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Intravascular Elastography:from Bench to Bedside

C.L. de Korte1, F. Mastik1, J.A. Schaar1,M. Sierevogel1,3, G. Pasterkamp3,

P.W. Serruys1 and A.F.W van der Steen1,2

1Erasmus University, Thoraxcentre, Rotterdam, The Netherlands 2Interuniversity Cardiology Institute of the Netherlands

3Experimental Cardiology Laboratory, University Medical Center, Utrecht, The Netherlands

Supported by Netherlands Organization for Scientific Research (NWO) and the Dutch Technology Foundation (STW)

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Background : Vulnerable plaque

Plaque vulnerability :

Plaque composition• Large lipid pool

Mechanical properties

• High strain region

• Thin fibrous cap• presence of Macrophages

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Background : Principle of elastography

Soft Harduncompressed

compressed

• The response of tissue to mechanical excitation (e.g. compression) is a function of its mechanical properties.

Force Soft Hard

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IVUS elastography

(t1, P1)

(t2, P2)

Processing

IVUS at 100mmHg

IVUS at 80mmHg

IVUS elastogram

strain1%

0%

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strain1%

0%

Picrosirius-red Anti-CD68 antibodyAlpha-actin

Circulation 102(6) 617-623 (2000)

IVUS elastography plaque characterization

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Vulnerable plaque detection

In vitro 25 human coronary arteries with78 cross-sections.

Histology:• lipid core (> 40%) • thin cap with moderate/heavy macrophage infiltration

Elastography:• high strain region on the surface of the plaque• an adjacent low strain region

Definition used for plaque Vulnerability :

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strain1%

0%

Picrosirius-red Anti-CD68 antibodyAlpha-actin

IVUS elastography vulnerable plaque detection

Circulation 104 (17): II-459 (2001)

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Sensitivity and Specificity

300 0.5 1 1.5 2 2.5

Strain [%]

1

Strain 1.26 %: Sensitivity 88%

Specificity 89%

Circulation 104 (17): II-459 (2001)

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IVUS elastography in patients• Patients referred for Percutaneous Coronary intervention

• Pre intervention IVUS assessment of the culprit lesionusing 20 MHz JOMED Avanar® IVUS catheter.

• JOMED InVision Gold Echo system with digital acquisition system for off-line processing

• Find phase of heart-cycle with minimal motion of catheter since motion decreases elastographic quality.

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0 20 40 60 80 100 12040

60

80

100

120

140

Frame no.

Intra

-cor

onar

ypr

essu

re [m

mH

g]In vivo elastography

Strain [%]

1.0

0.0

Eur Heart J 23(5): 405-413 (2002)

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Cross-section LAD of patient with U.A.P

Strain [%]2.0

0.0

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Patient with Angina Pectoris

Strain [%]1.0

0.0

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Intravascular Elastogram of lesion pre-stenting

Strain [%]1.0

0.0

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Intravascular Elastogram of stented lesion

Strain [%]1.0

0.0

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• 6 Yucatan minipigs of 40 kg.• Acquired elastographic data in left and right

femoral and external iliac artery (n=24).• Cross-sections marked using angiography after

termination.• Processed for histology: Elastic-von

GiessonPicro-Sirius redAcid Phosphatase

Validation in atherosclerotic Yucatan minipig

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Echogram and elastogram obtained in vivo in Yucatanstrain

1%

0%

Elastic-von Giesson Picro-Sirius red Acid PhosphatasePolarized light

Circulation 105 (14): 1627-1630 (2002)

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Correlation elastography with histology

• Relation mean strain in total plaque with plaque composition (fibrous, fatty, macrophages)

Tissue mean std

Normal segments (n=6) 0.21 0.09

Early fatty lesion (n=9) 0.46 0.17

Early fibrous lesion (n=3) 0.24 0.03

Advanced fibrous lesion (n=6) 0.22 0.04

Strain [%]

*

* P=0.007

Circulation 105 (14): 1627-1630 (2002)

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Correlation elastography with histology

• Presence of a high strain spot (>1% strain) with presence of fat and or macrophages.

fat no fat

M no M

Circulation 105 (14): 1627-1630 (2002)

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3 Dimensional Elastography

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Conclusion

Intravascular Ultrasound Elastography: A powerful technique to identify

the vulnerable plaque.