scholarly journals Magnetic susceptibility mapping of brain tissue in vivo using MRI phase data

2009 ◽  
Vol 62 (6) ◽  
pp. 1510-1522 ◽  
Author(s):  
Karin Shmueli ◽  
Jacco A. de Zwart ◽  
Peter van Gelderen ◽  
Tie-Qiang Li ◽  
Stephen J. Dodd ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Brain Tissue ◽  
Susceptibility Mapping ◽  
Phase Data

scholarly journals DeepQSM - Using Deep Learning to Solve the Dipole Inversion for MRI Susceptibility Mapping

2018 ◽  
Author(s):  
Kasper Gade Bøtker Rasmussen ◽  
Mads Kristensen ◽  
Rasmus Guldhammer Blendal ◽  
Lasse Riis Østergaard ◽  
Maciej Plocharski ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Magnetic Susceptibility ◽  
Iron Homeostasis ◽  
Nerve Fibers ◽  
Susceptibility Mapping ◽  
Source Inversion ◽  
Tissue Properties ◽  
Ill Posed ◽  
Phase Data

Quantitative susceptibility mapping (QSM) aims to extract the magnetic susceptibility of tissue from magnetic resonance imaging (MRI) phase measurements. The mapping of magnetic susceptibility in vivo has gained broad interest in several fields of science and medicine because it yields relevant information on biological tissue properties, predominantly myelin, iron and calcium. Thereby, QSM can also reveal pathological changes of these key components in devastating diseases such as Parkinson’s disease, Multiple Sclerosis, or hepatic iron overload. As QSM requires the solution of an ill-posed field-to-source-inversion, current techniques utilize manual optimization of regularization parameters to balance between smoothing, artifacts and quantification accuracy. We trained a fully convolutional deep neural network - DeepQSM - to invert the magnetic dipole kernel convolution. This network is capable of solving the ill-posed field-to-source inversion on real-world in vivo MRI phase data without the need for manual parameter tuning, which proves that this network has generalized the underlying mathematical principle of the dipole inversion. We demonstrate that DeepQSM’s susceptibility maps enable identification of deep brain substructures that are not visible in MRI phase data and provide information on their respective magnetic tissue properties. We illustrate DeepQSM’s clinical relevance in a patient with multiple sclerosis showing its sensitivity to white matter lesions. In summary, DeepQSM can be used to determine the composition of myelin sheets of nerve fibers in the brain, and to assess quantitative information on iron homeostasis and its dysregulation, and will subsequently contribute to a better understanding of these biological processes in health and disease.

scholarly journals Quantitative assessment of microvasculopathy in arcAβ mice with USPIO-enhanced gradient echo MRI

2016 ◽  
Vol 36 (9) ◽  
pp. 1614-1624 ◽  
Author(s):  
Jan Klohs ◽  
Andreas Deistung ◽  
Giovanna D Ielacqua ◽  
Aline Seuwen ◽  
Diana Kindler ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Iron Oxide ◽  
Superparamagnetic Iron Oxide ◽  
Brain Regions ◽  
Susceptibility Mapping ◽  
Amyloid Angiopathy ◽  
Gradient Echo ◽  
Quantitative Susceptibility Mapping ◽  
Focal Uptake

Magnetic resonance imaging employing administration of iron oxide-based contrast agents is widely used to visualize cellular and molecular processes in vivo. In this study, we investigated the ability of [Formula: see text] and quantitative susceptibility mapping to quantitatively assess the accumulation of ultrasmall superparamagnetic iron oxide (USPIO) particles in the arcAβ mouse model of cerebral amyloidosis. Gradient-echo data of mouse brains were acquired at 9.4 T after injection of USPIO. Focal areas with increased magnetic susceptibility and [Formula: see text] values were discernible across several brain regions in 12-month-old arcAβ compared to 6-month-old arcAβ mice and to non-transgenic littermates, indicating accumulation of particles after USPIO injection. This was concomitant with higher [Formula: see text] and increased magnetic susceptibility differences relative to cerebrospinal fluid measured in USPIO-injected compared to non-USPIO-injected 12-month-old arcAβ mice. No differences in [Formula: see text] and magnetic susceptibility were detected in USPIO-injected compared to non-injected 12-month-old non-transgenic littermates. Histological analysis confirmed focal uptake of USPIO particles in perivascular macrophages adjacent to small caliber cerebral vessels with radii of 2–8 µm that showed no cerebral amyloid angiopathy. USPIO-enhanced [Formula: see text] and quantitative susceptibility mapping constitute quantitative tools to monitor such functional microvasculopathies.

