Basic Principles
What magnetic property are nuclei in when they are outside of an applied magnetic field?
Random orientation
On a T2 image, CSF appears:
Hyperintense
What is the vessel called that holds the liquid cryogens?
Cryostat
What is the center point of all three gradients called?
Isocenter
What is the 180°pulse used for?
Rephasing
What occurs when an oscillating object is exposed to the same oscillating frequency as the object?
Resonance
Proton Density Weighted images have a ______ TR and a ______ TE.
Long TR, Short TE
What kind of magnet has the most power consumption?
Electromagnet
What are the three tasks of the gradient coils?
Slice selection, Phase encoding, Frequency encoding
What pulse sequence has a turbo factor?
Fast Spin Echo
Another name for protons that align in the anti-parallel orientation are:
High energy or spin down
T1 relaxation time is ______% of the longitudinal magnetization.
63% recovery
What is the preferred method for digitally storing images?
PACS
What is the most common way to fill K space?
Spiral or radial
In a Gradient Echo Pulse sequence what is used to excite the magnetic moments?
Variable flip angle
What makes up the Larmor Equation?
Gyromagnetic ratio multiplied by the magnetic field strength
What controls the amount of T2 weighting?
TE
What is the conductor used in nearly all superconducting MRI scanners?
Niobium-titanium
How many data points need to be collected per cycle? What theorem states that?
Two, Nyquist Theorem
What kind of pulse sequence is used to collect data in less than a second?
Echo Planar Imaging
Another name for T2 Decay is:
Spin-spin relaxation
What weighting is better for visualizing pathology?
T2
What is measured in G/cm?
Gradient strength
What is the “duration of the frequency encoding gradient?”
Sampling time or acquisition window
What weighting and pulse sequence has a long TR and a short TE?
Proton Density CSE