scholarly journals Imaging of the pial arterial vasculature of the human brain in vivo using high-resolution 7T time-of-flight angiography

2021 ◽  
Author(s):  
Saskia Bollmann ◽  
Hendrik Mattern ◽  
Michaël Bernier ◽  
Simon R Robinson ◽  
Daniel Park ◽  
...  
Keyword(s):  
Blood Flow ◽  
High Resolution ◽  
Human Brain ◽  
Blood Supply ◽  
Time Of Flight ◽  
Image Resolution ◽  
Pial Arteries ◽  
Isotropic Resolution ◽  
Tof Mra

The pial arterial vasculature of the human brain is the only blood supply to the neocortex, but quantitative data on the morphology and topology of these mesoscopic vessels (diameter 50-300 μm) remains scarce. Because it is commonly assumed that blood flow velocities in these vessels are prohibitively slow, non-invasive time-of-flight MRI angiography (TOF-MRA)-which is well-suited to high 3D imaging resolutions-has not been applied to imaging the pial arteries. Here, we provide a theoretical framework that outlines how TOF-MRA can visualize small pial arteries in vivo, by employing extremely small voxels at the size of individual vessels. We then provide evidence for this theory by imaging the pial arteries at 140-μm isotropic resolution using a 7T MRI scanner and prospective motion correction, and show that pial arteries one voxel-width in diameter can be detected. We conclude that imaging pial arteries is not limited by slow blood flow, but instead by achievable image resolution. This study represents the first targeted, comprehensive account of imaging pial arteries in vivo in the human brain. This ultra-high-resolution angiography will enable the characterization of pial vascular anatomy across the brain to investigate patterns of blood supply and relationships between vascular and functional architecture.

Microvascular features that suggest effectors of blood-flow regulation in the brain: Evidence by SEM of corrosion casts of intracerebral vessels

1990 ◽  
Vol 48 (3) ◽  
pp. 274-275
Author(s):  
Enrico D.F. Motti ◽  
Hans-Georg Imhof ◽  
Gazi M. Yasargil
Keyword(s):  
Blood Flow ◽  
Perfusion Pressure ◽  
Corrosion Casts ◽  
Cerebral Microcirculation ◽  
Pial Arteries ◽  
Random Occurrence ◽  
Brain Arteries ◽  
Homogeneous Network ◽  
The Brain

Physiologists have devoted most attention in the cerebrovascular tree to the arterial side of the circulation which has been subdivided in three levels: 1) major brain arteries which keep microcirculation constant despite changes in perfusion pressure; 2) pial arteries supposed to be effectors regulating microcirculation; 3) intracerebral arteries supposed to be deprived of active cerebral blood flow regulating devices.The morphological search for microvascular effectors in the cerebrovascular bed has been elusive. The opaque substance of the brain confines in vivo investigation to the superficial pial arteries. Most morphologists had to limit their observation to the random occurrence of a favorable site in the practically two-dimensional thickness of diaphanized histological sections. It is then not surprising most investigators of the cerebral microcirculation refer to an homogeneous network of microvessels interposed between arterioles and venules.We have taken advantage of the excellent depth of focus afforded by the scanning electron microscope (SEM) to investigate corrosion casts obtained injecting a range of experimental animals with a modified Batson's acrylic mixture.

scholarly journals High-Resolution Mapping of Myeloarchitecture In Vivo: Localization of Auditory Areas in the Human Brain

2014 ◽  
Vol 25 (10) ◽  
pp. 3394-3405 ◽  
Author(s):  
Federico De Martino ◽  
Michelle Moerel ◽  
Junqian Xu ◽  
Pierre-Francois van de Moortele ◽  
Kamil Ugurbil ◽  
...  
Keyword(s):  
High Resolution ◽  
Human Brain ◽  
High Resolution Mapping ◽  
Resolution Mapping

scholarly journals Whole-Brain High-Resolution Metabolite Mapping with 3D Compressed-Sensing-SENSE-LowRank 1H FID-MRSI

2020 ◽  
Author(s):  
Antoine Klauser ◽  
Paul Klauser ◽  
Frédéric Grouiller ◽  
Sebastien Courvoisier ◽  
Francois Lazeyras
Keyword(s):  
High Resolution ◽  
Brain Regions ◽  
Low Rank ◽  
Acquisition Time ◽  
Resonance Spectroscopy ◽  
Brain Anatomy ◽  
Reconstruction Technique ◽  
Whole Brain ◽  
Isotropic Resolution

