1. Biological Measurement 1 BIOE 571

2. History of ultrasound and importance to medicine Basic imaging modes
I. Topics Covered Today
History of ultrasound and importance to medicine
Basic imaging modes
Ultrasound Propagation
Reflection and Transmission
Generation of ultrasound

3. Bioeffects of Ultrasound and HIFU
My Research Interests
Bioeffects of Ultrasound and HIFU

4. Bioeffects of Ultrasound and HIFU
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

5. Homework – 1-2 per lecture (not too difficult)…
Grading
Homework – 1-2 per lecture (not too difficult)…
Homework may include a small amount of coding, so need to know a little Matlab.

6. History of Ultrasound
First of all: what is ultrasound?

7. 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

8. 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

9. History of Ultrasound
First ultrasound systems for imaging humans was developed in 1950s by Howry and Wild

10. History of Ultrasound
Imaging device of Howry and Wild. The water filled gun turret came from a World War II B29-Bomber. Boy have we come a long way!!!

11. History of Ultrasound
Tomographic image of neck from Howry and Wild. The image showed details not visible with X-ray scanners of the day.

12. 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.

13. 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.

14. 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.

15. Ultrasound Compared to Other Modalities:

16. Ultrasound Compared to Other Modalities
Modality US
X-Ray CT
MRI
Imaged
Mechanical properties
Tissue absorption
Biochemistry
Resolution
0.3-3 mm
~ 1mm
Penetration
3-25 cm
through
Safety
Safe
Ionizing radiation

17. 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
Cost
Low
High
Very high

18. Ultrasound

21. 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

22. B-Mode Image

23. B-Mode Image

24. M-Mode Image

25. 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.

26. Doppler

27. Color Flow Imaging

28. Harmonic Imaging: Pulse Inversion
Harmonic image using pulse inversion, image by Sonoace.

29. Strain image (left) and B-mode image (right) of lymph node.
Strain Imaging
Strain image (left) and B-mode image (right) of lymph node.

30. Shear Wave Imaging

31. Ultrasonic Attenuation in Tissues
Tissue dB/MHzy/cm y
Blood
Liver
Muscle
Brain
Fat
Breast
Bone

32. Sound Speed in Tissues
Measurements of speed of sound in biological media
Media Sound speed (m/s)
Skin
Muscle
Breast
Brain
Blood
Fat
Bone
Spleen
Cartilage

34. Example Problem a) b) c) d) None of the above
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) b) c)
d) None of the above ρ c ρ c ρ 2c ρ ρ c 2 2 2 2 L L

35. Example Problem a) b) c) d) None of the above
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) b) c)
d) None of the above ρ c ρ c ρ 2c ρ ρ c 2 2 2 2 L L
WHY???

36. 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 2c ρ ρ c 2 2 2 2 L L