Magnetic Resonance Imaging
Task 1 A
Principles of an MRI:
Magnetic resonance = Nuclei with an odd number of protons and neutrons have a SPIN. This
means that they will behave like tiny bar magnets.
Nuclear spin
Nuclear spin is a subatomic particle (proton or neutron) spinning around its axis. If a nucleus has a
complete spin, depends on how many protons and neutrons it has. Nuclei containing the same
number of protons and neutrons balance their cumulative spins. Nuclei with an uncommon number
of protons, or an unusual number of neutrons, or both, have a complete spin. This spin is calculated
with a quantum number of the nuclear spin. A nuclei's nuclear spin quantity depends on the non-
pairing protons / neutrons and will be a positive integer multiple of 0.5. If a nucleus has a spin it will
exhibit nuclear magnetic resonance and will interact with other magnetic fields.
Precession
Precession is a wobbling motion which occurs when an object that spins is the subject of an external
force. The proton of a hydrogen nucleus, which is important to MRI, spins around its axis giving it an
angular moment. It creates a magnetic field and gets a magnetic dipole moment (MDM) parallel to
the rotation axis through the protons positive charge and its spin. When placed in a magnetic field,
the time of the magnetic dipole precedes the direction of the angular frequency magnetic field
(Larmor frequency). The Larmor equation suggests that the precession frequency at the strengths of
the higher field is greater.
Task 1 A
Principles of an MRI:
Magnetic resonance = Nuclei with an odd number of protons and neutrons have a SPIN. This
means that they will behave like tiny bar magnets.
Nuclear spin
Nuclear spin is a subatomic particle (proton or neutron) spinning around its axis. If a nucleus has a
complete spin, depends on how many protons and neutrons it has. Nuclei containing the same
number of protons and neutrons balance their cumulative spins. Nuclei with an uncommon number
of protons, or an unusual number of neutrons, or both, have a complete spin. This spin is calculated
with a quantum number of the nuclear spin. A nuclei's nuclear spin quantity depends on the non-
pairing protons / neutrons and will be a positive integer multiple of 0.5. If a nucleus has a spin it will
exhibit nuclear magnetic resonance and will interact with other magnetic fields.
Precession
Precession is a wobbling motion which occurs when an object that spins is the subject of an external
force. The proton of a hydrogen nucleus, which is important to MRI, spins around its axis giving it an
angular moment. It creates a magnetic field and gets a magnetic dipole moment (MDM) parallel to
the rotation axis through the protons positive charge and its spin. When placed in a magnetic field,
the time of the magnetic dipole precedes the direction of the angular frequency magnetic field
(Larmor frequency). The Larmor equation suggests that the precession frequency at the strengths of
the higher field is greater.