There is a growing interest of the neuroscience community to map the distribution of brain metabolites in vivo. Magnetic resonance spectroscopy imaging (MRSI) is often limited by either a poor spatial resolution and/or a long acquisition time which severely limits its applications for clinical or research purposes. We developed a novel acquisition-reconstruction technique combining fast 1H-FID-MRSI sequence accelerated by random k-space undersampling and a low-rank and total-generalized variation (TGV) constrained model. This framework was applied to the brain of four healthy volunteers. Following 20 min acquisition, reconstruction and quantification, the resulting metabolic maps with a 5 mm isotropic resolution reflected the detailed neurochemical composition of all brain regions and revealed part of the underlying brain anatomy. Contrasts and features from the 3D metabolite distributions were in agreement with the literature and consistent across the four subjects. The successful combination of the 3D 1H-FID-MRSI with a constrained reconstruction enables the detailed mapping of metabolite concentrations at high-resolution in the whole brain and with an acquisition time that is compatible with clinical or research settings.

scholarly journals High resolution atlas of the venous brain vasculature from 7 T quantitative susceptibility maps

2018 ◽  
Author(s):  
Julia Huck ◽  
Yvonne Wanner ◽  
Audrey P. Fan ◽  
Anna-Thekla Jäger ◽  
Sophia Grahl ◽  
...  
Keyword(s):  
Human Brain ◽  
Blood Oxygen Level Dependent ◽  
7 Tesla ◽  
Cerebral Vein ◽  
Registration Method ◽  
Isotropic Resolution ◽  
Common Location ◽  
Susceptibility Maps ◽  
Venous Vasculature

AbstractThe vascular organization of the human brain can determine neurological and neurophysiological functions, yet thus far it has not been comprehensively mapped. Aging and diseases such as dementia are known to be associated with changes to the vasculature and normative data could help detect these vascular changes in neuroimaging studies. Furthermore, given the well-known impact of venous vessels on the blood oxygen level dependent (BOLD) signal, information about the common location of veins could help detect biases in existing datasets. In this work, a quantitative atlas of the venous vasculature using quantitative susceptibility maps (QSM) acquired with a 0.6 mm isotropic resolution is presented. The Venous Neuroanatomy (VENAT) atlas was created from 5 repeated 7 Tesla MRI measurements in young and healthy volunteers (n = 20, 10 females, mean age = 25.1 ± 2.5 years) using a two-step registration method on 3D segmentations of the venous vasculature. This cerebral vein atlas includes the average vessel location, diameter (mean: 0.84 ± 0.33 mm) and curvature (0.11 ± 0.05 mm−1) from all participants and provides an in vivo measure of the angio-architectonic organization of the human brain and its variability. This atlas can be used as a basis to understand changes in the vasculature during aging and neurodegeneration, as well as vascular and physiological effects in neuroimaging.

scholarly journals Collateral Supply in Preclinical Cerebral Stroke Models

2021 ◽  
Author(s):  
Philippe Bonnin ◽  
Nathalie Kubis ◽  
Christiane Charriaut-Marlangue
Keyword(s):  
Blood Flow ◽  
Blood Supply ◽  
Time Course ◽  
Imaging Techniques ◽  
Artery Occlusion ◽  
Added Value ◽  
Cerebral Stroke ◽  
Collateral Blood Flow ◽  
Pial Arteries ◽  
Pharmacological Agents

AbstractEnhancing the collateral blood supply during the acute phase of cerebral ischemia may limit both the extension of the core infarct, by rescuing the penumbra area, and the degree of disability. Many imaging techniques have been applied to rodents in preclinical studies, to evaluate the magnitude of collateral blood flow and the time course of responses during the early phase of ischemic stroke. The collateral supply follows several different routes at the base of the brain (the circle of Willis) and its surface (leptomeningeal or pial arteries), corresponding to the proximal and distal collateral pathways, respectively. In this review, we describe and illustrate the cerebral collateral systems and their modifications following pre-Willis or post-Willis occlusion in rodents. We also review the potential pharmaceutical agents for stimulating the collateral blood supply tested to date. The time taken to establish a collateral blood flow supply through the leptomeningeal anastomoses differs between young and adult animals and between different species and genetic backgrounds. Caution is required when transposing preclinical findings to humans, and clinical trials must be performed to check the added value of pharmacological agents for stimulating the collateral blood supply at appropriate time points. However, collateral recruitment appears to be a rapid, beneficial, endogenous mechanism that can be stimulated shortly after artery occlusion. It should be considered a treatment target for use in addition to recanalization strategies.

scholarly journals Superficial white matter fiber systems impede detection of long-range cortical connections in diffusion MR tractography

