ultrasound

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