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The 2003 Nobel Prize in Physiology/Medicine was awarded to two scientists:
Paul C. Lauterbur and Peter Mansfield who made seminal discoveries that
were the basis for the development of magnetic resonance into a useful
imaging method.
MRI: Stepping through the anatomy
In the last two decades, the technology of MRI has developed rapidly making
tremendous contribution in medicine. In 2002, approximately 22,000 MRI scanners
were in use worldwide, and more than 60 million examinations were performed.
All the sophisticated detail of an MRI scan, particularly in the case of
brain and spinal cord exam, comes without the use of ionizing radiation.
Improved diagnosis in cancer, the use of detailed three-dimensional images
as a pre-operative tool, along with non-invasive angiography has all contributed
to reducing suffering for the patient.
New Technologies in MR:
MRS: Physicians have long realized that to understand
the play of the dynamics within the human organism, one must not only
be able to read the script, i.e., visualize the anatomy but also participate
in authoring the script at a biochemical and molecular level. Hence, more
and more, technologies are trying to look at biochemistry and functioning
of the organism at a molecular level. One such technology is magnetic
resonance spectroscopy. MRS may reveal a metabolite that is not normally
present or an abnormal quantity of a metabolite that is usually present.
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Differences in Brain Spectra between Tumor
and Normal Tissue |
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1D magnetic resonance spectrum
(MRS)
2D MRS (contour plot) showing more cerebral
metabolites and better separation |
Functional MRI: fMRI refers to a phenomenon discovered
in the early 1990s – Blood Oxygenation Level Dependent (BOLD) effect.
MR signal can be made sensitive to local changes in the oxygenation of
the blood following neural activation. Local neural activation increases
local cerebral blood flow more than local oxygen metabolism rate so blood
oxygenation increases in activated parts of the brain.
Diffusion and Perfusion MRI: These techniques stand
at the forefront of physiologically-sensitive radiologic imaging. Diffusion
imaging is designed to study the movement of water molecules. Such a study
finds a range of applications in stroke, infection, and metabolic diseases.
In addition, the advent of white matter fiber tracking via the techniques
heralds a new application. Perfusion-weighted imaging assesses the perfusion
of the microvasculature after rapid injection of a gadolinium contrast
agent.
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