Magnetic Resonance - Technology Information Portal Welcome to MRI Technology
Info
  Sheets

Out-
      side
 



 
 'Magnetization' 
SEARCH FOR    
 
  2 3 5 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Result : Searchterm 'Magnetization' found in 11 terms [] and 116 definitions []
previous     86 - 90 (of 127)     next
Result Pages : [1 2 3]  [4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ... ]
Searchterm 'Magnetization' was also found in the following services: 
spacer
News  (1)  Forum  (3)  
 
Longitudinal Relaxation
 
Return of longitudinal magnetization to its equilibrium value after excitation;; requires exchange of energy between the nuclear spins and the lattice. See also T1 Time.
spacer
 
• Related Searches:
    • Relaxivity
    • Transverse Relaxation Time
    • Relaxation Effect
    • Spin Lattice Relaxation Time
    • R1
Searchterm 'Magnetization' was also found in the following service: 
spacer
Radiology  (3) Open this link in a new window
Longitudinal Relaxation Time
 
The T1 time constant, which determines the rate at which excited protons return to equilibrium within the lattice. The longitudinal relaxation time is a measure of the time taken for spinning protons to realign with the external magnetic field. The magnetization will grow after excitation from zero to a value of about 63% of its final value in a time of T1.

See also T1 Time.
 
Images, Movies, Sliders:
 Brain MRI Images T1  Open this link in a new window
 Sagittal Knee MRI Images T1 Weighted  Open this link in a new window
 
spacer

• View the DATABASE results for 'Longitudinal Relaxation Time' (5).Open this link in a new window

MRI Resources 
Service and Support - Shielding - Colonography - Stimulator pool - MRI Accidents - MRI Technician and Technologist Schools
 
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.
•
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
 
spacer

• View the DATABASE results for 'MRI History' (6).Open this link in a new window


• 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    
Searchterm 'Magnetization' was also found in the following services: 
spacer
News  (1)  Forum  (3)  
 
Macroscopic Magnetic Moment
 
spacer
Searchterm 'Magnetization' was also found in the following service: 
spacer
Radiology  (3) Open this link in a new window
Magnetic ForcesMRI Resource Directory:
 - MRI Accidents -
 
Forces can result from the interaction of magnetic fields. Pulsed magnetic field gradients can interact with the main magnetic field during the MRI scan, to produce acoustic noise through the gradient coil.
Magnetic fields attract ferromagnetic objects with forces, which can be a lethal danger if one is hit by an unrestrained object in flight. One could also be trapped between the magnet and a large unrestrained ferromagnetic object or the object could damage the MRI machine.
Access control and personnel awareness are the best preventions of such accidents. The attraction mechanism for ferromagnetic objects is that the magnetic field magnetizes the iron. This induced magnetization reacts with the gradient of the magnetic field to produce an attraction toward the strongest area of the field. The details of this interaction are very dependent on the shape and composition of the attracted object. There is a very rapid increase of force as one approaches a magnet. There is also a torque or twisting force on objects, e.g. a long cylinder (such as a pen or an intracranial aneurysm clip) will tend to align along the magnet's field lines. The torque increases with field strength while the attraction increases with field gradient.
Depending on the magnetic saturation of the object, attraction is roughly proportional to object mass. Motion of conducting objects in magnetic fields can induce eddy currents that can have the effect of opposing the motion.

See also Duty Cycle.

See also the related poll result: 'Most outages of your scanning system are caused by failure of'
spacer

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

 
Further Reading:
  Basics:
How strong are magnets?
   by my.execpc.com    
Magnetic Field of the Strongest Magnet
2003   by hypertextbook.com    
  News & More:
Imaging chain faces regulators after inmate, guard get stuck to MRI machine
Friday, 1 December 2023   by healthimaging.com    
Measuring magnetic force field distributions in microfluidic devices: Experimental and numerical approaches
Saturday, 2 December 2023   by analyticalsciencejournals.onlinelibrary.wiley.com    
Two stuck to MRI machine for 4 hrs
Tuesday, 11 November 2014   by www.mumbaimirror.com    
New imaging project for new applications in cancer diagnostics
Monday, 27 March 2017   by www.news-medical.net    
MRI Resources 
Implant and Prosthesis - MRI Technician and Technologist Schools - Equipment - Claustrophobia - Collections - Services and Supplies
 
previous      86 - 90 (of 127)     next
Result Pages : [1 2 3]  [4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ... ]
 Random Page
 
Share This Page
FacebookTwitterLinkedIn

MR-TIP    
Community   
User
Pass
Forgot your UserID/Password ?    



Next big thing in MRI will be :
AI 
remote operator 
personalized protocols 
helium-free 
molecular MRI 
portable MRI 

Look
      Ups





MR-TIP.com uses cookies! By browsing MR-TIP.com, you agree to our use of cookies.

Magnetic Resonance - Technology Information Portal
Member of SoftWays' Medical Imaging Group - MR-TIP • Radiology-TIP • Medical-Ultrasound-Imaging • 
Copyright © 2003 - 2024 SoftWays. All rights reserved. [ 21 November 2024]
Terms of Use | Privacy Policy | Advertising
 [last update: 2024-02-26 03:41:00]