Ultrasonography uses high frequency sound waves to non-invasively image soft tissues. It is used for both diagnostic purposes like organ imaging and measurement as well as therapeutic purposes like HIFU and lithotripsy. Ultrasound has a range above human hearing and most diagnostic instruments use 1-10 MHz. It provides greyscale images based on tissue density and is useful for visualizing soft tissue structures and blood flow.

1. ULTRASONOGRAPHY INTRODUCTION
• Ultrasonograpy is a non-invasive imaging modality using high
frequency sound waves.
• Used
-For diagnostic
- Tomographic imaging of soft tissues
- to quantitate the functional movement of organ
- to measure the size of the organ`
- to study the patterns of blood flow
- to assess fetal age
- For therapeutic purpose—
- HIFU- Knifeless surgery
- Physiotherapy
- Lithotripsy

2. • The human ear can detect
frequencies in the range of
20 -20000 Hz.
• Sound above this range is
known as Ultrasound.
• Used for both diagnostic and
therapeutic purposes.
• Most diagnostic instruments
use sound in the range of 1-10
MHz

3. • THE IMAGE is displayed
in various shades of grey
PULSE-ECHO ” PRINCIPLE
depending on tissue Piezo- Electric crystal (Lead Zirconate
density Titanate- PZT)
e.g. bone appears white
and fluid appears black.
• The number of shades of
grey displayed by the
machine is around 256,
but the human eye can
perceive only 16 shades of
grey. This improves the ULTRASONOGRAPHY DEMONSTRATES
THE STRUCTURE OF TISSUE RATHER
resolution of the picture. THAN TISSUE TYPE.

4. A ) ULTRASOUND WAVES NEED MEDIUM FOR TRAVELLING
• Velocity (V= ν ) of sound is constant in soft body
tissue but increase with intensity of medium.

5. B) Attenuation / reduction in intensity
• US beam is attenuated as it travels through tissues
• Echoes reflected back towards the transducer are also
attenuated.
• Factors contributing to Attenuation are:
1. Absorption:
• Energy in ultrasound beam is absorbed by tissues and is
converted into heat.
• It is the basis of therapeutic ultrasound.

6. 2. Acoustic impedance- ‘Z’
 It is the resistance offered by tissues to the sound waves.
 Z tissue = Tissue density x Velocity of sound in that Tissue

7. 3. Reflection: It is basis of diagnostic ultrasound
• Sound Waves Are Reflected Back Towards transducers
giving rise to echo.
• It Occurs
– if two adjuscent tissues have different Z
– occurs at patient transducer interface - poor coupling
– incidence angle
– “Z” (TISSUE DENSITY) determines the % of the reflected
beam as it passed from one tissue to another.

8. Sound reflection at various interfaces

9. 3. Scattering:
• It occurs when the beam encounters irregular interface.
• Angle of US beam interacting with this interface results
in scattering in all direction.
• CAUSES ARTIFACTS

10. 4. Refraction:
• sound waves bend at CURVED
interfaces
• Angle of incidence.
• Affects both transmission &
reflection
• Can create artifacts
5. Transmission:
 When [Z] of tissues at interface are same- allow
penetration to depth

11. A.
COMPONENTS OF AN ULTRASONOGRAPHIC MACHINE
• TRANSDUCERS
• CONTROL PANEL
• COMPUTER
• PRINTER
• COUPLING GEL
TRANSDUCER
• Function: To send and receive signals
• Piezo – electric crystal (Lead zerconate titanate)
• FREQUENCY- Resolution Vs Penetration
• Lower the frequency, lesser resolution, greater
penetration.
• Greater the frequency, greater resolution, lesser
penetration.

12. TYPES OF TRANSDUCERS
LINEAR ARRAY TRANSDUCERS Thin
rectangular clips lined side by
side (60-256 crystal in line)
Beam produced is rectangular
Applications: superficial structures
Vascular, Small Parts

13.  CURVI-LINEAR TYPE
 Shaped in a curve –
 Trapezoidal view –

 both superficial & deeper
structures are imaged.

14. SECTOR TYPE
• Single crystal oscillates to
provide fan shaped beam
• Small size, more
maneuverability
• Used for thoracic and
abdominal organs through
small contact area
Applications
Cardiac , Abdomen , Transcranial , Vascular

15. MISCELLANEOUS TRANSDUCERS
• US TRANSDUCER with a Biopsy probe
guide
• Endoscopic - Esophageal probe

16. Image Display Modes
A-Mode (Amplitude mode)
Single Ultrasound beam is used
The returning echoes are shown
as peaks along the horizontal
axis.
The height of the peak is directly
proportional to the strength of
the echo.
Gives information about the
organ boundaries.

