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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

                                                         1
                                        17th   March , 2003
Our Gold Aim

Prediction
 of Stroke
               2
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
                                                3
Some facts

In 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/
                                                                           4
    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/
                                                   5
          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)

                                                          6
          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
                                                                      7
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)




                                                                8
Contributing Risk Factors

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




                                                                9
       Important point

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


                          10
 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.
                                     11
 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%)

                                         12
What mainly causes
  blood cut off ?


                     13
Short answer:
   Plaque

                14
What are Plaques ?


                     15
    “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/
                                                        16
    Stable and Unstable Plaque




Heart Center Online , http://www.heartcenteronline.com   17
Unstable Plaque = Vulnerable Plaques




Heart Center Online , http://www.heartcenteronline.com   18
Texas Heart Institute Heart Information Center , www.vp.org   19
             Plaques in Carotid artery
                  cause stroke




                                                         20
Heart Center Online , http://www.heartcenteronline.com
     MRI from Human Carotid Plaque




                                                      21
Courtesy of Dr. Chun Yuan, University of Washington
 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.”
                                    22
Courtesy of Dr. Kallikazoros
      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
                                                  23
    Continue …

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




                                                    24
         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
                                                             25
  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



                                                       26
Courtesy of Uchida et al , Japan
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.
             - Doesn’t give information about
               inflammation
             - Low spatial resolution ( ~ 200 µm )
             - Deeper plaque is not imaged
                                                           27
Courtesy of Nissen, Yock and Fitzgerald
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                             28
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
                                                                      29
Courtesy of Mark Brenzinski,James Fujimoto and Eric Swanson
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
                                                                  30
Courtesy of de korte et al.
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
                                                            31
Courtesy of Ergin Atalar
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
                                                   32
Courtesy of Rumberger,Aard,Raggi, and others
   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/   33
A good idea

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

                                    34
             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.


                                          35
        suggestion

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


                                 36
 Special thanks to Association for
Eradication of Heart Attack - AEHA ,
         http://www.vp.org/




                                 37
Thank you for your
time and attention

Any Comments, Suggestions and Questions ?


                                            38

				
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