4 Instructions for Use Fabius MRI SW 3.n
Magnetic Resonance (MR) Definitions
Term Meaning
MR Magnetic Resonance
MRI Magnetic Resonance Imaging
MRT Magnetic Resonance Tomography
MR Safe An item that poses no known hazards in all MR environments.
MR Environment This term is used to describe the general environment present in
the vicinity of an MRT scanner. In particular, this refers to the
area within the 5-gauss line around the scanner. Characteristics
of the environment include the following:
1) the static magnetic field (the range of 0.2 to 3 tesla is most
common, but it can exceed 4.0 tesla*) and associated spatial
gradients;
2) rapidly changing magnetic fields (imaging gradients ~kHz);
and
3) radio frequency (RF) magnetic field pulses (on the order of
tens to hundreds of MHz, i.e., in the FM radio band).
The "MR Environment" includes anywhere in the MR procedure
room, including the center of the bore of the MRT scanner.
*1 tesla = 10000 gauss
Five-Gauss Line This line specifies the perimeter around an MRT scanner within
which the static magnetic fields are higher than five gauss. Five
gauss and below are considered "safe” levels of static magnetic
field exposure for the general public. (5 gauss = 0.50 mtesla)
Image Artifact This is a general term that refers to an inappropriate image
signal at a specified spatial location. lt is generally characterized
as increased signal intensity in an area which is known to
contain no signal producing material or decreased signal
intensity (voids) where signal should be produced.
MR Conditional An item that has been demonstrated to pose no known hazards
in a specified MR enviroment with specified conditions of use.
Field conditions that define the specified MR enviroment include
field strength, spatial gradient, dB/dt (time rate of change of the
magnetic field), radio frequency (RF) fields and specific
absorption rate (SAR).
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