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Introduction to Endoscopic Ultrasound

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Title: Introduction to Endoscopic Ultrasound


1
Introduction to Endoscopic Ultrasound
2
  • 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 damages (whether direct, indirect, special,
    incidental, consequential or otherwise) that may
    arise from or be incurred in connection with the
    information provided or any use thereof.

3
Fundamentals of Ultrasound
4
Diagnostic Ultrasound Devices
  • 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 90s
  • Ultrasound is now used commonly inside the body,
    as well as, external to the body.

5
Sound Waves - Definitions
  • Sound is a mechanical disturbance in the air
  • 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

6
Sound Waves - Particle Vibration
  • Sound wave
  • vibrations of air particles
  • called a plane longitudinal wave when vibration
    is along sound waves 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

7
String Example
  • 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
  • but these particles do not move along the string

8
Frequency - Definition
  • As particles vibrate, they generate successive
    regions of elevated and reduced air pressure
  • 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

9
Ultrasound - Frequency
  • Ultrasound
  • 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

10
Intensity
  • 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
  • Its measured as a ratio to another intensity
    the logarithmic scale used is called the decibel
    (dB)

11
Propagation
  • 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

12
Propagation
  • 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
  • in an ultrasound image, these structures will
    display bright echoes at their interface and no
    echoes beyond the interface

13
Attenuation
  • Attenuation is the reduction in intensity as the
    wave propagates
  • 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

14
Attenuation
  • 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)

15
Attenuation
  • 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

16
Attenuation
  • Advantages of endoscopic ultrasound devices
  • they move the transducer closer to the target,
    thereby permitting the use of higher frequencies
  • extracorporeal ultrasound transducers typically
    use 3-7 MHz

17
Transducers
  • A. Definition
  • Transducers convert energy from one form into
    another
  • 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
  • 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

18
Transducers
  • B. Piezoelectric Effect
  • Ultrasound transducers operate on piezoelectric
    principles
  • 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

19
Transducers
  • 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 pulse-echo
    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

20
Transducers
  • C. Construction
  • 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

21
Transducers
  • D. Types
  • transducers may have just one or many
    piezoelectric elements
  • 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
  • from a few degrees, SECTOR SCANNING
  • to a full 360 rotation in a plane perpendicular
    to the transducers axis, RADIAL SCANNING
  • the speed of this rotation, whether it is
    mechanical or electronic is referred to as the
    SWEEP SPEED

22
Transducers
  • Radial Scanning
  • 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
  • water is used because it is an excellent
    acoustically conductive medium

23
Transducers
  • Multi-Element Arrays
  • more sophisticated arrays and digital
    beam-forming have most overcome some of the
    disadvantages of inexpensive linear arrays from
    the past, such as
  • 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

24
Transducers
  • E. Gain
  • 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
  • GAIN increases the intensity of the transmitted
    ultrasound pulse amplifying the weak signals
    received

25
Transducers
  • It is also possible to selectively vary this GAIN
  • 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)
  • Olympus has included this capability on the EUS
    radial system and calls it the SENSITIVITY TIME
    CONTROL (STC)

26
Transducers
  • F. Display
  • Scan
  • 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
    television-type monitor
  • format of this image is typically either a linear
    or sector scan
  • the sector scan (the most common) views in a
    pie-shaped wedge from a central echogenic point
  • a linear scan produces a rectangular shaped image
    originating from multiple points along the top of
    this rectangle

27
Transducers
  • Mode
  • in addition to the two main types of scans, there
    are also at least three different types of
    display modes
  • 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
  • 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

28
Conclusion
  • Ultrasound is becoming popular in medical
    diagnoses because it is
  • 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

29
Conclusion
  • 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

30
Conclusion
  • 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

31
Capital Equipment
32
Mechanical Radial Processors
33
EU-M30 (no longer available)
  • Integration one monitor, one keyboard, and one
    cart needed for EVIS and EUS
  • More compact unit fits easily on the EVIS cart
  • EVIS/EUS Picture-in-Picture

34
EU-M30S
  • Used strictly for endoscopic probes
  • Compatible with through the scope probes and
    rigid rectal probes
  • Easy to use keyboard with built-in trackball

35
EU-M60
  • 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

36
Mechanical Radial Endoscopes
37
GF-UM160
  • 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

38
GF-UM130/GF-UMQ130
  • 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

7.5 MHz
12 MHz
39
Curvilinear Array Processors
40
EU-C60
  • Compact electrical Curved-Linear Array (CLA)
    transducer
  • One cart Solution (complete integration)
  • Simple operation
  • Power Doppler capability
  • Less than 110,000 USD (CLA echoendoscope and
    processor)

41
Curvilinear Radial Array Processor
42
Aloka SSD-Alpha 5
  • 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

43
High-Density Digital Front-end
  • Aloka developed a high-speed digital processor
    specifically for ultrasonic signal processing.
  • ?
  • Succeeded in downsizing the front-end

44
Pixel Focus
  • Enhancement of lateral resolution
  • Achieved uniform beam characteristics from near
    to far field

45
Multi-beam Processing
  • Transmits/receives from multiple directions,
    generating a composite image in real-time
  • Resulting high temporal resolution

Multi-beam Processing
46
Integrated Image Management System iDMS
  • send data to a server through LAN in DICOM format
    (optional)
  • store data in Tiff, BMP, JPEG as well as DICOM
    format to MO

