MRI lecture

Radiation

The transfer of energy in the form of particles or waves.

Diagnostic Imaging Energy Forms

Different forms of radiation are used in diagnostic imaging.

Types of Radiation

Radiation from radios, visible light, and x-rays are the same in nature but differ in energy.

Dr. Raymond Damadian

One of the inventors of MRI.

Primary Magnetic Field in MRI

The MRI magnet creates the primary magnetic field.

Tesla Strength

1 Tesla is equal to 10,000 gauss.

MRI Magnets

MRI magnets are electromagnets.

Creating a Powerful Magnetic Field in MRI

A high amount of current is needed to create a powerful magnetic field in MRI.

Effect of High Current in a Wire

A magnetic field is created when high current runs through a wire.

Cooling System in MRI

Superconducting magnets are surrounded by a cooling system such as liquid helium at -453°F.

Superconductivity in MRI

No electrical resistance means current flows indefinitely, maintaining the magnetic field.

Most Abundant Substance for MRI

Water is the most abundant substance in the body and is important for MRI, making up about 70%.

Water Molecule Interaction in MRI

MRI primarily interacts with hydrogen nuclei (protons) in the water molecule.

Magnetic Field Generation in Atoms

Moving charged particles like electrons and protons generate a magnetic field in an atom.

Hydrogen Protons in MRI Magnetic Field

Some hydrogen protons align with and others against the magnetic field in an MRI.

Inducing Signals in MRI Imaging

Radiofrequency (RF) pulses induce the human body to emit signals in MRI imaging.

RF Coils in MRI

RF coils send and receive radio waves from hydrogen nuclei.

Larmor Frequency

The resonant frequency at which hydrogen nuclei absorb energy in a magnetic field.

MRI Resonance Principle

Every molecule or particle has a resonant frequency to which they are tuned.

Gradient Coils in MRI

Gradient coils alter the main magnetic field to localize signals.

Emergency Shutdown in MRI

An emergency shutdown of an MRI system does not turn off the magnet; the magnetic field remains active.

Quench in MRI

A rapid loss of superconductivity and magnetic field, boiling off liquid helium.

Effects of Quenching an MRI Magnet

Magnetic field collapses in less than 3 minutes; 24-72 hours of downtime with rapid boil-off of cryogen.

MRI Procedure in Emergencies

Quenching the magnet may be used in life-threatening situations.

Importance of Magnet in MRI Safety

The phrase 'Bet on the Magnet!' emphasizes magnet importance in MRI safety.

MRI Safety Zones

Designated areas with specific safety protocols around the MRI machine.

MRI Applications

Uses can include brain scans, joint imaging, cardiovascular studies, etc.

Electromagnetic Radiation

The radiation associated with radios, visible light, and x-rays are the same, just with different amounts of energy.

Strength of MRI Magnet

The MRI magnet is 60,000 times the earth’s magnetic field.

Charged Particle Field Generation

Any charged particle which is moving generates a magnetic field along with its electrical field.

Protons and Radio Waves in MRI

Protons are spinning charged particles; when they realign with the magnetic field, it creates an oscillating disturbance in the form of a radio wave.

Hydrogen Protons After Radio Waves Turn Off

When the radio waves are then turned off, the hydrogen protons return to their alignment with the magnetic field.

Electromagnetic Coils in MRI

Electromagnetic coils are used to alter the main magnetic field.