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BIRADS: Ultrasound ™

Background Echotexture

Mass Features:

Shape

Orientation

Margins

Lesion Boundary

4

BIRADS: Ultrasound ™

Echo Pattern

Posterior Acoustic Features

Surrounding tissue

Calcifications

Special Cases

Vascularity

Breast Ultrasound

Physics

Breast Ultrasound

Physics

Imaging principles you need

to know to get great images

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Mass characterization requires

excellent images

0.5 cm

Excellent images require

knowledge of the physical

principles of ultrasound.

Excellent images require knowledge

of the physical principles of

ultrasound.

The user must use this knowledge to

optimize each scan and distinguish

artifacts from real findings.

Spatial

resolution

Contrast

resolution

Resolution

Frequency

Beam width

Focal Zone

~200µ

ACR & AIUM Guidelines

Breast ultrasound should be

performed with a high-

resolution scanner with a

center frequency of at least

10 MHz.

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Axial ResolutionWavelength (λ) = length (mm) of 1 cycle

Period = time (in seconds) to complete 1 cycle

pre

ssure

0.0000001 sec

Frequency (f) = 1 / period

= 1/0.0000001 = 10,000,000 Hz = 10 MHz

1.0 MHz

3.0 MHz

5.0 MHz

7.5 MHz

10.0 MHz

15.0 MHz 0.10 mm

1.5 mm

Frequency = Spatial resolution

0.15 mm

0.5 mm

0.3 mm

0.2 mm

Effect of frequency on axial resolution

0.4 mm

5.0 MHz

Wavelength

0.3 mm

(300µ)

Pulse length

~ 0.9 mm

(900µ)

0.4 mm

15.0 MHz

Wavelength

0.1 mm

(100µ)

Pulse length

~ 0.3 mm

(300µ)

0.01

0.01

5.0 MHz 10.0 MHz

1.0

00.1

1.0

dep

th

Frequency = Penetration

ACR & AIUM Guidelines

The highest frequency capable of

adequate penetration to the depth of

interest should be used.

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Patient Positioning

• Supine oblique or supine position is

preferred to reduce breast

thickness and to improve

visualization of deeper tissues.

Patient Positioning

• The medial breast is effectively studied with the patient in a supine position.

• One or both arms should be elevated behind the head or neck to stretch the pectoralis muscle for better fixation and immobilization of the breast.

•

Patient Positioning

• The upper outer quadrant and entire

lateral breast are usually best evaluated

if the patient is positioned with the

ipsilateral shoulder elevated by a pillow

or wedge.

•

Scanning Technique

• When scanning, the transducer should

be perpendicular to the skin surface.

• Transducer coupling to the skin should

be gentle and give complete contact.

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Scanning Technique

• Compression is useful to avoid refraction and scattering

from normal structures when sound penetration is

insufficient, and to examine tissue elasticity of benign

and malignant findings.

• The scanning procedure should involve overlapping

scanning planes. These may be parasagittal,

transverse, radial, or antiradial.

ACR & AIUM Guidelines

Penetration decreases as

frequency increases. The

use of broad bandwidth

instrumentation is

encouraged.

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ACR & AIUM Guidelines

Focal zone selection, gain

settings, and fields of view

should be optimized to

obtain high-quality images.

Resolution

Frequency

Beam width

Focal Zone

~200µ

Beam Width

L = lateral E = elevation

Lateral Resolution

C

B

A

Linear Array

Dead zone

Focal Zone

Elevation focus

C

B

A

Linear Array

Elevation focus

(Slice thickness)

0.0 cm

1.0 cm

2.0 cm

Effect of beam width on lateral

resolution

* * * *

~100µ (0.1 mm)

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A common error in breast ultrasound is improper

placement of the focal zone(s). This may obscure

subtle margin features, calcifications and introduce low

level echoes in cysts.

ACR & AIUM Guidelines

Dead zone should be limited to less

than 2-3 mm.

Instrument used must provide

adjustable focal zones.

The focal zone should be set at the

depth of the lesion.

ACR & AIUM Guidelines

The patient should be positioned to

minimize the thickness of the portion

of the breast being evaluated.

