Instrumentation of MRI Flashcards
_______ is the amount of time a gradient coil remains at a certain amplitude.
Duty time
Multiple coil elements linked with multiple receiver coils are called ________ ________and are compatible with parallel imaging
Phased array coils
The liquid cryogen used to maintain the temperature on superconducting magnets is
Helium
Shimming is utilized to
Balance any uneven field homogeneities
What MRI systems are responsible for providing the means for alignment (net magnetization of spinning protons)?
- Static magnetic field
- B0
Measured in mT/m/s, ________ is the combination of gradient amplitude and rise time.
Slew rate
True or False
Resistant magnets can have either horizontal or vertical magnetic field directions depending on how they are conducted.
True
What are the correct layers from outer to inner most layers of the hardware an MRI scanner
Main magnet, shim coils, gradient coils, RF coils
Superconducting magnets possess a “cold head” that pumps cryogen to keep the magnet internal temperature at which temperatures?
-269°C
4°K
The gradient system is:
- Used to specially localized a certain area of the body
- Located in the MR unit layered behind the transmit coil
Faradays law of electromagnetism can be shown using the “right hand thumb rule”, the thumb symbolizes:
Current
Faradays law of electromagnetism or induction states: “If a loop of wire is moved through a magnetic field _________ will be created”.
A current voltage
The major difference between electromagnets and permanent magnets is:
Electromagnets rely on a constant power source
What would be the effects of doubling the magnetic field strength?
The signal to noise will be double.
If a receiver coil is properly tuned (transmit gain outside of range), what will the result be on image quality?
A decrease in SNR.
