# Magnetic Resonance Imaging

## Presentation on theme: "Magnetic Resonance Imaging"— Presentation transcript:

Magnetic Resonance Imaging
MRI

Objectives: Advantages of MRI over other Modalities
Discuss the MRI historical development, and to know the significant person who discovered MRI. MRI discovery time line Persons involved What are their Contributions Overview of the basic principle of MRI Advantages of MRI over other Modalities Different Components of MRI

Historical Influence to MRI
MRI Topic 1

Democritus In early 400B.C First to theorize that all matter consist of both invisible and indivisible particles Greeks Also noted and observed that a piece of amber, when rubbed by fur, would attract specific particles or object.

AMBER

MAGNESIA TURKEY City of Magnesia is the origin of the term magnetism.
Observed that when certain rock formation were spun on their axes, they always and immediately returned to their original orientation. These magnetize structure, which are called lodestone.

LODESTONE

BAPTISTE-JOSEPH FOURIER
Introduced a complex mathematics that translate raw MR signals into spatial location while serving emperor napoleon of France

Our ancestors theorize that there was relationship between electricity and magnetism.
However, its relationship remained unsolve until approximately 2000 years later.

Hans Christian Oersted
1819 discovered that electricity produces magnetism when he noted that a compass needle would deflect in the presence of an electric charge.

Michael Faraday Stated and successfully demonstrated that electricity can produce magnetism. In 12 years later, michael faraday stated For his contribution, and many others michael faraday is regarded by many as the father of electricity.

Michael Faraday Calculated the velocity and propagation of electromagnetic waves and predicted the existence of other waves in addition to the ultraviolet and infrared regions. In 12 years later, michael faraday stated For his contribution, and many others michael faraday is regarded by many as the father of electricity.

Sir James Clerk Maxwell
In 1860 discovered magnetic lines of force could be mathematically expressed.

Heinrich Hertz of Germany
In 1868 discovered that invisible electromagnetic wave do exist and that all electromagnetic waves are identifiable by their characteristic wave frequency values.

Heinrich Hertz of Germany
Electromagnetic spectrum – the categorical arrangement of the wave energies corresponding to their properties, began to take form.

Nov. 8, 1895 discovered the x-ray Marie Curie In 1896 discovered the gamma rays by experimenting on radioactive phosphors. Their discoveries soon demonstrated that high frequency wave energies were identifiable, detectable, measurable and often biologically damaging.

Post WORLD WAR II Some of the technology advances associated with the world war 2 laid the groundwork for utilizing sonograpghy (submarine detection) and nuclear medicine (atomic energy) for human.

Felix Bloch & Edward Purcell
1946 Explore the mystery of atom. They noted that when a test tube sample of a pure substance was magnetically energized and RF bombarded the excited atoms themselves would respond by singing their own atomic ‘’tune’’.

Felix Bloch & Edward Purcell

Felix bloch & edward purcell
These tune signal were detected and recorded into spectroscopic images, corresponding to their frequency values. Virtually overnight Nuclear Magnetic Resonance (NMR). The prelude to MRI, was about to be born.

Felix bloch & edward purcell
Bloch and Purcell were recipients of the Novel Price in 1952 for their major contribution in uniquely discovering and implementing the use of atomic energy for analytical purposes.

END…

Magnetic Resonance Imaging
(BASIC PRINCIPLES) MRI TOPIC 2

MRI Originally called Nuclear Magnetic Resonance or NMR.
“Nuclear” indicated that the radioactive atomic nucleus played an important role.

Basic Principle of MR A certain atomic nuclei, if placed in a magnetic field, can be stimulated by (absorb energy from) radio waves of the correct frequency. Following this stimulation, the nuclei release the extra absorbed energy by transmitting radiowaves (the MR) signal, which can be received by an antenna and analyzed.

Behavior of a hydrogen nuclei

Advantages of MRI over other Modalities
Contrast Resolution Multi-Planar Imaging No Radiation

CONTRAST RESOLUTION Principal advantage of MRI
Allows visualization of low- density objects with similar soft tissue characteristics, such as liver- spleen or white matter – gray matter It is a function of several intrinsic properties of the tissue being imaged.

MRI HAS HIGH CONTRAST RESOLUTION

Multi-Planar Imaging Ability to obtain direct transverse, sagittal, coronal and oblique plane images

CORONAL VIEW

SAGITTAL VIEW TRANSVERSE VIEW

TRUE OR FALSE? TRUE OR FALSE?????

MRI uses RF electromagnetic radiation and magnetic fields, which do not cause ionization and therefore do not have associated potentially harmful effects of ionizing radiation

MRI Hardware 3 main components: Gantry Computer Operating Console

Gantry Is the large, usually cylindrical device that accommodates the patient during imaging MRI gantry does not have moving parts- everything is electronically controlled The patient aperture is usually cm in diameter

WHERE IS THE GANTRY??

RF COILS RF coils which is called the RF probe, surrounds the patient in this aperture Gradient coils, shim coils, and in the case of an electromagnetic, primary coils all surrounds the RF probe to produce the static magnetic field

RF COILS BODY COIL HEAD COIL

Computer Similar to CT, only faster and bigger
During MRI examination, more data are collected and the computations required are longer and more difficult than the CT

Operating Console MRI patient does not move
MRI console has RF controls rather than kVp, mA and scan time controls

MRI OPERATING CONSOLE

MRI Overview The hydrogen nuclei in the Patient- protons- behave like tiny magnets Hydrogen makes up 80 % of all atoms found in the human body, making hydrogen extremely useful for MRI. Because Hydrogen is a single- charge spinning nucleons, the hydrogen nucleus exhibit relatively strong magnetism

END..

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