1
Mani Montazemi, RDMS
Baylor College of Medicine
Division of Maternal-Fetal Medicine
Department of Obstetrics and Gynecology
Manager, Maternal Fetal Center Imaging
Texas Children’s Hospital, Pavilion for Women
Houston Texas
&
Clinical Instructor
Thomas Jefferson University Hospital
Philadelphia, Pennsylvania
Introduction to
Ultrasound Principles
A D B
Basic Principles of Ultrasound
• Ultrasound diagnostically is used in 2 ways
US Principles Image Orientation Artifacts Masses Instrumentation
Basic Principles of Ultrasound
• Ultrasound diagnostically is used in 2 ways – Anatomic information
US Principles Image Orientation Artifacts Masses Instrumentation
Basic Principles of Ultrasound
• Ultrasound diagnostically is used in 2 ways – Anatomic information – Blood flow information
US Principles Image Orientation Artifacts Masses Instrumentation
What is
Ultrasound?
US Principles Image Orientation Artifacts Masses Instrumentation
What is
Ultrasound?
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Basic Principles of Ultrasound
• What is “sound” – Sound is a form of energy
US Principles Image Orientation Artifacts Masses Instrumentation
Basic Principles of Ultrasound
• What is “sound” – Sound is a form of energy
• What is “energy”
– Energy is the capacity to do work • Moving an object, heating the room, lighting
electricity
US Principles Image Orientation Artifacts Masses Instrumentation
Basic Principles of Ultrasound
• Sound is mechanical energy transmitted by pressure waves in a material medium – Sound is not electromagnetic – Matter must be present for sound to travel
US Principles Image Orientation Artifacts Masses Instrumentation
How Does an
Ultrasound
Instrument
Work?
US Principles Image Orientation Artifacts Masses Instrumentation
Pulsed-echo Principle
• The energy within a pulsed-echo system is electrical, but the energy in the patient’s body is sound, which is mechanical
US Principles Image Orientation Artifacts Masses Instrumentation
What is a Transducer?
• Converts one form of energy into another form
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US Principles Image Orientation Artifacts Masses Instrumentation
Video Clip - Transducer Transducer Frequency
2.25 3.5 5.0
– 2.25 MHz
– 3.5 MHz
– 5 - 6 MHz
– 7.5 -10 MHz
– 9.0 MHz
– 12 -17 MHz
US Principles Image Orientation Artifacts Masses Instrumentation
Transducer Configurations
• Curved linear • Straight linear • Conventional
sector • Microsector • Endocavity • Intraoperative
US Principles Image Orientation Artifacts Masses Instrumentation
Image Configurations
Linear Curved Sector
US Principles Image Orientation Artifacts Masses Instrumentation
Transducer Configurations
• Mechanical • Phased array
US Principles Image Orientation Artifacts Masses Instrumentation
Transducer Configurations
• Mechanical – moving parts
– Wobbler or rotating – Single or multi-element – Mechanical beam steering & focusing – Motor driven/fluid filled scan head – FOV is sector – Single or multi-frequency
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Transducer Configurations
• Phased array – no moving parts
– Flat linear – Curved linear – Sector
US Principles Image Orientation Artifacts Masses Instrumentation
Curved Linear Array Transducer
• Multi-element • Elements arranged in an arc and are sequentially pulsed • FOV is trapezoidal-sector • Produce larger FOV • Benefits:
– High quality imaging – Faster frame rate – Electronic focusing
US Principles Image Orientation Artifacts Masses Instrumentation
US Principles Image Orientation Artifacts Masses Instrumentation
Video Clip - Transducer Categories of Sound
Infra Sound below 20 Hz
Audible Sound 20-20,000 Hz
Ultrasound Above 20,000 Hz
Sound is categorized according
to the frequency of vibration per seconds
US Principles Image Orientation Artifacts Masses Instrumentation
Frequencies Used For
Medical Diagnostic Ultrasound
Are Normally Above 1 MHz
One cycle / second = one Hertz (Hz)
One thousand cycles / second = one Kilohertz (kHz)
One Million cycles / second = one Megahertz
US Principles Image Orientation Artifacts Masses Instrumentation
Resolution: What is it?
