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Result : Searchterm 'Diffusion' found in 8 terms [] and 36 definitions []
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DiffusionForum -
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The process by which molecules or other particles intermingle and migrate due to their random thermal motion. Microscopic particles are jittering around with translational and rotational motions as a result of their thermal energy, which is half the Boltzmann constant multiplied by the absolute temperature of the system (˝kT) per degree of freedom (3 directions of translation and 3 directions of rotation for ordinary particles).
MRI provides a sensitive technique for measuring diffusion of some substances. These diffusive processes mean that particles reach areas of low from areas of high concentration, thus leading to equilibration. In body fluids, the distribution of capillaries within tissues is such that transport over macroscopic distances is accomplished by the blood circulation, while over intercapillary distances substances are carried by diffusion. The fluid diffusion constant is itself inversely proportional to the viscosity and the radius of the diffusing particles.
See also Diffusion Tensor Imaging and Diffusion Weighted Imaging.

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    • Diffusion Weighted Sequence
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    • Diffusion Time
    • Parallel Imaging Technique
    • Boltzmann Distribution
 
Further Reading:
  Basics:
Conventional MRI and MR Angiography of Stroke
2012   by www.mc.vanderbilt.edu    
EVALUATION OF HUMAN STROKE BY MR IMAGING
2000
Diffusion-Weighted MRI in the Body: Applications and Challenges in Oncology
Friday, 1 June 2007   by www.ajronline.org    
  News & More:
EORTC study aims to qualify ADC as predictive imaging biomarker in preoperative regimens
Monday, 4 January 2016   by www.eurekalert.org    
Functional imaging with diffusion-weighted MRI for lung biopsy planning: initial experience
Thursday, 10 July 2014   by 7thspace.com    
Diffusion-weighted MRI sensitive for metastasis in pelvic lymph nodes
Sunday, 15 June 2014   by www.2minutemedicine.com    
Connecting the dots: Water diffusion MRI reveals plasticity networks in remote nonstimulated brain regions
Monday, 31 March 2014   by medicalxpress.com    
Searchterm 'Diffusion' was also found in the following services: 
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Diffusion Time
 
Images obtained by a diffusion weighted sequence (e.g. the Stejskal-Tanner sequence) reflect the diffusion as an attenuation of signal intensity. The diffusion time is the time elapsed between the leading edges of the diffusion gradient lobes of this sequence.
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Further Reading:
  Basics:
Diffusion-Weighted MRI in the Body: Applications and Challenges in Oncology
Friday, 1 June 2007   by www.ajronline.org    
MRI Resources 
Shielding - Implant and Prosthesis pool - Blood Flow Imaging - Bioinformatics - Fluorescence - Distributors
 
Diffusion Tensor ImagingInfoSheet: - Sequences - 
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 - Diffusion Weighted Imaging -
 
(DTI) Diffusion tensor imaging is the more sophisticated form of DWI, which allows for the determination of directionality as well as the magnitude of water diffusion. This kind of MR imaging can estimates damage to nerve fibers that connect the area of the brain affected by the stroke to brain regions that are distant from it, and can be used to determine the effectiveness of stroke prevention medications.
DTI (FiberTrak) enables to visualize white matter fibers in the brain and can map (trace image) subtle changes in the white matter associated with diseases such as multiple sclerosis and epilepsy, as well as assessing diseases where the brain’s wiring is abnormal, such as schizophrenia.
The fractional anisotropy (FA) gives information about the shape of the diffusion tensor at each voxel. The FA is based on the normalized variance of the eigenvalues. The fractional anisotropy reflects differences between an isotropic diffusion and a linear diffusion. The FA range is between 0 and 1 (0 = isotropic diffusion, 1 = highly directional).
The development of new imaging methods and some useful analysis techniques, such as 3-dimensional anisotropy contrast (3DAC) and spatial tracking of the diffusion tensor tractography (DTT), are currently under study.

