Introduction to Ultrasound Imaging

1. ULTRASOUND IMAGING
mlml l
Anjan Dangal
B.Sc.Medical imaging
Technology
National Academy of Medical
Sciences,
Bir Hospital, Kathmandu,
Nepal

2. Application
• Ultrasound Imaging is used in following medical working Areas
Hospital
General Practise
Physical Therapy practice
Obstetrics centres
Veterinary centres

3. Following medical specialism may use
Ultrasound Imaging
• Internal Medicine
• Radiology
• Surgery
• Cardiology

4. Goals
• Diagnosis
• Treatment
Ultrasound treatment is performed to treat prostate cancer (HIFU), for example, or for kidney stone removal
(lithotripsy) or during physical therapy. The intensity of ultrasound determines whether it is suitable for
diagnostic or therapeutic purposes.

5. Please pay attention to the Image
• This is an Ultrasound Image of?
A snail
Liver
Heart
Just Air
Correct! The ‘hollow’ structures in the middle are blood vessels running in the liver. Liver tissue has the characteristic
‘speckles’ as a structure.

6. This is an Ultrasound Image of ?
• Ice cream
• A liver
• The Aorta
• Bone and Muscle
Bone and Muscle: This is an ultrasound image of the bone in the forearm, with muscles, tendons, fat, and skin as
surrounding tissue.

7. In this ultrasound image you see that there is a structure
measured. What structure is measured here most likely?
• Spleen
• Kidney
• Liver
• Aorta
• Stomach
This is a typical dimension of a kidney in this orientation. Make also note of the typical structure of the kidney, where you can
see that is located next to the liver, making this the right kidney.

8. In this ultrasound image there is an overlay with coloring.
What is indicated with the blue and red colors here?
• A artery and a Vein
• Small and Large Intestine
• Trachea and Esophagus
This is the Doppler technique to visualize the structures

9. Next Content
Ultrasound in Medical Imaging

10. Intensive care Unit
• Intensivist deploys ultrasound to
assess heart function, the status of
fluid in the lungs and for guiding
interventions.
• The use is focused on quick and
easy assessments.
• If more profound ultrasound
examination is required, they will
refer the patient to a more
specialized sonographer.
• They use Ultrasound for the
insertion of central venous catheter.

11. Physiotherapy
• Physiotherapist uses to
assess structures such as
tendons, muscles, bones,
joints, capsules, ligaments
and nerves, among others.
• Ultrasound helps her to
confirm or disprove earlier
diagnoses, refer the patient
earlier to specialised
physicians, or even change
their own therapy
approach.

12. Radiology
• Radiologist and sonographers uses
ultrasound to visualize the anatomy as well
as physiology of all the regions of body. For
Example: they may focus on the abdominal
organs, which are very suitable for
ultrasound assessment.
• The liver, gall bladder, pancreas, spleen,
kidneys, aorta, and urine bladder may be
examined.
• Only those organs containing air - such as
the stomach and intestines - are more
difficult to assess.

13. Obstetrics
• During pregnancy, women
visits sonographers multiple
times and get various pieces
of information about their
future child - like gender*,
growth, potential
abnormalities, and/or a 3D
impression.

14. Vascular Surgery
• Doppler imaging is
frequently used here, to
analyse blood flow
velocity and direction.
• The health of all kinds of
blood vessels can thus be
checked upon, including
vessel lumen narrowing,
widening and
insufficiency.

15. Next Content
Technology behind Ultrasound Imaging

16. What do you know?

17. When you hear someone talking, the sound
of his/her voice reaches your ear because:
• A. The air particles travel from the speaker’s mouth to your ear
• B. The air particles apply force to each other creating a travelling wave
• C. Light particles cause your ear to start vibrating
• D. Light particles travel from the speaker’s mouth to your ear
• E. Light particles apply force to each other creating a travelling wave
Correct Answer : B

18. Ultrasound is:
A. Like normal sound, but very loud
B. Like normal sound, but with a high frequency
C. Like normal sound, but with a high velocity
Correct Answer: B when the frequency is higher than 20Khz

19. Can Humans Hear Ultrasound?
• A. Yes
• B. Yes, but only if you only make ultrasound
• C. No, because it would damage your hearing immediately
• D. No, ultrasound is beyond the human hearing range

20. Basic Physics of Sound

21. What is Sound?
• Sound is mechanical disturbance from a state of equilibrium that
propagates through an elastic medium.
• medium, which could be air or water, and we create a disturbance.
• Disturbance propagates through the medium, and we have a sound
wave.
• So Sound is a pressure wave moving through the medium.

