DIAGNOSTICS Prof. Ivo Hrazdira, MD., DSc. WHAT IS

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ULTRASOUND IN MEDICAL DIAGNOSTICS
Prof. Ivo Hrazdira, MD., DSc.
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WHAT IS ULTRASOUND?

• Acoustic vibrations of frequencies higher than 20
  kHz, non audible by human ear
• According to the type of interaction with cells
  and tissues
  - ACTIVE ULTRASOUND
  high intensity (applications in physical
  therapy and surgery)
  - PASSIVE ULTRASOUND low intensity
  (applications in medical diagnostics)

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ACOUSTIC PARAMETERS

• Source
  
• - FREQUENCY
  - INTENSITY
• Medium
  - SPEED OF PROPAGATION
  - ACOUSTIC IMPEDANCE
  - ATTENUATION -
  absorption
  
  
  
  .
  - scattering

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DIAGNOSTIC ULTRASOUND

• PHYSICAL PRINCIPLE
  ULTRASONIC WAVES PASSING THROUGH THE BODY
  ARE PARTIALLY REFLECTED ON TISSUE INTERFACES.
  REFLECTIONS (ECHOES) ARE RECEIVED, PROCESSED AND
  DISPLAYED

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HISTORY OF ULTRASOUND

• PREPARATORY PERIOD
• 1842 - DOPPLER PRINCIPLE OF FREQUENCY
• SHIFT
• 1880 - BROTHERS CURIE DISCOVERY OF
• PIEZOELECTRIC PHENOMENON
• 1916 - LANGEVIN AND CHILOWSKI
• CONSTRUCTION OF THE FIRST
  ULTRASOUND
• GENERATOR (SONAR)
• 1929 - SOKOLOV BASIS OF NON-DESTRUCTIVE
• ULTRASOUND MATERIAL TESTING

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HISTORY OF DIAGNOSTIC ULTRASOUND

• FIRST ATTEMPS
• 1942 - DUSSIK HYPERPHONOGRAPIE (TRANSMISSION
  METHOD)
• 1949 - KEIDEL HEART VOLUME MEASUREMENT
• 1949 - UCHIDA A-MODE ENCEPHALOGRAPHY
• 1950 - WILD TISSUE DIFFERENTIATION
• 1951 - WAGAI BILL STONE DETECTION

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HISTORY OF DIAGNOSTIC ULTRASOUND

• 1942 - FIRST ATTEMP - UNSUCCESSFUL
• CLINICAL APPLICATIONS
• 1950 - 1D IMAGING (A- MODE)
• 1954 - ECHOCARDIOGRAPHY (M-MODE)
• 1955 - 2D - IMAGE OF ABDOMEN (B - MODE)
• 1958 - 2D - IMAGING IN OBSTETRICS
• 1958 - 2D - IMAGING IN OPHTHALMOLOGY
• 1968 - TRANSRECTAL EXAMINATION
• 1968 - FIRST CONTRAST IMAGING (SALINE)

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HISTORY OF DIAGNOSTIC ULTRASOUND

• CLINICAL APPLICATIONS (CONTINUED)
• 1978 - TRANSESOPHAGEAL EXAMINATION
• 1990 - BROAD-BAND TRANSDUCERS
• 1992 - 3D IMAGING IN OB/GYN
• 1992 - TRANSPULMONARY ECHOCONTRAST
• AGENTS
• 1996 - NATIVE HARMONIC IMAGING
• 1998 4D (3D imaging in real time)

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DIAGNOSTIC DEVICE

• MAIN PARTS OF A DIAGNOSTIC DEVICE
• ELECTROACOUTIC TRANSDUCER
• GENERATOR OF ELECTRIC IMPULSES
• PROCESSING OF RECEIVED ECHOES
• DISPLAY
• RECORDING SYSTEM

