State of the art in Detection of Vulnerable Plaques

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State of the art in Detection of Vulnerable
Plaques

• Presented by Shahryar Rahnamayan
• Ph.D. student
• Supervisors Prof. H. R. Tizhoosh
• Prof. M. Salama
• 
  17th
  March , 2003

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Our Gold Aim

• Prediction of Stroke

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Overview

• Some facts
• Stroke risk factors
• What cause stroke?
• What are Plaques?
• Plaques in carotid artery
• Some techniques for detection of Plaques
• Main factors for evaluation of techniques
• Conclusion

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Some factsIn Canada

• 63500 stroke Cases happened in 1999
• ( Ontario ranked first (36.31) , Quebec ranked
  second (25.75 ) )
• Canadian Institute for Health Information (CIHI).
  http//secure.cihi.ca/

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In US Stroke every 45 seconds !!!

• the third largest killer , after heart disease
  and cancer. About 700,000 People have strokes
  each year. About 500,000 of these are first
  attacks , and 200,000 are recurrent attacks.
• Stroke costs 30 to 40 billion per year.
• Texas Heart Institute , http//www.tmc.edu/

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Stroke Risk Factors

• Risk Factors That Can Be Treated
• High Blood Pressure ( 1 in 4 American adults )
• Heart disease ( at twice the risk )
• Atherosclerosis ( hardening of the arteries)
• High red blood cell count ( can lead to blood
  clots )
• Transient ischemic attacks (TIAs )
• ( temporarily blocks an artery in the brain
  or neck)

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Stroke Risk Factors

• Risk Factors That Can't Be Changed
• Age ( after 55, double every ten years )
• Gender ( for men 19 higher than women )
• Race ( for African Americans- Afro-American - is
  twice )
• Diabetes ( because of circulation problems, for
  women is greater)
• Prior stroke ( ten times !)
• Heredity

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Risk Factors That Can't Be Changed (Continued)

• Carotid artery disease ( fatty deposits found in
  the carotid artery )
• Geographic location ( e.g. Stroke belt in US)
• Season and climate ( extreme temperature, e.g.
  June in Canada )
• Socioeconomic factors ( lower income)

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Contributing Risk Factors

• Smoking ( doubles the risk )
• Heavy alcohol use
• Physical inactivity ( 30-40 min. 3-4 time very
  week)
• Obesity ( BMI gt 30 kg/msq.)
• Birth Control Pills ( if combined with other
  factors like smoking)

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Important point

• Many heart attack and stroke victims do not
  have symptoms in advanced.

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What is a stroke?

• A stroke is an injury to the brain that may
  also severely affect the body. A stroke happens
  when blood supply to part of the brain is cut off
  or when there is bleeding into or around the
  brain.

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Blood flow to the brain can be blocked in two
ways

• A clump of blood called a blood clot blocks an
  artery in the brain or neck. ( 80 )
• A weakened artery bursts in the brain. ( 20)

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What mainly causes blood cut off ?
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• Short answer
• Plaque

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What are Plaques ?
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• Plaque is a combination of cholesterol,
  other fatty materials, calcium, and blood
  components that stick to the artery wall lining.
  A hard shell or scar covers the plaque. Plaques
  have various sizes and shapes. Some plaques are
  unstable and can rupture or burst. When this
  happens, it causes blood clotting inside the
  artery. If a blood clot totally blocks the
  artery, it stops blood flow completely. This is
  what happens in most heart attacks and strokes.
• Oral Chelation Therapy , http//www.oralchelation.
  ca/

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Stable and Unstable Plaque
Heart Center Online , http//www.heartcenteronline
.com
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Unstable Plaque Vulnerable Plaques
Heart Center Online , http//www.heartcenteronline
.com
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Texas Heart Institute Heart Information Center ,
www.vp.org
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Plaques in Carotid artery cause stroke
Heart Center Online , http//www.heartcenteronline
.com
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MRI from Human Carotid Plaque
Courtesy of Dr. Chun Yuan, University of
Washington
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Relation between heart disease and obstruction in
major artery

• Study findings showed
• Heart disease increased from 17 in people
  without obstruction in the carotid artery to 46
  in those with obstruction of greater than 75 in
  at least one major artery.