22. • The source of sound is characterised mainly by its frequency-- the
number of vibrations or the number of cycles per second, expressed
in Hertz.

24. Speed of Sound

25. Relation ship of wavelength, velocity and
Frequency
• Wavelenght of sound = speed of sound/ frequency
C/F
For a Typical Tissue ( c= 15oom/s)
Frequency Wavelenght
1MHZ 1.5mm
5MHZ 0.3mm
10MHZ 0.15mm
20MHZ 0.075mm

26. Conclusion : What is Sound
• pressure wave with a frequency >20 Hz.
• ultrasound has frequencies >20 Khz that nobody can hear.
• ultrasound imaging, we use frequencies >1Mhz.
• Propagation speed 0f 1500m/s
• Wavelenght of 1.5mm or smaller

27. Where is Ultrasound?

28. In Nature
• 1794, it has been discovered that bats, use ultrasound to navigate by
echo reflection.
• For bats, ultrasound is not ultrasound because they can hear
frequencies even up to 200 kilohertz.
• Use to find flying insects, even at a distance of a few metres.

29. In Nature
• Dogs, unlike humans, are able to hear sounds up to 60 kilohertz,

30. • The first technical use of ultrasound has been in sonar for nautical
use.
• Sonar means Sound Navigation and Ranging.

31. • Disaster with the Titanic that has catalysed the development of
ultrasound devices.
• And since then, there has be a large interest in ultrasound safety
systems.

32. Medical Use of Ultrasound for Imaging
• Dr. Karl Dussik from Austria in the '40s of the 20th century.
• He used a separate source of ultrasound and a detector. So he made a
kind of transmission mode measurements, and the images that he
obtained can be compared with the shadow images as obtained with
x-ray imaging.
• And in this way, using ultrasound, he could image the ventricles of the
brain.

34. There is the use of ultrasound in nature by
animals, and in ships for safety, and we have
seen the ultrasound for medical purposes. So
ultrasound is everywhere, but you just can't
hear it.

35. How can we make and detect Ultrasound
Transducer

36. • a transducer is a system that transforms one form of energy into
another form of energy.
• And an ultrasound transducer makes ultrasound.
• So it transforms an electrical pulse into a wave of ultrasound.

39. Piezoelectric crystals

41. Curvilinear Probe
• Curvilinaer surface
• Sector Shaped field
• Abdomen

42. Linear Probe 1
• straight surface
• Parallel or rectangular field
• Arteriel or Musculoskeletal

43. Linear Probe 2
• Small probe / window
• Traingular field
• Cardiography

45. Based of frequency
• High Frequency transducer
• Low Frequency transducer

46. High frequency Transducer
• emit waves of short wavelength and a frequency of 7-18 MHz.
• are unable to travel very far, are used to image superficial structures or
organs close to the skin surface.
• result in a higher resolution means superficial tissue is seen in greater
detail
• Used for Imaging
Superficial blood vessels
Breasts
Testes
Thyroid
Nerves
Superficial skin lumps
Lung

47. Low Frequency Ultrasound
• emit sound waves which have a long wave length and a frequency of
2-5 MHz.
• These sound waves penetrate deeper into the body but have a lower
resolution than the High Frequency Transducer.
• The scanning applications for a Low Frequency Transducer include;
• Abdomen – liver, spleen, kidney, gall bladder, bladder
• Aorta
• Obstetrics
• Focused Assessment using Sonography for Trauma (FAST) scan
• Lung
• Muscle Biofeedback

