guillaume lemaître françois rameau

Guillaume LemaîtreFrançois Rameau

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Medical Imaging Techniques

François RameauGuillaume Lemaître

17th February 2009

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Outline

Introduction

Radiography

Computed Tomography (CT)

Magnetic Resonance Imaging (MRI)

Positron Emission Tomography (PET)

Medical ultrasonography


Conclusion

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Outline

Introduction

Radiography



Positron Emission Tomography (PET)Medical ultrasonography


Conclusion

IntroductionRadiographyComputed TomographyMagnetic Resonance ImagingPositron Emission TomographyMedical ultrasonographyConclusion

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Introduction



Computer vision and imaging theory are used in medical imaging techiques

Important to know basic notions of these technologies

Medical imaging allows to :

Create a reconstruction of human body

Reveal, diagnose and examine diseases

Study of metabolism and morphology

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Outline

Introduction

Radiography

Computed Tomography (CT)Magnetic Resonance Imaging (MRI)




Conclusion


FunctionningField of useAdvantages/Disadvantages

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Radiography – Functionning




First Radiograph in 1895

X-ray : wavelength = 5 picometers

The film provides a measure of the ray attenuation in tissue

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Radiography – Functionning




White represents high densityBlack represents low density

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Radiography – Field of use




Bones imaging

Dental domain

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Radiography – Advantages/Disadvantages




Advantages:

Disadvantages::

Excellent for imaging bones

Noninvasive

Good availability

Harmful rays

Bad results for soft tissues

Low cost

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Outline

Introduction

Radiography


Magnetic Resonance Imaging (MRI)Positron Emission Tomography (PET)



Conclusion



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Computed Tomography (CT) – Functionning




A recent technology (1970)

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Use X-rays

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Examples of slices with CT :

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Computed Tomography (CT) – Field of use




Cardiac Imaging

Bones Imaging

Cerebral Imaging

Reconstitution of organs in 3D

Pulmonary Imaging

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Computed Tomography (CT) – Advantages/Disadvantages




Advantages:

Disadvantages::

Excellent for bones imaging

Provides 3D anatomical information

Good availability

Harmful rays

Bad result for soft tissue

Claustrophobia

Noninvasive

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Outline

Introduction

Radiograph






Conclusion



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Magnetic Resonance Imaging (MRI) – Functionning




First Imaging in 1975

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Structure of MRI :

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MRI is based on NMR : Nuclear Magnetic Resonance

Consequence :

Use spin theory

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Spin theory :

Compass needle

Hydrogenous Atom

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Initial Position :

Position of moment

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Parallel direction:

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Parallel direction:

Parallel directionAntiparallel direction

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Excitation - Relaxation :

Excite moment of spin with Lamor frequency defined by :

NoyauSpin Net

γ(MHz/T)

1H 1/2 42,58

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Align moment of spin on xy scale :

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Calculate relaxation time

Long relaxtion time = high energy emittedShort relaxation time = low energy emitted

Reception of energy with antenna

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Examples of slices with MRI :

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Magnetic Resonance Imaging (MRI) – Field of use




Angio – MRI

Cardiac – MRI

Cholangio – MRI

Cerebral – MRI

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Magnetic Resonance Imaging (MRI) – Advantages/Disadvantages




Advantages:

Disadvantages::

Main modality for image guided surgerySuperb ability to discriminate between subtle differences in tissue characteristicsVery safe

Less accurate for bone scanningProblem with metal corps

Problem of avaibilaty

Cost of machine MRI (3 million €)

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Outline

Introduction

Radiography






Conclusion



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Positron Emission Tomography (PET) – Functionning




Injection of radioactive product :Fluorine associated with glucoseThe device emits positrons

Positrons create reaction with tracer (radioactive product) : Gamma ray

Emission of gamma ray is detected by the machine

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Positron Emission Tomography (PET) – Functionning




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Positron Emission Tomography (PET) – Field of use




Oncology

Neurology

Cardiology

Psychiatry

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Positron Emission Tomography (PET) – Advantages/Disadvantages




Advantages:

Disadvantages::

Functional imaging

Used in a lot of domains

Amount of radiation is small

Invasive method

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Outline

Introduction

Radiography






Conclusion



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Medical ultrasonography – Functionning




First Imaging in 1979

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Transducter :

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Transducter :

Emit ultrasounds

Receive the echo of ultrasounds emitted

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Translation of echo :

Compare the emitted frequency and the received frequency

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Examples of slices and reconstruction with ultrasonography :

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Medical ultrasonography – Field of use




Cardiology

Endocrinology

Gyneacology

Obstetrics

Ophtalmology

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Medical ultrasonography – Advantages/Disadvantages




Advantages:

Disadvantages::

Noninvasive

Clean & safe

In-expensive

NoisyGas filled and bony structures cannot be imaged because they absorb ultrasound waves.

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Outline

Introduction

Radiography






Conclusion


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Conclusion



Constant development in medical imaging

Each method is specific

Thanks for your attention

guillaume lemaître françois rameau

Documents

imaging theory

technologiesmedical

soft tissueslow cost

high densityblack

low density

ray attenuation

basic notions

diseasesstudy of metabolism