Transcript Introduction to Endoscopic Ultrasound  Notice: This presentation is for your general knowledge and background only.

Introduction to
Endoscopic Ultrasound

Notice: This presentation is for your general knowledge
and background only. The presentation includes
information from various sources (see listing at the end
of the presentation) considered to be dependable.
However, we make no representations, warranties or
other expressed or implied warranties or guarantees
regarding the accuracy, reliability or completeness of the
information. Proper attribution should be provided for
any use of the information contained in this presentation.
Under no circumstance shall Olympus or its employees,
consultants, agents or representatives be liable for any
costs, expenses, losses, claims, liabilities or other
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consequential or otherwise) that may arise from or be
incurred in connection with the information provided or
any use thereof.
Fundamentals of
Ultrasound
Diagnostic Ultrasound
Devices
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Over a quarter century ago, ultrasound probes
were almost entirely of the extracorporeal type
In the last 25 years, the use of endoscopic,
endorectal, and transvaginal probes has
increased.
Miniature probes were also introduced in the
early 90’s
Ultrasound is now used commonly inside the
body, as well as, external to the body.
Sound Waves - Definitions
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Sound is a mechanical disturbance in the air
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starts with vibration of sound source
travels through air and impinges on eardrum
This mechanical disturbance exhibits physical
characteristics of a WAVE
Air acts as the MEDIUM for sound travel or
PROPAGATION
The source is the TRANSMITTER
The eardrum is the RECEIVER
Sound Waves - Particle
Vibration
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Sound wave:
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vibrations of air particles
called a plane longitudinal wave when vibration is
along sound wave’s line of travel
these particles only vibrate, they do not propagate
and will remain in their original positions when the
sound stops, however, mechanical energy does
travel from transmitter to receiver
String Example
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One end fixed, one end free
Free end is shaken vertically up and down
This causes a wave to travel along string
The wave consists of vertical vibrations of the
individual parts of string
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but these particles do not move along the string
Frequency - Definition
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As particles vibrate, they generate successive
regions of elevated and reduced air pressure
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particles that move toward each other compress
the air and raise pressure
particles moving away from each other lower
pressure
A complete cycle of disturbance, therefore,
consists of a compression followed by a
rarefaction (or minimized pressure) with a
smooth graduation in between
The number of these cycles which occur each
second is called the FREQUENCY of the sound
wave
Ultrasound - Frequency
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Ultrasound
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sound waves with frequencies greater than
(a million cycles per second is referred to
as 1 MHz) 20 thousand cycles per second,
or 20 kHz (just beyond the range of human
hearing)
diagnostic US uses frequencies in the
range of 1-20 million cycles per second
Intensity
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Mechanical energy is what travels from the
sound source to the sound receiver
The rate of energy transported by the sound
wave is measured by a parameter called
INTENSITY
Intensity can also be referred to as power
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It’s measured as a ratio to another intensity; the
logarithmic scale used is called the decibel (dB)
Propagation
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Sound or US travels through any given
medium at a constant speed, called the
SPEED OF PROPAGATION
This speed is affected by density and
compressibility, or elasticity of the
transmitting medium
In diagnostic US, this medium is human
tissue
Propagation
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Inelastic tissue, such as scar or tumor, impedes sound
waves while elastic tissue allows passage more easily
Dense tissue transmits the sound wave more efficiently
than less dense tissue; this is why ultrasound waves
cannot travel across gaseous interfaces
 gases by definition have very low density
 elimination of gas from the target area is essential to
quality imaging
 bone and other calcification, while dense, transmits
ultrasound waves poorly due to their low
compressibility (inelasticity) and high reflectivity
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in an ultrasound image, these structures will display bright
echoes at their interface and no echoes beyond the interface
Attenuation
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Attenuation is the reduction in intensity
as the wave propagates
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absorption, scattering, and the specular
reflection at a boundary can all contribute
to attenuation
in ultrasound, these wave characteristics
can work individually and in combination
Attenuation
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Water is, by far, the most acoustically
conductive medium commonly available
