Chapter 1- Basic Principles Flashcards
There are two different views of MRI and they are :
Quantum theory and classical
The classical theory focuses more on how the universe works “mechanically”
True
The quantum theory focuses more on the different energy levels of protons and neutrals and electrons
True or False?
True
An atom is organized into “____” which are two or more atoms arranged together?
a molecule
In humans, the most abundant atom is hydrogen.
True or False
True
An atom consists of a central nucleus and orbiting ___
electrons
Protons and neutrons are subcategories of
nucleons
the sum of the protons in a nucleus is called
anomic number
The sum of the protons and neutrons in a nucleus is called the
mass number or atomic weight
When an atom has less neutrons than protons this is called an
isotope
Electrons are particles that spin around the nucleus
True or False
True
Protons have a ____ electrical charge
positive, negative or none
positive
Neutrons have a ____ electrical charge
positive, negative or none
No net charge
Electrons have a ____ electrical charge
positive, negative or none
negative
An atom is considered electrically stable if the number of electrons ____ the number of protons?
equals, is less, is more
equals
How can we alter the balance of an electrically stable atom?
apply energy to knock out the electrons from the atom. This will produce electrical instability.
This is called an ION
the process of knocking out electrons is called
ionization
What are the three types of motion in an atom?
Electrons spinning in their own axis
electrons orbiting the nucleus
the nucleus spinning on its own axis.
If an atom has an even atomic and mass number, (6 protons 6neutrons mass 12), will it have a spin?
no
if they have an even number , half the nucleons spin one direction and the other half another direction which cancels itself out??
How is angular momentum caused?
in nuclei with an odd number of protons, odd number of neutrons, the spin directions are not equal and opposite so it will have a net spin.
What is the large magnetic field of the MRI scanner called?
B 0
What is the magnetic field measured in ?
teslas
The influence of B 0 prouces an additional spin or wobble of the magnetic moment of hydrogen around b0.
True
What is another name for precessional frequency?
Larmor Frequency
What does RF stand for?
radiofrequency
How would you explain “phase”
it refers to the position of magnetic moments on their precessional path at any moment in time.
The magnetic moment travels thru 360 degrees during one rotation.
True or False
True
What is the difference in out of phase and in phase?
In phase means the magnetic moment of hydrogen are at the SAME place on the precessional path at the moment in time
Out of phase means the magnetic moments of hydrogen are at DIFFERENT places on the precessional path.
Out of phase is also called ____
incoherent
in phase is also called
coherent.
Resonance is also called “reverb”
True
Resonance is achieved by transmitting an RF pulse called a ____
RF excitation pulse
Excitation means “energy giving”
True
A RF exciation pulse ____ energy to hydrogen nucleu and causes a net ___ to the number of high energy spin down nuclei
Takes energy/ gives energy
net increase or net decrease.
it gives energy to cause a net increase
The process at which hydrogen loses its energy is called
relaxation
Explain what TR is
TR is the time from the application of one RF excitation pulse for each slice.
TR is measured in seconds
True or False
FALSE
Tr is measured in milliseconds
TR determines the amount of longitudinal relaxation that occurs between the end of 1 RF pulse to the next.
True or False
True
Explain what TE is
The time from the application of the RF pulse to the peak of signal induced in the receiver coil.
TE is measured in milliseconds.
True or False
True
TE determins how much decay of transverse magnetization occurs.
True
TE controls the amount of T2 relaxation.
True
