scholarly journals Evidence of the diffusion time dependence of intravoxel incoherent motion in the brain

2019 ◽  
Vol 82 (6) ◽  
pp. 2225-2235 ◽  
Author(s):  
Dan Wu ◽  
Jiangyang Zhang
Keyword(s):  
Time Dependence ◽  
Diffusion Time ◽  
Intravoxel Incoherent Motion ◽  
The Brain

scholarly journals Time dependence and distribution of hematoporphyrin derivative in the brain tumor

1985 ◽  
Vol 5 (3) ◽  
pp. 73-78
Author(s):  
Sadao Kaneko ◽  
Kouichi Tokuda ◽  
Shinji Sugimoto ◽  
Hiroshi Abe ◽  
Yoshihiro Kakiuchi ◽  
...  
Keyword(s):  
Brain Tumor ◽  
Time Dependence ◽  
Hematoporphyrin Derivative ◽  
The Brain

Enhancing intravoxel incoherent motion parameter mapping in the brain using k -b PCA

2018 ◽  
Vol 31 (12) ◽  
pp. e4008 ◽  
Author(s):  
Georg R. Spinner ◽  
Johannes F.M. Schmidt ◽  
Constantin von Deuster ◽  
Christian Federau ◽  
Christian T. Stoeck ◽  
...  
Keyword(s):  
Motion Parameter ◽  
Intravoxel Incoherent Motion ◽  
Parameter Mapping ◽  
The Brain

scholarly journals A time-dependent diffusion MRI signature of axon caliber variations and beading

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Hong-Hsi Lee ◽  
Antonios Papaioannou ◽  
Sung-Lyoung Kim ◽  
Dmitry S. Novikov ◽  
Els Fieremans
Keyword(s):  
Time Dependence ◽  
Diffusion Mri ◽  
Cellular Level ◽  
3 Dimensional ◽  
Non Invasive ◽  
Brain White Matter ◽  
Cell Dimensions ◽  
Micrometer Scale ◽  
Exciting Possibility ◽  
The Brain

AbstractMRI provides a unique non-invasive window into the brain, yet is limited to millimeter resolution, orders of magnitude coarser than cell dimensions. Here, we show that diffusion MRI is sensitive to the micrometer-scale variations in axon caliber or pathological beading, by identifying a signature power-law diffusion time-dependence of the along-fiber diffusion coefficient. We observe this signature in human brain white matter and identify its origins by Monte Carlo simulations in realistic substrates from 3-dimensional electron microscopy of mouse corpus callosum. Simulations reveal that the time-dependence originates from axon caliber variation, rather than from mitochondria or axonal undulations. We report a decreased amplitude of time-dependence in multiple sclerosis lesions, illustrating the potential sensitivity of our method to axonal beading in a plethora of neurodegenerative disorders. This specificity to microstructure offers an exciting possibility of bridging across scales to image cellular-level pathology with a clinically feasible MRI technique.

scholarly journals Investigation of field and diffusion time dependence of the diffusion-weighted signal at ultrahigh magnetic fields

2013 ◽  
Vol 26 (10) ◽  
pp. 1251-1257 ◽  
Author(s):  
Nicolas Kunz ◽  
Stéphane V. Sizonenko ◽  
Petra S. Hüppi ◽  
Rolf Gruetter ◽  
Yohan van de Looij
Keyword(s):  
Magnetic Fields ◽  
Time Dependence ◽  
Diffusion Time ◽  
Diffusion Weighted ◽  
Ultrahigh Magnetic Fields ◽  
And Diffusion

scholarly journals A Software Package for the Modeling of Electrophysiological Activity Data

2022 ◽  
Vol 17 (1) ◽  
pp. 1-10
Author(s):  
A.I. Boyko ◽  
S.D. Rykunov ◽  
M.N. Ustinin
Keyword(s):  
Time Series ◽  
Time Dependence ◽  
Software Package ◽  
Dipole Model ◽  
Input Output ◽  
Equivalent Current Dipole ◽  
Current Dipole ◽  
Output Module ◽  
Calculation Module ◽  
The Brain

A complex of programs has been developed for computer modeling of multichannel time series recorded in various experiments on electromagnetic fields created by the human body. Sets of coordinates and directions of sensors for magnetic encephalographs of several types, electroencephalographs and magnetic cardiographs are used as models of devices. To study the human brain, magnetic resonance tomograms are used as head models; to study the heart, a body model in the form of a half-space with a flat boundary is used. The sources are placed in the model space, for them the direct problem is solved in the physical model corresponding to the device used. For a magnetic encephalograph and an electroencephalograph, an equivalent current dipole model in a spherical conductor is used, for a magnetic cardiograph, an equivalent current dipole model in a flat conductor or a magnetic dipole model is used. For each source, a time dependence is set and a multichannel time series is calculated. Then the time series from all sources are summed and the noise component is added. The program consists of three modules: an input-output module, a calculation module and a visualization module. The input-output module is responsible for loading device models, brain models, and field source parameters. The calculation module is responsible for directly calculating the field and transforming coordinates between the index system and the head system. The visualization module is responsible for the image of the brain model, the position of the field sources, a graphical representation of the amplitude-time dependence of the field sources and the calculated values of the total field. The user interface has been developed. The software package provides: interactive placement of field sources in the head or body space and editing of the amplitude-time dependence; batch loading of a large number of sources; noise modeling; simulation of low-channel planar magnetometers of various orders, specifying the shape of the device, the number of sensors and their parameters. Magnetic and electric fields produced by sources in the brain areas responsible for processing speech stimuli are considered. The resulting multichannel signal can be used to test various data analysis methods and for the experiment planning.