Blood has one of the next lowest
coefficients and it is 4500 times worse
(this is a very important aspect of
diagnostic US)
Attenuation
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A very important principle regarding attenuation
is its dependency on frequency
 attenuation will increase if a higher ultrasound
frequency is used; this translates into a
reduction in tissue depth that can be imaged
 unfortunately, using higher frequencies to yield
greater resolution will reduce total signal
penetration
 approximate effective tissue penetration, or
imaging depth, for 5, 7.5, 12 & 25 MHz
frequencies are 15, 10, 5 , & 1 cm respectively
Attenuation
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Advantages of endoscopic ultrasound
devices
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they move the transducer closer to the
target, thereby permitting the use of higher
frequencies
extracorporeal ultrasound transducers
typically use 3-7 MHz
Transducers
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A. Definition
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Transducers convert energy from one form
into another
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a pressure transducer changes the mechanical energy
resulting from a pressure change into an electrical
signal
the speaker in your stereo system is also a transducer
operating in reverse of what was just described
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it converts electrical signals into magnetic field variations
forcing the speaker cone to vibrate
these vibrations generate pressure changes, or sound
waves, which our ears receive and reconvert into
electrical impulses that our brain interprets
Transducers
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B. Piezoelectric Effect
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Ultrasound transducers operate on
piezoelectric principles
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specific crystalline materials, such as quartz, are
layered on opposite parallel faces with a conducting
silver alloy
when a pressure is exerted to squeeze the crystal, an
electrical potential develops between the opposite
faces
if this pressure reverses, the generated voltage
polarity would reverse as well; this is the ultrasound
detection aspect of the piezoelectric effect
a voltage can also be applied across the crystal,
causing it to change thickness, deforming or straining
it; this is the ultrasound generation aspect
Transducers
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In both cases, the voltage changes are
directly proportional to the strain generated
Alternating voltages would produce crystal
vibrations
This is the basic principle behind the pulseecho technique, in which a brief pulse of
sound waves is emitted and a subsequent
listening interval is allotted during which the
reflected waves are received
Transducers
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C. Construction
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to permit abrupt short pulses of sound waves, a
dampening material is placed adjacent to the crystal
sound is transmitted in accordance with crystal
orientation and/or the use of acoustically coupled
mirrors
these waves are focused, as with visible light, at a
particular distance, called the FOCAL LENGTH,
where the best resolution obtained is called the
FOCAL POINT
Transducers
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D. Types
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transducers may have just one or many piezoelectric
elements
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multi-element transducers are called ARRAYS
arrays can be aligned in a linear fashion, along either a
transverse or longitudinal axis
arrays can also be aligned in a curved (i.e. curvilinear,
convex) orientation
the transducer element can be mechanically rotated
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from a few degrees, SECTOR SCANNING
to a full 360° rotation in a plane perpendicular to the
transducer’s axis, RADIAL SCANNING
the speed of this rotation, whether it is mechanical or
electronic is referred to as the SWEEP SPEED
Transducers
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Radial Scanning
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consists of a probe, totally immersed in a
contained acoustic medium (i.e. oil, parafin,
distilled water) with the US wave passing through
this medium and into the patient through a thin
plastic window
after introduced into the body, the probe is either
immersed in water, or a balloon surrounding the
probe is filled with water
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water is used because it is an excellent acoustically
conductive medium
Transducers
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Multi-Element Arrays
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more sophisticated arrays and digital beamforming have most overcome some of the
disadvantages of inexpensive linear arrays from
the past, such as:
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poor resolution in the direction perpendicular to the
direction of the beam
the individual small transducers of these systems have a
relatively short near-field and, therefore, typically have
much less resolution at greater depth
Transducers
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E. Gain
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attenuation weakens the intensity of the
ultrasound waves, thereby reducing the
resolution of generated images
to some degree, this can be compensated
for by using GAIN
