Review of the epidemiology and variability of LRRK2 non-p.Gly2019Ser pathogenic mutations in Parkinson's disease.

Parkinson's disease (PD) is a heterogenous neurodegenerative disorder. Genetic factors play a significant role, especially in early onset and familial cases. Mutations are usually found in the gene, but their importance varies.

Platelet-to-lymphocyte ratio and neutrophil-tolymphocyte ratio may reflect differences in PD and MSA-P neuroinflammation patterns.

Aim Of The Study: To assess the usefulness of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in evaluating the inflammatory process in alpha-synucleinopathies.

Clinical Rationale For The Study: The role of neuroinflammation in PD and MSA pathogenesis is indisputable. However, there is no method available in everyday use that would enable its evaluation.

Virtual injections using 4D flow MRI with displacement corrections and constrained probabilistic streamlines.

Purpose: Streamlines from 4D-flow MRI have been used clinically for intracranial blood-flow tracking. However, deterministic and stochastic errors degrade streamline quality. The purpose of this study is to integrate displacement corrections, probabilistic streamlines, and novel fluid constraints to improve selective blood-flow tracking and emulate "virtual bolus injections.

Simultaneous 3D-TOF angiography and 4D-flow MRI with enhanced flow signal using multiple overlapping thin slab acquisition and magnetization transfer.

Purpose: To investigate the fusion of 3D time-of-flight principles into 4D-flow MRI to enhance vessel contrast and signal without an exogenous contrast agent, enabling simultaneous in-flow based angiograms.

Methods: A 4D-flow MRI technique was developed consisting of multiple overlapping slabs with intermittent magnetization transfer preparation. The scan time penalty associated with multiple slab acquisitions was mitigated by using undersampled distributed spiral trajectories and compressed sensing reconstruction.

Spatial dependency and the role of local susceptibility for velocity selective arterial spin labeling (VS-ASL) relative tagging efficiency using accelerated 3D radial sampling with a BIR-8 preparation.

Purpose: Velocity selective arterial spin labeling (VS-ASL) is a promising approach for non-contrast perfusion imaging that provides robustness to vascular geometry and transit times; however, VS-ASL assumes spatially uniform tagging efficiency. This work presents a mapping approach to investigate VS-ASL relative tagging efficiency including the impact of local susceptibility effects on a BIR-8 preparation.

Methods: Numerical simulations of tagging efficiency were performed to evaluate sensitivity to regionally varying local susceptibility gradients and blood velocity.

Cardiorespiratory Fitness Associates with Cerebral Vessel Pulsatility in a Cohort Enriched with Risk for Alzheimer's Disease.

Background: There is increasing evidence that vascular disease risk factors contribute to evolution of the dementia syndrome of Alzheimer's disease (AD). One important measure of cerebrovascular health is pulsatility index (PI) which is thought to represent distal vascular resistance, and has previously been reported to be elevated in AD clinical syndrome. Physical inactivity has emerged as an independent risk factor for cardiovascular disease.

Association of Cardiovascular and Alzheimer's Disease Risk Factors with Intracranial Arterial Blood Flow in Whites and African Americans.

Background: Alzheimer's disease (AD) has a higher prevalence among African Americans. Targeting cardiovascular and metabolic risk factors may be potential mechanisms to modify AD risk and address racial/ethnic disparities in AD dementia.

Objective: This study investigated relationships among cardiovascular and metabolic risk factors, APOE genotype, AD biomarkers, and intracranial arterial blood flow in Whites and African Americans enriched for AD risk.

Composite MRA: statistical approach to generate an MR angiogram from multiple contrasts.

Purpose: To develop a method to use information from multiple MRI contrasts to produce a composite angiogram with reduced sequence-specific artifacts and improved vessel depiction.

Methods: Bayesian posterior vessel probability was determined as a function of black blood (BB), contrast enhanced angiography (CE-MRA), and phase-contrast MRA (PC-MRA) intensities from training subjects (N = 4). To generate composite angiogram in evaluation subjects (N = 12), the voxel-wise vessel probabilities were weighted with a confidence measure and combined as a weighted product to yield angiogram intensity.

Serial Quantitative and Qualitative Measurements of Flow in Vein of Galen Malformations Using 4-Dimensional Flow Magnetic Resonance Imaging (Phase Contrast Vastly undersampled Isotropic PRojection).

