Biomedical Imaging by liaoqinmei

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									Biomedical Imaging 2


  Class 1 – Introduction
        01/22/08



                           BMI2 SS08 – Class 1 “Introduction” Slide 1
Course instructor
Dr. Harry L. Graber
Research Assistant Professor of Pathology / SUNY Downstate Medical
Center / Room BSB 4-132, (718) 270-1286 /
harry.graber@downstate.edu

A.B., Chemistry                       1983,   Washington University,
                                              St. Louis, MO
Ph.D., Physiology and Biophysics      1998,   SUNY Health Science
                                              Center, Brooklyn, NY
Postdoctoral Fellow                   1998,   SUNY Downstate
                                              Medical Center
Res. Asst. Professor                  2001,   SUNY Downstate
                                              Medical Center

Research Focus:        Optical Tomography - Image Reconstruction and
                       Signal Analysis

                                                  BMI2 SS08 – Class 1 “Introduction” Slide 2
Lecture hours / locations, credits

• Classes

   – Location:                    SUNY DMC HSEB 8J

   – Hours:                       Tuesday, 10:00 AM to 1:00 PM


• Credits

   –   Classroom Participation:   15%
   –   Homework:                  20%
   –   Exam1:                     30%
   –   Exam2:                     35%




                                                   BMI2 SS08 – Class 1 “Introduction” Slide 3
 Course materials

• No specific textbook

• Topic-specific readings (research papers, review papers, scientific
  magazine articles, internet pages) will be provided as needed

• Lecture notes and copies of assigned readings will be posted for
  download at http://OTG.downstate.edu/download.htm




                                                  BMI2 SS08 – Class 1 “Introduction” Slide 4
What is This Course About?




                     BMI2 SS08 – Class 1 “Introduction” Slide 5
Imaging Modalities Covered in BMI1

•   X-ray Projection Radiography
•   X-ray Computed Tomography
•   Nuclear Imaging
     – Planar Scintigraphy
     – Positron Emission Tomography
     – Single Photon Emission Computed Tomography
•   Ultrasound
•   Magnetic Resonance Imaging
     – Structural MRI (anatomy)



                                             BMI2 SS08 – Class 1 “Introduction” Slide 6
Imaging Modalities Covered in BMI1

• In brief, structural imaging (SI) techniques
   – With one significant exception




                                      BMI2 SS08 – Class 1 “Introduction” Slide 7
Imaging Modalities Covered in BMI2

• Functional imaging (FI) methods
   – Diffuse Optical Tomography
   – Optical Coherence Tomography
   – Functional MRI (fMRI)
   – Electroencephalographic Imaging
   – Magnetoencephalography
   – Combined, or multi-mode, imaging

• But what does “functional” mean?

                                        BMI2 SS08 – Class 1 “Introduction” Slide 8
 Meaning of “functional” is context-specific
• Always involves examination of what tissue is doing
   – But how this examination is carried out is different for different
     methods
   – In some cases, functional imaging just means producing as
     many structural images as you can, as fast as you can
• Example: functional x-ray CT
   – Same goes for some kinds of functional ultrasound
• What about MRI?




                                                      BMI2 SS08 – Class 1 “Introduction” Slide 9
Varieties of fMRI
• Diffusion-weighted Imaging
• Perfusion Imaging
   – Contrast-agent-based
   – Magnetic Resonance Angiography / Venography
       • Saturation-based
       • Bipolar-gradient-based
   – Arterial Spin Labeling
• Diffusion Tensor Imaging
• Magnetic Susceptibility Imaging
   – Contrast-agent-based
   – Blood Oxygen Level Dependent

                                     BMI2 SS08 – Class 1 “Introduction” Slide 10
Some Modalities Are Inherently Functional
• A: Abdominal x-ray CT image (structural/anatomical)
• B: PET image of same tissue section (functional)
• C: Co-registered x-ray CT and PET images




                                        BMI2 SS08 – Class 1 “Introduction” Slide 11
 FI Usually Is More “Indirect” than SI
• Direct imaging = (essentially) no math needed
   – Laws of physics do the work
   – e.g., Project an image onto a piece of film with a lens


• Indirect imaging = lots of math required
   – Computers used to process the measurement data and
     reconstruct images