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DIAGNOSTIC DEVICES
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TRANSDUCERS (imaging lines)
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TRANSDUCERS
sector
convex
linear
transvaginal/transrectal
transesophageal
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DIAGNOSTIC ULTRASOUND

• IMAGING METHODS
  - A MODE (one-dimensional)
  - B MODE (two-dimensional,
• three-dimensional)
  
• DOPPLER METHODS
  - CW
  - PULSED
  
  - COLOUR
• COMBINED METHODS (duplex, triplex)

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PRINCIPLE OF A- AND B- IMAGING
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DIAGNOSTIC FREQUENCIES

• 2 - 6 MHz
  abdominal ultrasound, obstetrical
  and gynaecological exam, echocardiography,
  transcranial Doppler
• 7.5 - 14 MHz
  small parts, vascular Doppler,
  musculoskelatal ultrasound

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DIAGNOSTIC FREQUENCIES

• 10 - 20 MHz
  ophthalmology, special vascular exam
• 20 - 50 MHz
  endoluminal exam, ultrasound biomicroscopy
  (ophthalmology, dermatology)

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A- AND B- MODE IN OPHTHALMOLOGY
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B- MODE IN ABDOMINAL REGION
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B- MODE IN OBSTETRICS
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B- MODE IN MUSCULOSKELETAL ULTRASOUND
Meniscal Tear
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B- AND M- MODE IN CARDIOLOGY
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PROGRESS IN ULTRASONOGRAPHY

• IMPROVED IMAGE DISPLAY
• - digital technology
• - 3D/4D imaging
• IMPROVED SIGNAL DETECTION
• - echo-enhancing agents
  
• - harmonic imaging

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PROGRESS IN ULTRASONOGRAPHY

• NOVEL METHODS
• - anisotropic imaging
• - perfusion imaging
• - elastography
• NOVEL APPLICATIONS
• - intraoperative
• - intraluminal

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DIGITAL TECHNOLOGY

• BROADBAND SCANHEADS/ BROADBAND BEAMFORMING
• - captures full tissue signature
• EXTENDED SIGNAL PROCESSING
• - digitally preserves entire signal
• TISSUE SPECIFIC IMAGING
• - improves signal/noise ratio for detection
• of small, low-contrast lesions

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DIGITAL TECHNOLOGY
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BROADBAND TECHNOLOGY
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BROADBAND TECHNOLOGY IMAGES
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WHAT ARE ECHOCONTRAST AGENTS?

• AIR OR GAS MICROBUBBLES, FREE OR INCAPSULATED IN
  A POLYMER COVER
• ACCORDING TO THEIR HIGHER DIFFERENCE IN ACOUSTIC
  IMPEDANCE, CONTRAST AGENTS ENHANCE THE
  ECHOGENICITY OF THE BODY SPACE IN WHICH THEY WERE
  INTRODUCED

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ECHOCONTRAST AGENTS

• CATEGORY OF ECHOCONTRAST AGENTS
• GAS BUBBLES INTRODUCED INTO THE ORGANISM
  (ECHOVIST, LEVOVIST, ALBUNEX, ECHOVIEW)
• GAS BUBBLES FORMED IN THE ORGANISM (ECHOGEN)

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ECHOCONTRAST AGENTS

• IN VASCULAR IMAGING
• - enhance weak signals resulting from deep
  vessels or slow flow (hyperaemia, ischaemia)
• - improve signals from malignant
  neovascularization
• IN NON-VASCULAR IMAGING
• - increase the reflectivity of particular normal
  or pathologic tissues (targeted agents)
• - delineate body cavities and communications

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INCAPSULATED BUBBLES(scanning electronmicrograph)
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HARMONIC IMAGING

• NEW MODE OF ULTRASOUND IMAGING, IN WHICH THE
  FUNDAMENTAL FREQUENCY OF RETOURNING ECHOES IS
  SUPPRESSED AND SIGNALS OF HARMONIC FREQUENCY ARE
  RECEIVED, PROCESSED AND DISPLEYED

