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Result : Searchterm 'Gradient' found in 59 terms [] and 252 definitions []
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Field EchoInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
(FE) Echo produced by reversing the direction of the magnetic field gradient to cancel out the position-dependent phase shifts that have accumulated due to the gradient.

See also Gradient Echo Sequence.
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Radiology  (1) Open this link in a new windowUltrasound  (3) Open this link in a new window
Fourier Transformation Imaging
 
MR imaging techniques in which at least one dimension is phase encoded by applying variable gradient pulses along that dimension before reading out the MR signal with a magnetic field gradient perpendicular to the variable gradient. The Fourier transformation is then used to reconstruct an image from the set of encoded MR signals. An imaging technique of this type is spin warp imaging.

See also Spin Warp Imaging.
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• View the DATABASE results for 'Fourier Transformation Imaging' (7).Open this link in a new window

 
Further Reading:
  Basics:
Fourier Transforms and 2-D Image Processing
   by robotics.eecs.berkeley.edu    
  News & More:
Fourier Transform Imaging of Spin Vortex Eigenmodes
Friday, 13 August 2004   by www.physik.uni-regensburg.de    
MRI Resources 
Blood Flow Imaging - Open Directory Project - Most Wanted - Cardiovascular Imaging - Brain MRI - Jobs pool
 
Golay CoilInfoSheet: - Coils - 
Intro, 
Overview, 
etc.MRI Resource Directory:
 - Coils -
 
This term is commonly used for a particular kind of gradient coil, commonly used to create magnetic field gradients perpendicular to the main magnetic field. A golay coil (a special kind of saddle coils) produces a linear gradient in the x and y axes that requires wires running along the bore of the magnet. Such a coil produces a very linear field, but the linearity is lost rapidly away from the central plane. A number of pairs with different axial separations can be used to improve this.
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News  (6)  Resources  (7)  Forum  (35)  
 
MEDIC TechniqueInfoSheet: - Sequences - 
Intro, 
Overview, 
Types of, 
etc.
 
Multiple echoes acquired in a gradient echo scan are combined into an image, for less artifacts and higher SNR; the early echoes provide increased SNR, whilst later echoes boost contrast. This sequence type is also known as MERGE (Multiple Echo Recombined Gradient Echo)

See also Multi Echo Data Image Combination, Bipolar Gradient Pulse.
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• View the NEWS results for 'MEDIC Technique' (15).Open this link in a new window.
 
Further Reading:
  Basics:
Cutting Edge Imaging of THE Spine
February 2007   by www.pubmedcentral.nih.gov    
Searchterm 'Gradient' was also found in the following services: 
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Radiology  (1) Open this link in a new windowUltrasound  (3) Open this link in a new window
MRI History
 
•
Sir Joseph Larmor (1857-1942) developed the equation that the angular frequency of precession of the nuclear spins being proportional to the strength of the magnetic field. [Larmor relationship]
•
In the 1930's, Isidor Isaac Rabi (Columbia University) succeeded in detecting and measuring single states of rotation of atoms and molecules, and in determining the mechanical and magnetic moments of the nuclei.
•
Felix Bloch (Stanford University) and Edward Purcell (Harvard University) developed instruments, which could measure the magnetic resonance in bulk material such as liquids and solids. (Both honored with the Nobel Prize for Physics in 1952.) [The birth of the NMR spectroscopy]
•
In the early 70's, Raymond Damadian (State University of New York) demonstrated with his NMR device, that there are different T1 relaxation times between normal and abnormal tissues of the same type, as well as between different types of normal tissues.
•
In 1973, Paul Lauterbur (State University of New York) described a new imaging technique that he termed Zeugmatography. By utilizing gradients in the magnetic field, this technique was able to produce a two-dimensional image (back-projection). (Through analysis of the characteristics of the emitted radio waves, their origin could be determined.) Peter Mansfield further developed the utilization of gradients in the magnetic field and the mathematically analysis of these signals for a more useful imaging technique. (Paul C Lauterbur and Peter Mansfield were awarded with the 2003 Nobel Prize in Medicine.)
•
In 1975, Richard Ernst introduced 2D NMR using phase and frequency encoding, and the Fourier Transform. Instead of Paul Lauterbur's back-projection, he timely switched magnetic field gradients ('NMR Fourier Zeugmatography'). [This basic reconstruction method is the basis of current MRI techniques.]
•
1977/78: First images could be presented. A cross section through a finger by Peter Mansfield and Andrew A. Maudsley. Peter Mansfield also could present the first image through the abdomen.
•
In 1977, Raymond Damadian completed (after 7 years) the first MR scanner (Indomitable). In 1978, he founded the FONAR Corporation, which manufactured the first commercial MRI scanner in 1980. Fonar went public in 1981.
•
1981: Schering submitted a patent application for Gd-DTPA dimeglumine.
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1982: The first 'magnetization-transfer' imaging by Robert N. Muller.
•
In 1983, Toshiba obtained approval from the Ministry of Health and Welfare in Japan for the first commercial MRI system.
•
In 1984, FONAR Corporation receives FDA approval for its first MRI scanner.
•
1986: Jürgen Hennig, A. Nauerth, and Hartmut Friedburg (University of Freiburg) introduced RARE (rapid acquisition with relaxation enhancement) imaging. Axel Haase, Jens Frahm, Dieter Matthaei, Wolfgang Haenicke, and Dietmar K. Merboldt (Max-Planck-Institute, Göttingen) developed the FLASH (fast low angle shot) sequence.
•
1988: Schering's MAGNEVIST gets its first approval by the FDA.
•
In 1991, fMRI was developed independently by the University of Minnesota's Center for Magnetic Resonance Research (CMRR) and Massachusetts General Hospital's (MGH) MR Center.
•
From 1992 to 1997 Fonar was paid for the infringement of it's patents from 'nearly every one of its competitors in the MRI industry including giant multi-nationals as Toshiba, Siemens, Shimadzu, Philips and GE'.
•
 
Images, Movies, Sliders:
 Cardiac Infarct Short Axis Cine Overview  Open this link in a new window
    

Courtesy of  Robert R. Edelman
 
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• View the NEWS results for 'MRI History' (1).Open this link in a new window.
 
Further Reading:
  Basics:
Magnetic Resonance Imaging, History & Introduction
2000   by www.cis.rit.edu    
A Short History of the Magnetic Resonance Imaging (MRI)
   by www.teslasociety.com    
Fonar Our History
   by www.fonar.com    
  News & More:
Scientists win Nobels for work on MRI
Tuesday, 10 June 2003   by usatoday30.usatoday.com    
2001 Lemelson-MIT Lifetime Achievement Award Winner
   by web.mit.edu    
MRI's inside story
Thursday, 4 December 2003   by www.economist.com    
MRI Resources 
Societies - Hospitals - Process Analysis - PACS - Education pool - Liver Imaging
 
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MRI is trending to low field magnets :
reduced costs will lead to this change 
AI will close the gap to high field 
only in remote areas 
is only temporary 
never 

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