Intravascular ultrasound (IVUS) can be used to characterize plaque and select populations for interventional diagnosis and treatment. IVUS has the potential to identify vulnerable plaque by measuring plaque volume and distinguishing tissue types, with a sensitivity of 90% and specificity of 95%. While current IVUS systems provide high resolution imaging, research aims to improve tissue contrast and resolution through techniques analyzing the radiofrequency signal and comparing IVUS to other imaging modalities. IVUS is widely used today for intravascular imaging but continued advances may help identify individuals at high risk of heart events.

1. Intravascular Ultrasound for
Plaque Characterization
Scott R. Smith
Boston Scientific Corporation
The 3rd Vulnerable Plaque Symposium
March 16, 2002

2. Who needs interventional diagnosis
and treatment?
Population Size Annual Risk
Healthy People Huge <<1%
“Risk Factors” Really Big ~1%
Walking Time
Bombs
Still quite a few >10%
Summary of
National Heart, Lung, and Blood Institute
Workshop on Cardiovascular Risk Assessment

3. Diagnosis of Vulnerable Plaque
selecting a population
positive negative
67%
positive predictive value
99%
negative predictive value
likelyhood ratio
test
9% 5%
total unaffected
14%
true positive false positive
1% 86%
87%
false negative true negative
positive
negative
18
90% 95%
sensitivity specificity
10% 90%
total affected
Total 100
at risk 10
treated 14
saved 9
unnecessary 5
missed 1

4. Plaque Structure
Courtesy of
Dr. Renu Virmani
Armed Forces Institute
of Pathology

5. IVUS Plaque Imaging
Ruptured plaque

6. Boston Scientific Imaging Systems
Atlantis™ SR Plus Catheter Galaxy™ IVUS System
Features & Intended Benefits
• Tapered tip; 2.5 Fr. Crossing
Profile
• High definition 40MHz IVUS
catheter.
• 6F Guide Catheter
Compatibility.

7. Galaxy™ System Features and
Intended Benefits
Time-Saving Features
– Image Bookmarking
– LongView™ longitudinal
measurements
– Pullback sled
Enhanced Ease of Use
– TraceAssist™ automatic
lumen trace function
– Angiographic compatibility
– Push button control

8. Galaxy™ System Research
Capabilities
Expanded Functionality
– Digital image storage
– Patient database
– Pre/post intervention analysis.
RF Output
– Direct Access to RF signal for
acquisition and analysis
– Future plans may include
direct RF signal acquisition

9. Imaging vs. Analysis
RF
Rectified and Log compressed
Low passed filtered - 10MHz
One image vector

10. Other Imaging Modalities
IVUS acoustic
impedance
MRI proton
relaxation
Thermal temperature
OCT refractive
index
Spectroscopy chemical
bonds
Independence
Spatial resolution
Contrast

11. Conclusion
• Intravascular Ultrasound currently widely used
for intravascular imaging
• Broad potential for plaque volume
measurement and tissue characterization
• Variety of research efforts aimed at improving
tissue contrast and resolution
Thanks to:
– Tat Jin Teo, PhD - BSC Imaging
– Renu Virmani, MD - AFIP
– Jay Kokate, PhD - BSC Applied Research