scholarly journals Effects of diffusion time on non-Gaussian diffusion and intravoxel incoherent motion (IVIM) MRI parameters in breast cancer and hepatocellular carcinoma xenograft models

2018 ◽  
Vol 7 (1) ◽  
pp. 205846011775156 ◽  
Author(s):  
Mami Iima ◽  
Tomomi Nobashi ◽  
Hirohiko Imai ◽  
Sho Koyasu ◽  
Tsuneo Saga ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Hepatocellular Carcinoma ◽  
Magnetic Resonance ◽  
Mouse Models ◽  
Diffusion Time ◽  
Intravoxel Incoherent Motion ◽  
Benign Tumors ◽  
Xenograft Models ◽  
Non Gaussian ◽  
Carcinoma Xenograft

Background Perfusion-related intravoxel incoherent motion (IVIM) and non-Gaussian diffusion magnetic resonance (MR) parameters are becoming important biomarkers for differentiating malignant from benign tumors without contrast agents. However, diffusion-time dependence has rarely been investigated in tumors. Purpose To investigate the relationship between diffusion time and diffusion parameters in breast cancer and hepatocellular carcinoma xenograft mouse models. Material and Methods Diffusion-weighted MR images (DWI) were obtained on a 7-T magnetic resonance imaging (MRI) scanner at two different diffusion times (9.6 ms and 27.6 ms) in human breast cancer (MDA-MB-231) and hepatocellular carcinoma (HepG2 and PLC/PRF/5) xenograft mouse models. Perfusion-related IVIM (fIVIM and D*) and non-Gaussian diffusion (ADC0 and K) parameters were estimated. Parametric maps of diffusion changes with the diffusion times were generated using a synthetic apparent diffusion coefficient (sADC) obtained from b = 438 and 2584 s/mm2. Results ADC0 values significantly decreased when diffusion times were changed from 9.6 ms to 27.6 ms in MDA-MB-231, HepG2, and PLC/PRF/5 groups ( P = 0.0163, 0.0351, and 0.0170, respectively). K values significantly increased in MDA-MB-231 and HepG2 groups ( P < 0.0003 and = 0.0007, respectively); however, no significant difference was detected in the PLC/PRF/5 group. fIVIM values increased, although not significantly ( P = 0.164–0.748). The maps of sADC changes showed that diffusion changes with the diffusion time were not homogeneous across tumor tissues. Conclusion Diffusion MR parameters in both breast cancer and HCC xenograft models were found to be diffusion time-dependent. Our results show that diffusion time is an important parameter to consider when interpreting DWI data.

scholarly journals FORMATION AND LIFE-TIME OF MEMORY DOMAINS IN THE DISSIPATIVE QUANTUM MODEL OF BRAIN

2000 ◽  
Vol 14 (08) ◽  
pp. 853-868 ◽  
Author(s):  
ELEONORA ALFINITO ◽  
GIUSEPPE VITIELLO
Keyword(s):  
Time Dependence ◽  
Life Time ◽  
External World ◽  
Neural Circuitry ◽  
Quantum Model ◽  
Electrical Dipole ◽  
Internal Parameters ◽  
Memory States ◽  
The Brain ◽  
Dynamic Formation

We show that in the dissipative quantum model of brain the time-dependence of the frequencies of the electrical dipole wave quanta leads to the dynamical organization of the memories in space (i.e., to their localization in more or less diffused regions of the brain) and in time (i.e., to their longer or shorter life-time). The life-time and the localization in domains of the memory states also depend on internal parameters and on the number of links that the brain establishes with the external world. These results agree with the physiological observations of the dynamic formation of neural circuitry which grows as brain develops and relates to external world.

scholarly journals Monitoring the Level of 14C-Labelled Selegiline Following Oral Administration

2017 ◽  
Vol 11 (1) ◽  
pp. 1-8
Author(s):  
Huba Kalász ◽  
Kornélia Tekes ◽  
Erzsébet B. Faigl ◽  
Zita Pöstényi ◽  
Eszter Berekméri ◽  
...  
Keyword(s):  
Serum Level ◽  
Oral Administration ◽  
Time Dependence ◽  
Tissue Distribution ◽  
Intraperitoneal Injection ◽  
Intraperitoneal Administration ◽  
Reversed Phase ◽  
Reversed Phase Hplc ◽  
Body Compartments ◽  
The Brain

Background: Selegiline [(-)-deprenyl] is widely used for the treatment of Parkinson’s disease in humans. Objective: Time-dependence of tissue distribution of selegiline following per os administration to rats. Method: Oral administration of radiolabeled selegiline to rats resulted in a pattern of tissue distribution similar to that following intraperitoneal injection. Analyses were done using both reversed-phase HPLC and also by counting radioactivity in various body compartments of rats. Results: As a consequence of oral administration of 30 mg/kg of selegiline, its level in the stomach was extremely high (179.57 µg/g tissue through 54.67 µg/g at 15 min to 120 min), that is one magnitude higher than that in the serum level. High selegiline concentrations were also detected in the lacrimal glands (7.45 µg/g), kidneys (6.87 µg/g), livers (6.01 µg/g) and lungs (3.47 µg/g) after 30 minutes of application, which were higher than after intraperitoneal injections. Conclusion: The relatively high tissue levels remained for 120 min monitoring. Selegiline levels in the brain (1.69 µg/g) and in the testes (1.88 µg/g) were also considerably higher than following intraperitoneal administration during the entire period of observation (15 to 120 min).

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