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Isotropic Voxel
 
A voxel that is uniform in all directions.
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• Related Searches:
    • Spatial Resolution
    • Volumetric Imaging
    • T1W High Resolution Isotropic Volume Examination
    • Isotropic
    • Multiplanar Reconstruction
 
Further Reading:
  News & More:
Voxel-based structural magnetic resonance imaging (MRI) study of patients with early onset schizophrenia
Monday, 22 December 2008   by 7thspace.com    
MRI Resources 
Hospitals - Implant and Prosthesis pool - Non-English - Equipment - Musculoskeletal and Joint MRI - Software
 
Contrast Enhanced Magnetic Resonance AngiographyInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - MRA -
 
(CE MRA) Contrast enhanced MR angiography is based on the T1 values of blood, the surrounding tissue, and paramagnetic contrast agent.
T1-shortening contrast agents reduces the T1 value of the blood (approximately to 50 msec, shorter than that of the surrounding tissues) and allow the visualization of blood vessels, as the images are no longer dependent primarily on the inflow effect of the blood. Contrast enhanced MRA is performed with a short TR to have low signal (due to the longer T1) from the stationary tissue, short scan time to facilitate breath hold imaging, short TE to minimize T2* effects and a bolus injection of a sufficient dose of a gadolinium chelate.
Images of the region of interest are performed with 3D spoiled gradient echo pulse sequences. The enhancement is maximized by timing the contrast agent injection such that the period of maximum arterial concentration corresponds to the k-space acquisition. Different techniques are used to ensure optimal contrast of the arteries e.g., bolus timing, automatic bolus detection, bolus tracking, care bolus. A high resolution with near isotropic voxels and minimal pulsatility and misregistration artifacts should be striven for. The postprocessing with the maximum intensity projection (MIP) enables different views of the 3D data set.
Unlike conventional MRA techniques based on velocity dependent inflow or phase shift techniques, contrast enhanced MRA exploits the gadolinium induced T1-shortening effects. CE MRA reduces or eliminates most of the artifacts of time of flight angiography or phase contrast angiography. Advantages are the possibility of in plane imaging of the blood vessels, which allows to examine large parts in a short time and high resolution scans in one breath hold. CE MRA has found a wide acceptance in the clinical routine, caused by the advantages:
3D MRA can be acquired in any plane, which means that greater vessel coverage can be obtained at high resolution with fewer slices (aorta, peripheral vessels);
the possibility to perform a time resolved examination (similarly to conventional angiography);
no use of ionizing radiation; paramagnetic agents have a beneficial safety.
 
Images, Movies, Sliders:
 CE-MRA of the Carotid Arteries  Open this link in a new window
    
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 CE MRA of the Aorta  Open this link in a new window
    
SlidersSliders Overview

 CE-MRA of the Carotid Arteries Colored MIP  Open this link in a new window
    
SlidersSliders Overview

 
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• View the DATABASE results for 'Contrast Enhanced Magnetic Resonance Angiography' (14).Open this link in a new window


• View the NEWS results for 'Contrast Enhanced Magnetic Resonance Angiography' (2).Open this link in a new window.
 
Further Reading:
  Basics:
Contrast-Enhanced MR Angiography(.pdf)
   by ric.uthscsa.edu    
CONTRAST ENHANCED MR ANGIOGRAPHY – PRINCIPLES, APPLICATIONS, TIPS AND PITFALLS(.pdf)
  News & More:
CONTRAST-ENHANCED MRA OF THE CAROTIDS(.pdf)
PERIPHERAL VASCULAR MAGNETIC RESONANCE ANGIOGRAPHY(.pdf)
CONTRAST ENHANCED MRI OF THE LIVER STATE-OF-THE-ART(.pdf)
MRI Resources 
MRI Physics - Corporations - Mobile MRI Rental - Anatomy - Knee MRI - MRI Centers
 
Multiplanar Reconstruction
 
(MPR) The postprocessing reformatting of a 3D data set into 2D slices of arbitrary thickness at any angle. For a good resolution thin slices, isotropic voxel and overcontiguous slices (overlapping slices) for good signal are advantageous.
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• View the DATABASE results for 'Multiplanar Reconstruction' (3).Open this link in a new window

MRI Resources 
Intraoperative MRI - Safety Products - Veterinary MRI - MRI Technician and Technologist Jobs - Bioinformatics - Services and Supplies
 
Volumetric Imaging
 
Volumetric imaging is a 3D technique where all the MRI signals are collected from the entire tissue sample and imaged as a whole entity, therefore providing a high signal to noise ratio. The acquisition of isotropic voxels or thin slices with high spatial resolution allows to create multiplanar reconstructions in all planes; a compensation for the usually longer scan time. The acquisition time can be reduced by parallel imaging technique.
New T2 weighted variants of 3D sequences (FSE-XETA, T2-SPACE, VISTA) have been introduced that differ from conventional FSE sequences. An echo train containing up to 200 echoes obtained at a minimum echo spacing allows very fast acquisition. A flip angle modulation (flip angle sweep - FAS) during the FSE readout carries magnetization as long as possible to avoid blurring and provide optimal signal at the effective echo time. This type of imaging is well suited for brain and spine MRI procedures.
Newer T1 weighted variants include Liver Acquisition with Volume Acquisition (LAVA) and T1W High Resolution Isotropic Volume Examination (THRIVE), which have advantages for dynamic breath hold imaging in liver and abdominal examinations.

See also Volume Imaging, 3 Dimensional Imaging.
 
Images, Movies, Sliders:
 Brain MRI Sagittal T1 001  Open this link in a new window
    
 Circle of Willis, Time of Flight, MIP  Open this link in a new window
    
SlidersSliders Overview

 MRI of the Skull Base  Open this link in a new window
    
SlidersSliders Overview

 
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• View the DATABASE results for 'Volumetric Imaging' (4).Open this link in a new window


• View the NEWS results for 'Volumetric Imaging' (1).Open this link in a new window.
 
Further Reading:
  Basics:
Cutting Edge Imaging of THE Spine
February 2007   by www.pubmedcentral.nih.gov    
3-D VOLUMETRIC IMAGING FOR STEREOTACTIC LESIONAL AND DEEP BRAIN STIMULATION SURGERY
MRI Resources 
Databases - PACS - Pregnancy - Portals - MRCP - Pathology
 
Diffusion Tensor ImagingInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.MRI Resource Directory:
 - 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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• View the DATABASE results for 'Diffusion Tensor Imaging' (9).Open this link in a new window


• View the NEWS results for 'Diffusion Tensor Imaging' (2).Open this link in a new window.
 
Further Reading:
  Basics:
EVALUATION OF HUMAN STROKE BY MR IMAGING
2000
  News & More:
What MRI-Derived Data and Other Factors Reveal About White Matter Hyperintensity in Former Football Players
Saturday, 23 December 2023   by www.diagnosticimaging.com    
Effect of gadolinium-based contrast agent on breast diffusion-tensor imaging
Thursday, 6 August 2020   by www.eurekalert.org    
Learning difficulties linked to poor brain connectivity
Monday, 2 March 2020   by cosmosmagazine.com    
New imaging technique reveals early brain damage caused by hypertension
Friday, 18 September 2015   by www.medicalnewstoday.com    
Imaging shows structural changes in mild traumatic brain injury
Thursday, 25 October 2007   by www.eurekalert.org    
MRI Resources 
Examinations - MR Guided Interventions - MRI Technician and Technologist Career - Manufacturers - Contrast Enhanced MRI - Mobile MRI
 
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