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State of the art in State of the art in Detection of Vulnerable Detection of Vulnerable

PlaquesPlaques

Presented by : Shahryar Rahnamayan Ph.D. student Supervisors : Prof. H. R. Tizhoosh Prof. M. Salama

17th March , 2003

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Our Gold AimOur Gold Aim

Prediction of StrokeStroke

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OverviewOverview

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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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/

Some factsSome facts

In Canada :In Canada :

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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/

In US : In US : SStroke every 45 seconds !!!troke every 45 seconds !!!

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Stroke Risk FactorsStroke 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 FactorsStroke Risk Factors

Risk Factors That Can't Be ChangedAge ( 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 Risk Factors That Can't Be Changed (Continued)(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 FactorsContributing Risk Factors

Smoking ( doubles the risk )

Heavy alcohol usePhysical inactivity ( 30-40 min. 3-4 time very week)

Obesity ( BMI > 30 kg/msq.)

Birth Control Pills ( if combined with other factors like smoking)

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Important point Important point

Many heart attack and stroke victims do not have symptoms

in advanced.

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What is a stroke?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 Blood flow to the brain can be blocked in two ways: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 What mainly causes bloodblood cut offcut off ??

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Short answer:

PlaquePlaque

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What areWhat are PlaquesPlaques ??

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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 PlaqueStable and Unstable Plaque

Heart Center Online , http://www.heartcenteronline.com

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Unstable Plaque = Vulnerable PlaquesUnstable Plaque = Vulnerable Plaques

Heart Center Online , http://www.heartcenteronline.com

19Texas Heart Institute Heart Information Center , www.vp.org

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Plaques in Carotid artery cause Plaques in Carotid artery cause strokestroke

Heart Center Online , http://www.heartcenteronline.com

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MRI from Human Carotid PlaqueMRI from Human Carotid Plaque

Courtesy of Dr. Chun Yuan, University of Washington

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Relation between heart disease Relation between heart disease and obstruction in major artery 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 Some Techniques for detection of Plaquesof 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 …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 Main factors for evaluation of techniquestechniques

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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AngioscopyAngioscopyBased 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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IVUSIVUSProvides 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 imagedCourtesy of Nissen, Yock and Fitzgerald

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Intravascular ThermographyIntravascular ThermographyIn 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)Optical Coherence Tomography (OCT)Measures the intensity of reflected near-infrared light from tissueMeasures 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 ElastographyIntravascular Ultrasound ElastographyAssesses the elasticity level of tissue based on cross-correlating the Assesses the elasticity level of tissue based on cross-correlating the

IVUS images acquired at different intra-arterial pressures applied to IVUS images acquired at different intra-arterial pressures applied to the arterial wallthe 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 MRIIntravascular MRIAn internal receiver coil is implanted at the tip of a catheterAn 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)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 another classification for Plaques detection TechniquesPlaques 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 ideaA good idea

Using Combination of

MorphologicalMorphological and FunctionalFunctional imaging

e.g. : IVUS + Doppler velocity

measurements

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ConclusionConclusion

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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suggestionsuggestion

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 Thank you for your time and attentiontime and attention

Any Comments, Suggestions and Questions ?