48. Interaction of Ultrasound with matter

49. Acoustic Impediance
• Acoustic impedance (Z) is a physical property of tissue. It
describes how much resistance an ultrasound beam encounters as it
passes through a tissue.
• Acoustic impedance depends on:
• the density of the tissue (d, in kg/m3)
• the speed of the sound wave (c, in m/s)
• Z = d x c

50. Acoustic Impediance continue

51. • It is easier for sound waves to travel through fluid, more difficult to
travel through an organ like the liver and virtually impossible to travel
through bone.
• Sound Wave can be :
1. Reflected
2. Refracted
3. Absorbed or
4. Scattered

52. Reflection
• Angle of incidence Equals
angle of reflection.
• Best Reflection: face of
transducer parallel to
interface
• Improves Quality
• Structures consisting of
calcium will reflect sound
completely and there will
not be any transmission of
the sound wave past these
highly reflective interfaces.
This causes a dark shadow
(posterior shadowing)
behind the bright
(hyperechoic) reflective
interface.

53. Refraction
• When the sound wave strikes a
curved surface it is refracted.
There are many curved structures
within the body (cyst, gallbladder,
renal contour) that can cause a
refraction artifact.
• The sound wave is refracted away
from the curved interface
resulting in no sound returning to
the transducer from immediately
below the rounded interface,
creating a black void on the
image.

54. Scattering
• Scattering occurs when the
reflective interfaces are very
small. This occurs through out
the organs but is most easily
demonstrated when we scan
organs containing air.
• The tiny air molecules contained
in bowel gas and lungs are
strong reflectors, due to the
difference in acoustic impedance
with the surrounding tissue,
meaning they appear white on
the screen.
• Air also scatters the sound wave
so the image that is formed
appears irregular and ill defined.

55. Absorption

56. Modes of Ultrasound

57. A mode
• A for Amplitude
• 1 dimension
• display of amplitude spikes
of different heights.
• Hardly Used now

58. B mode
• Brightness mode
• display of 2D map of B-Mode data,
• most common form of ultrasound
imaging.
• Unlike A-Mode, this based on
brightness
with the absence of vertical spikes.
Therefore,
the brightness depends upon the
amplitude
or intensity of the echo.
B-Mode will display an image of large
and small dots, which represent strong
and weak echoes, respectively

59. M Mode • M-Mode, or Motion Mode (also
called Time Motion or TM-Mode),
is the display of a one-dimensional
image that is used for analyzing
moving body parts commonly in
cardiac and fetal cardiac imaging.
• accomplished by recording the
amplitude and rate of motion in
real time by repeatedly measuring
the distance of the object from the
single transducer at a given
moment.
• The single sound beam is
transmitted and the reflected
echoes are displayed as dots of
varying intensities thus creating
lines across the screen.

60. Characteristics of Sonographic Image
• Sonographer must be able to analyzea mass to determine its border
are smooth, irregular, poorly defined, thin , or thick to further define
its characteristics .
• Once mass is suspected , acoustic property must be evaluated to
determine if it is heterogenous, homogenous, hyperechoic,
hypoechoic, isoechoic or anechoic.

61. Hyperechoic
• A hyperechoic mass may
represent a tumor,
thrombus, or
calcification; the lesion
present with bright echo
reflectors and possibly
shadowing beyond it

62. Hypoechoic
• hypoechoic lesion is
characterized by very
low-level echoes with
a good posterior
border.

63. Isoechoic
• An isoechoic mass shows
nearly the same texture
pattern as the
surrounding parenchyma
with no significant
change in the through
transmission

64. Anechoic
• An anechoic mass
shows no internal
echoes, has smooth
walls, and displays
increased through
transmission.

65. Why Ultrasound Image is with so much noise
• Speckles: mark with large number of small spots or patches of colour.

67. Doppler Effect
• Christian Doppler in 1842
• an increase (or decrease) in the
frequency of sound, light, or other
waves as the source and observer
move towards (or away from) each other.