Background: Vein of Galen malformations (VoGMs) induce cerebrovascular dysfunction through arterial steal and venous hypertension resulting, if untreated, in severe neurologic morbidity and mortality. Noninvasive techniques for quantitative, serial evaluation of cerebrovascular hemodynamics in VoGMs are lacking. This proof of concept study using quantitative blood flow measurements from 4-dimensional flow magnetic resonance imaging may be useful as a noninvasive biomarker to guide timing of intervention and assess disease progression and treatment outcomes.

Measurement of microvascular cerebral blood volume changes over the cardiac cycle with ferumoxytol-enhanced T MRI.

Purpose: This feasibility study investigates the non-invasive measurement of microvascular cerebral blood volume (BV) changes over the cardiac cycle using cardiac-gated, ferumoxytol-enhanced MRI.

Methods: Institutional review board approval was obtained and all subjects provided written informed consent. Cardiac gated MR scans were prospectively acquired on a 3.

Robust Motion Correction Strategy for Structural MRI in Unsedated Children Demonstrated with Three-dimensional Radial MPnRAGE.

Purpose To develop and evaluate a retrospective method to minimize motion artifacts in structural MRI. Materials and Methods The motion-correction strategy was developed for three-dimensional radial data collection and demonstrated with MPnRAGE, a technique that acquires high-resolution volumetric magnetization-prepared rapid gradient-echo, or MPRAGE, images with multiple tissue contrasts. Forty-four pediatric participants (32 with autism spectrum disorder [mean age ± standard deviation, 13 years ± 3] and 12 age-matched control participants [mean age, 12 years ± 3]) were imaged without sedation.

Circumferential Thick Enhancement at Vessel Wall MRI Has High Specificity for Intracranial Aneurysm Instability.

Purpose To identify wall enhancement patterns on vessel wall MRI that discriminate between stable and unstable unruptured intracranial aneurysm (UIA). Materials and Methods Patients were included from November 2012 through January 2016. Vessel wall MR images were acquired at 3 T in patients with stable (incidental and nonchanging over 6 months) or unstable (symptomatic or changing over 6 months) UIA.

Pressure Mapping and Hemodynamic Assessment of Intracranial Dural Sinuses and Dural Arteriovenous Fistulas with 4D Flow MRI.

The feasibility of 4D flow MR imaging to visualize flow patterns and generate relative pressure maps in the dural venous sinus in healthy subjects ( = 60) and patients with dural arteriovenous fistulas ( = 7) was investigated. Dural venous drainage was classified based on torcular Herophili anatomy by using 4D flow MR imaging-derived angiograms and magnitude images. Subjects were scanned in a 3T clinical MR imaging system.

Comparison of ferumoxytol-based cerebral blood volume estimates using quantitative R and R2* relaxometry.

Purpose: Cerebral perfusion is commonly assessed clinically with dynamic susceptibility contrast MRI using a bolus injection of gadolinium-based contrast agents, resulting in semi-quantitative values of cerebral blood volume (CBV). Steady-state imaging with ferumoxytol allows estimation of CBV with the potential for higher precision and accuracy. Prior CBV studies have focused on the signal disrupting T2* effects, but ferumoxytol also has high signal-enhancing T relaxivity.

Non contrast, Pseudo-Continuous Arterial Spin Labeling and Accelerated 3-Dimensional Radial Acquisition Intracranial 3-Dimensional Magnetic Resonance Angiography for the Detection and Classification of Intracranial Arteriovenous Shunts.

Objectives: The aim of this study was to assess the sensitivity and specificity of pseudo-continuous arterial spin labeling (PCASL) magnetic resonance angiography (MRA) with 3-dimensional (3D) radial acquisition for the detection of intracranial arteriovenous (AV) shunts.

Materials And Methods: A total of 32 patients who underwent PCASL-MRA, clinical magnetic resonance imaging (MRI)/MRA exam, and digital subtraction angiography (DSA) were included in this retrospective analysis. Twelve patients presented with AV shunts.

Intracranial Arterial 4D Flow in Individuals with Mild Cognitive Impairment is Associated with Cognitive Performance and Amyloid Positivity.

