Ultrasound uses high-frequency sound waves to image inside the body. It has several main parts including a transducer probe that sends and receives sound waves. There are different imaging modes like B-mode which provides two-dimensional cross-sectional images and Doppler which evaluates blood flow velocity. Ultrasound is widely used in areas like obstetrics to monitor fetuses and cardiology to examine the heart. It has benefits of being non-invasive, portable, and having no long-term side effects.

1. Basics of Ultrasound
Dr. Mohan Kumar
M.S.(Ay.)

2. History
The bat use Ultrasound for navigation

3. ULTRASOUND: BASIC
DEFINITION
 Ultrasound is acoustic(sound) energy in the form
of waves having a frequency above the human
hearing range(i.e. 20KHz)
 Ultrasound is a way of using sound waves to look
inside the human body.

4. Pan-Scanner - The transducer rotated in a semicircular arc
around the patient (1957)

5. Scan converter allowed for the first time to use the
upcoming computer technology to improve US

6. Ultrasound Parts

7. The Ultrasound Machine
A basic ultrasound machine has the followingparts:
1. Transducer probe - probe that sends and receives the sound
waves
2. Central processing unit (CPU) - computer that does all of the
calculations and contains the electrical power supplies for itself
and the transducer probe
3. Transducer pulse controls - changes the amplitude, frequency
and duration of the pulses emitted from the transducer probe
4. Display - displays the image from the ultrasound data processed
by the CPU
5. Keyboard/cursor - inputs data and takes measurements from
the display
6. Disk storage device (hard, floppy, CD) - stores the acquired
images
7. Printer - prints the image from the displayed data

8. ULTRASONOGRAPHY
• Ultrasonography or diagnostic sonography is an
ultrasound based diagnostic imaging technique used
for visualizing internal body structures.

9. MAIN IMAGING
MODES
GREY SCALE
IMAGING
A-Mode
B-Mode
M-Mode
DOPPLER IMAGING
Continuous wave Doppler
 Power Doppler
 Color Doppler
 Duplex Doppler
Pulsed wave Doppler

10. A MODE
Simplest form of ultrasound
imaging which is based on
the pulse-echo principle.
A scans can be used to
measure distances.
A scans only give one
dimensional information
 Not so useful for imaging
Used for echo-
encephalography and echo-
ophthalmoscopy

11. B MODE
 B stands for Brightness
B scans give two dimensional
information about the cross-
section.
Generally used to measure
cardiac chambers
dimensions, assess valvular
structure and function.

12. Development of the B-mode Ultrasound image quality

13. M MODE
 M stands for motion
This represents
movements of
structures over time.
M Mode is commonly
used for measuring
chamber dimensions.
This is analogous to
recording a video in
ultrasound.

14. DOPPLER IMAGING
It is a general term used to
visualize velocities of moving
tissues.
Doppler ultrasound evaluates
blood velocity as it flows
through a blood vessel.
Blood flow through the heart
and large vessels has certain
characteristics that can be
measured using Doppler
instruments.

15. BLOOD FLOW PATTERNS
LAMINAR FLOW
of flow
at vessel
• Layers
(normal)
• Slowest
wall
• Fastest within center
of vessel
TURBULENT
FLOW
• Obstructions
disrupt laminar flow
• Disordered
directions of flow

16. TYPES OF DOPPLER ULTRASOUND
1. CONTINUOUS WAVE DOPPLER (CW)
Uses different crystals to
send and receive the signal
One crystal constantly sends
a sound wave of a single
frequency,
constantly
the
receives
other
the
reflected signal

17. 2. PULSED WAVE
DOPPLER
 Produces short
bursts/pulses of
sound
 Uses the same
crystals to send and
receive the signal
 This follows the same
pulse-echo technique
used in 2D image
formation.

18. 3. COLOR
DOPPLER
Utilizes pulse-echo Doppler flow
principles to generate a color
image.
Image is superimposed on the
2D image.
The red and blue display
provides information regarding
DIRECTION and VELOCITY of
flow.
Used for general assessment of
flow in the region of interest
Gives only descriptive or semi
quantitative information on blood
flow.

19. 4. POWER
DOPPLER
5 times more sensitive in
detecting blood flow than
color doppler.
It can get those images
that are impossible with
color doppler.
Used to evaluate blood
flow through vessels within
solid organs.

20. APPLICATIONS
 Obstetrics and Gynecology
1. Measuring the size of the fetus
2. Determining the sex of the baby
3. Monitoring the baby for various procedures
 Cardiology
1. Seeing the inside of the heart to identify abnormal functions
2. Measuring blood flow through the heart and major bloo
vessels
 Urology
1. Measuring blood flow through the kidney
2. Locating kidney stones
3. Detecting prostate cancer at early stage

21. RISKS
The two major risks involved with Ultrasound are:
 Development of heat:
Tissues or water absorb the ultrasound energy
which
increases their temperature locally.
 Formation of bubbles ( cavitation):
When dissolved gases come out of solution due
to
local heat caused by Ultrasound.

22. BENEFITS
 Images muscle, soft tissues very well
 Renders “live images” where most desirable
section is selected
 Shows structure of organs
 No long-term side-effects
 Widely available and comparatively flexible
 Highly portable
 Relatively inexpensive
 Spatial resolution is better in high frequency
ultrasound scanners

23. LIMITATIONS
 Sonographic devices have trouble penetrating bone
Sonography performs very poorly when there is a gas
between the transducer and organ of interest
Body habitus has large influence on image quality
Method is operator-dependent
No scout image as there is with CT and MRI