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MRI, FBP and phase encoding

MRI, FBP and phase encoding. Spins. Precession. RF pulse. T1 and T2. Bloch Equations. Receiver. T1 and T2. Effect of tissue. Slice selection. Slice selection. FBP. Filtered Back Projection. Filtered B a ck Projection. Filtered Back Projection. Filtered backprojection.

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MRI, FBP and phase encoding

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  1. MRI, FBP and phase encoding

  2. Spins

  3. Precession

  4. RF pulse

  5. T1 and T2

  6. Bloch Equations

  7. Receiver

  8. T1 and T2

  9. Effect of tissue

  10. Slice selection

  11. Slice selection

  12. FBP

  13. Filtered Back Projection

  14. Filtered Back Projection

  15. Filtered Back Projection

  16. Filtered backprojection • Filter the measured projection data at different projection • angles with a special function. • Backproject the filtered projection data to form the • reconstructed image. • Filtering can be implemented in 2 ways, in the spatial domain, the filter operation is • equivalent to to convolving the measured projection data using a special convolving • function h(t) • More efficient multiplication will be in the spatial frequency domain. • FFT the measured projection data into the frequency domain: • p(,)=FT {p(t, ) • Multiply the the fourier transform projections with the special function. • Inverse Fourier transform the product p’(,).

  17. Phase Encoding

  18. Phase encoding

  19. K space

  20. K Space

  21. Partial K space reconstruction

  22. Partial K space reconstruction

  23. Partial K space reconstruction

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