17. B-Mode (Brightness mode):
• Multiple Ultrasound beams
are used.
• Returning echo is depicted
as the dots.
• Brightness of the dot is
directly proportional to the
strength of the echo.
• So, is also called as the
“Grey- Scale imaging”.
• 2D image –
• most popular mode of
display

18. Real-Time B- Mode Ultrasonography
Real-time B-mode
scanners display a moving
gray scale image of cross
sectional anatomy

19. M- Mode (Time-Motion mode)
• Single Ultrasound beam is used.
• Returning echoes depicted as dots.
• Position of dot will denote depth of
organ -- along the vertical axis.
• Moving structure (Time) on
horizontal axis.
• Brightness of dot denote the
strength of echo.
• It is used
– Echocardiography-

20. SCANNING PROCEDURE
• First the organ to be scanned
is decided- case history,
complaint, symptoms,
clinical examination, lab
examination, radiological
examination etc
• With the knowledge of the
topographic anatomy, use
the ‘acoustic window’
(Easiest and the nearest site
for passing the ultrasound
wave into the desired
organs)

22. DORSAL RECUMBANCY - abdomen

23. Selection of transducer
• It depends on
– Size of animals
– Depth of organ.
– Objective : Choose the highest frequency that will
penetrate to the depth needed for the particular
examination and gives highest resolution.
• Small dog, cats  7.5 to 10.0 MHz
• Medium dogs  5 MHz
• Large dogs  3.5 to 5.0 MHz
• Large animals  2.0 to 3.5 MHz

26. Scanning controls
• Near /Far Gain:- alter
Basic set of controls
amplification of returning
echoes
• Time compensation
gain:
• Depth- determine the depth
of US image
• Freeze- real time image can be
temporarily frozen

27. IMAGE INTERPRETATION
• Hyper-echoic / Echogenic
/Echo Rich- WHITE AREAS
– Given by highly reflective
interface such as bone or
air.
• Hypo- Echoic / Echo poor-
GREY AREAS
– Given by interface of
moderate reflection.
– Anechoic/echo lucent/echo
free- BLACK AREAS
• Denotes the complete
transmission of the sound
as through the fluids.
– Iso echoic- THE STRUCTURE OF TISSUE
RATHER THAN TISSUE TYPE.

28. •TISSUES IN ORDER OF  Interpretation based on
INCREASING ECHOGENECITY
texture of organ
•Bile, urine
•Renal medulla  Uniform/ regular
•Muscle /homogenous
•Renal cortex
•Liver
 Non-uniform/ irregular/
•Storage fat
non-homogenous
•Spleen
•Prostate
•Renal sinus  Fine Granular / Coarse
•Structural fat, vessel walls Granular
•Bone, gas, organ
boundaries, calculi

29. IMAGING OF REPRODUCTIVE TRACT
objectives
– Presence or absence of a pregnancy
– Identify the location of the pregnancy –
intrauterine or extrauterine.
– Assess the growth and development of the fetus.
– Placental localization-
– Assess the amount of liquor amnii.
– Assess the fetal age.

30. Time of Sonographic recognition of
canine fetal structures

31. 3.TESTES
• Topography:
– Testicles are superficial structures- high freq. transducer used.
– Non scrotal testicles search should begin in inguinal region.
• NORMAL APPEARANCE
– well circumscribed, smooth outline, oval in shape
– parenchyma moderately echogenic
Sagital image Transverse image

32. IMAGING OF THE THORACIC CAVITY
• Dis advantages: Not easy to image.
– the rib cage
– air within the lungs
• Transducer is placed
– on Inter costal Spaces,
– behind the xiphisternum
– at the thoracic inlet.

33. DUPLEX DOPPLER ULTRASONOGRAPHY
• Involves the simultaneous use of real time
B-Mode imaging and pulsed doppler ultrasound
PRINCIPLE OF DOPPLER: Blood cells moving towards
transducer give bright echoes & which move
away from transducer give weak echoes.
-Towards transducer – red / yellow / orange
-Away from transducer – blue/green

34. FORMS OF DOPPLER
• Pulsed Doppler:
• Continuous Doppler:
Uses:
-to identify structures by the presence or absence of
blood flow to organ
-to detect thrombus or clot in blood vessel
-to study direction of blood flow & associated
abnormality

35. Advantages of ultrasound
• It is a non- invasive diagnostic technique
• Differentiation of soft tissue abnormalities
• Visualization of intra- organ anomaly
• Technique can be performed on any patient
i.e., old, dyspnoeic and comatose patients
• No known harmful effects
• Visualiztion of Biopsy being taken.

36. Constraints
• Ultrasound imaging is not suitable
– Examination of tissues lying below bones
– Air containing organs – lungs, intestine etc
• Clipping / shaving of hairs –aesthetic value
• Application of coupling medium such as mineral
oil, aqueous gel - desquamation of cells leading to
metastasis.
• High capital investment involved
• Technical expertise