Download Biological Measurement 1 BIOE 571

Biological Measurement 1
BIOE 571
Oelze - ECE 571 Lecture 1
I. Topics Covered Today
• History of ultrasound and importance to
medicine
• Basic imaging modes
• Ultrasound Propagation
• Reflection and Transmission
• Generation of ultrasound
Oelze - ECE 571 Lecture 1
My Research Interests
• Bioeffects of Ultrasound and HIFU
Oelze - ECE 571 Lecture 1
My Research Interests
• Bioeffects of Ultrasound and HIFU
• Cancer detection using spectral imaging
techniques
• Ultrasound computed tomography for
characterizing soft tissues
• Coded excitation to improve ultrasound
image quality
• HIFU therapy and therapy monitoring
using ultrasound
Oelze - ECE 571 Lecture 1
Grading
• Homework – 1-2 per lecture (not too
difficult)…
• Homework may include a small amount of
coding, so need to know a little Matlab.
Oelze - ECE 571 Lecture 1
History of Ultrasound
• First of all: what is ultrasound?
Oelze - ECE 571 Lecture 1
History of Ultrasound
• First of all: what is ultrasound?
– Pressure waves at frequencies higher than audible
range (> 20 kHz)
• Compared to X-Rays (and CT) ultrasound is
safe and does not produce harmful bioeffects
unless used at very high intensity
• The safety of ultrasound makes it desirable as
an imaging modality
Oelze - ECE 571 Lecture 1
History of Ultrasound
• Initially used as a surgical device and studied
for its bioeffects (much of this groundbreaking
work was conducted at the Bioacoustics
Research Laboratory at the U of I).
• High intensity ultrasound waves were used in
water (SONAR) to detect submarines during
world war II
• This led to the idea of using ultrasound as an
imaging device
Oelze - ECE 571 Lecture 1
History of Ultrasound
• First ultrasound systems for imaging humans
was developed in 1950s by Howry and Wild
Oelze - ECE 571 Lecture 1
History of Ultrasound
Imaging device of Howry and Wild. The water
filled gun turret came from a World War II B29Bomber. Boy have we come a long way!!!
Oelze - ECE 571 Lecture 1
History of Ultrasound
Tomographic image of neck from Howry and Wild.
The image showed details not visible with X-ray
scanners of the day.
Oelze - ECE 571 Lecture 1
History of Ultrasound
• First ultrasound systems for imaging humans
was developed in 1950s by Howry and Wild
• The main problem with US scanning was
consistent contact. Water was the medium used
initially to match into tissue but it was not
feasible to put people in tanks of water to
image.
• Late 1950s Dr. Wild developed the first hand
held 15 MHz transducer contacting skin directly.
Oelze - ECE 571 Lecture 1
History of Ultrasound
• As early as 1957, blood velocity was estimated
using the Doppler effect by Japanese
researcher, Dr. Satomura.
• In 1965 the first real-time scanner was invented
with the advent of improved signal processing
and transducers.
• In 1971, the first arrays were introduced
allowing improved real-time scanning of
patients.
• From that point on, US begin to gain prevelance
in clinical applications.
Oelze - ECE 571 Lecture 1
History of Ultrasound
• In 1981, color flow mapping images were first
created with a US image of tissue
superimposed with blood velocity images.
• In the 1990s, high-end scanners became digital.
• And 3-D imaging began to emerge.
Oelze - ECE 571 Lecture 1
Ultrasound Compared to Other Modalities:
Oelze - ECE 571 Lecture 1
Ultrasound Compared to Other Modalities
Modality
US
X-Ray
CT
MRI
Imaged
Mechanical
properties
Tissue
absorption
Tissue
absorption
Biochemistry
Resolution
0.3-3 mm
~ 1mm
~ 1mm
~ 1mm
Penetration
3-25 cm
through
through
through
Safety
Safe
Ionizing
radiation
Ionizing
radiation
Safe
Oelze - ECE 571 Lecture 1
Ultrasound Compared to Other Modalities
Modality
US
X-Ray
CT
MRI
Speed
100 f/s
Minutes
30 s to
minutes
10 f/s
Portability
Excellent
Good
Poor
Poor
Cost
Low
Low
High
Very high
Oelze - ECE 571 Lecture 1
Ultrasound
Oelze - ECE 571 Lecture 1
Oelze - ECE 571 Lecture 1
Oelze - ECE 571 Lecture 1
Imaging Modes of Ultrasound
•
•
•
•
•
•
•
•
B-mode: Brightness-mode
M-Mode: Motion mode
C-mode: Coronal mode
Doppler imaging modes (color flow, power
Doppler)
Contrast and Tissue Harmonic Imaging
Strain Imaging
Shear Wave Imaging
Future Modes
Oelze - ECE 571 Lecture 1
B-Mode Image
Oelze - ECE 571 Lecture 1
B-Mode Image
Oelze - ECE 571 Lecture 1
M-Mode Image
Oelze - ECE 571 Lecture 1
C-Mode Image
A C-Mode ultrasound
image of a uterus with a
submucus fibroid taken
from a 3-D ultrasound
image of the uterus.
Oelze - ECE 571 Lecture 1
Doppler
Oelze - ECE 571 Lecture 1
Color Flow Imaging
Oelze - ECE 571 Lecture 1
Harmonic Imaging: Pulse Inversion
Harmonic image using pulse inversion, image by Sonoace.
Oelze - ECE 571 Lecture 1
Strain Imaging
Strain image (left) and B-mode image (right) of
lymph node.
Oelze - ECE 571 Lecture 1
Shear Wave Imaging
Oelze - ECE 571 Lecture 1
Ultrasonic Attenuation in Tissues
Tissue
dB/MHzy/cm
y
Blood
0.14
1.21
Liver
0.45
1.05
Muscle
0.57
1.0
Brain
0.58
1.3
Fat
0.6
1
Breast
0.75
1.5
Bone
3.54
0.4-2.2
Oelze - ECE 571 Lecture 1
Sound Speed in Tissues
Measurements of speed of sound in biological media
Media
Sound speed (m/s)
Skin
1500-1750
Muscle
1550-1600
Breast
1430-1550
Brain
1520-1550
Blood
1540-1600
Fat
1350-1470
Bone
2500-4200
Spleen
1520-1570
Cartilage
1660-1670
Oelze - ECE 571 Lecture 1
Oelze - ECE 571 Lecture 1
Example Problem
A source (which also acts as a receiver) propagates a delta
function through a medium with two layers spaced a distance L
apart. What might the return signal look like?
a)
ρ
c
ρ
c
ρ
2
2
2
2c
2
b)
c)
L
d) None of the above
Oelze - ECE 571 Lecture 1
ρ
L
c
Example Problem
A source (which also acts as a receiver) propagates a delta
function through a medium with two layers spaced a distance L
apart. What might the return signal look like?
a)
ρ
c
ρ
c
ρ
2
2
2
2c
2
b)
c)
L
d) None of the above
Oelze - ECE 571 Lecture 1
WHY???
ρ
L
c
Example Problem
A source (which also acts as a receiver) propagates a delta
function through a medium with two layers spaced a distance L
apart. What might the return signal look like?
Have to take speed of sound into
account
ρ
c
ρ
c
ρ
2
2
2
L
Oelze - ECE 571 Lecture 1
2c
ρ
2
L
c