11. 2.2 Manipulating magnetization Application of magnetic field B 0 Precessing proton in B 0 -> Splitting of energy states-> ↓
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14. 2.2 Manipulating magnetization Pictures of magnetization ← Spin distribution Magnetization-> Fluctuating magnetization vector ↓
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22. 2.4 MR signal detection Spatial Encoding So what is A? Ans: Fourier transform of Detected MR signal …… …… Result: Originally unknown _______________________ …… ……
23. 2.4 MR signal detection Spatial Encoding 1. Phase Encoding: Switch on a magnetic field gradient of amplitude G y in y-direction just after the spins have been excited and precess on xy-plane: - “Phase Shift” of spins relative to each others - phase angle:
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25. 2.4 MR signal detection Spatial Encoding 4. Fourier Transform: - Through Fourier Transform of the MR signal: - we can know the amplitudes of different frequencies and phases in the k -space, which in turns proportional to the brightness of the picture elements.
28. Patient Patient table Scanner Magnet Gradient Coils Radio Frequency Coils 2.5 Structure of MRI machine
29. 3. About MRI 3.1 History of MRI developments 3.2 Applications 3.3 Future
30. 3.1 History of MRI developments 1938 Nuclear magnetic resonance by I.I. Rabi Mid-1940s First detection of NMR in bulk matter 1950s Discovery of chemical shift and spin-spin coupling 1960s Development of pulse Fourier-transform NMR 1973 First NMR image by Paul Lauterbur, who shared the Nobel Prize in medicine in 2003 1975 2D NMR by Ernst, which earned him the 1991 Nobel Prize in chemistry 1977 First study performed on human 1980s k -space formalism
31. 3.1 History of MRI developments Paul Lauterbur ’s images ← Oil in peanuts Cross-section of a mouse -> (shadows are lungs)