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FORMS OF HARMONIC IMAGING

• CONTRAST HARMONIC IMAGING
• microbubbles of echo enhancing agents are able
  to resonate and emit harmonic signal
• NATIVE HARMONIC IMAGING
• harmonic signal is produced by oscillation of
  tissue structures due to the non-linear
  propagation of ultrasound

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PRINCIPLE OF HARMONIC IMAGING
supression
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HARMONIC IMAGING
stone
FUNDAMENTAL HARMONIC
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3-D IMAGING

• 3-D IMAGING TECHNOLOGY ALLOWS PHYSICIANS TO
  VIEW PATIENTS NORMAL AND PATHOLOGIC ANATOMY AS A
  VOLUME IMAGE
• IT IS SUGGESTED THAT 3-D IMAGING WILL PROVIDE A
  CENTRAL INTEGRATING FOCUS IN ULTRASOUND
  DIAGNOSTICS

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3-D IMAGING

• PHYSICAL PRINCIPLE
• THE TRANSDUCER IS MOVED DURING EXPOSURE (linear
  shift, swinging, rotation)
• RECEIVED ECHOES ARE STORED IN THE MEMORY
• THE IMAGE IN THE CHOSEN PLAIN IS RECONSTRUCTED
  MATHEMATICALY

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3D IMAGING
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3-D COLOUR DOPPLER SONOGRAPHY

• REPRESENTS A COMBINATION OF 3-D AND POWER DOPPLER
  TECHNOLOGY transducer elements are
  electronically or manually sectored during
  exposure
• 3D CDS ALLOWS DEPICTION OF THE OVERALL
  VASCULARITY IN THE AREA OF INTEREST (esp.
  tumours)

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3D COLOUR DOPPLER IMAGING
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ANISOTROPIC IMAGING

• PHYSICAL PRINCIPLE
• IN ULTRASOUND TECHNOLOGY, ANISOTROPY REPRESENTS A
  DIRECTIONAL DEPENDENCY OF BACKSCATTERED WAVES
• THIS MODALITY CAN BE USED FOR DIFFERENTIATING
  NORMAL ANISOTROPIC TISSUES FROM ISOTROPIC
  ABNORMALITIES

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ANISOTROPIC IMAGING

• AREAS OF CLINICAL APPLICATIONS
• CARDIOLOGY MYOCARDIUM EXAMINATION
• NEPHROLOGY EXAMINATION OF RENAL CORTEX
• MUSCULOSKELETAL ULTRASOUND EXAMINATIONS OF
  TENDONS AND CARTILAGES

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ELASTOGRAPHY

• METHOD FOR IMAGING THE ELASTIC PROPERTIES OF
  TISSUES
• REPRESENTS AN IMAGING ANALOGY TO PHYSICAL
  EXAMINATION BY TOUCH
• DIFFERENCES IN MECHANICAL PROPERTIES OF TISSUES
  CAN BE IMAGED IN 2D- OR 3D- COLOUR-SCALE MANNER

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ELASTOGRAPHY
MODEL MIMICING CONTRAST LESION IN PROSTATE
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ELASTOGRAPHY(benign and malignant lesion of the
breast)
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ENDOLUMINAL IMAGING
Transversal view of oesophageal sphincter
1 mucosa, 2 submucosa, 3 circular muscle, 4
intermuscular connective tissue, 5 longitudinal
muscle, 6 adventitia
2D and 3D image of advanced oesophageal cancer
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DOPPLER ULTRASOUND

• A.Ch. Doppler (1803-1853)
• DOPPLER PRINCIPLE (1842) - frequency shift due to
  the movement of the source or reflector
• DOPPLER METHODS SERVE IN MEDICINE FOR
  
  - DETECTION OF TISSUE MOVEMENTS
  
  - MEASUREMENT OF BLOOD FLOW VELOCITY AND
  DIRECTION

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MILESTONES OF DOPPLER ULTRASOUND