47
Aloka SSD-Alpha5 Configurations
SSD-Alpha5 SSD-Alpha5-PRN SSD-Alpha5-NET S
SD-Alpha5-NET-PRN Above configurations avail w/
CD-R for additional 360 DV-W22PUB-Field (CD-R
installed on-site)
48
Aloka SSD-5000 (no longer available)
  • Compact electrical Curved-Linear Array (CLA)
    transducer
  • Aloka World first manufacturer of medical
    ultrasound system.
  • Invented/patented first Color Doppler system

49
Electronic Radial Endoscope
50
ORAE Olympus Radial Array Endoscope
  • 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

51
ORAE Olympus Radial Array Endoscope
52
ORAE Images
Gastric Submucosal Tumor (GST)
53
Gastric Cancer (SM)
54
ORAE Doppler Images
Color Doppler ( Color Flow )
Power Doppler
55
ORAE Tissue Harmonics
56
ORAE
  • Model GF-UE160-AL5
  • Availability Immediate

57
Curvilinear Array Endoscopes (CLA)
58
Curvilinear Array Endoscopes (CLA)
  • 3 sets ONLY 2 are available today
  • Aloka compatible
  • EU-C60 compatible (Olympus)
  • Dornier compatible (no longer sold)
  • 2 scope choices, the difference is in the channel
    sizes
  • P (puncture) 2.8 mm
  • For FNA with a 22 G needle
  • T (therapeutic) 3.7 mm
  • For FNA with a 22 G needle or larger.
  • Suitable for pancreatic cyst drainage under
    fluoroscopic guidance

59
CLA Endoscopes
  • Additional Specs
  • Slim 11.8 mm insertion tube
  • Angulation 130o Up 90o Down, Left Right
  • Total length 1575 mm
  • Scanning method Electronic
  • Contact Method Balloon method or sterile
    de-aerated water immersion method (balloon part
    number MAJ-249)
  • Not NBI capable

60
CLA Endoscopes
  • Major Applications
  • 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

61
Susie Scopes (GF-UCT160-OL5 GF-UC160P-OL5)
  • Compatible with the EU-C60
  • 7.5 MHz frequency
  • Scanning range 150o

62
Aloka Compatible (GF-UCT140-AL5 GF-UC140P-AL5)
  • Compatible with Alokas SSD-5000 or the
    SSD-Alpah5 (all configurations)
  • Frequencies 5, 6, 7.5 10 MHz
  • Scanning range 180o
  • Forceps elevator
  • Color Doppler Power Doppler for interpreting
    blood flow conditions

63
Probes
64
MAJ-935 Probe Driving Unit
  • Compatible with
  • Current radial probes
  • DPR (Dual Plane Reconstruction) Probes

65
Esophagoscope
  • MH-908
  • Slim Insertion Tube facilitates passage through a
    stenotic esophagus
  • Monorail guidewire system
  • Max O.D. 8.2 mm
  • Freq. 7.5 MHz

66
Rectal Probes
  • RU-75M-R1/RU-12M-R1
  • 7.5 MHz for optimal imaging depth / 12 MHz
    suitable for surface layer examination.
  • Superior insertion capability with
    narrow-diameter distal end (12 mm OD)

67
Catheter Mini-Probes
68
Mini-Probes
  • UM-2R/3R
  • 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
  • O.D. 1.7 mm. (distal 850 mm) 2.0 mm (proximal)
  • 20 MHz freq.

69
Mini-Probes
  • UM-G20-29R
  • Wire-guided capability allows easy approach to
    papilla.
  • 2.9 mm._at_ tip (compatible with 3.2 mm Ch.) 2.4 mm
    OD
  • 20 MHz freq.

70
Mini-Probes
  • UM-BS20-26R
  • Ultra-slim Balloon probe (compatible with 2.8 mm
    Ch.)
  • 20 MHz freq.

71
Mini-Probes
  • UM-S30-25R
  • 30 MHz freq.
  • Ideal for examination of surface layers
  • compatible with 2.8 mm Ch.
  • UM-S30-20R
  • 30 MHz freq.
  • Ideal for examination of surface layers
  • 1.7 mm (distal 850 mm) 2.0 mm OD (compatible
    with std. bronchoscopes).

72
Dual Plane Reconstruction
73
DPR Probes
  • UM-DP12-25R/ UM-DP20-25R
  • 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

74
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.

75
(No Transcript)
76
Real-Time 3D Reconstruction
77
3 D Cross-Sections
Linear Image
Radial Images
3-D Image
78
EU-M60 3-D Reconstruction
79
EU-M60 3-D Upgrade Products Needed
  • MAJ-1330 Kit (3-D Software)
  • EU-M60 Processor
  • MAJ-935 Drive Unit
  • DPR Probe UM-DP12-25R, UM-DP20-25R

80
EUS-guided FNA needles
81
EZ Shot FNA NEEDLE
  • 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.

82
PowerShot FNA NEEDLE
  • Designed specifically for use with all Olympus
    CLA scopes.
  • Spring-loaded activation.
  • Adjustable sheath length.
  • Reusable sheath and handle.
  • 22G coaxial needle w/ sharp stylet.
  • Patented echogenic tip.

83
Sources
  1. Endosonography, Elsevier Inc 2006
  2. www.mayoclinic.com/health/ultrasound
  3. Basic Ultrasound, John Wiley Sons 1995
  4. Digital Human Anatomy and Endoscopic
    Ultrasonography, BV Decker, Inc 2005
  5. Endoscopic Ultrasonography, Blackwell Science
    2001
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