scholarly journals Studying magnetic susceptibility, microstructural compartmentalisation and chemical exchange in a formalin-fixed ex vivo human brain specimen

2021 ◽  
Author(s):  
Kwok-Shing Chan ◽  
Renaud Hedouin ◽  
Jeroen Mollink ◽  
Anne-Marie van Cappellen van Walsum ◽  
Jose P Marques
Keyword(s):  
Magnetic Susceptibility ◽  
White Matter ◽  
Human Brain ◽  
In Vivo Imaging ◽  
Chemical Exchange ◽  
Ex Vivo ◽  
Signal Phase ◽  
Brain Specimen ◽  
Formalin Fixed

Purpose: Ex vivo imaging is a preferable method to study the biophysical mechanism of white matter orientation-dependent signal phase evolution. Yet, how formalin fixation, commonly used for tissue preservation, affects the phase measurement is not fully known. We, therefore, study the impacts of formalin fixation on magnetic susceptibility, microstructural compartmentalisation and chemical exchange measurement on human brain tissue. Methods: A formalin-fixed, post-mortem human brain specimen was scanned with multiple orientations with respect to the main magnetic field direction for robust bulk magnetic susceptibility measurement with conventional quantitative susceptibility imaging models. Homogeneous white matter tissues were subsequently excised from the whole-brain specimen and scanned in multiple rotations on an MRI scanner to measure the anisotropic magnetic susceptibility and microstructure-related contributions in the signal phase. Electron microscopy was used to validate the MRI findings. Results: The bulk isotropic magnetic susceptibility of ex vivo whole-brain imaging is comparable to in vivo imaging, with noticeable enhanced non-susceptibility contributions. The excised specimen experiment reveals that anisotropic magnetic susceptibility and compartmentalisation phase effect were considerably reduced in formalin-fixed white matter tissue. Conclusions: Despite formalin-fixed white matter tissue has comparable bulk isotropic magnetic susceptibility to those measured via in vivo imaging, its orientation-dependent components in the signal phase related to the tissue microstructure is substantially weaker, making it less favourable in white matter microstructure studies using phase imaging.

Ex vivo and in vivo imaging of human brain tissue with different OCT systems

2019 ◽  
Author(s):  
Paul Strenge ◽  
Birgit Lange ◽  
Christin Grill ◽  
Wolfgang Draxinger ◽  
Veit Danicke ◽  
...  
Keyword(s):  
Human Brain ◽  
Brain Tissue ◽  
In Vivo Imaging ◽  
Ex Vivo ◽  
Human Brain Tissue

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.

scholarly journals Mapping magnetic susceptibility anisotropies of white matter in vivo in the human brain at 7T

NeuroImage ◽  
2012 ◽  
Vol 62 (1) ◽  
pp. 314-330 ◽  
Author(s):  
Xu Li ◽  
Deepti S. Vikram ◽  
Issel Anne L. Lim ◽  
Craig K. Jones ◽  
Jonathan A.D. Farrell ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
White Matter ◽  
Human Brain

scholarly journals GFP-Aequorin Protein Sensor for Ex Vivo and In Vivo Imaging of Ca 2+ Dynamics in High-Ca 2+ Organelles

2016 ◽  
Vol 23 (6) ◽  
pp. 738-745 ◽  
Author(s):  
Paloma Navas-Navarro ◽  
Jonathan Rojo-Ruiz ◽  
Macarena Rodriguez-Prados ◽  
María Dolores Ganfornina ◽  
Loren L. Looger ◽  
...  
Keyword(s):  
In Vivo Imaging ◽  
Ex Vivo ◽  
Protein Sensor

[P2-420]: A COMPARISON OF BRAIN WHITE MATTER HYPERINTENSITY BURDEN ASSESSED IN VIVO AND EX VIVO

2017 ◽  
Vol 13 (7S_Part_16) ◽  
pp. P794-P795
Author(s):  
Arman P. Kulkarni ◽  
Arnold M. Evia ◽  
Julie A. Schneider ◽  
David A. Bennett ◽  
Konstantinos Arfanakis
Keyword(s):  
White Matter ◽  
Ex Vivo ◽  
White Matter Hyperintensity ◽  
Brain White Matter

scholarly journals Ex Vivo and In Vivo Imaging and Biodistribution of Aptamers Targeting the Human Matrix MetalloProtease-9 in Melanomas

PLoS ONE ◽  
2016 ◽  
Vol 11 (2) ◽  
pp. e0149387 ◽  
Author(s):  
David Kryza ◽  
Frédéric Debordeaux ◽  
Laurent Azéma ◽  
Aref Hassan ◽  
Olivier Paurelle ◽  
...  
Keyword(s):  
In Vivo Imaging ◽  
Ex Vivo ◽  
Matrix Metalloprotease

Ex vivo measurement of tissue distribution of a nitroxide radical after intravenous injection and its in vivo imaging using a rapid scan ESR-CT system

