Characterizing the contrast of white matter and grey matter in high-resolution phase difference enhanced imaging of human brain at 3.0 T

Pathophysiological mechanisms of neurological disorders in patients with coronavirus disease 2019 (COVID-19) are poorly understood, partly because of a lack of high-resolution neuroimaging data. We applied SynthSR, a convolutional neural network that synthesizes high-resolution isotropic research-quality data from thick-slice clinical MRI data, to a cohort of 11 patients with severe COVID-19. SynthSR successfully synthesized T1-weighted MPRAGE data at 1 mm spatial resolution for all 11 patients, each of whom had at least one brain lesion. Correlations between volumetric measures derived from synthesized and acquired MPRAGE data were strong for the cortical grey matter, subcortical grey matter, brainstem, hippocampus, and hemispheric white matter (r=0.84 to 0.96, p≤0.001), but absent for the cerebellar white matter and corpus callosum (r=0.04 to 0.17, p>0.61). SynthSR creates an opportunity to quantitatively study clinical MRI scans and elucidate the pathophysiology of neurological disorders in patients with COVID-19, including those with focal lesions.

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Identification of three antigens in human brain associated with similar antigens on human leukaemic cells

Biochemical Journal ◽

10.1042/bj2250291 ◽

1985 ◽

Vol 225 (2) ◽

pp. 291-299 ◽

Cited By ~ 16

Author(s):

E J Quackenbush ◽

T F Cruz ◽

M A Moscarello ◽

M Letarte

Keyword(s):

Monoclonal Antibodies ◽

White Matter ◽

Human Brain ◽

Sodium Dodecyl Sulphate ◽

Grey Matter ◽

Lymphocytic Leukaemia ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Acute Lymphocytic Leukaemia ◽

Leukaemia Cell Line

Monoclonal antibodies prepared against a non-T and non-B acute-lymphocytic-leukaemia cell line were tested for reactivity against human brain tissue. Several of the monoclonal antibodies were found to react specifically with brain fractions. Three antigens, 44H4, 44D7 and 44D10, were identified in white matter. Although 44D10 was absent from grey matter, the levels of 44H4 and 44D7 antigens present in grey matter were 2- and 4-fold higher respectively than in white matter. Fractionation of white matter indicated that all three antigens were absent from the multilamellar compact myelin, but associated with a membrane fraction of higher density. All three antigens, which required detergent for solubilization from the membranes, were purified by affinity to monoclonal antibodies and/or were analysed by immunoblotting. The 44H4 and 44D10 antigens were single polypeptide chains with Mr 94000 and 80000 respectively when resolved by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Monoclonal antibody 44D7 reacted with a complex of a Mr greater than 120000 under non-reducing conditions in the presence of sodium dodecyl sulphate. This complex dissociated on reduction into four bands with Mr values of 80000, 57000, 47000 and 41000. The brain antigens are present on proteins similar to, or identical with, those isolated from acute-lymphocytic-leukaemia cells.

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Extensive heterogeneity in white matter intensity in high-resolution T2*-weighted MRI of the human brain at 7.0 T

NeuroImage ◽

10.1016/j.neuroimage.2006.05.053 ◽

2006 ◽

Vol 32 (3) ◽

pp. 1032-1040 ◽

Cited By ~ 113

Author(s):

Tie-Qiang Li ◽

Peter van Gelderen ◽

Hellmut Merkle ◽

Lalith Talagala ◽

Alan P. Koretsky ◽

...

Keyword(s):

White Matter ◽

High Resolution ◽

Human Brain

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Rapid Communication: Response of the Human Brain to a Hypercapnic Acid Load in Vivo

Clinical Science ◽

10.1042/cs0790001 ◽

1990 ◽

Vol 79 (1) ◽

pp. 1-3 ◽

Cited By ~ 8

Author(s):

T. A. D. Cadoux-Hudson ◽

B. Rajagopalan ◽

J. G. G. Ledingham ◽

G. K. Radda

Keyword(s):

White Matter ◽

Human Brain ◽

Intracellular Ph ◽

Grey Matter ◽

Resonance Spectroscopy ◽

Rotating Frame ◽

End Tidal ◽

End Tidal Co2 ◽

Deep Brain

1. The aim of this investigation was to measure the change in intracellular pH of human brain in vivo in response to hypercapnia. 2. Five healthy male subjects inspired air for 20 min and then 5% CO2/95% O2 for 30 min, of which the first 10 min was used to achieve a steady-state end-tidal CO2 measurement. 3. 31P nuclear magnetic resonance spectroscopy was used to measure intracellular pH while breathing air and during hypercapnia. Simultaneous localization between superficial and deep brain was achieved by using the phase-modulated rotating frame imaging technique. One subject volunteered to breath air for a further phase-modulated rotating frame imaging study while recovering from hypercapnia. 4. End-tidal CO2 increased when breathing 5% CO2/95% O2 (on air, 5.57 ± 0.21%; on 5% CO2/95% O2, 6.41 ± 0.16%; rise = +0.84 ± 0.09%; means ± sem) causing a reduction in brain intracellular pH, which was more pronounced in deep brain (5 cm = mainly white matter, from 7.02 ± 0.006 pH units to 6.96 ± 0.001 pH units, mean ± sem) than in superficial brain (2 cm = mainly grey matter, from 7.02 ± 0.006 pH units to 7.00 ± 0.006 pH units, mean ± sem). 5. The white matter responded to hypercapnia with a greater fall in intracellular pH than the grey matter. This could either be due to differences in blood flow between grey and white matter in response to hypercapnia or to differences in intracellular pH regulation/buffering between these two tissues.

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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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