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216 elastography using ivus


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216 elastography using ivus

  1. 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. 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. 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. 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. 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. 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. 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. 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. 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. 10. Questions: • Do plaques with positive (expansive) remodeling exhibit higher strain comparing to plaques with negative (constrictive) remodeling, regardless of plaque components?
  11. 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