DIAGNOSTIC ULTRASOUND-3.pdf

DIAGNOSTIC
ULTRASOUND
MAAJID MOHI UD DIN MALIK
LECTURER COPMS ADESH UNIVERSITY
BATHINDA PUNJAB
MAAJIDMALIKOFFICIAL@GMAIL.COM

CONTENTS
 INTRODUCTION
 PRINCIPLE OF ULTRASOUND
 GENERATION AND DETECTION OF ULTRASOUD
 MAIN IMAGING MODES
 ULTRASOUND MACHINE
 TRANSDUCER PROBES
 WORKING PROCEDURE OF ULTRASOUND
 APPLICATIONS
 BENEFITS
 LIMITATIONS

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.

ULTRASOUND IS A LONGITUDINAL MECHANICAL WAVE WHERE
PARTICLE DISPLACEMENT IS PARALLEL TO THE PROPAGATION OF
WAVE
Longitudinal
wave
Transverse
wave

PRINCIPLE OF ULTRASOUND
 Ultrasound waves are created by a vibrating crystal within a
ceramic probe.
 Waves travel through the tissue and are partly reflected at each
tissue interface.
 “Piezoelectric “ principle- electric current causes crystal to
vibrate, returning waves create electric current.
Following phenomenon occur when ultrasound propagates
through medium:
 Reflection
 Refraction
 Diffraction
 Attenuation
 Scattering

GENERATION OF ULTRASOUND
 Ultrasound waves are usually both
generated and detected by a piezoelectric
crystal.
 The crystal deforms under the
influence of an electric field and, vice-
versa.
 When an alternating voltage is applied
over the crystal, a compression wave
with the same frequency is generated.
 Generally used piezoelectric
materials are: PZT(lead zirconate titanate)
and PVDF( polyvinylidene difluoride)

INTERACTION OF
ULTRASOUND WITH TISSUE

PIEZOELECTRIC CRYSTALS
 The thickness of the crystal determines the frequency
of the scan head.
Low
Frequency 3
MHz
High
Frequency
10 MHz

FREQUENCY AND
RESOLUTION
HIGH FREQUENCY= HIGH RESOLUTION
3.5 MHz(sector) 7.5 MHz(linear)

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

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

AMODE
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

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.

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.

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.

DOPPLER EFFECT
Apparent change in received frequency due to a relative
motion between a sound source and sound receiver
Sound TOWARD receiver = frequency
Sound AWAYfrom receiver = frequency

WHAT DEFINES A GOOD
DOPPLER
 No background noise
 Clear audible signal
 Accurate display of velocities

ULTRASOUND MACHINE

APPLICATIONS
Applications available on the ultrasound system
 Abdominal
 Cardiac
 Gynecological
 Intraoperative
 Musculoskeletal
 Neonatal head
 Obstetrical
 Pediatric
 Transcranial and Trans esophageal
 Vascular

GENERAL COMPONENTS OF
MACHINE
System control
panel
 System monitor
 PC
 E box
System power
supply

TRANSDUCER
Electronic device that converts energy from
one form to another.
Ultrasound transducers converts electrical
pulse into sound pulse and sends sound pulse
into the body and listens for returning echoes
generated by tissue interfaces and again
converts sound pulse into electrical signal.
 Piezoelectric transducers are used in
ultrasound.

ATRANSDUCER PROBE

TRANSDUCER PROBES
Probes are generally described by the size and shape of
their face(“footprint”). There are 3 basic types of probe
used in emergency and critical-care ultrasound.
 Linear array probe
 Curvilinear array probe
 Phased array probe

STRAIGHT LINEARARRAY
PROBE
It is designed for superficial imaging
Crystals are aligned in a linear fashion within a flat head and
produce sound waves in a straight line.
Image produced is rectangular in shape
Probe has higher frequency ( 5-13 MHz) providing
better resolution and less penetration.

CURVILINEAR PROBE
 Also called convex probe
 Used for scanning deeperstructures
 Crystals are aligned along a curved surface which results in a wide field of view
 Image created is sector shaped.
 Probes have frequency between 1-8 MHz allowing greater penetrationand
less resolution.
 Generally used in abdominal and pelvic applications.

PHASEDARRAY PROBE
 Crystals are grouped closely together.
 Sound waves originate from a single point and fan outward,
creating a sector-type image.
 Has smaller and flatter footprint than the curvilinear probe.
Probe has frequency between 2-8 MHz
Generally used for cardiac imaging, Imaging between ribs and
small spaces.

ENDOCA
VITARY PROBE
Has a curved face
Has higher frequency than curvilinear probe ( 8-13
MHz)
Probe’s elongated shape allows it to be inserted
close to the anatomy being evaluated.
Curved face creates a wide field of view of almost
1800
High frequency provides superior resolution
Most commonly used for gynecological applications

SPECIAL PROBES
Linear intraoperative
probe
Volume convex probe
Used in neurosurgery
Used in obstetrics
Transesophageal probe
Used in cardiology,
surgery

APPLICATIONS
 Obstetrics and Gynecology
1. Measuring the size of the fetus
2. 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 blood
vessels
 Urology
1. Measuring blood flow through the kidney
2. Locating kidney stones
3. Detecting prostate cancer at early stage

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

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

DIAGNOSTIC ULTRASOUND-3.pdf

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DIAGNOSTIC ULTRASOUND-3.pdf