MAGNETIC RESONANCE IMAGING (MRI) |
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Magnetic Resonance Imaging (MRI) was first used in 1946. The ability
to produce tomographic images, however, only become available from the
late seventies, with a breakthrough in 1981 when EMI which also designed
the first X-Ray CT Scanner designed a superconducting MRI scanner for use
at the Hammersmith Hospital, UK. The two forms of magnetic resonance techniques
used for medical diagnosises are Electron Spin Resonance(ESR) and Nuclear
Magnetic Resonance(NMR). In ESR, magnetic resonance is achieved by
electron whiles NMR use energy absorption by nucleus to achieve the effects.
NMR is investigated in this resource. While X-ray computer tomography (CT)
had been a medical diagnostic breakthrough in providing cross-sectional
views of the body, imaging is only limited to the transaxial plane.
MRI, on the other hand, could provide spatial resolution of a fraction of a millimetre
while the patient is not subject to any hazards such as ionising radiation.
As MRI reflects local molecular structures and interactions, it could also
provide tissue information. The whole phenomenon of magnetic resonance
is brought about to the subject by bombarding it with electromagnetic radiation,
inducing an absorption of this incident radiation and raises a lower energy
state to a high energy excited state within a molecule.
While MRI scanner comprises no moving parts, complex signal control
and acquisition procedures has to be carried out. Further more, computation-intensive
process in image reconstruction and display functions from the detected
signals are required.
This technique of imaging using Magnetic Resonance was traditionally
known as Nuclear Magnetic Resonance (NMR). However, to avoid the
term's association with 'nuclear', which people often associates with dangerous
ionising radiation, this imaging modality is now often referred to as Magnetic
Resonance Imaging (MRI).