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GAIN increases the intensity of the transmitted
ultrasound pulse amplifying the weak signals
received
Transducers
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It is also possible to selectively vary this GAIN
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echoes from deeper structures will be more
greatly attenuated, simply because they must
penetrate more tissue than shallower structures
by amplifying the deeper (later) echo signal
voltages more than closer (earlier) signals, it is
possible to compensate for this difference in
attenuation; this feature is referred to as TIME
GAIN COMPENSATION (TGC)
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Olympus has included this capability on the EUS
radial system and calls it the SENSITIVITY TIME
CONTROL (STC)
Transducers
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F. Display
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Scan
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after transducers detect signal strength and direction,
this information must be processed, displayed, and
possibly stored in some format
the display takes the form of an image on a televisiontype monitor
format of this image is typically either a linear or sector
scan
the sector scan (the most common) views in a pieshaped wedge from a central echogenic point
a linear scan produces a rectangular shaped image
originating from multiple points along the top of this
rectangle
Transducers
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Mode
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in addition to the two main types of scans, there are
also at least three different types of display modes
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the earliest type of diagnostic US was the A-mode unit; this unit
usually displays its image on an oscilloscope screen which shows a
plot of echo signal amplitude, or strength, against time delay after
the initial transmission pulse
one of the major drawbacks of A-mode scanning is that it only
acquires information of a single line through the tissue
the B-mode overcomes this one dimensional aspect by presenting a
two-dimensional cross-section through the area of interest
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the location of the highly reflective tissues are displayed as bright
spots on a dark background
different levels of brightness, or gray scale, correlate with the signal
strength of the echo
this is the type of system that the vast majority of ultrasound
systems use today
Conclusion
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Ultrasound is becoming popular in medical
diagnoses because it is:
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non-invasive
painless
without side effects
relatively inexpensive
Studies may be repeated as often as desired
allowing for follow-up after different treatments
Ultrasound has proven to be invaluable for
imaging soft tissues, while conventional X-rays
are principally sensitive to hard tissues
Conclusion
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Endoscopic ultrasound offers the advantage of
using higher frequency sound waves to obtain
images with improved resolution
 this is possible since the higher tissue penetration
capability of lower resolution frequencies (3 & 5
MHz) is not required due to the close proximity of
the ultrasound transducer and area of interest
The other distinct advantage is the absence of
gases (especially air) and calcifications (particularly
bone) which interfere with the quality and amount
of information retained in the generated images
Ultrasound now ranks as a major diagnostic tool in
medicine
Conclusion
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Its applications are constantly expanding to new areas of
the body with novel examination techniques also being
developed
Firmly established ultrasound procedures exist in the
areas of obstetrics, gynecology, neurology, ophthalmology,
cardiology, thyroid and breast, and general abdominal
imaging
General abdominal imaging is now the major reason why
ultrasound is being investigated and happens to be one of
the prime applications for EUS as well
There is no question as to the huge potential that exists in
placing this instrument in the hands of the
Gastroenterologist for GI tract and retroperitoneal organ
imaging
Capital Equipment
Mechanical Radial
Processors
EU-M30 (no longer available)
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Integration: one
monitor, one keyboard,
and one cart needed for
EVIS and EUS
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More compact unit fits
easily on the EVIS cart
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EVIS/EUS Picture-inPicture
EU-M30S
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Used strictly for
endoscopic probes
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Compatible with
“through the scope”
probes and rigid rectal
probes
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Easy to use keyboard
with built-in trackball
EU-M60
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Integration: one monitor, one
keyboard, and one cart needed
for EVIS and EUS
 EVIS/EUS Picture-in-Picture
 Compatible with all
mechanical EUS probes and
scopes
 DPR: Dual Plane
Reconstruction
 Full system integration with
EVIS EXERA
 Superb imaging with new
Broadband transducer
 New user-friendly endoscope
and keyboard design
 Storage of image data
Mechanical Radial
Endoscopes
GF-UM160
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Excellent Imaging with new
Broadband Transducer,
5/7.5/12/20 MHz with single
T/D.
