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UCLA NS 172

Neuroimaging and MRI Physics. Other Resources. These slides were condensed from several excellent online sources. Credit is given where appropriate. If you would like a more thorough introductory review of MR physics, see the following:1. Robert Cox's slideshow, (f)MRI Physics with Hardly Any Mat

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UCLA NS 172

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    1. UCLA NS 172/272/Psych 213 Brain Mapping and Neuroimaging Instructor: Ivo Dinov, Asst. Prof. In Statistics and Neurology University of California, Los Angeles, Winter 2006 http://www.stat.ucla.edu/~dinov/ http://www.loni.ucla.edu/CCB/Training/Courses/NS172_2006.shtml

    2. Neuroimaging and MRI Physics

    3. Other Resources

    4. References “Foundation of Medical Imaging,” Z.H. Cho, J.P. Jones, M. Singh, John Wiley & Sons, Inc., New York 1993, ISBN 0-471-54573-2 “Principles of Medical Imaging,” K.K. Shung, M.B. Smith, B. Tsui, Academic Press, San Diego 1992, ISBN 0-12-640970-6 “Handbook of Medical Imaging,” Vol. 1, Physics and Psychophysics, J. Beutel, H. L. Kundel, R. L. Van Metter (eds.), SPIE Press 2000, ISBN 0-8194-3621-6 Brain Mapping: The Methods, by Arthur W. Toga & John Mazziotta

    5. Introduction: What is Medical Imaging? Goals: Create images of the interior of the living human body from the outside for diagnostic purposes. Biomedical Imaging is a multi-disciplinary field involving Physics (matter, energy, radiation, etc.) Math (linear algebra, calculus, statistics) Biology/Physiology Engineering (implementation) Computer science (image reconstruction, signal processing, visualization)

    6. BMI methods: X-Ray imaging Year discovered: 1895 (Röntgen, NP 1905) Form of radiation: X-rays = electromagnetic radiation (photons) Energy / wavelength of radiation: 0.1 – 100 keV / 10 – 0.01 nm (ionizing) Imaging principle: X-rays penetrate tissue and create shadowgram of differences in density. Imaging volume: Whole body Resolution: Very high (sub-mm) Applications: Mammography, lung diseases, orthopedics, dentistry, cardiovascular, GI, neuro

    7. Electromagnetic Spectrum

    8. Radio wave devices

    9. BMI methods: X-Ray Computed Tomography Year discovered: 1972 (Hounsfield, NP 1979) Form of radiation: X-rays Energy / wavelength of radiation: 10 – 100 keV / 0.1 – 0.01 nm (ionizing) Imaging principle: X-ray images are taken under many angles from which tomographic ("sliced") views are computed Imaging volume: Whole body Resolution: High (mm) Applications: Soft tissue imaging (brain, cardiovascular, GI)

    10. Electromagnetic Spectrum

    11. BMI methods: Nuclear Imaging (PET/SPECT) Year discovered: 1953 (PET), 1963 (SPECT) Form of radiation: Gamma rays Energy / wavelength of radiation: > 100 keV / < 0.01 nm (ionizing) Imaging principle: Accumulation or "washout" of radioactive isotopes in the body are imaged with x-ray cameras. Imaging volume: Whole body Resolution: Medium – Low (mm - cm) Applications: Functional imaging (cancer detection, metabolic processes, myocardial infarction)

    12. Electromagnetic Spectrum – PET/SPECT

    13. Functional Brain Imaging - Positron Emission Tomography (PET)

    14. Functional Brain Imaging - Positron Emission Tomography (PET)

    15. Functional Brain Imaging - Positron Emission Tomography (PET)

    16. BMI methods: Magnetic Resonance Imaging Year discovered: 1945 (Bloch & Purcell) 1973 (Lauterburg, NP 2003) 1977 (Mansfield, NP 2003) 1971 (Damadian, SUNY DMS) Form of radiation: Radio frequency (RF) (non-ionizing) Energy / wavelength of radiation: 10 – 100 MHz / 30 – 3 m (~ 10-7 eV) Imaging principle: Proton spin flips are induced, and the RF emitted by their response (echo) is detected. Imaging volume: Whole body Resolution: High (mm) Applications: Soft tissue, functional imaging

    17. Electromagnetic Spectrum

    18. BMI methods: Ultrasound Imaging Year discovered: 1952 (Norris, clinical: 1962) Form of radiation: Sound waves (non-ionizing) Frequency / wavelength of radiation: 1 – 10 MHz / 1 – 0.1 mm Imaging principle: Echoes from discontinuities in tissue density/speed of sound are registered. Imaging volume: < 20 cm Resolution: High (mm) Applications: Soft tissue, blood flow (Doppler)

    19. Electromagnetic Spectrum

    20. BMI methods: Optical Tomography Year discovered: 1989 (Barbour) Form of radiation: Near-infrared light (non-ionizing) Energy / wavelength of radiation: ~ 1 eV/ 600 – 1000 nm Imaging principle: Interaction (absorption, scattering) of light w/ tissue. Imaging volume: ~ 10 cm Resolution: Low (~ cm) Applications: Perfusion, functional imaging

    21. BMI methods: Optical Tomography

    22. Electromagnetic Spectrum

    23. Recipe for MRI

    24. History of NMR

    25. History of fMRI

    26. Necessary Equipment

    27. The Big Magnet

    28. Magnet Safety - The whopping strength of the magnet makes safety essential. Things fly – Even big things!

    29. Subject Safety

    30. Protons

    31. What nuclei exhibit this magnetic moment (and thus are candidates for NMR)?

    32. Outside magnetic field – random orientation In Mag Field - Protons align with field

    33. Radio Frequency

    34. Larmor Frequency

    35. RF Excitation

    36. Cox’s Swing Analogy

    37. Relaxation and Receiving

    38. T1 and TR

    39. Spatial Coding: Gradients

    40. How many fields are involved after all?

    41. Precession In and Out of Phase

    42. T2 and TE

    43. Echos

    44. T1 vs. T2

    45. T1 vs. T2 – contrast and noise

    46. Properties of Body Tissues

    47. MRI of the Brain - Sagittal

    48. MRI of the Brain - Axial

    49. MRI Quality Determinants

    50. MRI Quality Determinants – period = 1/frequency

    51. K-Space – an MRI literature fancy name for Fourier space

    52. A Walk Through (sampling from ) K-space

    53. T2*

    54. Susceptibility

    55. Signal-to-Noise Ratio (SNR)

    56. Motion Correction

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