Basics of Diagnostic Ultrasound

Introduction to Ultrasound Physics.
Principle of Operation of Imaging Ultrasonic Equipment
Application of Ultrasound in Medicine

1. Diagnostic Ultrasound
Done By: Eng. Ibrahim Tayyan

2. Points to be discussed in our lecture
•Physics of Ultrasound
•Principles of Ultrasonic Imaging
•Types of Probes
•Usage of Ultrasonic equipments in general
•Some Areas of Applications

3. Physics of Ultrasound
•Ultrasonic wave: It is an acoustic (sound) wave with a
frequency above audible frequency. (I.e. above 20 KHz)
•Velocity= Wavelength x Frequency
v = x Hz

4. Physics of Ultrasound
Properties of Ultrasonic waves:
1) Reflection
2) Refraction
3) Penetration through medium
4) Scattering
5) Transmitting and building up
heat

5. Principles of Ultrasonic imaging
•A transducer is used to convert electrical energy into
acoustic energy.
•Transducer in general consists of many crystals with
different lengths and widths.
•These crystals are made of piezo electric materials
such as PZT & quartz

6. Principles of Ultrasonic imaging
•When you apply a high
voltage, there will be stress and
strain forces that will lead into
production of vibrations that
will produce sound waves

7. Principles of Ultrasonic imaging
•Crystal depth must be half the
wavelength to be produced
•Thinner crystal, higher the frequency,
as speed of sound is constant
•Blocking material, prevents the
reverse direction of wave, and
therefore prevents heat build up
•Insulated cover ensures uni-
directional wave, while plastic
housing protects the inner
materials

8. Principles of Ultrasonic imaging
•Many waves are produced, and they are represented as an
acoustic beam.
•These produced waves will penetrate the
body, and according to the acoustic
medium, the wave will be reflected back to
the transducer
•Waves will fully penetrate blood and water
•The reflected wave will be converted
into electrical signal, amplified, applied
to signal conditioning circuits, applied
to computerised programs and finally
displayed on a CRT or other monitor

9. Principles of Ultrasonic imaging
•Higher frequency, higher axial resolution, lower penetration.
•The narrower the beam produced, the higher the lateral
resolution
•Time gain control ensures that the reflected wave from
far regions are not lost due to their distance, by raising
the gain linearlly or exponentially with the depth of
penetration.
•For diagnostic use, frequency ranges from 2 to 15 MHz

10. Types of probes

11. Types of probes
Probe Type Freq range Application
Convex 2.5 to 5 MHz Obstetrics, abdomens, small parts
Transvaginal4 to 8 MHz Gynacology
Linear 6.5 to 15 MHz Superficial vessels, muscoskeletal
Phased Array3.5 to 8 MHz Cardiology
Transrectal 4 to 8 MHz Rectum
Radial --- -----
4D probes 3.5 to 5 MHz Motion of baby

12. Usage of Ultrasound in general
Diagnostic (2.5 to 15 MHz)Therapeutic ( less than 1.5 MHz)

13. Usage of Ultrasound in general
A –mode (Amplitude mode)
•The fundamental of
ultrasonic imaging
•Spikes represents the
location of tissue
•Currently it is used only for
ophthalmic uses

14. Usage of Ultrasound in general
B mode (Grey Scale or brightness mode)
•It is an A-mode but in 2D
•Image depends on gray scaling

15. Usage of Ultrasound in general
M mode (Motion mode)
•It shows the motion of B-
mode wave
•Used for determining the
movement of tissues such
as heart valves
•You can measure the
heart rate, velocity of
blood and measure other
parameters that are useful
for the cardiologist

16. Usage of Ultrasound in general
M mode (Motion mode)
•The guideline is used to
determine the location of
moving tissue
•Heart rate is measured
by taking the distance
between the first and the
third peak of the
waveform produced
•You can control the gain
and M-sweep speed

17. Usage of Ultrasound in general
Doppler mode
•Divided into 2 modes:
Pulsed and continous
•Used for measuring the
velocity of moving fluids in
general.
•By waveform and doppler
sound produced, a vascular
physician can determine
many parameters that are
valuable for him

18. Usage of Ultrasound in general
Doppler mode
•Its principle differs from ultrasound, although the wave
produced is accoustic wave
•A wave is transmitted into a
moving object to find its velocity
•When an object is moving
away from wave source, the
frequency of that object is
lower than the source’s freq
and vice-versa

19. Usage of Ultrasound in general
Color Doppler mode
•According to the color’s
intensity of the vessel, the
user can determine the flow
of blood and the location of
vessels narrowing
•Light : slow or little
•Dark: Fast or high
•Red: Towards probe
•Blue: Away from probe

20. Mode
Display
Features Application
A mode According the location of tissue
borders a spike is produced
Ophthamlic
B mode You can view a 2D display of
your organs and tissues
Widely used for every applications except
eyes, brain and tongue
M mode For viewing the motion of tissuesCardiology
Pulsed
doppler
Waves are transmitted in a pulse
wave form, used to measure low
velocities of blood flow
Vascular
Continuous
doppler
Continuous waves are transmitted
to measure high velocities and
pressure gradient
Vascular and Cardiology
Color
doppler
Intensity of blood flow and power
angiography
Vascular
3D mode View organs in 3D imaging
constructed by computer
Obstetrics, urology and abdominal
4D mode 3D mode in motion mode image is
directly taken by probe
Obstetrics

21. Some Areas of Applications
Anaesthesiology:
Ultrasound Guided Neural
Blockade
•Direct visualization of needle
•Increase success rates
•Decrease complication rates
•Allows smaller doses of
anaesthetic agent to be used
•Better post-op pain management
•Limit block to the body part
undergoing surgery
•Reduced need for other
analgesics (opioids)
•Minimal side effects

22. Some Areas of Applications
Intensive Critical Care:
Venous Catheters
Placement

23. Some Areas of Applications
Emergency Division:
Trauma ultrasound: BAT/penetrating trauma; haemoperitoneum;
haemothorax; FAST;PREP;FASTER AAA: abdominal aortic aneurysm
Emergency OB: 1
st
trimester bleeding; rule in IUP (not rule out ectopic);
fetal viability
Emergency Echo: pericardial effusion; tamponade;
Biliary ultrasound: gallstones (cholelithiasis); inflammation of the
gallbladder (cholecystitis)
Renal ultrasound: hydronephrosis; renal stones
Other: procedural; foreign bodies; torsions etc
Focused Assessment with Sonography in Trauma
(FAST)

24. Some Areas of Applications
Ob/Gyn Cardiology

25. Some Areas of Applications
Renal Ultrasound Vascular
Ultrasonography

26. Some Areas of Applications
Endocrinology MSK
And Many More…