Monocytes as Carriers of Magnetic Nanoparticles for Tracking Inflammation in the Epileptic Rat Brain

2019 ◽  
Vol 16 (7) ◽  
pp. 637-644 ◽  
Author(s):  
Hadas Han ◽  
Sara Eyal ◽  
Emma Portnoy ◽  
Aniv Mann ◽  
Miriam Shmuel ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Ex Vivo ◽  
In Vivo Studies ◽  
Nanoparticle Distribution ◽  
Spontaneous Seizures ◽  
Systemic Distribution ◽  
Hippocampal Ca1 ◽  
Pilocarpine Model

Background: Inflammation is a hallmark of epileptogenic brain tissue. Previously, we have shown that inflammation in epilepsy can be delineated using systemically-injected fluorescent and magnetite- laden nanoparticles. Suggested mechanisms included distribution of free nanoparticles across a compromised blood-brain barrier or their transfer by monocytes that infiltrate the epileptic brain. Objective: In the current study, we evaluated monocytes as vehicles that deliver nanoparticles into the epileptic brain. We also assessed the effect of epilepsy on the systemic distribution of nanoparticleloaded monocytes. Methods: The in vitro uptake of 300-nm nanoparticles labeled with magnetite and BODIPY (for optical imaging) was evaluated using rat monocytes and fluorescence detection. For in vivo studies we used the rat lithium-pilocarpine model of temporal lobe epilepsy. In vivo nanoparticle distribution was evaluated using immunohistochemistry. Results: 89% of nanoparticle loading into rat monocytes was accomplished within 8 hours, enabling overnight nanoparticle loading ex vivo. The dose-normalized distribution of nanoparticle-loaded monocytes into the hippocampal CA1 and dentate gyrus of rats with spontaneous seizures was 176-fold and 380-fold higher compared to the free nanoparticles (p<0.05). Seizures were associated with greater nanoparticle accumulation within the liver and the spleen (p<0.05). Conclusion: Nanoparticle-loaded monocytes are attracted to epileptogenic brain tissue and may be used for labeling or targeting it, while significantly reducing the systemic dose of potentially toxic compounds. The effect of seizures on monocyte biodistribution should be further explored to better understand the systemic effects of epilepsy.

scholarly journals Protein Kinase A Distribution in Meningioma

Cancers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1686 ◽  
Author(s):  
Caretta ◽  
Denaro ◽  
D’Avella ◽  
Mucignat-Caretta
Keyword(s):  
Brain Tissue ◽  
Catalytic Subunit ◽  
Therapeutic Interventions ◽  
Normal Brain ◽  
Local Concentration ◽  
Correlation Pattern ◽  
Catalytic Subunits ◽  
Tissue Specimens ◽  
Pka Catalytic Subunit

