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

Diffusion tensor imaging (DTI) is a neuroimaging MR technique, which allows in vivo and non-destructive visualization of myeloarchitectonics in the neural tissue and provides quantitative estimates of WM integrity by measuring molecular diffusion. It is based on the phenomenon of diffusion anisotropy in the nerve tissue, in that water molecules diffuse faster along the neural fibre direction and slower in the fibre-transverse direction. On the basis of their topographic location, trajectory, and areas that interconnect the various fibre systems of the mammalian brain are divided into commissural, projectional and association fibre systems. DTI has opened an entirely new window on the white matter anatomy with both clinical and scientific applications. Its utility is found in both the localization and the quantitative assessment of specific neuronal pathways. The potential of this technique to address connectivity in the human brain is not without a few methodological limitations. A wide spectrum of diffusion imaging paradigms and computational tractography algorithms has been explored in recent years, which established DTI as promising new avenue, for the non-invasive in vivo mapping of structural connectivity at the macroscale level. Further improvements in the spatial resolution of DTI may allow this technique to be applied in the near future for mapping connectivity also at the mesoscale level. DOI: http://dx.doi.org/10.3126/njr.v1i1.6330 Nepalese Journal of Radiology Vol.1(1): 78-91

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Cerebrospinal fluid-suppressed high-resolution diffusion imaging of human brain

Magnetic Resonance in Medicine ◽

10.1002/mrm.1910370117 ◽

1997 ◽

Vol 37 (1) ◽

pp. 119-123 ◽

Cited By ~ 53

Author(s):

James C. Falconer ◽

Ponnada A Narayana

Keyword(s):

Cerebrospinal Fluid ◽

High Resolution ◽

Human Brain ◽

Diffusion Imaging

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

10.1101/2021.06.09.447807 ◽

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.

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High resolution in-vivo diffusion imaging of the human hippocampus

NeuroImage ◽

10.1016/j.neuroimage.2018.01.034 ◽

2018 ◽

Vol 182 ◽

pp. 479-487 ◽

Cited By ~ 4

Author(s):

Sarah Treit ◽

Trevor Steve ◽

Donald W. Gross ◽

Christian Beaulieu

Keyword(s):

High Resolution ◽

Diffusion Imaging ◽

Human Hippocampus

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

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1418198112 ◽

2015 ◽

Vol 112 (21) ◽

pp. E2820-E2828 ◽

Cited By ~ 226

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.

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A High-Resolution In Vivo Atlas of the Human Brain’s Benzodiazepine Binding Site of GABAA Receptors

10.1101/2020.04.10.035352 ◽

2020 ◽

Author(s):

Martin Nørgaard ◽

Vincent Beliveau ◽

Melanie Ganz ◽

Claus Svarer ◽

Lars H Pinborg ◽

...

Keyword(s):

High Resolution ◽

Human Brain ◽

Mrna Expression ◽

Brain Regions ◽

Mrna Levels ◽

Gamma Aminobutyric Acid ◽

Healthy Human ◽

Brain Functions ◽

The Brain

ABSTRACTGamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human brain and plays a key role in several brain functions and neuropsychiatric disorders such as anxiety, epilepsy, and depression. The binding of benzodiazepines to the benzodiazepine receptor sites (BZR) located on GABAA receptors (GABAARs) potentiates the inhibitory effect of GABA leading to the anxiolytic, anticonvulsant and sedative effects used for treatment of those disorders. However, the function of GABAARs and the expression of BZR protein is determined by the GABAAR subunit stoichiometry (19 genes coding for individual subunits), and it remains to be established how the pentamer composition varies between brain regions and individuals.Here, we present a quantitative high-resolution in vivo atlas of the human brain BZRs, generated on the basis of [11C]flumazenil Positron Emission Tomography (PET) data. Next, based on autoradiography data, we transform the PET-generated atlas from binding values into BZR protein density. Finally, we examine the brain regional association with mRNA expression for the 19 subunits in the GABAAR, including an estimation of the minimally required expression of mRNA levels for each subunit to translate into BZR protein.This represents the first publicly available quantitative high-resolution in vivo atlas of the spatial distribution of BZR densities in the healthy human brain. The atlas provides a unique neuroscientific tool as well as novel insights into the association between mRNA expression for individual subunits in the GABAAR and the BZR density at each location in the brain.

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Speckle modulation enables high-resolution wide-field human brain tumor margin detection and in vivo murine neuroimaging

Scientific Reports ◽

10.1038/s41598-019-45902-9 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Derek Yecies ◽

Orly Liba ◽

Elliott D. SoRelle ◽

Rebecca Dutta ◽

Edwin Yuan ◽

...

Keyword(s):

Brain Tumor ◽

High Resolution ◽

Human Brain ◽

Wide Field ◽

Human Brain Tumor ◽

Tumor Margin ◽

Margin Detection

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High resolution spectroscopy and chemical shift imaging of hyperpolarized 129 Xe dissolved in the human brain in vivo at 1.5 tesla

Magnetic Resonance in Medicine ◽

10.1002/mrm.26241 ◽

2016 ◽

Vol 75 (6) ◽

pp. 2227-2234 ◽

Cited By ~ 31

Author(s):

Madhwesha Rao ◽

Neil J. Stewart ◽

Graham Norquay ◽

Paul D. Griffiths ◽

Jim M. Wild

Keyword(s):

High Resolution ◽

Chemical Shift ◽

Human Brain ◽

Chemical Shift Imaging ◽

High Resolution Spectroscopy

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A 48-Channel Receive Array Coil for Mesoscopic Diffusion-Weighted MRI of Human ex vivo Brain Imaging on the 3T Connectome Scanner

10.1101/2021.02.24.432713 ◽

2021 ◽

Author(s):

Alina Scholz ◽

Robin Etzel ◽

Markus W May ◽

Mirsad Mahmutovic ◽

Qiyuan Tian ◽

...

Keyword(s):

High Resolution ◽

Human Brain ◽

Brain Imaging ◽

Ex Vivo ◽

Whole Brain ◽

Diffusion Weighted ◽

Noise Amplification ◽

Head Coil ◽

Array Coil

AbstractIn vivo diffusion-weighted magnetic resonance imaging is limited in signal-to-noise-ratio (SNR) and acquisition time, which constrains spatial resolution to the macroscale regime. Ex vivo imaging, which allows for arbitrarily long scan times, is critical for exploring human brain structure in the mesoscale regime without loss of SNR. Standard head array coils designed for patients are sub-optimal for imaging ex vivo whole brain specimens. The goal of this work was to design and construct a 48-channel ex vivo whole brain array coil for high-resolution and high b-value diffusion-weighted imaging on a 3T Connectome scanner. The coil was validated with bench measurements and characterized by imaging metrics on an agar brain phantom and an ex vivo human brain sample. The two-segment coil former was constructed for a close fit to a whole human brain, with small receive elements distributed over the entire brain. Imaging tests including SNR and G-factor maps were compared to a 64-channel head coil designed for in vivo use. There was a 2.9-fold increase in SNR in the peripheral cortex and a 1.3-fold gain in the center when compared to the 64-ch head coil. The 48-channel ex vivo whole brain coil also decreases noise amplification in highly parallel imaging, allowing acceleration factors of approximately one unit higher for a given noise amplification level. The acquired diffusion-weighted images in a whole ex vivo brain specimen demonstrate the applicability of the developed coil for high-resolution and high b-value diffusion-weighted ex vivo brain MRI studies.

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