plaques

Shared by: liwenting

Tags

Stats

views:: 46
posted:: 3/13/2010
language:: English
pages:: 38

Public Domain

Document Sample

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 ?