Transcript Monday_overview - Vanderbilt University Institute of Imaging

Introduction to Modern
Medical Imaging
Allen T. Newton, Ph.D.
Institute of Imaging Science, Department of
Radiology
Vanderbilt University
PAVE 2014
Medical Imaging
• The goal is to better visualize structure or function in the
living or non-living organism, animal or human
• Involves collaborations with mathematicians, physicists,
engineers, chemists and biologists
• Work with physicians to meet their diagnostic and
treatment evaluation needs
• Look at a couple of key components of medical imaging
• Look at some examples from MRI, ultrasound, CT
Chemistry
Physics
Biology
Imaging
Science
Medicine
Computer
Science
Math
Engineering
Radiologists (MD)
4 yrs of college
4 yrs of medical school
Physicist/engineer (PhD)
4 yrs of college
5-7 yrs of graduate school
improve
interpret
Medical Imaging
create
Technologists (RT)
2-4 yrs of college
2 yrs of technical school
How do we make medical images?
http://www.andor.com/image_lib/lores/introduction
The Major Imaging Modalities
• Magnetic Resonance Imaging (MRI)
• X-ray Imaging
• Computed Tomography (CT)
• Positron Emission Tomography (PET)
• Ultrasound (US)
The Major Imaging Modalities
• Magnetic Resonance Imaging (MRI)
• X-ray Imaging
• Computed Tomography (CT)
• Positron Emission Tomography (PET)
• Ultrasound (US)
The Major Imaging Modalities
• Magnetic Resonance Imaging (MRI)
• X-ray Imaging
• Computed Tomography (CT)
• Positron Emission Tomography (PET)
• Ultrasound (US)
The Major Imaging Modalities
• Magnetic Resonance Imaging (MRI)
• X-ray Imaging
• Computed Tomography (CT)
• Positron Emission Tomography (PET)
• Ultrasound (US)
So, you are playing soccer…
• … you collide with another player, and collapse in
pain on the ground
• You have pretty intense pain in your lower left leg
• How bad is it and how do we find out?
So, you go to the Emergency Room…
• … and the attending physician orders an X-ray of your injured leg
• What are they looking for?
• What will the X-ray show?
 The X-ray shows a
bad break in your tibia
General Message:
What is the problem?
Can imaging solve the problem?
How?
Image adapted from http://www.gentili.net/image.asp
Spatial Resolution
32x32, 7.5 mm2
128x128, 1.87 mm2
64x64, 3.75 mm2
256x256, 0.93 mm2
Spatial resolution
7T MRI, 0.6x0.6x1.0 mm3 resolution
Contrast
A Magnetic Resonance Imaging Scanner
Magnetic Resonance imaging
• Can generate 2D and 3D views in any plane
• Uses no ionizing radiation
• Extremely versatile modality
• Spatial resolution: humans~100, animals~25 microns
Axial
Coronal
Sagittal
Magnetic Resonance imaging
Magnetic Resonance imaging
MRI showing blood vessels in brain
Magnetic Resonance imaging
Assessing brain white matter tracks
• Bright in coherent white matter
• Darker where
1) Fibers diverge/cross, or
2) No preferred orientation
• Orientation is color code by direction
 Red = Right/Left
 Green = Anterior/Posterior
 Blue = Superior/Inferior
• Reveals structure within white matter
Adam Anderson, Ph.D.
Magnetic Resonance imaging
Finding white matter tracks
 Establishes connections between different brain regions
Adam Anderson, Ph.D.
Some examples from cancer imaging
MRI in cancer imaging
SI (arb. units)
0.50
0.45
0.40
0.35
0.30
0
2
4
6
8
time (min)
anatomical MRI
Signal Intensity time courses
3D rendering of tumor
X-rays in cancer imaging, 1/2
Mrs. Röntgen's hand, the first X-ray
picture of the human body ever taken
Mammogram displaying
calcification, increased density
X-rays in cancer imaging, 2/2
• Standard radiography yields a 2-D projection of a 3D object, whereas CT
allows for true 3-D image acquisition
• CT acquires a series of projections from many angles around the subject; each
set of projections is then reconstructed via a “backprojection” algorithm
• Developed by Sir Godfrey Houndsfield, won 1972 Nobel Prize in Medicine/Physiology
• Spatial resolution: humans~200 microns, animals~35 micron
www.radiologyinfo.org/
Munden, et al, Radiology, 2005; 237:803-18
PET in cancer imaging, 1/2
• Some radioactive isotopes (18F, 15O, etc) emit positrons:
A
A
X
Q  e
Z
Z 1
• Such elements can be incorporated into metabolically relevant compounds
• Emitted positron encounters electron, they annihilate leaving 2 photons traveling
in opposite directions which are measured by ring of detectors
• Images generated using very similar
computations as in CT
• Spatial resolution: humans and
animals ~2 mm
• Most common PET tracer is FDG
(flourodeoxyglucose), a glucose analog
18FDG
18FDG
(blood)
(tissue)
18FDG-6-PO
X
(cells)
4
PET in cancer imaging, 2/2
www.breastcancer.org
CT
PET
CT/PET
Dominique Delbeke
This week
Today: Overview
Tuesday: X-Ray & Computed Tomography
(CT)
Wednesday: Ultrasound, SPECT, PET
Thursday: MRI
Friday: fMRI lab !!!!!!