Factors affecting signal intensisty

  • Created by: Joel
  • Created on: 12-03-15 14:57
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  • Factors affecting signal intensity
    • Density of protons
      • The time taken for the excited protons to return to their normal orientation, using up their extra energy.
    • Contrast in type of tissue
      • Specific pulse sequences can be selected to give a desired image eg. Weighted is best to show soft tissue. T2 weighted shows area which has been affected by disease e.g fluid area.
    • Field strength of gradient coils
      • The greater the number of H protons the larger the signal. In air and outer bone (no H) appear dark.
    • RF pulse signal
      • When a large gradient field is used, better resonance occurs over a smaller distance therefore better resolution of the image.
    • Relaxation time
      • Repeatedly exciting protons then allow them to relax allow us to see the differences between the tissue types.
    • Sequence of RF pulse
      • certain sequences of pulses can be chosen to give you the  your target image. T1 is weighted more to show your body's tissue more and T2 for areas with fluids


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