Nearly the same handling as
a regular scope
Lightweight - Easier Handling
Easier Storage and
Reprocessing
by Detachable Ultrasound
Cable
Integrated Scope ID Function
Distal end O.D.: 12.7 mm
Insertion tube O.D.: 10.5 mm
GF-UM130/GF-UMQ130
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7.5 MHz
12 MHz
Endoscopic ultrasound
and video images via a
single scope
Dual transducers:
7.5/12 MHz or 7.5/20
MHZ
Distal end O.D.: 12.7
mm
Insertion tube O.D.:
10.5 mm
Curvilinear Array
Processors
EU-C60
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Compact electrical CurvedLinear Array (CLA)
transducer
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One cart Solution (complete
integration)
Simple operation
Power Doppler capability
Less than 110,000 USD
(CLA echoendoscope and
processor)
Curvilinear & Radial Array
Processor
Aloka SSD-Alpha 5
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Newly developed high-density
digital front end
Pixel Focus
Multi-Beam Focusing and
Processing
Integrated Data Management
System (iDMS) is now
standard
Simple keyboard operation
with user customization
Quad frequency
Aloka SSD-Alpha5 Configurations
• SSD-Alpha5
• SSD-Alpha5-PRN
• SSD-Alpha5-NET
• SSD-Alpha5-NET-PRN
Above configurations avail w/ CD-R for additional $360
• DV-W22PUB-Field (CD-R installed on-site)
Aloka SSD-5000 (no longer
available)
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Compact electrical
Curved-Linear Array
(CLA) transducer
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Aloka: World first
manufacturer of
medical ultrasound
system.
Invented/patented
first Color Doppler
system
Electronic Radial
Endoscope
ORAE: Olympus Radial
Array Endoscope
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Full 360° scan angle
Tissue Harmonics
Quad frequencies
(5, 6, 7.5, & 10MHz).
Image rotation function
Forward-oblique optics
Color/Power Doppler
Completely submersible
Lens cleaning function
Extensive angulation
Autoclavable, lubricant-free
Air/Water & Suction Valves
ORAE Images
Gastric Submucosal Tumor (GST)
5MHz
7.5MHz
10MHz
Gastric Cancer (SM)
7.5 Hz
6.0 Hz
10.0 Hz
ORAE Doppler Images
Color Doppler ( Color Flow )
Power Doppler
ORAE Tissue Harmonics
Std
THI
Curvilinear Array
Endoscopes (CLA)
Curvilinear Array Endoscopes (CLA)
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3 sets – ONLY 2 are available today
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Aloka compatible
EU-C60 compatible (Olympus)
Dornier compatible (no longer sold)
2 scope choices, the difference is in the channel
sizes
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P (puncture) = 2.8 mm
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For FNA with a 22 G needle
T (therapeutic) = 3.7 mm
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For FNA with a 22 G needle or larger.
Suitable for pancreatic cyst drainage under fluoroscopic
guidance
CLA Endoscopes
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Additional Specs:
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Slim 11.8 mm insertion tube
o
o
Angulation: 130 Up; 90 Down, Left & Right
Total length: 1575 mm
Scanning method: Electronic
Contact Method: Balloon method or sterile deaerated water immersion method (balloon part
number = MAJ-249)
Not NBI capable
CLA Endoscopes
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Major Applications
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Assistance in the staging and tissue
acquisition of malignant disease through
EUS-guided FNA (fine needle aspiration)
Assessment of benign disease
Interventional applications such as celiac
plexus block or neurolysis and pseudocyst
drainage
“Susie” Scopes
(GF-UCT160-OL5 & GF-UC160P-OL5)
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Compatible with the
EU-C60
7.5 MHz frequency
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Scanning range: 150
Aloka Compatible
(GF-UCT140-AL5 & GF-UC140P-AL5)
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Compatible with Aloka’s
SSD-5000 or the SSDAlpah5 (all configurations)
Frequencies: 5, 6, 7.5 &
10 MHz
o
Scanning range: 180
Forceps elevator
Color Doppler & Power
Doppler for interpreting
blood flow conditions
Probes
MAJ-935 Probe Driving Unit
Compatible with:
 Current radial probes
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DPR (Dual Plane Reconstruction)
Probes
Esophagoscope
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MH-908
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Slim Insertion Tube facilitates
passage through a stenotic
esophagus
Monorail guidewire system
Max O.D.: 8.2 mm
Freq.: 7.5 MHz
Rectal Probes
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RU-75M-R1/RU-12M-R1
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7.5 MHz for optimal
imaging depth / 12 MHz
suitable for surface layer
examination.