Courtesy of Dr. Kallikazoros
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Some Techniques for detection of Plaques

• 1. Angioscopy
• 2. Intravascular Ultrasound (IVUS)
• 3. Intravascular Thermography
• 4. Intravascular Optical Coherence Tomography
  (OCT)
• 5. Intravascular Elastography
• 6. Intravascular MRI
• 7. Intravascular Nuclear Imaging
• 8. Intravascular Electrical Impedance Imaging
• 9. Intravascular (Photonic) Spectroscopy

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Continue

• 10. Intravascular Tissue Doppler
• 11. Electron Beam Tomography (EBT)
• 12. Multi-slice Fast Spiral Computed Tomography

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Main factors for evaluation of techniques

• Safeness
• Invasive (part of the body is entered) or
  non-invasive
• Kind of information that gives
• Resolution
• Cost
• Acquisition time
• Localization
• Simplicity
• Easiness to apply

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• Angioscopy
• Based on fiber-optic transmission of visible
  light
• - Adv.
• - anatomic
• - simple
• - Disadv.
• - just surface of plaque is
  visualized
• - limited spatial resolution
• - needs a proximal occluding
  balloon

Courtesy of Uchida et al , Japan
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• IVUS
• Provides real-time , cross-sectional and
  high-resolution
• images with 3-D reconstruction capabilities
• - Adv.
• - Shows morphology of plaque
• - Differs between stable and
  unstable plaques
• - Disadv.
• - Doesnt give information
  about inflammation
• - Low spatial resolution (
  200 µm )
• - Deeper plaque is not imaged

Courtesy of Nissen, Yock and Fitzgerald
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• Intravascular Thermography
• In two kinds contact-based ( thermistor ) and
  non-contact based ( side-viewing infrared
  fiber-optic )
• - Adv.
• - Simplicity in theory
• - Gives information about
  inflammation
• - Disadv.
• - Plaque temperature is
  affected by blood flow is measured
• - Needs a proximal occluding
  balloon to provide blood-free field
  
• - Not give information about
  eroded but non-inflamed
• plaques

Courtesy of Volcano Therapeutics Inc. and
http//www.tmc.edu
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• Optical Coherence Tomography (OCT)
• Measures the intensity of reflected near-infrared
  light from tissue
• - Adv.
• - Very high resolution ( 10
  µm )
• - Near video rate ( 8
  frames/sec. )
• - Catheters are small ( 0.014
  inch )
• - Disadv.
• - Long image acquisition time
• - Cost
• - Limited penetration
• - Lack of physiologic data

Courtesy of Mark Brenzinski,James Fujimoto and
Eric Swanson
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• Intravascular Ultrasound Elastography
• Assesses the elasticity level of tissue based on
  cross-correlating the IVUS images acquired at
  different intra-arterial pressures applied to the
  arterial wall
• - Adv.
• - little cost added to IVUS
• - Provides novel information
  ,Showing stiffness
• - Disadv.
• - Lack of chemical inferences

Courtesy of de korte et al.
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• Intravascular MRI
• An internal receiver coil is implanted at the tip
  of a catheter
• - Adv.
• - high resolution ( 50 µm)
• - lack of ionizing radiation
• - Disadv.
• - Long image acquisition time
• - High cost

Courtesy of Ergin Atalar
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• Electron Beam Tomography (EBT)
• Calcium imaging
• - Adv.
• - Quick and easy
• - Provides information about
  total burden of atherosclerosis
• - Disadv.
• -Can not distinguish unstable
  from stable Plaque
• - Not accurate

Courtesy of Rumberger,Aard,Raggi, and others
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another classification for Plaques detection
Techniques

• Morphology imaging ( IVUS, OCT,)
• Activity imaging ( Thermography, Nuclear, )

Association for Eradication of Heart Attack -
AEHA , http//www.vp.org/
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A good idea

• Using Combination of
• Morphological and Functional imaging
• e.g. IVUS Doppler velocity measurements

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Conclusion

• Early detection of vulnerable Plaque is huge
  help for cardiovascular scientists to predict and
  prevent sudden death , most of mentioned
  techniques are in early research stage and call
  for scientist with any background to challenge.

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suggestion

• Doing joint project with great research centers
  like
• Vulnerable Plaque Research Department

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• Special thanks to Association for Eradication of
  Heart Attack - AEHA , http//www.vp.org/

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Thank you for your time and attention

• Any Comments, Suggestions and Questions ?