Name: Vidéo: Quantitative Susceptibility Mapping of a Human Brain Using Ex-Vivo Magnetic Resonance Imaging - Expérience
Uploaded: 2025-05-30T13:18:43.000+00:00
Duration: 1 min 9 s
Description: 22 vues. Quantitative Susceptibility Mapping of a Human Brain Using Ex-Vivo Magnetic Resonance Imaging

quantitative susceptibility mapping of a human brain using ex-vivo magnetic resonance imaging

Quantitative Susceptibility Mapping of a Human Brain Using Ex-Vivo Magnetic Resonance Imaging

Quantitative susceptibility mapping, or QSM, quantifies the magnetic susceptibility of brain tissue, which reflects its cellular composition, like myelin content.Begin by acquiring ex-vivo magnetic resonance imaging or MRI data of a fixed human brain hemisphere.Use 3D gradient magnetic fields to magnetize the tissue and collect signals at multiple time points or echoes to reduce background noise and artifacts and enhance the signals.Generate phase maps for all echoes, ensuring the removal of any artifacts caused by trapped air within the brain tissue.Using appropriate MRI data processing tools, create a total field map of the hemisphere.&#160;Remove unwanted background magnetic fields while preserving the variations caused by tissue properties.Generate a susceptibility map using specialized algorithms and suppress any streaking artifacts to quantify the brain's magnetic susceptibility.

quantitative-susceptibility-mapping-human-brain-using-ex-vivo

Research

JoVE Encyclopedia of Experiments

Neuroscience

Neuroimaging

Advanced Microscopy & Imaging Technologies

22 vues. Quantitative Susceptibility Mapping of a Human Brain Using Ex-Vivo Magnetic Resonance Imaging

Vidéo: Quantitative Susceptibility Mapping of a Human Brain Using Ex-Vivo Magnetic Resonance Imaging - Expérience

Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease

Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of living systems. Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using qMRI methods. The MRI acquisition protocol begins with localizer images (used to locate the position of the body and tissue of interest within the MRI system), quality control measurements of relevant magnetic field distributions, and structural imaging for general anatomical characterization. The qMRI portion of the protocol includes measurements of the longitudinal and transverse relaxation time constants (T1 and T2, respectively). Also acquired are diffusion-tensor MRI data, in which water diffusivity is measured and used to infer pathological processes such as edema. Quantitative magnetization transfer imaging is used to characterize the relative tissue content of macromolecular and free water protons. Lastly, fat-water MRI methods are used to characterize fibro-adipose tissue replacement of muscle. In addition to describing the data acquisition and analysis procedures, this paper also discusses the potential problems associated with these methods, the analysis and interpretation of the data, MRI safety, and strategies for artifact reduction and protocol optimization.

Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using non-invasive magnetic resonance imaging methods.

Quantitative Imagerie par résonance magnétique de la maladie du muscle squelettique

Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of ...

Recherche

JoVE Journal

Médecine

High-resolution Structural Magnetic Resonance Imaging of the Human Subcortex In Vivo and Postmortem

The focus of this study was to test the resolution limits of structural MRI of a postmortem brain compared to living human brains. The resolution of structural MRI in vivo is ultimately limited by physiological noise, including pulsation, respiration and head movement. Although imaging hardware continues to improve, it is still difficult to resolve structures on the millimeter scale. For example, the primary visual sensory pathways synapse at the lateral geniculate nucleus (LGN), a visual relay and control nucleus in the thalamus that normally is organized into six interleaved monocular layers. Neuroimaging studies have not been able to reliably distinguish these layers due their small size that are less than 1 mm thick.
The resolving limit of structural MRI, in a postmortem brain was tested using multiple images averaged over a long duration (~24 h). The purpose was to test whether it was possible to resolve the individual layers of the LGN in the absence of physiological noise. A proton density (PD)1 weighted pulse sequence was used with varying resolution and other parameters to determine the minimum number of images necessary to be registered and averaged to reliably distinguish the LGN and other subcortical regions. The results were also compared to images acquired in living human brains. In vivo subjects were scanned in order to determine the additional effects of physiological noise on the minimum number of PD scans needed to differentiate subcortical structures, useful in clinical applications.

High-resolution Structural Magnetic Resonance Imaging of the Human Subcortex In Vivo and Postmortem

Here we present a protocol to determine the minimum number images that needed to be registered and averaged to resolve subcortical structures and test whether the individual layers of the LGN could be resolved in the absence of physiological noise.

Haute résolution structurelle Imagerie par résonance magnétique de la sous-cortex humain<I&gt; In Vivo</I&gt; Et Postmortem

The focus of this study was to test the resolution limits of structural MRI of a postmortem brain compared to living human brains. The resolution of ...

Neurosciences

Quantitative Mapping of Specific Ventilation in the Human Lung using Proton Magnetic Resonance Imaging and Oxygen as a Contrast Agent

Specific ventilation imaging (SVI) is a functional magnetic resonance imaging technique capable of quantifying specific ventilation &#8213; the ratio of the fresh gas entering a lung region divided by the region&#8217;s end-expiratory volume &#8213; in the human lung, using only inhaled oxygen as a contrast agent. Regional quantification of specific ventilation has the potential to help identify areas of pathologic lung function. Oxygen in solution in tissue shortens the tissue&#8217;s longitudinal relaxation time (T1), and thus a change in tissue oxygenation can be detected as a change in T1-weighted signal with an inversion recovery acquired image. Following an abrupt change between two concentrations of inspired oxygen, the rate at which lung tissue within a voxel equilibrates to a new steady-state reflects the rate at which resident gas is being replaced by inhaled gas. This rate is determined by specific ventilation. To elicit this sudden change in oxygenation, subjects alternately breathe 20-breath blocks of air (21% oxygen) and 100% oxygen while in the MRI scanner. A stepwise change in inspired oxygen fraction is achieved through use of a custom three-dimensional (3D)-printed flow bypass system with a manual switch during a short end-expiratory breath hold. To detect the corresponding change in T1, a global inversion pulse followed by a single shot fast spin echo sequence was used to acquire two-dimensional T1-weighted images in a 1.5&#160;T MRI scanner, using an eight-element torso coil. Both single slice and multi-slice imaging are possible, with slightly different imaging parameters. Quantification of specific ventilation is achieved by correlating the time-course of signal intensity for each lung voxel with a library of simulated responses to the air/oxygen stimulus. SVI estimations of specific ventilation heterogeneity have been validated against multiple breath washout and proved to accurately determine the heterogeneity of the specific ventilation distribution.

Specific ventilation imaging is a functional magnetic resonance imaging technique that allows for quantification of regional specific ventilation in the human lung, using inhaled oxygen as a contrast agent. Here, we present a protocol to collect and analyze specific ventilation imaging data.

Cartographie quantitative de la ventilation spécifique dans le poumon humain utilisant l’imagerie par résonance magnétique de proton et l’oxygène comme agent de contraste

Specific ventilation imaging (SVI) is a functional magnetic resonance imaging technique capable of quantifying specific ventilation &#8213; the ratio of ...

Quantitative Susceptibility Mapping of a Human Brain Using Ex-Vivo Magnetic Resonance Imaging

Transcription

Quantitative Imagerie par résonance magnétique de la maladie du muscle squelettique

Haute résolution structurelle Imagerie par résonance magnétique de la sous-cortex humain

Cartographie quantitative de la ventilation spécifique dans le poumon humain utilisant l’imagerie par résonance magnétique de proton et l’oxygène comme agent de contraste