MRI FS

1. Raymond Damadian invented the first MRI
scanning machine and preformed the first scan
on a live patient in 1977 to diagnose cancer.
Damadian’s research into sodium and
potassium molecules in living cells lead him on
to experiment with the nuclear magnetic
resonance (NMR) first (where atomic nuclei
absorb and emit electromagnetic radiation
within a magnetic field). He theorised that
tumour and normal tissue can be distinguished
by NMR due to their ‘prolonged relaxation
times’ (Wakefield, 2000).
Magnetic
Resonance
Imaging
Magnetic Resonance imaging
(MRI) is a non-invasive
imaging modality that
produces 3-dimensional
images of the body, using
protons and magnetic field
manipulation
Hydrogen is the most abundant element
in the body and are comprised of 1
proton and 1 electron.
When there is no magnetic field applied,
these protons situate in random
positions.
However, when an external magnetic
force is applied, the protons are
stimulated to align with the magnetic
field.
The MRI machine emits radio-frequency waves
through the patient’s body, which stimulates the
protons spin on their own axis’s, this is called
precession.
The speed and frequency of the spin is dependent on
the strength of the magnetic applied.
When the radio waves are turned off the proton
return to their aligned state and release energy in
radio-frequency signals.
The amount of energy released depends on the type of
tissue they are in. These signals are picked up by
receiver coils in the MRI machine which are then sent
to a computer to detect the differences in energy
release to produce contrast and detailed images of
organs and tissues
(National Institute of Biomedical Imaging and Bioengineering, n.d.)
There are 2 types of contrast images that MRIs can produce: T1
weighted and T2 weighted MRI: (Kawahara and Nagata, 2021)
T1 reflects the time it takes for
protons to realign with the
external magnetic field (recovery)
= the faster the time for
realignment/ recovery, the
brighter the tissue appears e.g.
water
T2 reflects the time taken for the
protons to shift from spinning in
phase to spinning out of phase
(decay)
= the faster the time for relaxation,
the darker the tissue appears on
the MRI scan e.g. bone