• Clarity & sharpness of an ultrasound image • The capability of clearly distinguishing two
points located close to each other on the sonogram
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US Principles Image Orientation Artifacts Masses Instrumentation
Video Clip – Safety Safety - Prudent Use
Minimize risk
Minimize exposure
Medical indication only Minimize exposure time
Minimize exposure output
US Principles Image Orientation Artifacts Masses Instrumentation
Ultrasound Safety
• Prudent use dictates that the principle of ALARA be observed and the ultrasound power levels be maintained As Low As Reasonably Achievable, in order to provide the maximum benefit / risk ratio
US Principles Image Orientation Artifacts Masses Instrumentation
Output Display Values
• Power • Thermal Index – heat
– Ratio of the in-situ power to the acoustic power required to raise tissue temprature by 1o C
• Mechanical Index – cavitation
– Acoustic output in terms of the likelihood of tissue cavitation
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Caution
US Principles Image Orientation Artifacts Masses Instrumentation
Image Orientation &
Scanning Planes
Scanning Planes
• Longitudinal • Transverse • Oblique
US Principles Image Orientation Artifacts Masses Instrumentation
Sagittal Scan
• Longitudinal, vertical planes • Divide the body into left & right
US Principles Image Orientation Artifacts Masses Instrumentation
Sagittal Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Sagittal Scan
A
P
H F
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Sagittal Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Sagittal Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Sagittal Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Sagittal Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Maternal Head Maternal Feed
Anterior
Posterior
Sagittal Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Sagittal Scan
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US Principles Image Orientation Artifacts Masses Instrumentation
H F
Anterior
Posterior
Sagittal Scan
US Principles Image Orientation Artifacts Masses Instrumentation
US Principles Image Orientation Artifacts Masses Instrumentation
H F
US Principles Image Orientation Artifacts Masses Instrumentation
Anterior
Posterior
US Principles Image Orientation Artifacts Masses Instrumentation
Transverse Scan
• Horizontal, transaxial planes • Divide the body into superior & inferior
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Transverse Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Transverse Scan
A
P
R L
US Principles Image Orientation Artifacts Masses Instrumentation
Transverse Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Transabdominal Transverse
US Principles Image Orientation Artifacts Masses Instrumentation
Transverse Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Twin Pregnancy
Transverse Scan
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Oblique Scan
• Oblique planes • Inclined from the standard planes • In any direction
US Principles Image Orientation Artifacts Masses Instrumentation
Oblique Scan
US Principles Image Orientation Artifacts Masses Instrumentation
Artifacts
• Posterior Enhancement • Acoustical Shadowing • Attenuation • Reverberations • Refraction
US Principles Image Orientation Artifacts Masses Instrumentation
Posterior Enhancement
• Increased intensity in echoes from reflectors behind a structure that weakly attenuates sound
• Classical feature of fluid
US Principles Image Orientation Artifacts Masses Instrumentation
Posterior Enhancement
US Principles Image Orientation Artifacts Masses Instrumentation
UT
OV
Posterior Enhancement
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Acoustical Shadowing
• Marked decrease in intensity of echoes from reflectors that lie behind a structure that is strongly reflecting or attenuating sound
• Complete lack of acoustical & anatomical information in the area of shadowing
US Principles Image Orientation Artifacts Masses Instrumentation
Acoustical Shadowing
US Principles Image Orientation Artifacts Masses Instrumentation
Acoustical Shadowing
US Principles Image Orientation Artifacts Masses Instrumentation
