Mani Montazemi, RDMS - Scott Memorial Libraryjeffline.jefferson.edu/jurei/Limited_OB_0617/Work...

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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


• Ultrasound diagnostically is used in 2 ways – Anatomic information



• Ultrasound diagnostically is used in 2 ways – Anatomic information – Blood flow information


What is

Ultrasound?


What is

Ultrasound?


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• What is “sound” – Sound is a form of energy



• 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



• Sound is mechanical energy transmitted by pressure waves in a material medium – Sound is not electromagnetic – Matter must be present for sound to travel


How Does an

Ultrasound

Instrument

Work?


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


What is a Transducer?

• Converts one form of energy into another form


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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


Transducer Configurations

• Curved linear • Straight linear • Conventional

sector • Microsector • Endocavity • Intraoperative


Image Configurations

Linear Curved Sector



• Mechanical • Phased array



• 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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• Phased array – no moving parts

– Flat linear – Curved linear – Sector


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



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


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


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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Video Clip – Safety Safety - Prudent Use

Minimize risk

Minimize exposure

Medical indication only Minimize exposure time

Minimize exposure output


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


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


Image Orientation &

Scanning Planes

Scanning Planes

• Longitudinal • Transverse • Oblique


Sagittal Scan

• Longitudinal, vertical planes • Divide the body into left & right


Sagittal Scan


Sagittal Scan

A

P

H F


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Sagittal Scan


Sagittal Scan


Sagittal Scan


Sagittal Scan


Maternal Head Maternal Feed

Anterior

Posterior

Sagittal Scan


Sagittal Scan


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H F

Anterior

Posterior

Sagittal Scan



H F


Anterior

Posterior


Transverse Scan

• Horizontal, transaxial planes • Divide the body into superior & inferior


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Transverse Scan


Transverse Scan

A

P

R L


Transverse Scan


Transabdominal Transverse


Transverse Scan


Twin Pregnancy

Transverse Scan


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Oblique Scan

• Oblique planes • Inclined from the standard planes • In any direction


Oblique Scan


Artifacts

• Posterior Enhancement • Acoustical Shadowing • Attenuation • Reverberations • Refraction


Posterior Enhancement

• Increased intensity in echoes from reflectors behind a structure that weakly attenuates sound

• Classical feature of fluid




UT

OV



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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







Head






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Attenuation

• Reduction of the sound beam’s amplitude and intensity as it travels through a medium


Attenuation


Normal

Attenuation


Attenuation


Reverberations

• When 2 or more reflectors in the sound path cause multiple, repetitive artifactual echoes


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Reverberations


Reverberations



Video Clip – Artifacts Cervix – US Appearance


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


Echogenicity

• Echogenicity of a structure is described relative to surrounding or adjacent tissue


• Anechoic • Hypoechoic • Hyperechoic


Echogenicity Anechoic

• Sonolucent • No internal echoes


Anechoic


Anechoic


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Anechoic


Anechoic

Hyperechoic

• High intensity echoes • Increased echogenicity • Echogenic


Hyperechoic


Hyperechoic


Hyperechoic

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Hypoechoic

• Low intensity echoes • Decreased echogenicity


Hypoechoic


Clotted Blood

Hemoperitoneum


Echotexture

• Homogeneous • Heterogeneous


Homogeneous

• Uniform echoes • Fine, smooth texture


Homogeneous


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Homogeneous


Heterogeneous

• Non-uniform echoes • Irregular texture


Heterogeneous


Normal

Heterogeneous


Normal

Types of Masses

• Cystic • Solid • Complex


Cystic Masses

• Anechoic • Fluid filled • Smooth, well defined margins • Posterior enhancement


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Cystic Masses


Cystic Masses


Cephalocele

Solid Masses

• Contains varying amounts of internal echoes • Regular or irregular margins • Poorly defined back wall • Posterior attenuation of sound • Distal acoustic shadow


Solid Masses


Uterine Leiomyoma – US Findings

• Discrete solid mass – single or multiple



• Variable echogenecity – hypoechoic, hyperechoic


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Diagnostic Challenge


Solid Masses


Complex Masses

• Predominantly Cystic • Mostly cystic • Posterior enhancement • Internal echoes • Thin or thick septations • Thin or thick walls


Hemorrhagic Cyst

• Lace-like pattern of internal echoes


Mural Nodule vs. Clot


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Mural Nodule vs. Clot


Complex Masses

Normal


Sacrococcygeal Teratoma

Complex Masses


Complex Masses


Cervical Teratoma

Complex Masses


Cystic Lymphangioma

Complex Masses

• Predominantly Solid • Mostly echogenic • Internal cystic changes • Posterior attenuation


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Complex Masses

Hepatoblastoma


Normal

Describing A Mass

• Size • Shape, borders, wall • Acoustic properties (cystic, solid, complex) • Posterior enhancement or attenuation • Location


TRV Pelvis


How Would You

Describe This Mass?

How Would You

Describe This Mass?

In the right adnexa


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,


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,


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.


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.


Basic System Overview


Patient Data Entry


Patient Data Entry


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Transducer / Exam Selection


Transducer / Exam Selection


Transducer Selection

Resolution vs. Penetration • Right frequency for penetration • Highest frequency for resolution

Probe Handling


?

Probe Handling – “Sagittal”

Incorrect



Incorrect


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Incorrect



Correct




Probe Handling – “Transverse”

Incorrect



Incorrect



Correct


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Probe Handling – “Don’t”


Probe Handling


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


Overall Gain - Increase


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Overall Gain - Decrease






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


Time Gain Compensation

Near Field

Mid Field

Far Field




Time Gain Compensation Brighter

Darker




Time Gain Compensation Brighter


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Darker





US Principles Image Orientation Artifacts Masses Instrumentation The diagnosis is only As good as the information your image provides

What Constitute a Good Image?


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


Depth


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


Focus Region of minimum beam width in a focused ultrasound beam


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Focus


Focus

Don’t Get Fooled By Poor Technique

Pay Attention to Focal Zone


Ancillary Functions

Cine Loop

• Stores and displays images with no loss of quality


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


Sac Diameter

OB Calculations • Select [Single/A/B] soft key if needed


OB Calculations • Highlight and select Biometry or AFI


Measurements • Calipers, Add Caliper • Individual measurements

– Trace, Ellipse • Measures area and

circumference


OB Worksheet

• Edit or Delete Measurements • Enter Previous Exam Data • Enter Comments


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OB Worksheet


OB Worksheet


OB Worksheet


Thank You

Mani Montazemi, RDMS - Scott Memorial Libraryjeffline.jefferson.edu/jurei/Limited_OB_0617/Work...

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