69. Types of Doppler
• Continuous Doppler
• Pulsed Doppler
• Color Flow

70. Continuous Doppler
• Continuous wave of Ultrasound wave send to body
• Reflected Echo recorded
• Velocity shown over function of time
• Not Imaging but Monitoring of Blood Flow

71. Pulse Wave Doppler
• a technique in which the transducer emits ultrasound in pulses
• 3 types
• Power Doppler
• Color Doppler
• Spectral Doppler.

72. Power Doppler
• power Doppler; An ultrasound technique that is used to obtain
images that are difficult or impossible to obtain using standard color
Doppler and to provide greater detail of blood flow, especially in
vessels that are located inside organs.
• Images of vessels ( Angiography)

73. Color Doppler
• Both speed and direction of flow
in low flow rate.
• Flow towards the probe is red and way is blue

74. Spectral Doppler
• spectral Doppler displays the blood flow measurements graphically,
displaying flow velocities recorded over time.

75. Clinical Applications

76. Abdomen and Retroperitoneum
• Generally Includes survey of abdominal cavity from the diaphragm to
the level of umbilicus.
• Specific protocols are followed to image the texture, border, and
anatomical relationships and blood flow patterns in the liver, biliary
systems, pancreas, spleen, vascular structures, retroperitoneum and
kidney

77. • Air and gas in abdominal cavity may obstruct ultrasound beam.
• Upper abdominal Ultrasound is best performed after a patient has
been fasting for 6 hours.
• Fasting also allows gallbladder and bile duct to be distended for
adequate visualization.

78. Superficial Structures
• Superficial structures such as thyroid, breast, scrotum and penis are
imaged best with ultrasound using high frequency transducer.
• In conjuction with mammography, ultrasound is able to characterize
the texture of breast mass to determine if mass is fluid filled ,
complex or solid.

79. Gynecologic Application
• Transabdominal examination of the female pelvis includes
visualization of the distended urinary bladder, uterus, cervix,
endometrial canal, vagina, ovaries, and supporting pelvic
musculature. The
• full bladder helps to push the small bowel superiorly out of the pelvic
cavity, flattens the body of the uterus, and serves as a sonic window
to image the pelvic structures.
• The fallopian tubes and broad ligaments are usually seen only when
the patient presents with excessive free fluid or ascites within the pel
vic cavity.

80. • Endovaginal Ultrasound has now become the preferred procedure
for imaging the endometrium, myometrium and ovaries.
• A high-frequency transducer is inserted into the vagina to image the
uterus, cervix, fallopian tubes, ovaries, and adnexal area in coronal and
sagittal planes

81. Obstetric Application
Ultrasound is helpful for defining both normal and abnormal
development of anatomy.
A detailed ultrasound examination can access complications of
pregnancy such as neural tube defects, skeletal or limb anomalies,
cardiac defects, gastrointestinal and genitourinary defects, and head
anomalies

83. Neonatal Ultrasonography
• Premature infant is susceptible to intracranial haemorrhage during
stress of delivery and struggle to survive.

84. Other Special Types of Probes
• Endo cavity probes: To look deep inside body
• Have to inserted into body orfice

85. Prostate Imaging
• Through Rectum
• Trans rectal probe
• Gidance to tissue biopsy

86. Cervix/ Uterus
• Through Vagina
• Tans vaginal probe

87. Trans Esophageal Echo cardiography
• Images of Heart are made through wall of Esophagus.

88. Echo Endoscopy
• Inserted in Colon.
• To observe cyst or poly in colon wall
• To observe bile ducts or pancreas

89. Intra vascular Ultrasound probes
• Imaging inside coronary artery
• Needs vascular ascess.

90. Conclusion
Ultrasound has rapidly emerged as a
powerful, noninvasive, high-yield clinical
diagnostic examination for various applications
in medicine.
Expected advancements
include further developments in
transducer design, image resolution, tissue
characterization applications, color
flow sensitivity, and four-dimensional reconstruction
of images.

91. Ref:
• Ultrasound Imaging: Whats Inside, Massive Open Online Course,
Univerty of Twente, Netherland
• Merills, Volume 3
• Radiopedia.org
• Radiology Info.org