Intravascular Ultrasound for Plaque Characterization

Scott R. SmithBoston Scientific Corporation

The 3rd Vulnerable Plaque SymposiumMarch 16, 2002

Who needs interventional diagnosis and treatment?

Population Size Annual Risk

Healthy People Huge <<1%

“Risk Factors” Really Big ~1%

Walking TimeBombs

Still quite a few >10%

Summary ofNational Heart, Lung, and Blood InstituteWorkshop on Cardiovascular Risk Assessment

Diagnosis of Vulnerable Plaqueselecting a population

positive negative67%positive predictive value99%negative predictive value

likelyhood ratio

test

9% 5%

total unaffected

14%true positive false positive

1% 86% 87%false negative true negative

positive

negative

1890% 95%sensitivity specificity

10% 90%total affected

Total 100at risk 10treated 14saved 9unnecessary 5missed 1

Plaque Structure

Courtesy of Dr. Renu VirmaniArmed Forces Institute of Pathology

IVUS Plaque Imaging

Ruptured plaque

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.

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

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

Imaging vs. Analysis

RF

Rectified and Log compressed

Low passed filtered - 10MHz

One image vector

Other Imaging Modalities

IVUS acousticimpedance

MRI protonrelaxation

Thermal temperatureOCT refractive

indexSpectroscopy chemical

bonds

IndependenceSpatial resolution Contrast

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