For evaluation of lesions in, on, or

just beneath the skin, a stand-off

device or thick layer of gel may be

helpful.

ACR & AIUM Guidelines

Gain settings, as well as

focal zone selections

should be optimized to

obtain high-quality images.

Contrast

Resolution

Slice thickness

Focal zone

Gain

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0.01

0.01

5.0 MHz 10.0 MHz

1.0

00.1

1.0d

ep

th

Frequency = Penetration Most tissues attenuate sound at

approximately

1 dB / cm / MHz

A - Power P1 = 1.00 (100%)

B - Power P2 = .01 (01%)

0 dB

-20 dB

2 cm

10 MHz

+0

+0 dB

+0 dB

+0 dB

+2 dB

+0 dB

+0 dB

+0 dB +0

+0 dB

+4 dB

+0 dB

+2 dB

+0 dB

+0 dB

+0 dB

+0

+0 dB

+4 dB

+8 dB

+2 dB

+0 dB

+0 dB

+0 dB+0

+0 dB

+4 dB

+8 dB

+2 dB

+16 dB

+0 dB

+0 dB

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+0

+0 dB

+4 dB

+8 dB

+2 dB

+16 dB

+32 dB

+0 dB +0

+0 dB

+4 dB

+8 dB

+2 dB

+16 dB

+32 dB

+64 dB

Shadowing / Enhancement

f = 10 MHz

-10 +10 = 0 - 3 +10 = +7

-15 +15 = 0 - 8 +15 = +7

- 0 + 0 = 0

+ 0 + 5 + 10 + 15 + 20

-20 +20 = 0 - 13+20 = +7

0 cm

0.5 cm

1.0 cm

1.5 cm

2.0 cm

- 00 dB

- 05 dB

- 10 dB

- 15 dB

- 20 dB

Gain (dB)

ACR & AIUM Guidelines

Gain and TGC settings should be

adjusted to allow simple cysts to be

distinguished from solid masses.

Gain should not be too low to prevent

recognition of internal echoes that are

truly present in a mass.

Artifacts

Ultrasound images are based on

assumptions regarding the

interaction of sound with tissue.

Often these assumptions are

incorrect.

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Echo Assumptions

The beam is narrow and

uniform in width.

The beam travels directly

to and from the echo-

producing interfaces.

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Conventional Compound

Fo F1

Harmonic Imaging

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ACR & AIUM Guidelines

Doppler frequencies above

5 MHz.

Wall filter of 50 - 100 Hz

Pulse Repetition Frequency

(PRF) ~ 1000 Hz

Elastography

Elastography, or tissue stiffness

assessment, is among the new feature

categories applicable to sonographic

analysis of masses, to be included in the

Associated Findings section in BI-RADS

– Ultrasound, edition 2.

Strain ElastogaphyShear wave elastography

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ACR & AIUM Guidelines

To minimize errors in communication

or interpretation, if elastography is

performed, the color scales should

be annotated to denote hardness or

softness.

Conclusions

An understand of the principles of

ultrasound is essential in the production

and analysis of breast masses with

ultrasound.

Views / Images

• Lesions should be viewed in two perpendicular projections.

• At least one set of images of a lesion should be obtained without calipers.

• The maximal dimensions of a mass should be included.

• If volume analysis is needed, three-dimensional measurements should be obtained.

84

Fibroadenoma

10ab

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Labeling

• The images should be labeled as to right or left breast,

the lesion’s location, and the orientation of the probe

with respect to the patient.

• The location of the lesion should be recorded; the

quadrant should be specified or the location can be

indicated by using clock notation, distance from the

nipple, or shown on a diagram of the breast.

Correlation

• Correlate with mammographic and other breast

imaging studies and physical examination

• Current examination should be compared with

prior studies as appropriate.

• When a specific lesion is examined, its precise

position should be noted on the image.

Reporting

• Reporting should be in accordance with ACR Standard on Communication: Diagnostic Radiology and contain:

• Indications for the examination.

• The position of the lesion(s) as represented on a clock face with its distance from the nipple.

• A description of any lesion(s) and adjacent features including the size of maximum diameter(s) or extent.

• An opinion regarding provisional diagnosis(es) and significance of finding(s)