Acoustical Shadowing
Head
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Acoustical Shadowing
US Principles Image Orientation Artifacts Masses Instrumentation
Acoustical Shadowing
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Acoustical Shadowing
US Principles Image Orientation Artifacts Masses Instrumentation
Attenuation
• Reduction of the sound beam’s amplitude and intensity as it travels through a medium
US Principles Image Orientation Artifacts Masses Instrumentation
Attenuation
US Principles Image Orientation Artifacts Masses Instrumentation
Normal
Attenuation
US Principles Image Orientation Artifacts Masses Instrumentation
Attenuation
US Principles Image Orientation Artifacts Masses Instrumentation
Reverberations
• When 2 or more reflectors in the sound path cause multiple, repetitive artifactual echoes
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Reverberations
US Principles Image Orientation Artifacts Masses Instrumentation
Reverberations
US Principles Image Orientation Artifacts Masses Instrumentation
US Principles Image Orientation Artifacts Masses Instrumentation
Video Clip – Artifacts Cervix – US Appearance
US Principles Image Orientation Artifacts Masses Instrumentation
Artifacts
• Posterior Enhancement • Acoustical Shadowing • Attenuation • Reverberations • Refraction
Echogenicity
• Intensity of echoes reflected by tissues or structures from inside the body
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Liquids Solids
Vessels & Ducts Soft Tissue Bone
Gallbladder Fibrous Cysts Gall Stone
Urinary Bladder Tumors Kidney Stone
Cysts Polyps & Lesions Calcific Plaque
US Principles Image Orientation Artifacts Masses Instrumentation
Echogenicity
• Echogenicity of a structure is described relative to surrounding or adjacent tissue
US Principles Image Orientation Artifacts Masses Instrumentation
• Anechoic • Hypoechoic • Hyperechoic
US Principles Image Orientation Artifacts Masses Instrumentation
Echogenicity Anechoic
• Sonolucent • No internal echoes
US Principles Image Orientation Artifacts Masses Instrumentation
Anechoic
US Principles Image Orientation Artifacts Masses Instrumentation
Anechoic
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Anechoic
US Principles Image Orientation Artifacts Masses Instrumentation
Anechoic
Hyperechoic
• High intensity echoes • Increased echogenicity • Echogenic
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Hyperechoic
US Principles Image Orientation Artifacts Masses Instrumentation
Hyperechoic
US Principles Image Orientation Artifacts Masses Instrumentation
Hyperechoic
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Hypoechoic
• Low intensity echoes • Decreased echogenicity
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Hypoechoic
US Principles Image Orientation Artifacts Masses Instrumentation
Clotted Blood
Hemoperitoneum
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Echotexture
• Homogeneous • Heterogeneous
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Homogeneous
• Uniform echoes • Fine, smooth texture
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Homogeneous
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Homogeneous
US Principles Image Orientation Artifacts Masses Instrumentation
Heterogeneous
• Non-uniform echoes • Irregular texture
US Principles Image Orientation Artifacts Masses Instrumentation
Heterogeneous
US Principles Image Orientation Artifacts Masses Instrumentation
Normal
Heterogeneous
US Principles Image Orientation Artifacts Masses Instrumentation
Normal
Types of Masses
• Cystic • Solid • Complex
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Cystic Masses
• Anechoic • Fluid filled • Smooth, well defined margins • Posterior enhancement
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Cystic Masses
US Principles Image Orientation Artifacts Masses Instrumentation
Cystic Masses
US Principles Image Orientation Artifacts Masses Instrumentation
Cephalocele
Solid Masses
• Contains varying amounts of internal echoes • Regular or irregular margins • Poorly defined back wall • Posterior attenuation of sound • Distal acoustic shadow