It is becoming increasingly recognized that cerebrovascular disease is a contributing factor in the pathogenesis of Alzheimer's disease (AD). A unique 4D-Flow magnetic resonance imaging (MRI) technique, phase contrast vastly undersampled isotropic projection imaging (PC VIPR), enables examination of angiographic and quantitative metrics of blood flow in the arteries of the Circle of Willis within a single MRI acquisition. Thirty-eight participants with mild cognitive impairment (MCI) underwent a comprehensive neuroimaging protocol (including 4D-Flow imaging) and a standard neuropsychological battery.

Highly efficient maternal-fetal Zika virus transmission in pregnant rhesus macaques.

Infection with Zika virus (ZIKV) is associated with human congenital fetal anomalies. To model fetal outcomes in nonhuman primates, we administered Asian-lineage ZIKV subcutaneously to four pregnant rhesus macaques. While non-pregnant animals in a previous study contemporary with the current report clear viremia within 10-12 days, maternal viremia was prolonged in 3 of 4 pregnancies.

Macrovascular and microvascular cerebral blood flow in adults at risk for Alzheimer's disease.

Introduction: Capillary hypoperfusion is reported in asymptomatic adults at-risk for Alzheimer's disease (AD), but the extent that can be explained by reduced flow in intracranial arteries is unknown.

Methods: One hundred fifty-five asymptomatic adults enriched for AD risk (mean age 61 years) completed arterial spin labeling (pcASL) and 4D-flow MRI sequences. Voxel-wise regression models investigated the relationship between mean flow in bilateral cerebral arteries and capillary perfusion, and tested potential moderators of this relationship.

Time-of-Arrival Parametric Maps and Virtual Bolus Images Derived From Contrast-Enhanced Time-Resolved Radial Magnetic Resonance Angiography Improve the Display of Brain Arteriovenous Malformation Vascular Anatomy.

Objectives: Time-of-arrival (TOA) maps can be derived from high-resolution 4-dimensional (4D) contrast-enhanced magnetic resonance angiography (MRA) data sets to provide a quantitative description of contrast material arrival time in each voxel. This information can further be processed to create a compressed time evolution curve that virtually shortens the contrast bolus (virtual bolus [VB]). The purpose of this project was to determine whether TOA-enhanced 4D MRA and/or VB imaging improve the display of contrast kinetics in patients with vascular disease.

Changes in intracranial venous blood flow and pulsatility in Alzheimer's disease: A 4D flow MRI study.

Cerebral blood flow, arterial pulsation, and vasomotion may be important indicators of cerebrovascular health in aging and diseases of aging such as Alzheimer's disease. Noninvasive markers that assess these characteristics may be helpful in the study of co-occurrence of these diseases and potential additive and interacting effects. In this study, 4D flow MRI was used to measure intra-cranial flow features with cardiac-gated phase contrast MRI in cranial arteries and veins.

Intracranial Arterial 4D-Flow is Associated with Metrics of Brain Health and Alzheimer's Disease.

Introduction: While cerebrovascular disease has long been known to co-occur with Alzheimer's disease (AD), recent studies suggest an etiologic contribution to AD pathogenesis. We used 4D-Flow magnetic resonance imaging (MRI) to evaluate blood flow and pulsatility indices in the Circle of Willis. We hypothesized decreased mean blood flow and increased pulsatility, metrics indicative of poor vascular health, would be associated with cerebral atrophy and an AD cerebrospinal fluid (CSF) profile.

4D flow MRI for intracranial hemodynamics assessment in Alzheimer's disease.

Cerebral blood flow, arterial pulsation, and vasomotion play important roles in the transport of waste metabolites out of the brain. Impaired vasomotion results in reduced driving force for the perivascular/glymphatic clearance of beta-amyloid. Noninvasive cerebrovascular characteristic features that potentially assess these transport mechanisms are mean blood flow (MBF) and pulsatility index (PI).

Accelerated Time-Resolved Contrast-Enhanced Magnetic Resonance Angiography of Dural Arteriovenous Fistulas Using Highly Constrained Reconstruction of Sparse Cerebrovascular Data Sets.

Objective: Time-resolved contrast-enhanced magnetic resonance angiography (MRA) is commonly used to noninvasively characterize vascular malformations. However, the spatial and temporal resolution of current methods often compromises the clinical value of the examinations. Constrained reconstruction is a temporal spatial correlation strategy that exploits the relative sparsity of vessels in space to dramatically reduce the amount of data required to generate fast high-resolution time-resolved contrast-enhanced MRA studies.