This document discusses intravascular ultrasound elastography (IVUS), a technique that measures the elastic properties and stiffness of vessel walls and atherosclerotic plaque. It can identify soft, lipid-rich plaques that are more vulnerable to rupture compared to hard, calcified plaques. The document summarizes a study that found IVUS elastography could successfully identify fatty plaques in vivo in an atherosclerotic pig model, with 100% sensitivity and 80% specificity. The study also showed this technique had high sensitivity and specificity for identifying lipid and macrophages within plaques. However, questions remain about how it can detect plaque inflammation and what normal and abnormal elasticity values mean clinically.

1. Editorial Slides
VP Watch, April 10, 2002, Volume 2, Issue 14
Elastography; An Add-On to Your IVUS for
Detection of Vulnerable Plaque?

2. The composition of atherosclerotic plaque is a
major determinant of its vulnerability to rupture.
Soft plaques with large lipid core and thin fibrous
cap are more vulnerable to rupture.
Intravascular elastography is measuring local
elastic properties (stiffness) of vessel wall using
IVUS.1
The technique is able to discriminate
between soft and hard materials. 2

3.  The principle is that soft material will strain
more compared with hard material when a force
is applied on the tissue. 1
For example plaques
with large lipid core strain differently from highly
calcified plaques. 3
 Elastography has been clinically used in
other fields such as breast cancer and prostate
cancer. 4

4.  Fibrous tissue has lower strain values than
fibro-fatty tissue, and the latter one has
lower strain levels than fatty tissue.
Identification of these 3 tissue types on the
basis of their echogenesity (IVUS) is not
possible. 2
 In an earlier ex vivo study De Korte and his
colleagues showed different mean strain
values in fibrous, fibro-fatty, and fatty
atherosclerotic plaques in human coronary
and femoral arteries. 2

5.  As reported in this issue of VPWatch,
de Korte, Schaar, van der Steen, and their
colleagues showed that IVUS elastography is
feasible in vivo in an atherosclerotic pig
model.5
 They showed that Elastography has a high
sensitivity to identify fatty material.5

6. Echogram and Elastogram Obtained in vivo
in Yucatan Pig Coronary
Elastic-von Giesson Picro-Sirius red
Polarized light
Acid Phosphatase
De korte et al.; Circulation 105 (14): 1627-1630 (2002)

7. In this study de Korte and colleagues
found the sensitivity of 100% with a
corresponding specificity of 80% to
identify fatty plaques for a strain value
of 0.35%. 5
They also showed high-strain spot has
75% sensitivity and 100% specificity to
identify lipid. A 92% sensitivity and
92% specificity was found to identify
the presence of macrophages. 5

8. Conclusion
• In vivo coronary elastography using IVUS
catheter is feasible.
• IVUS elastography is able to determine
plaques with large lipid core from fibrous
rich plaques.

9. Questions:
• IVUS elastography at best can identify
lipid rich plaques from fibrotic plaques.
The question is how elastography can
directly detect plaque inflammation?
• What are the normal and abnormal values
to use elastography for making clinical
decision?

10. Questions:
• Do plaques with positive (expansive)
remodeling exhibit higher strain comparing
to plaques with negative (constrictive)
remodeling, regardless of plaque
components?

11. References
1) Ophir J, Céspedes EI, Ponnekanti H, et al. Elastography: a method for imaging the
elasticity in biological tissues. Ultrason Imaging. 1991;13:111–134.
2) de Korte CL, van der Steen AF, Cepedes EI, Pasterkamp G, Carlier SG, Mastik F,
Schoneveld AH, Serruys PW, Bom N; Characterization of plaque components and
vulnerability with intravascular ultrasound elastography.
Phys Med Biol. 2000 Jun;45(6):1465-75.
3) van der Steen AF, de Korte CL, Cespedes EI.; Intravascular ultrasound
elastography.Ultraschall Med.
4) Hiltawsky KM, Kruger M, Starke C, Heuser L, Ermert H, Jensen A.Freehand
ultrasound elastography of breast lesions: clinical results. Ultrasound Med Biol. 2001
Nov;27(11):1461-9.
5) Chris L. de Korte, Marion J. Sierevogel, Frits Mastik, Chaylendra Strijder, Johannes
A. Schaar, Evelyn Velema, Gerard Pasterkamp, P.W. Serruys, and Anton F.W. van
der Steen; Identification of Atherosclerotic Plaque Components With Intravascular
Ultrasound Elastography In Vivo: A Yucatan Pig Study Circulation 2002 105: 1627 -
1630