Transcript Biomedical Imaging I - SUNY Downstate Medical Center
Biomedical Imaging 2
Class 1 – Introduction 01/22/08
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Course instructor
Dr. Harry L. Graber
Research Assistant Professor of Pathology / SUNY Downstate Medical Center / Room BSB 4-132, (718) 270-1286 / [email protected]
A.B., Chemistry Ph.D., Physiology and Biophysics Postdoctoral Fellow Res. Asst. Professor Research Focus: 1983, 1998, 1998, 2001, Washington University, St. Louis, MO SUNY Health Science Center, Brooklyn, NY SUNY Downstate Medical Center SUNY Downstate Medical Center Optical Tomography - Image Reconstruction and Signal Analysis
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Lecture hours / locations, credits
• Classes – Location: – Hours: SUNY DMC HSEB 8J Tuesday, 10:00 AM to 1:00 PM • Credits – Classroom Participation: 15% – Homework: 20% – Exam1: 30% – Exam2: 35%
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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
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What is This Course About?
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Imaging Modalities Covered in BMI1
• X-ray Projection Radiography • X-ray
C
omputed
T
omography • Nuclear Imaging – Planar Scintigraphy –
P
ositron
E
mission
T
omography –
S
ingle
P
hoton
E
mission
C
omputed
T
omography • • Ultrasound
M
agnetic
R
esonance
I
maging –
Structural
MRI (anatomy)
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Imaging Modalities Covered in BMI1
• In brief,
structural imaging
(SI) techniques
– With one significant exception
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Imaging Modalities Covered in BMI2
•
Functional
imaging (FI) methods
–
D
iffuse
O
ptical
T
omography –
O
ptical
C
oherence
T
omography –
F
unctional MRI (fMRI) –
E
lectro
e
ncephalo
g
raphic Imaging –
M
agneto
e
ncephalo
g
raphy – Combined, or multi-mode, imaging
• But what does “functional” mean?
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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?
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Varieties of fMRI
•
D
• Perfusion Imaging – Contrast-agent-based – iffusion-
M w
eighted agnetic
R I
maging esonance • Saturation-based
A
ngiography /
V
enography • Bipolar-gradient-based –
A
rterial
S
pin
L
abeling •
D
• Magnetic Susceptibility Imaging – Contrast-agent-based – iffusion
B
lood
T O
ensor
I
xygen maging
L
evel
D
ependent
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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
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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
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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
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Tentative Syllabus
1) 01/22 Introduction; diffuse optical tomography (DOT) 2) 01/29 DOT 3) 02/05 Image post-processing & time-series analysis, Pt. 1 4) 02/12 Optical coherence tomography (OCT) 5) 02/19 fMRI – diffusion-weighted, perfusion 6) 02/26 fMRI – perfusion 7) 03/04 Exam1 8) 03/11 fMRI – BOLD 9) 03/18 OSA Conference, no class 10) 03/25 Image post-processing & time-series analysis, Pt. 2 11) 04/01 fMRI – diffusion-tensor imaging 12) 04/08 EEG/MEG principles 13) 04/15 EEG imaging 14) 04/22 MEG imaging 15) 04/29 DOT’s “relatives”: fluorescence OT, bioluminescence OT, correlation tomography, optoacoustic tomography 16) 05/06 Exam2 17) 05/13 Wrap-up
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Electromagnetic spectrum
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Diffuse Optical tomography (DOT)
• Year discovered: ~1988 • Form of radiation: Near-infrared light (non ionizing) • Energy / wavelength of radiation: • Imaging principle: • Imaging volume: • Resolution: • Applications: ~1 eV / 600 –1000 nm Interaction (absorption, elastic scattering) of light w/ tissue ~10 3 cm 3 Low (~1cm) Perfusion, functional imaging
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DOT and CT: Superficial Similarities, Essential Differences
• Generation: x-ray tube • Detection: Detector arrays (ion.-chambers, scint. + photodiode) • Computer reconstruction of 2D slices/ 3D volumetric images Source Object Detector
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Principles of DOT
• Scattering dominated • Limited penetration depth (~cm), low res. (mm-cm) • Economic,
functional
(hemodynamics) obstacle (absorber) Clear medium obstacle (absorber) Scattering medium 10 6 10 5 10 4 Hb 10 3 10 2 400 HbO 2 500 600 700 800 Wavelength [nm] 900 1000 light source S detector D D S D D D
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DOT Instrumentation
2-3 cm Source / Detector 1 Detector 2 Detector 3 Scalp Bone CSF Cortex
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DOT Applications
Breast Brain SPECT Arm
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