Prelim-Endterm Flashcards
A greek philosopher in 4000 B.C theorize that all matter is made of both indivisible and invisible particles “atoms.”
Democritus
west turkey discovered “loadstones.” Used for navigation religiory and magical purpose.
Magnesia
in 1819 discovered that electricity produces magnetism.
Hans christian oersted
1831 twelve years after the discovery of oersted discovered electricity.
Michael faraday
made the heart of MRI mathematics “Fourier transform.”
Jean-Baptiste-Joseph Fourier
1860 discovered magnetic lines of force could be mathematically expressed. Electrical and magnetic fields coexist at a 90-degree angle.
Sir James clerk Maxwell of Scotland
1868 discovered invisible electromagnetic waves exist with varying frequencies.
Heinrich hertz of Germany
discovered rotating magnetic field.
Nikola Tesla
First described and measured in molecular beams on magnetic resonance, Rabi method involved using electromagnetic of approximately 0.21 and a hairpin coil producing an oscillatory RF-field of about 3.5 MHz. The RF-field was maintained at a constant frequency and the main magnetic field was varied by changing its current. Rabi then passed a “molecular beam” of lithium chloride (LiCi) molecules through a vacuum chamber and subsequently into the magnetic apparatus in 1938 he and his team reported energy absorption/resonance peak for both Li and Ci as predicted. Rabi named this phenomenon “nuclear magnetic resonance”.
Isidor Isaac Rabi
their development of new ways and methods for nuclear magnetic precision measurements, expanded the technique for use on liquids and solids in NMR, for which they shared the Nobel prize 1952.
Felix Bloch and Edward Purcell
physician/physicist July 3, 1977, performed the 1st MRI whole body transaxial proton density weighted slice image. It took 4 hrs and 45 mins for the 1st scan, father of MRI (Magnetic Resonance Imaging), indomitable name of Damadian’s whole body scanner.
Dr. Raymond Damadian
demonstration of use of magnetic gradients for spatial localization and actual demonstration of 1-D imaging (1D MR image) which lead to the experiments of…
1952
designed the gradient coils, developed a way to generate the 1st MRI image in 2D and 3D, using gradients
Dr. Paul Lauterbur
from university of Nottingham then developed a mathematical technique that would allow scans to take seconds rather than hours and produce clearer images than Lauterbur had.
Peter Mansfield-
Owing to __ a mathematical technique called a __ could then be used to recover the desired image greatly speeding up the image process
Larmor precession, Fourier transformation
selective excitation or sensitization of tomographic image slice was invented by sir Peter Mansfield’s group.
1974
Richard ernst’s group invented the two dimensional Fourier transformation.
1975
Clow and Young produced the 1st published image of human head.
1978
General electric introduced high field 1.5 tesla systems
1984
for their discoveries concerning magnetic resonance imaging Paul Lauterbur and Sir Peter Mansfield were awarded the Nobel prize for medicine & physiology.
2003
a magnet whose magnetic field originates from permanently ferromagnetic materials (permanent magnet) to generate a magnetic field between two poles of magnet. There is no requirement for additional electrical power or cooling, and the iron-core structure of the magnet leads to a limited fringe field and no missile effect. Due to weight considerations __ magnets are usually limited to maximum field strength of 0.3-.5T
Permanent magnet
A type of magnet that utilizes the principle of electromagnetism to generate magnetic field. Typically large current values and significant cooling of the magnet coil is required. The resistive magnets does not require cryogens but needs a constant power supply to maintain a homogenous magnetic field and can be quite expensive to maintain. Resistive magnets fall into two general categories- iron core and air core.
Electromagnets or resistive system
Magnets that are partially built from superconducting materials and therefore reach much higher magnetic field intensity. Coil windings of superconducting magnets are made of wires of a type 2 superconductor. Liquid helium (-459F,0 K -273C) is commonly used as a coolant, which consequently conclude refilling. There are cryogen-free superconducting magnets with a closed-cycle refrigerating system at horizon. Superconducting magnets typically exhibits field strengths of greater than 0.5T, operate Clinically up to 3T and have a horizontal field orientation which makes them prone to missile effects without significant magnetic shielding.
Superconducting magnet
4-7 tesla
Ultrahigh field