A new Ultrasound modality: US Elastography

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A new Ultrasound modalityUS Elastography

• Joel Chabriais

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Why Elastography?

• In old Egypt, 5 000 years ago, physicians
  examined the different parts of the body to
  evaluate elasticity, they knew that a hard mass
  in an organ is pathologic.
• In Greek ancient age, for Hippocratic medicine,
  palpating was an essential time of physical
  examination.
• In 21st century, imaging take preeminent place in
  medicine and Elastography could be considered as
  an  imaging palpation 

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What is Elastography?

• Elastography is an imaging technique to measure
  the stiffness of tissues.
• Images are acquired before and after soft
  compression of tissues and the deformation is
  evaluated.
• Initially elastography used manual compression
  and was only qualitative, now some methods
  appears to apply a non operator dependant
  compression.

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Elastography and US

• Elastography was developed first in the US
  field.
• Three step approach
• Organs mechanically stressed by either external
  or internal forces.
• Measurement of tissues movement induced.
• Qualitative or quantitative evaluation of tissue
  elastic properties from the measured displacement
  of tissues.

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Several Approaches

• Manual compression by operator using the
  transducer (static elastography).
• Organ compression by heartbeat or vascular
  pulsations.
• Push pulse waves compression.
• Supersonic shear waves.

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Static Elastography
Axial and lateral deformations after an axial
constraint
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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Ueno Staging
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SCORE 3
Fibroadenoma
DCIS
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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IDC
14x8 mm
9x6 mm
Fibroadenoma
6 x 5 mm
5 x 3 mm
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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IDC
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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Static ElastographyDevelopment Quantitative
Analysis
This measurement quantify elasticity correlation
between two regions. The FLR is independent of
the compression movement. The 1st region define
the lesion and the 2d is the reference (fat).
a
b
c
d
Mean Elasto Fat
FLR
Mean Elasto Lesion
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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Tsukuba University Hospital, JAPAN
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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155 lesions (108 Benign and 47 Malign) / 140
Patients
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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Elastography improvements

• Compression/Decompression Movements
• Displacement speed measurement
• Integral -gt Elasticity
• Elasto Q Mode
• Information at decompression
• Automatic selection of the best cycle
• ROI on fat and lesion
• Quantification

Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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SuperSonic Elastography
Acquisition time lt 30 ms !!
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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Supersonic Elastography

• Significant difference benign versus malign
• Cancers E 170.1 41.6 kPa
• Benign lesions E 53.5 19.8 kPa

n 36
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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µ (kPa)
IDC GRADE III
µ (kPa)
Fibrous Mastopathy
Courtesy of Dr Anne Tardivon - Institut Curie -
Paris
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Fields of Application in Medicine

• Breast
• Thyroid
• Liver
• Prostate

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Elastography in DICOM Why?

• Now, several vendors are coming on the market
• Until 2008 1 vendor had products for sale.
• 2008 3 vendors.
• 2009 several announcements ? 6 vendors or more.
• probably every US vendor at short term.
• At this time, only secondary capture or US
  objects.
• All specific information to elastography are lost.

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Elastography in DICOM Why?

• More and more clinical applications.
• New BI-RADS edition, planned for 2010, will take
  into account US elastography for breast imaging.
• Users would like to be able to store elastography
  information in their PACS
• Additional attributes in US objects?
• New objects?
• Some pathology needs elastography follow-up
• ? Probably DICOM SR templates needed

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Elastography in DICOMWho is Concerned?

• Elastography is US ? WG 12
• Elastography for Breast imaging ? WG 15
• Elastography needs DICOM SR templates ? WG 8
• Other?

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Elastography in DICOMHow To Go Further?

• A motion to ask the concerned WG to investigate
  the domain to determine if further works needed?
• Report to DICOM Standards Committee?

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US Elastography

• And after?

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MRE is coming!!!
WG 16 wake-up

• But it is another story -)

Magnetic Resonance Elastography