1. Advanced carotid plaque characterization: Assessment of vulnerability
William A. Gray MD
Director of Endovascular Services
Associate Professor of Clinical Medicine

2. I have no real or apparent conflicts of interest to report.
William A. Gray, MD
I have no real or apparent conflicts of interest to report.

3. Overview Potential importance of carotid plaque morphology
Methods of carotid plaque characterization
Contrast-enhanced ultrasound
MRI
PET
Intravascular ultrasound with virtual histology
Perspectives

4. Intra-plaque hemorrhage
The “smoking gun”
Fat-suppressed T1
Fat-suppressed T2
Intra-plaque hemorrhage

5. Potential importance of carotid plaque morphology
Key factors in advanced plaque relating to activity
Condition of the fibrous cap
Size of the necrotic core
Degree of intra-plaque hemorrhage
Extent of inflammatory activity
May have relevance in:
Natural history of plaque and stroke
Impact of medical therapy
Selecting the at-risk asymptomatic patient for revascularization
Selecting revascularization method

6. The culprit carotid plaque
Large (voluminous), lipid-rich necrotic core
Thin over-lying fibrous cap (TCFA)
Inflammatory cell infiltration
Proteolysis
Apoptosis
Angiogenesis/neovascularization

7. Contrast-enhanced ultrasound
Definity IV injection
Lipid pools
Intraplaque vessels
Hoogi A et al. AJR 2011; 196:431–436

8. CEUS has good correlation with histology

9. MRI acquisition and enhancements
Fat-suppression
Reduces adjacent fat signals allowing better plaque characterization
Contrast imaging
Gadolinium
Differentiates fibrous cap from lipid core
USPIO (ultra-small paramagnetic iron oxide) allows detection of macrophage infiltration
Advances in receiver coil and pulse sequence design have resulted in high spatial resolution imaging of plaques

10. MRI plaque characterization
Fat-suppressed T1
Fat-suppressed T2
Source image TOF MRA
Masson-Trichrome
Watanabe Y et al. Neuroradiology (2010) 52:253–274

11. MRI and plaque at CEA Lipid core TOF MRA TOF source image
Fat-suppressed T1
Fat-suppressed T2
Lipid core
Watanabe Y et al. Neuroradiology (2010) 52:253–274

12. 18F-FDG (Fluorodeoxyglucose) PET
Coronal view of a 50-70% symptomatic stenosis of
the internal carotid artery on the left side in a 77-year-old
male patient as shown by FDG-PET-CT imaging.
Hermus L et al. Eur J Vasc Endovasc Surg (2010) 39, 125e133

13. Labeled MMPI (proteolysis) and Annexin A5 (apoptosis)
Hypercholestrolemic rabbit aorta
Hermus L et al. Eur J Vasc Endovasc Surg (2010) 39, 125e133

14. Intravascular US with virtual histology
Inglese L et al. J Cardiovasc Surg 2009;50:735-44
Matsumoto S et al. Cerebrovasc Dis 2010;29:468–475

15. Weak correlation with VH and debris
Matsumoto S et al. Cerebrovasc Dis 2010;29:468–475

16. Perspectives
In asymptomatic carotid stenosis, rates of stroke events either with natural history (~2%-3%/year), CAS or CEA (1.0%-1.5%) very low
PROSPECT coronary analogue
Any advanced plaque imaging modality with clinical utility would need:
High positive predictive value for a given marker(s) within a clinical relevant time window
It is akin to predicting earthquakes…

17. Thank you