Deregulation of intracellular signal transduction pathways is a hallmark of cancer cells, clearly differentiating them from healthy cells. Differential intracellular distribution of the cAMP-dependent protein kinases (PKA) was previously detected in cell cultures and in vivo in glioblastoma and medulloblastoma. Our goal is to extend this observation to meningioma, to explore possible differences among tumors of different origins and prospective outcomes. The distribution of regulatory and catalytic subunits of PKA has been examined in tissue specimens obtained during surgery from meningioma patients. PKA RI subunit appeared more evenly distributed throughout the cytoplasm, but it was clearly detectable only in some tumors. RII was present in discrete spots, presumably at high local concentration; these aggregates could also be visualized under equilibrium binding conditions with fluorescent 8-substituted cAMP analogues, at variance with normal brain tissue and other brain tumors. The PKA catalytic subunit showed exactly overlapping pattern to RII and in fixed sections could be visualized by fluorescent cAMP analogues. Gene expression analysis showed that the PKA catalytic subunit revealed a significant correlation pattern with genes involved in meningioma. Hence, meningioma patients show a distinctive distribution pattern of PKA regulatory and catalytic subunits, different from glioblastoma, medulloblastoma, and healthy brain tissue. These observations raise the possibility of exploiting the PKA intracellular pathway as a diagnostic tool and possible therapeutic interventions.

scholarly journals In Vivo and In Vitro Toxicodynamic Analyses of New Quinolone-and Nonsteroidal Anti-Inflammatory Drug-Induced Effects on the Central Nervous System

1999 ◽  
Vol 43 (5) ◽  
pp. 1091-1097 ◽  
Author(s):  
Hideki Kita ◽  
Hirotami Matsuo ◽  
Hitomi Takanaga ◽  
Junichi Kawakami ◽  
Koujirou Yamamoto ◽  
...  
Keyword(s):  
Brain Tissue ◽  
Threshold Concentration ◽  
Current Response ◽  
Drug Induced ◽  
Inhibition Ratio ◽  
New Quinolones ◽  
The Central Nervous System ◽  
Anti Inflammatory

ABSTRACT We investigated the correlation between an in vivo isobologram based on the concentrations of new quinolones (NQs) in brain tissue and the administration of nonsteroidal anti-inflammatory drugs (NSAIDs) for the occurrence of convulsions in mice and an in vitro isobologram based on the concentrations of both drugs for changes in the γ-aminobutyric acid (GABA)-induced current response in Xenopus oocytes injected with mRNA from mouse brains in the presence of NQs and/or NSAIDs. After the administration of enoxacin (ENX) in the presence or absence of felbinac (FLB), ketoprofen (KTP), or flurbiprofen (FRP), a synergistic effect was observed in the isobologram based on the threshold concentration in brain tissue between mice with convulsions and those without convulsions. The three NSAIDs did not affect the pharmacokinetic behavior of ENX in the brain. However, the ENX-induced inhibition of the GABA response in the GABAA receptor expressed in Xenopus oocytes was enhanced in the presence of the three NSAIDs. The inhibition ratio profiles of the GABA responses for both drugs were analyzed with a newly developed toxicodynamic model. The inhibitory profiles for ENX in the presence of NSAIDs followed the order KTP (1.2 μM) > FRP (0.3 μM) > FLB (0.2 μM). These were 50- to 280-fold smaller than those observed in the absence of NSAIDs. The inhibition ratio (0.01 to 0.02) of the GABAA receptor in the presence of both drugs was well-fitted to the isobologram based on threshold concentrations of both drugs in brain tissue between mice with convulsions and those without convulsions, despite the presence of NSAIDs. In mice with convulsions, the inhibitory profiles of the threshold concentrations of both drugs in brain tissue of mice with convulsions and those without convulsions can be predicted quantitatively by using in vitro GABA response data and toxicodynamic model.