Superior insertion
capability with narrowdiameter distal end (12
mm OD)
Catheter Mini-Probes
UM-2R/3R
(12/20 MHz)
UM-S20-20R
( 1.7mm OD, 2.0mm max OD)
UM-G20-29R
(Guide Wire Type)
UM-BS20-26R
(Balloon Sheath Type
2.6mm OD)
Mini-Probes
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UM-2R/3R
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“Thru-the-Scope”
application during routine
endoscopy
O.D.: 2.4 mm.
(compatible with
conventional GI scopes)
12 and 20 MHz available
UM-S20-20R
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O.D.: 1.7 mm. (distal 850
mm); 2.0 mm (proximal)
20 MHz freq.
Mini-Probes
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UM-G20-29R
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Wire-guided capability
allows easy approach to
papilla.
2.9 mm.@ tip
(compatible with 3.2 mm
Ch.); 2.4 mm OD
20 MHz freq.
Mini-Probes
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UM-BS20-26R
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Ultra-slim Balloon probe
(compatible with 2.8 mm
Ch.)
20 MHz freq.
Transducer
Water
Probe
Balloon
Water
Balloon Sheath
Mini-Probes
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UM-S30-25R
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30 MHz freq.
Ideal for examination of
surface layers
compatible with 2.8 mm
Ch.
UM-S30-20R
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30 MHz freq.
Ideal for examination of
surface layers
1.7 mm (distal 850 mm);
2.0 mm OD (compatible
with std. bronchoscopes).
Dual Plane Reconstruction
DPR Probes
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UM-DP12-25R/
UM-DP20-25R
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Spiral Scanning to create
dual plane review mode
image.
“Thru-the-Scope” application
during routine endoscopy
O.D.: 2.5 mm. (compatible
with conventional GI scopes)
12 and 20 MHz available
EU-M60 3-D Upgrade
(MAJ-1330)
• Dual Plane Reconstruction data (radial/linear scans)
used to generate 3-D or Multi Plane Reconstruction
(MPR) images.
• Images can be displayed in an oblique view with
surface rendering.
• Images can be rotated, zoomed,
and sectioned in any fashion.
• Able to measure depths and
volumes.
Surface
Rendering
Volume
Measurement
Oblique
Viewing
EU-M60: 3-D Reconstruction
EUS-guided FNA needles
EZ Shot FNA NEEDLE
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Designed specifically
for use with all Olympus
CLA scopes.
Disposable
22G coaxial needle w/
sharp stylet.
Patented echogenic tip.
Variable position locking
20 cc syringe &
stopcock.
PowerShot FNA NEEDLE
Designed specifically for use
with all Olympus CLA scopes.
•
•
•
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Spring-loaded activation.
Adjustable sheath length.
Reusable sheath and handle.
22G coaxial needle w/ sharp
stylet.
Patented echogenic tip.
Sources
1.
2.
3.
4.
5.
Endosonography, Elsevier Inc 2006
www.mayoclinic.com/health/ultrasound
Basic Ultrasound, John Wiley & Sons 1995
Digital Human Anatomy and Endoscopic
Ultrasonography, BV Decker, Inc 2005
Endoscopic Ultrasonography, Blackwell Science 2001