2015 ◽  
Vol 112 (21) ◽  
pp. E2820-E2828 ◽  
Author(s):  
Colin Reveley ◽  
Anil K. Seth ◽  
Carlo Pierpaoli ◽  
Afonso C. Silva ◽  
David Yu ◽  
...  
Keyword(s):  
White Matter ◽  
High Resolution ◽  
Human Brain ◽  
Long Range ◽  
Ex Vivo ◽  
Cortical Surface ◽  
Tracer Injection ◽  
Axonal Projections ◽  
Probabilistic Tracking

In vivo tractography based on diffusion magnetic resonance imaging (dMRI) has opened new doors to study structure–function relationships in the human brain. Initially developed to map the trajectory of major white matter tracts, dMRI is used increasingly to infer long-range anatomical connections of the cortex. Because axonal projections originate and terminate in the gray matter but travel mainly through the deep white matter, the success of tractography hinges on the capacity to follow fibers across this transition. Here we demonstrate that the complex arrangement of white matter fibers residing just under the cortical sheet poses severe challenges for long-range tractography over roughly half of the brain. We investigate this issue by comparing dMRI from very-high-resolution ex vivo macaque brain specimens with histological analysis of the same tissue. Using probabilistic tracking from pure gray and white matter seeds, we found that ∼50% of the cortical surface was effectively inaccessible for long-range diffusion tracking because of dense white matter zones just beneath the infragranular layers of the cortex. Analysis of the corresponding myelin-stained sections revealed that these zones colocalized with dense and uniform sheets of axons running mostly parallel to the cortical surface, most often in sulcal regions but also in many gyral crowns. Tracer injection into the sulcal cortex demonstrated that at least some axonal fibers pass directly through these fiber systems. Current and future high-resolution dMRI studies of the human brain will need to develop methods to overcome the challenges posed by superficial white matter systems to determine long-range anatomical connections accurately.

VASODILATOR PEPTIDES - CGRP AND VIP

1987 ◽  
Author(s):  
S Thom ◽  
A Hughes ◽  
G Martin ◽  
P Goldberg ◽  
P Server
Keyword(s):  
Blood Flow ◽  
Nervous System ◽  
Cerebral Arteries ◽  
Venous Occlusion ◽  
Dependent Manner ◽  
Pial Arteries ◽  
Parasympathetic System ◽  
Perivascular Nerves

The two peptides calcitonin gene related peptide (C6RP) and vasoactive intestinalpeptide (VIP) are widely distributed in animal species including man and a number ofdiverse actions of the peptides have been described [1,2]. They share vasoactive properties [3,4] and may have important functions as neurotransmitters in a non-adrenergic, non-cholinergic nervous system [5]. VIP has been located in perivascular nerves supplying several tissues and is co-stored with acetylcholine in the parasympathetic system [6]. CGRP has also been widely identified in the nervous system, the cardiovascular system and perivascular nerves, where it is located with substance P[7]. Our studies have assessed the activity of these peptides in a human vascular resistance bed -the forearm, and on isolated human blood vessels.Forearm studies were performed by infusingCGRP (10,30,100 ng/min) or ViP (10,30,100 ng/min) via the brachial artery for 5 min at each dose level and measuring blood flow by venous occlusion plethysmography. In vitro studies were performed using ringsegments of pulmonary, gastric, coronary, radial, and transverse cervical arteries freshly obtained from surgical resection specimens and cerebral arteries obtained from autogsy tissue within 4 hours of death. Vessels were mounted in organ baths containing Krebs buffer aerated with 95% 02, 5% C02 at 37C, and preconstricted using a submaximal concentration of noradrenaline (1-3 μM) or prostaglandin F2a (I-IO11μ7.CGRP or VIP was added to the tissue bath in a cumulative fashion. All arterial segments used for these studies relaxed in response to acetylcholine (0.1-3μM)or A23187 (0.1-3μM) and this was regarded as indicative of functional endothelial integrity. Studies were performed in the presence of indomethacin (lOμM). The endothelium was deliberately removed from some rings and in others haemoglobin (5μM) ormethylene blue (lOμM) were added to the tissue bath after the arterialrings were effectively relaxed by CGRP orVIP. Both peptides produced marked dose dependent increases in forearm blood flow; at 100 ng/min the mean net increase was 174 ± 24% (mean ±s.e.m.) with CGRP, and 223 + 34% (mean +s.e.m.) with VIP. In vitro CGRP (InM-lμM) relaxed preconstricted segments ofradial Tn=2), coronary (n=4), gastric (n=5) and cerebral (n=3) arteries in an endothelium dependent manner. VIP (1 nM - 1pm) also relaxed human gastric (n=2), splenic (n=2), cervical (n=3) and pulmonary (n=5) arteries VIP relaxation of the gastric and cervical arteries was dependent on the presence of endothelium; however, VIP inducedrelaxation of pulmonary artery was not dependent on functional endothelium. The endothelium dependent relaxations could be abolished either by luminal rubbing, additionor haemoglobin or methylene blue. Together these results might be taken to imply that the forearm vasodilatation response is mediated by EDRF. However, caution is necessary in extrapolating from in vitro observations of large vessels to the in vivo response of a resistance vascular bed.Others have demonstrated that the CGRPand VIP relaxatory responses of smaller human pial arteries (ID 250-600 pm) are endothelium independent [8] and preliminary work in our department supports this. The EDRF mechanism is cyclic GMP linked, but most of the studied functions of VIP and CGRP seem to be linked to a rise in cyclic AMP-. A further paradox is that the blood flow response to infused acetylcholine, the archetypal releaser of EDRF, is evanescent, and yet the vasodilator response to CGRP is persistent.