• “More indirect” means that additional, post-
  reconstruction operations are needed
   – Usually involves some type of comparison among images
     from data collected at different times

                                                BMI2 SS08 – Class 1 “Introduction” Slide 12
Instructional Emphasis
• Image contrast mechanisms
   – How is energy interacting with matter (i.e., tissue)
   – What is the image a picture of?
• Biological/clinical motivation
   – Why do we care about the parameter(s) in the image?
   – How is having this image going to help us?
      • How will it affect the treatment our patient is getting?
• Data analysis “from soup to nuts”
   –   Pre-processing operations
   –   Image reconstruction
   –   Post-processing operations
   –   “Post-post-” processing operations

                                                    BMI2 SS08 – Class 1 “Introduction” Slide 13
Tentative Syllabus
1)        Introduction; diffuse optical tomography (DOT)
      01/22
2)        DOT
      01/29
3)        Image post-processing & time-series analysis, Pt. 1
      02/05
4)        Optical coherence tomography (OCT)
      02/12
5)        fMRI – diffusion-weighted, perfusion
      02/19
6)        fMRI – perfusion
      02/26
7)        Exam1
      03/04
8)        fMRI – BOLD
      03/11
9)        OSA Conference, no class
      03/18
10)       Image post-processing & time-series analysis, Pt. 2
      03/25
11)       fMRI – diffusion-tensor imaging
      04/01
12)       EEG/MEG principles
      04/08
13)       EEG imaging
      04/15
14)       MEG imaging
      04/22
15)       DOT’s “relatives”: fluorescence OT, bioluminescence OT,
      04/29
          correlation tomography, optoacoustic tomography
16) 05/06 Exam2
17) 05/13 Wrap-up


                                                      BMI2 SS08 – Class 1 “Introduction” Slide 14
Electromagnetic spectrum




                           BMI2 SS08 – Class 1 “Introduction” Slide 15
Diffuse Optical tomography (DOT)
• Year discovered:                    ~1988

• Form of radiation:                  Near-infrared light (non-
                                      ionizing)

• Energy / wavelength of radiation:   ~1 eV / 600–1000 nm
• Imaging principle:                  Interaction (absorption, elastic
                                      scattering) of light w/ tissue
• Imaging volume:                     ~103 cm3
• Resolution:                         Low (~1cm)
• Applications:                       Perfusion, functional imaging



                                                 BMI2 SS08 – Class 1 “Introduction” Slide 16
 DOT and CT: Superficial Similarities, Essential
 Differences
• Generation: x-ray tube                                           Source
• Detection: Detector arrays (ion.-chambers,
  scint. + photodiode)
• Computer reconstruction of 2D slices/ 3D
  volumetric images



                                                    Object




                                                              Detector




                                               BMI2 SS08 – Class 1 “Introduction” Slide 17
               Principles of DOT
     • Scattering dominated
     • Limited penetration depth (~cm), low
       res. (mm-cm)
     • Economic, functional (hemodynamics)




                                                                                                                                             screen / detector
                                                                           screen / detector
light source




                                                                                                    light source
                                                                                                                                                                 light source               detector

                                                                                                                                                                                                   D
                                                                                                                                                                     S



               obstacle (absorber)                                                                                   obstacle (absorber)

                 Clear medium                                                                                            Scattering medium
                                                                                                                                                                                 S
                                                                                                                                                                         D                     D
                                                            106
                          Molar extinction coeff. [cm M ]
                         -1
                         -1




                                                            105


                                                            104                                Hb


                                                            103
                                                                          HbO2                                                                                           D                     D
                                                              2
                                                            10
                                                              400   500    600                 700                 800     900   1000
                                                                                                                                                                    BMI2 SS08 – Class 1 “Introduction” Slide 18
                                                                            Wavelength [nm]
DOT Instrumentation
                           Source / Detector 1

                                                 Detector 2

                  2-3 cm                                      Detector 3




                                                                Scalp


                                                                  Bone

                                                                        CSF

                                                                    Cortex




                                    BMI2 SS08 – Class 1 “Introduction” Slide 19
DOT Applications

                              Brain SPECT




       Breast
                         Arm




                   BMI2 SS08 – Class 1 “Introduction” Slide 20

								
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