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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.