• 1960 - CONTINUOUS WAVE DOPPLER (CWD)
• 1974 - PULSE WAVE DOPPLER (PWD)
• 1982 - TRANSCRANIAL DOPPLER (TCD)
• 1986 - COLOUR FLOW MAPPING (CFM)
• 1992 - CONTRAST HARMONIC IMAGING (CHI)
• 1994 - POWER DOPPLER (PD)
• 1996 - TISSUE DOPPLER IMAGING (TDI)

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DOPPLER EQUATION 1 (Doppler shift)
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DOPPLER EQUATION 2 (velocity)
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CONVENTIONAL DOPPLER METHODS
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FLOW DIRECTION
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MAIN VELOCITY CURVES
Low vascular impedance
High vascular impedance
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COLOUR FLOW MAPPING(right renal artery)
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COLOUR FLOW MAPPING(common carotid artery)
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COLOUR FLOW MAPPING
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NEW COLOUR DOPPLER IMAGING MODALITIES

• POWER DOPPLER (Colour Doppler Energy, Colour
  Doppler Angio)
• TISSUE DOPPLER IMAGING (TDI)
• 3-D COLOUR DOPPLER SONOGRAPHY (3D CDS)

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POWER DOPPLER

• NEW TECHNOLOGY OF DOPPLER SIGNAL PROCESSING, IN
  WHICH ITS ENERGY ISTEAD OF ITS AMPLITUDE IS
  RECORDED
• THE ENERGY IS RELATED TO THE SQUARE OF THE
  AMPLITUDE OF THE SIGNAL
• USING THIS TECHNOLOGY, EVEN WEAK SIGNALS
  (CORRESPONDING TO LOW FLOW RATES) CAN BE RECORDED

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DOPPLER SIGNAL ENERGY
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POWER DOPPLER(renal perfusion)
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POWER DOPPLER(increased thyroid perfusion)
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POWER DOPPLER(kinking of internal carotid artery)
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POWER DOPPLER

• ADVANTAGE
• - detection of very low blood flow
• - more complete displaying of the vascular bed
  
• - absence of aliasing and only little angle
• dependence
• DISADVANTAGE
• - loss of directional and partial loss of
  velocity
• information

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TISSUE DOPPLER IMAGING

• NEW COLOUR DOPPLER IMAGING MODALITY IN WHICH THE
  DOPPLER SIGNAL IS DERIVED FROM SLOW TISSUE
  MOVEMENTS
• THE SYSTEM SUPRESSES FAST VELOCITIES OF BLOOD
  FLOW AND RECORDS ONLY SLOW MOVEMENTS IN THE RANGE
  1 - 10mm/s

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CLINICAL IMPORTANCE OF TDI

• ASSESSMENT OF MYOCARDIUM MOVEMENTS DURING HEART
  CONTRACTION
• ASSESSMENT OF DISTENSIBILITYAND COMPLIANCE OF
  VESSEL WALL
• ASSESSMENT OF SKELETAL MUSCLES CONTRACTIBILITY
  AND TENDON MOVEMENTS

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TDI - HEART
Colour imaging of blood flow
TDI- Colour imaging of heart movements
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TDI - ARTERY
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FUTURE OF ULTRASONOGRAPHY

• In the medical imaging world, it is hard to
  beat ultrasound in following terms
• COST - EFFECTIVENESS
• RANGE OF APPLICATIONS
• SAFETY

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FUTURE OF ULTRASONOGRAPHY

• ACCORDING TO RECENT ADVANCES IN POWER DOPPLER,
  3-D IMAGING, CONTRAST AGENTS, HARMONIC IMAGING
  AND INTERVENTIONAL APPLICATIONS, ULTRASONOGRAPHY
  BECOMES THE PREFERRED DIAGNOSTIC IMAGING MODALITY
  OF THE 21TH CENTURY