarkers of neurodegeneration in ageing. The Calgary Normative Study (CNS) is an ongoing single-centre, prospective, longitudinal study that seeks to develop, test and assess quantitative magnetic resonance (MR) methods as potential biomarkers of neurodegeneration. The CNS has three objectives: first and foremost, to evaluate and characterise the dependence of the selected quantitative neuroimaging biomarkers on age over the adult lifespan; second, to evaluate the precision, variability and repeatability of quantitative neuroimaging biomarkers as part of biomarker validation providing proof-of-concept and proof-of-principle; and third, provide a shared repository of normative data for comparison to various disease cohorts.