2000 ◽  
Vol 18 (2) ◽  
pp. 151-156 ◽  
Author(s):  
Hitoshi Togashi ◽  
Taku Matsuo ◽  
Haruhide Shinzawa ◽  
Yoshio Takeda ◽  
Li Shao ◽  
...  
Keyword(s):  
Tissue Distribution ◽  
Intravenous Injection ◽  
In Vivo Imaging ◽  
Ex Vivo ◽  
Nitroxide Radical ◽  
Rapid Scan ◽  
Ct System

scholarly journals In Vivo Imaging of Peripheral Benzodiazepine Receptors in Mouse Lungs: A Biomarker of Inflammation

2005 ◽  
Vol 4 (4) ◽  
pp. 7290.2005.05133 ◽  
Author(s):  
Matthew J. Hardwick ◽  
Ming-Kai Chen ◽  
Kwamena Baidoo ◽  
Martin G. Pomper ◽  
Tomás R. Guilarte
Keyword(s):  
In Vivo Imaging ◽  
Ex Vivo ◽  
Inflammatory Diseases ◽  
Imaging Techniques ◽  
Benzodiazepine Receptors ◽  
Small Animal ◽  
Small Animal Pet ◽  
Planar Imaging ◽  
Peripheral Benzodiazepine Receptors

The ability to visualize the immune response with radioligands targeted to immune cells will enhance our understanding of cellular responses in inflammatory diseases. Peripheral benzodiazepine receptors (PBR) are present in monocytes and neutrophils as well as in lung tissue. We used lipopolysaccharide (LPS) as a model of inflammation to assess whether the PBR could be used as a noninvasive marker of inflammation in the lungs. Planar imaging of mice administrated 10 or 30 mg/kg LPS showed increased [123I]-( R)-PK11195 radioactivity in the thorax 2 days after LPS treatment relative to control. Following imaging, lungs from control and LPS-treated mice were harvested for ex vivo gamma counting and showed significantly increased radioactivity above control levels. The specificity of the PBR response was determined using a blocking dose of nonradioactive PK11195 given 30 min prior to radiotracer injection. Static planar images of the thorax of nonradioactive PK11195 pretreated animals showed a significantly lower level of radiotracer accumulation in control and in LPS-treated animals ( p < .05). These data show that LPS induces specific increases in PBR ligand binding in the lungs. We also used in vivo small-animal PET studies to demonstrate increased [11C]-( R)-PK11195 accumulation in the lungs of LPS-treated mice. This study suggests that measuring PBR expression using in vivo imaging techniques may be a useful biomarker to image lung inflammation.

Real-Time Ex-Vivo Magnetic Resonance Image—Guided Dissection of Human Brain White Matter: A Proof-of-Principle Study

2019 ◽  
Vol 125 ◽  
pp. 198-206 ◽  
Author(s):  
Giacomo Bertolini ◽  
Emanuele La Corte ◽  
Domenico Aquino ◽  
Elena Greco ◽  
Zefferino Rossini ◽  
...  
Keyword(s):  
White Matter ◽  
Magnetic Resonance ◽  
Human Brain ◽  
Real Time ◽  
Magnetic Resonance Image ◽  
Ex Vivo ◽  
Image Guided ◽  
Brain White Matter ◽  
Proof Of Principle

scholarly journals Convergent molecular, cellular, and cortical neuroimaging signatures of major depressive disorder

2020 ◽  
Vol 117 (40) ◽  
pp. 25138-25149
Author(s):  
Kevin M. Anderson ◽  
Meghan A. Collins ◽  
Ru Kong ◽  
Kacey Fang ◽  
Jingwei Li ◽  
...  
Keyword(s):  
Major Depressive Disorder ◽  
Negative Affect ◽  
Depressive Disorder ◽  
Single Cell ◽  
In Vivo Imaging ◽  
Ex Vivo ◽  
Integrated Analysis ◽  
Down Regulation ◽  
Major Depressive

Major depressive disorder emerges from the complex interactions of biological systems that span genes and molecules through cells, networks, and behavior. Establishing how neurobiological processes coalesce to contribute to depression requires a multiscale approach, encompassing measures of brain structure and function as well as genetic and cell-specific transcriptional data. Here, we examine anatomical (cortical thickness) and functional (functional variability, global brain connectivity) correlates of depression and negative affect across three population-imaging datasets: UK Biobank, Brain Genomics Superstruct Project, and Enhancing NeuroImaging through Meta Analysis (ENIGMA; combined n ≥ 23,723). Integrative analyses incorporate measures of cortical gene expression, postmortem patient transcriptional data, depression genome-wide association study (GWAS), and single-cell gene transcription. Neuroimaging correlates of depression and negative affect were consistent across three independent datasets. Linking ex vivo gene down-regulation with in vivo neuroimaging, we find that transcriptional correlates of depression imaging phenotypes track gene down-regulation in postmortem cortical samples of patients with depression. Integrated analysis of single-cell and Allen Human Brain Atlas expression data reveal somatostatin interneurons and astrocytes to be consistent cell associates of depression, through both in vivo imaging and ex vivo cortical gene dysregulation. Providing converging evidence for these observations, GWAS-derived polygenic risk for depression was enriched for genes expressed in interneurons, but not glia. Underscoring the translational potential of multiscale approaches, the transcriptional correlates of depression-linked brain function and structure were enriched for disorder-relevant molecular pathways. These findings bridge levels to connect specific genes, cell classes, and biological pathways to in vivo imaging correlates of depression.

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