Introduction of Medical Imaging and MRI

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Introduction of Medical Imaging and MRI

  1. 1. Introduction of Medical Imaging<br />Chun Yuan<br />
  2. 2. Organization of the Course<br /><ul><li>8 Lectures (1.5 hours per lecture)
  3. 3. Introduction of medical imaging and MRI
  4. 4. Basic concept of image formation
  5. 5. Basic pulse sequences and contrast manipulation
  6. 6. Image Reconstruction
  7. 7. RF pulse and gradient pulse
  8. 8. Fast imaging and advanced applications
  9. 9. MRI hardware
  10. 10. Functional MRI</li></li></ul><li>Text Books<br /><ul><li>Magnetic Resonance Imaging - Physical Principles and Sequence Design
  11. 11. ISBN: 0-471-35128-8
  12. 12. Authors: E. M. Haacke, R. W. Brown, M. R. Thompson, and R. Venkatesan
  13. 13. Publisher: John Wiley and Sons, 1999
  14. 14. Handbook of MRI Pulse Sequences
  15. 15. ISBN: 0-7803-4723-4
  16. 16. Authors: Bernstein, King, and Zhou
  17. 17. Publisher: Elsevier Publishing, 2004</li></li></ul><li>Credits<br />Home work<br />One for each day<br />60%<br />Term project<br />Topics will be provided<br />40%<br />
  18. 18. What is Medical Imaging<br />Introduce some form of radiation <br />electromagnetic<br />Acoustic<br />Observe its interaction with tissue<br />attenuation<br />scattering / reflection<br />Concentration<br />Convert the observations into a clinically meaningful image<br />film<br />computer<br />
  19. 19. Electromagnetic Spectrum<br />
  20. 20. Imaging Considerations<br /><ul><li>Type of information
  21. 21. anatomical - from head to toe
  22. 22. functional - cardiac, brain, etc.
  23. 23. quantitative vs. qualitative
  24. 24. Limitations
  25. 25. resolution
  26. 26. sensitive range (e.g. view angles)
  27. 27. speed
  28. 28. cost
  29. 29. invasiveness</li></li></ul><li>“Classical” methods<br />Images that are direct manifestations of the interaction<br />between radiation and tissue<br />Projection Radiography (Conventional X-ray)<br />Ultrasound<br />Conventional Nuclear Medicine<br />
  30. 30. Projection Radiography<br /><ul><li>Physical Principle: Variation in X-ray attenuation of different tissues
  31. 31. Methodology: A beam of X-rays is directed through a patient onto a film.
  32. 32. Image: An X-ray “shadow” of the patient.
  33. 33. History:
  34. 34. Roentgen’s discovery - 1895
  35. 35. Application to medicine – 1896
  36. 36. contrast materials - early 1900’s
  37. 37. angiography - 1927</li></li></ul><li>Projection Radiography System<br />
  38. 38. Projection Radiography Examples<br />Chest X-Ray<br />Angiogram<br />Mammogram<br />
  39. 39. Ultrasound<br /><ul><li>Physical Principle: Ultrasound waves scatter and reflect within the body
  40. 40. Methodology: A pulse of ultrasonic energy is propagated into the body and backscattered echoes record the depth of objects in the body.
  41. 41. Image: A “depth map” of patient organs.
  42. 42. History:
  43. 43. Concept derived from W.W.II sonar
  44. 44. Major clinical development - 1970’s</li></li></ul><li>Ultrasound System<br />
  45. 45. Ultrasound Mode<br />B-mode image<br />Longitudinal view of digital artery<br />Frequency: 40MHz<br />Resolution: up to 50mm<br />Doppler<br />Flow velocity in digital artery<br />
  46. 46. Nuclear Medicine<br /><ul><li>Physical Principle: Variable uptake of radioactive materials by different organs
  47. 47. Methodology: Inject patient with radiolabeled substance and record time-space pattern of radiation.
  48. 48. Image: A map of the radioactivity of the patient.
  49. 49. History:
  50. 50. Therapeutic administration of radiolabeled substances - 1950
  51. 51. Scintillation camera - 1952</li></li></ul><li>Nuclear Medicine System<br />
  52. 52. Nuclear Medicine Example<br />
  53. 53. “Computed” methods<br />Images that are formed using mathematical methods and computers from indirect measurements of the interaction between radiation and tissue<br />Computed Tomography (CT)<br />X-ray CT<br />PET<br />SPECT<br />Magnetic Resonance Imaging<br />(3D Ultrasound)<br />
  54. 54. Computed Tomography<br /><ul><li>Physical Principle: Projection slice theorem dictates how to reconstruct a 2-D image from multiple 1-D projections (Radon Transform).
  55. 55. Methodology: Obtain multiple projection images and reconstruct images using a computer.
  56. 56. Image: A 2-D slice mapping the patient’s X-ray attenuation coefficient (X-ray CT) or radioactivity (PET and SPECT).
  57. 57. History:
  58. 58. X-ray CT proposed - mid 1960’s
  59. 59. Early clinical use - 1972
  60. 60. PET and SPECT followed X-ray CT</li></li></ul><li>Computed Tomography System<br />
  61. 61. X-ray CT Example<br />
  62. 62. PET Example<br />
  63. 63. Magnetic Resonance Imaging<br /><ul><li>Physical Principle: Within a strong magnetic field, paramagnetic nuclei (usually hydrogen protons) will resonate in response to RF radiation
  64. 64. Methodology: Place patient in a magnet, irradiate with RF field, and record spatially encoded RF echoes.
  65. 65. Image: A map of proton concentration through a slice of the body.
  66. 66. History:
  67. 67. NMR discovered - 1940’s
  68. 68. Imaging proposed in 1972
  69. 69. Current generation of machines developed in 1980’s</li></li></ul><li>Nobel Prize for MRI<br />
  70. 70. MRI System<br />
  71. 71. MRI Example<br />
  72. 72. Star Artifacts in CT<br />
  73. 73. Shadow Artifacts in Ultrasound<br />
  74. 74. Wrap-around Artifacts in MRI<br />

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