MAGNETISM Flashcards
Which magnetic property results in -1 susceptibility?
Diamagnetic
Gadolinium is a:
Paramagnetic
When gadolinium is injected what happens?
Chelates (binding agent)
What represents a mass number of atoms?
Number of protons and neutrons in the nucleus
What is the spin value for hydrogen?
1/2
When placed in an external magnetic field, hydrogen protons will assume what?
1 of 2 spin states
Hydrogen protons in a low energy spin state are said to have their magnetic moment:
Aligned with the direction of the external magnetic field
Which field has the greatest difference between high and low energy spins?
3.0 Tesla
Human body is 80 percent what?
Water
What occurs within a few seconds of hydrogen protons being placed in magnetic field?
Thermal equilibrium
Increasing the strength of the external magnetic field will have:
Greater tissue magnetization
What is the gyromagnetic ratio for hydrogen?
42.6MHz/T
Resonant or precessional frequency of hydrogen when placed in a magnetic field is calculated by:
The Larmor Equation
Increasing B0 results in an increase in:
The resonant frequency
Which will exhibit the highest resonant frequency due to chemical shift?
Water base protons
Chemical shift at all field strength is:
3.5ppm
What is the process called of making the magnetic field as homogenous as possible?
Shimming
At thermal equilibrium, magnetic moments of hydrogen protons do not precess in phase primarily due to what?
Inhomogeneties and chemical shift
When using a 3D cartesian coordinate graph, magnetic field will be on which direction?
z-axis
The only magnetization which can be detected or measures is:
Transverse magnetization
B1 and B0 must be what to each other?
Perpendicular
Frequency range of RF used in 1.5T is close to:
FM radios
RF is tuned to frequency of
water
MR signals are created in the receiver coil according to:
Faradays law of induction