US Principles Image Orientation Artifacts Masses Instrumentation
Solid Masses
US Principles Image Orientation Artifacts Masses Instrumentation
Uterine Leiomyoma – US Findings
• Discrete solid mass – single or multiple
US Principles Image Orientation Artifacts Masses Instrumentation
Uterine Leiomyoma – US Findings
• Variable echogenecity – hypoechoic, hyperechoic
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Uterine Leiomyoma – US Findings
US Principles Image Orientation Artifacts Masses Instrumentation
Diagnostic Challenge
US Principles Image Orientation Artifacts Masses Instrumentation
Solid Masses
US Principles Image Orientation Artifacts Masses Instrumentation
Complex Masses
• Predominantly Cystic • Mostly cystic • Posterior enhancement • Internal echoes • Thin or thick septations • Thin or thick walls
US Principles Image Orientation Artifacts Masses Instrumentation
Hemorrhagic Cyst
• Lace-like pattern of internal echoes
US Principles Image Orientation Artifacts Masses Instrumentation
Mural Nodule vs. Clot
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Mural Nodule vs. Clot
US Principles Image Orientation Artifacts Masses Instrumentation
Complex Masses
Normal
US Principles Image Orientation Artifacts Masses Instrumentation
Sacrococcygeal Teratoma
Complex Masses
US Principles Image Orientation Artifacts Masses Instrumentation
Complex Masses
US Principles Image Orientation Artifacts Masses Instrumentation
Cervical Teratoma
Complex Masses
US Principles Image Orientation Artifacts Masses Instrumentation
Cystic Lymphangioma
Complex Masses
• Predominantly Solid • Mostly echogenic • Internal cystic changes • Posterior attenuation
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Complex Masses
Hepatoblastoma
US Principles Image Orientation Artifacts Masses Instrumentation
Normal
Describing A Mass
• Size • Shape, borders, wall • Acoustic properties (cystic, solid, complex) • Posterior enhancement or attenuation • Location
US Principles Image Orientation Artifacts Masses Instrumentation
TRV Pelvis
US Principles Image Orientation Artifacts Masses Instrumentation
How Would You
Describe This Mass?
How Would You
Describe This Mass?
In the right adnexa
US Principles Image Orientation Artifacts Masses Instrumentation
How Would You
Describe This Mass?
In the right adnexa there is a round, well marginated thin walled mass with a sharply defined back wall,
US Principles Image Orientation Artifacts Masses Instrumentation
How Would You
Describe This Mass?
In the right adnexa there is a round, well marginated thin walled mass with a sharply defined back wall, thin internal septations,
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How Would You
Describe This Mass?
In the right adnexa there is a round, well marginated thin walled mass with a sharply defined back wall, thin internal septations, low intensity echoes,
US Principles Image Orientation Artifacts Masses Instrumentation
How Would You
Describe This Mass?
In the right adnexa there is a round, well marginated thin walled mass with a sharply defined back wall, thin internal septations, low intensity echoes, and excellent posterior enhancement.
US Principles Image Orientation Artifacts Masses Instrumentation
How Would You
Describe This Mass?
In the right adnexa there is a round, well marginated thin walled mass with a sharply defined back wall, thin internal septations, low intensity echoes, and excellent posterior enhancement. The features are those of a complex, predominantly cystic mass.
US Principles Image Orientation Artifacts Masses Instrumentation
Basic System Overview
US Principles Image Orientation Artifacts Masses Instrumentation
Patient Data Entry
US Principles Image Orientation Artifacts Masses Instrumentation
Patient Data Entry
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Transducer / Exam Selection
US Principles Image Orientation Artifacts Masses Instrumentation
Transducer / Exam Selection
US Principles Image Orientation Artifacts Masses Instrumentation
Transducer Selection
Resolution vs. Penetration • Right frequency for penetration • Highest frequency for resolution
Probe Handling
US Principles Image Orientation Artifacts Masses Instrumentation
?