scholarly journals High-resolution in vivo diffusion imaging of the human brain with generalized slice dithered enhanced resolution: Simultaneous multislice (gSlider-SMS)

2017 ◽  
Vol 79 (1) ◽  
pp. 141-151 ◽  
Author(s):  
Kawin Setsompop ◽  
Qiuyun Fan ◽  
Jason Stockmann ◽  
Berkin Bilgic ◽  
Susie Huang ◽  
...  
Keyword(s):  
High Resolution ◽  
Human Brain ◽  
Diffusion Imaging ◽  
Enhanced Resolution ◽  
Simultaneous Multislice

scholarly journals Blood flow synchronization in renal microcirculation - a high-resolution imaging study.

2021 ◽  
Author(s):  
Dmitry D Postnov ◽  
Donald Marsh ◽  
Will Cupples ◽  
Niels-Henrik Holstein-Rathlou ◽  
Olga Sosnovtseva
Keyword(s):  
Blood Flow ◽  
Angiotensin Ii ◽  
High Resolution ◽  
Blood Vessels ◽  
Image Resolution ◽  
Laser Speckle ◽  
Field Of View ◽  
Large Field ◽  
Kidney Cortex ◽  
Vasoactive Agents

Aims: internephron signalling and interaction are fundamental for kidney function. Earlier studies have shown that nephrons signal to each other over short distances and adjust their activity accordingly. Micropuncture experiments revealed synchronous clusters of 2-3 nephrons formed from such interactions, while imaging and modelling results suggested the possibility of larger clusters. Such clusters are expected to play an important role in renal autoregulation, but their presence has not been confirmed and their size has not been estimated. In this study, we present methodology for high resolution renal blood flow imaging and apply it to estimate frequency and phase angle differences in kidney blood vessels under normal conditions and after administration of the vasoactive agents angiotensin II and acetylcholine. Methods and results: to resolve signals from separate arterioles in a sufficiently large field of view, we developed a method for renal laser speckle contrast imaging. Our setup provides imaging of blood flow in the kidney cortex with a limit of image resolution at 0.8 micrometres per pixel and the imaging frequency of 160Hz. We used the method to record from ~1.5x1.5 mm2 sections of the renal surface in anaesthetised Sprague-Dawley rats in unstimulated conditions and during IV infusion of the vasoconstrictor angiotensin II or the vasodilator acetylcholine. In each section, we resolved and segmented 94.8+-15.66 individual arterioles and venules, and analyzed blood flow using wavelet spectral analysis to identify clusters of synchronized blood vessels. Conclusions: we observed spatial and temporal evolution of blood vessel clusters of various sizes, including the formation of large (>90 vessels) long-lived clusters (>10 periods) locked at the frequency of the tubular glomerular feedback (TGF) mechanism. The analysis showed that synchronization patterns and thus the co-operative dynamics of nephrons change significantly when either of the vasoactive agents is administered. On average, synchronization was stronger (larger clusters, longer duration) with angiotensin II administration than in the unstimulated state or with acetyl choline. While it weakens with distance, increased synchronization duration spanned the whole field of view, and likely, beyond it. Neighbouring vessels tend to demonstrate in-phase synchronization, especially in the vasoconstricted condition, which is expected to cause locally increased pressure variation. Our results confirm both the presence of the local synchronization in the renal microcirculatory blood flow and the fact that it changes depending on the condition of the vascular network and the blood pressure, which might have further implications for the role of such synchronization in pathologies development.

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