Abstract P419: A Systematic Characterization of Brain Endothelial Cell Death in Intracerebral Hemorrhage

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Maulana Ikhsan ◽  
Marietta Zille
Keyword(s):  
Cell Death ◽  
Intracerebral Hemorrhage ◽  
Brain Tissue ◽  
Vascular Integrity ◽  
Regulated Cell Death ◽  
Injury Mechanisms ◽  
Endothelial Cell Death ◽  
Cell Death Mechanisms ◽  
Underlying Mechanisms

Introduction: Intracerebral hemorrhage (ICH) is a type of stroke caused by the loss of vascular integrity leading to bleeding within the brain tissue. Hematoma-derived factors cause secondary injury mechanisms such as cell death days to weeks after the event and in regions distant from the primary insult. Increasing evidence suggests that hemoglobin released by the hematoma is one of the major contributors to neuronal injury in ICH. To date, it is unclear whether brain endothelial cells (EC) are similarly vulnerable to hemolysis products and undergo regulated cell death. Hypothesis: We hypothesized that brain EC undergo multiple, different modes of cell death after ICH and that the underlying mechanisms are different compared to neurons. Methods: We systematically investigated cell death mechanisms in brain EC after exposure to the hemolysis product hemin. We used chemical inhibitors of apoptosis, autophagy, ferroptosis, necroptosis, and parthanatos and assessed biochemical markers of these cell death modes. Results: Brain EC viability was concentration-dependently decreased, starting at higher hemin concentrations than neurons. Treatment of EC with ferroptosis inhibitors protective against hemin toxicity in neurons and against ICH in vivo showed that only N-acetylcysteine and deferoxamine protected brain EC, while ferrostatin-1 and U0126 did not abrogate EC death. The autophagy inhibitor bafilomycin A1 also reduced EC death and hemin increased the expression of the autophagy marker LC3. While inhibitors against apoptosis and parthanatos were not effective, the necroptosis inhibitor GSK872 demonstrated a partial protective effect. Conclusions: Our data suggest that ICH induces different mechanisms of death in EC (ferroptosis and autophagy) compared to neurons (ferroptosis and necroptosis) and may thus warrant a combinatorial therapeutic approach. Further investigations in human and ovine ICH brain tissue are ongoing.

Brain glutamate metabolism during hypoxia and peripheral chemodenervation

1990 ◽  
Vol 69 (1) ◽  
pp. 147-154 ◽  
Author(s):  
B. Hoop ◽  
M. R. Masjedi ◽  
V. E. Shih ◽  
H. Kazemi
Keyword(s):  
Brain Tissue ◽  
Gamma Aminobutyric Acid ◽  
Glutamate Metabolism ◽  
Peripheral Chemoreceptor ◽  
Transfer Rates ◽  
Neural Excitability ◽  
Glutamate Concentration ◽  
Ventilatory Drive ◽  
Anesthetized Dogs

Glutamate stimulates resting ventilation by altering neural excitability centrally. Hypoxia increases central ventilatory drive through peripheral chemoreceptor stimulation and may also alter cerebral perfusion and glutamate metabolism locally. Therefore the effect of hypoxia and peripheral chemodenervation on cerebrospinal fluid (CSF) transfer rate of in vivo tracer amidated central nervous system glutamate was studied in intact and chemodenervated pentobarbital-anesthetized dogs during normoxia and after 1 h of hypoxia induced with 10 or 12% O2 in N2 breathing at constant expired ventilation and arterial CO2 tension. Chemodenervation was performed by bilateral sectioning of the carotid body nerves and cervical vagi. CSF transfer rates of radiotracer 13NH4+ and [13N]glutamine synthesized via the reaction, glutamate + NH4(+)----glutamine, in brain glia were measured during normoxia and after 1 h of hypoxia. At normoxia, maximal glial glutamine efflux rate jm = 103.3 +/- 11.2 (SE) mumol.l-1.min-1 in all animals. After 1 h of hypoxia in intact animals, jm = 78.4 +/- 10.0 mumol.l-1.min-1. In denervated animals, jm was decreased to 46.3 +/- 4.3 mumol.l-1.min-1. During hypoxia, mean cerebral cortical glutamate concentration was higher in denervated animals (9.98 +/- 1.43 mumol/g brain tissue) than in intact animals (7.63 +/- 1.82 mumol/g brain tissue) and corresponding medullary glutamate concentration tended to be higher in denervated animals. There were no differences between mean glutamine and gamma-aminobutyric acid concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

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