Probe Handling – “Sagittal”
Incorrect
US Principles Image Orientation Artifacts Masses Instrumentation
Probe Handling – “Sagittal”
Incorrect
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Probe Handling – “Sagittal”
Incorrect
US Principles Image Orientation Artifacts Masses Instrumentation
Probe Handling – “Sagittal”
Correct
US Principles Image Orientation Artifacts Masses Instrumentation
Probe Handling – “Sagittal”
US Principles Image Orientation Artifacts Masses Instrumentation
Probe Handling – “Transverse”
Incorrect
US Principles Image Orientation Artifacts Masses Instrumentation
Probe Handling – “Transverse”
Incorrect
US Principles Image Orientation Artifacts Masses Instrumentation
Probe Handling – “Transverse”
Correct
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Probe Handling – “Don’t”
US Principles Image Orientation Artifacts Masses Instrumentation
Probe Handling
US Principles Image Orientation Artifacts Masses Instrumentation
Basic Controls
• Freeze • Overall Gain • TGC • Depth • Focus
US Principles Image Orientation Artifacts Masses Instrumentation US Principles Image Orientation Artifacts Masses Instrumentation
Overall Gain
• An increase or decrease of the gain will change the brightness of the image
• Affects entire field of view
US Principles Image Orientation Artifacts Masses Instrumentation
Overall Gain - Increase
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Overall Gain - Increase
US Principles Image Orientation Artifacts Masses Instrumentation
Overall Gain - Increase
US Principles Image Orientation Artifacts Masses Instrumentation
Overall Gain - Decrease
US Principles Image Orientation Artifacts Masses Instrumentation
Overall Gain - Decrease
US Principles Image Orientation Artifacts Masses Instrumentation
Overall Gain - Decrease
US Principles Image Orientation Artifacts Masses Instrumentation
Overall Gain
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Time Gain Compensation • These slide pots controls
amplification of returning echo signals at specific depths
• The TGC compensates for loss in signal strength as the ultrasound beam passes through an organ
• Affects specific portions of the field of view
US Principles Image Orientation Artifacts Masses Instrumentation
Time Gain Compensation
Near Field
Mid Field
Far Field
US Principles Image Orientation Artifacts Masses Instrumentation
Time Gain Compensation
US Principles Image Orientation Artifacts Masses Instrumentation
Time Gain Compensation Brighter
Darker
US Principles Image Orientation Artifacts Masses Instrumentation
Time Gain Compensation
US Principles Image Orientation Artifacts Masses Instrumentation
Time Gain Compensation Brighter
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Time Gain Compensation
Darker
US Principles Image Orientation Artifacts Masses Instrumentation
Time Gain Compensation
US Principles Image Orientation Artifacts Masses Instrumentation
Time Gain Compensation
US Principles Image Orientation Artifacts Masses Instrumentation The diagnosis is only As good as the information your image provides
What Constitute a Good Image?
US Principles Image Orientation Artifacts Masses Instrumentation
What Constitute a Good Image?
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Depth
• Controls the depth of field of view
• When the image depth is
changed, the field of view increases or decreases
US Principles Image Orientation Artifacts Masses Instrumentation
Depth
US Principles Image Orientation Artifacts Masses Instrumentation
Depth
US Principles Image Orientation Artifacts Masses Instrumentation Too Small
Too Big
Just Right
Focus
• Transmit Zone – Highlights area of interest – Place at or slightly below
area of interest
US Principles Image Orientation Artifacts Masses Instrumentation
Focus Region of minimum beam width in a focused ultrasound beam
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Focus
US Principles Image Orientation Artifacts Masses Instrumentation US Principles Image Orientation Artifacts Masses Instrumentation
Focus
Don’t Get Fooled By Poor Technique
Pay Attention to Focal Zone
US Principles Image Orientation Artifacts Masses Instrumentation
Ancillary Functions
Cine Loop
• Stores and displays images with no loss of quality
US Principles Image Orientation Artifacts Masses Instrumentation
M-Mode • Useful in evaluating motion and velocity of
moving structures – Fetal Heart Motion
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OB Calculations
• Highlight and Select OB Calc
US Principles Image Orientation Artifacts Masses Instrumentation
Sac Diameter
OB Calculations • Select [Single/A/B] soft key if needed
US Principles Image Orientation Artifacts Masses Instrumentation
OB Calculations • Highlight and select Biometry or AFI
US Principles Image Orientation Artifacts Masses Instrumentation
Measurements • Calipers, Add Caliper • Individual measurements
– Trace, Ellipse • Measures area and
circumference
US Principles Image Orientation Artifacts Masses Instrumentation
OB Worksheet
• Edit or Delete Measurements • Enter Previous Exam Data • Enter Comments
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OB Worksheet
US Principles Image Orientation Artifacts Masses Instrumentation
OB Worksheet
US Principles Image Orientation Artifacts Masses Instrumentation
OB Worksheet
US Principles Image Orientation Artifacts Masses Instrumentation US Principles Image Orientation Artifacts Masses Instrumentation
Thank You
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