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Further Reading:
  Basics:
EVALUATION OF HUMAN STROKE BY MR IMAGING
2000
  News & More:
Imaging Technique for Spinal Cord Injury Shows Promise
Sunday, 22 December 2013   by www.wauwatosanow.com    
DTI: a New Diagnostic Tool for Injuries in Motor Vehicle Accidents
Saturday, 19 November 2011   by www.digitaljournal.com    
Imaging shows structural changes in mild traumatic brain injury
Thursday, 25 October 2007   by www.eurekalert.org    
Searchterm 'Diffusion' was also found in the following services: 
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(DWI) Magnetic resonance imaging is sensitive to diffusion, because the diffusion of water molecules along a field gradient reduces the MR signal. In areas of lower diffusion the signal loss is less intense and the display from this areas is brighter. The use of a bipolar gradient pulse and suitable pulse sequences permits the acquisition of diffusion weighted images (images in which areas of rapid proton diffusion can be distinguished from areas with slow diffusion).
Based on echo planar imaging, multislice DWI is today a standard for imaging brain infarction. With enhanced gradients, the whole brain can be scanned within seconds. The degree of diffusion weighting correlates with the strength of the diffusion gradients, characterized by the b-value, which is a function of the gradient related parameters: strength, duration, and the period between diffusion gradients.
Certain illnesses show restrictions of diffusion, for example demyelinization and cytotoxic edema. Areas of cerebral infarction have decreased apparent diffusion, which results in increased signal intensity on diffusion weighted MRI scans. DWI has been demonstrated to be more sensitive for the early detection of stroke than standard pulse sequences and is closely related to temperature mapping.
DWIBS is a new diffusion weighted imaging technique for the whole body that produces PET-like images. The DWIBS sequence has been developed with the aim to detect lymph nodes and to differentiate normal and hyperplastic from metastatic lymph nodes. This may be possible caused by alterations in microcirculation and water diffusivity within cancer metastases in lymph nodes.
See also Diffusion Weighted Sequence, Perfusion Imaging, ADC Map, Apparent Diffusion Coefficient, and Diffusion Tensor Imaging.

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Further Reading:
  Basics:
EVALUATION OF HUMAN STROKE BY MR IMAGING
2000
Novel MRI Technique Could Reduce Breast Biopsies, University of Washington Study
Tuesday, 2 October 2012   by www.eurekalert.org    
Quantitative Apparent Diffusion Coefficient Measurements Obtained by 3-Tesla MRI Are Correlated with Biomarkers of Bladder Cancer Proliferative Activity
   by www.plosone.org    
  News & More:
Use of diffusion magnetic resonance imaging to correlate the developmental changes in grape berry tissue structure with water diffusion patterns
Wednesday, 5 November 2014   by 7thspace.com    
Novel Imaging Technique Improves Prostate Cancer Detection
Tuesday, 6 January 2015   by health.ucsd.edu    
High-b-value Diffusion-weighted MR Imaging of Suspected Brain Infarction
2000   by www.ajnr.org    
Searchterm 'Diffusion' was also found in the following services: 
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Diffusion Weighted SequenceInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - Diffusion Weighted Imaging -
 
Diffusion weighted imaging can be performed similar to the phase contrast angiography sequence. The gradients must be increased in amplitude to depict the much slower motions of molecular diffusion in the body.
While a T1 weighted MRI pulse sequence is diffusion sensitive, a quantitative diffusion pulse sequence was introduced by Steijskal and Tanner. Its characteristic features are two strong symmetrical gradient lobes placed on either side of the 180° refocusing pulse in a spin echo sequence. These symmetrical gradient lobes have the sole purpose of enhancing dephasing of spins, thereby accelerating intravoxel incoherent motion (IVIM) signal loss.
Dephasing is proportional to the square of the time (diffusion time) during which the gradients are switched on and the strength of the applied gradient field. Therefore, the use of high field gradient systems with faster and more sensitive sequences, make diffusion weighting more feasible.
Areas in which the protons diffuse rapidly (swollen cells in early stroke, less restriction to diffusion) will show an increased signal when the echo is measured relative to areas in which diffusion is restricted. For increased accuracy of diffusion measurement and image enhancement, useful motion correction techniques such as navigator echo and other methods should be used. In addition to this, applying the b-value calculated by the strength and duration of motion probing gradients with a high rate of accuracy is very important.
See also Apparent Diffusion Coefficient, ADC Map, Lattice Index Map.

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• View the DATABASE results for 'Diffusion Weighted Sequence' (6).Open this link in a new window

 
Further Reading:
  Basics:
Diffusion-Weighted Imaging
   by spinwarp.ucsd.edu    
Diffusion Imaging: From Basic Physics to Practical Imaging
1999   by ej.rsna.org    
EVALUATION OF HUMAN STROKE BY MR IMAGING
2000
  News & More:
Functional imaging with diffusion-weighted MRI for lung biopsy planning: initial experience
Thursday, 10 July 2014   by 7thspace.com    
Diffusion-weighted MRI sensitive for metastasis in pelvic lymph nodes
Sunday, 15 June 2014   by www.2minutemedicine.com    
Hopkins researchers use diffusion MRI technique to monitor ultrasound uterine fibroid treatment
Monday, 8 August 2005   by www.eurekalert.org    
DWI Best in Subacute Stroke Imaging
Tuesday, 1 June 2004   by www.hospimedica.com    
MRI Resources 
MRCP - Mobile MRI - Health - Service and Support - Abdominal Imaging - MR Guided Interventions
 
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