Howtosignalprocessing
- What is the phase encoding gradient in MRI?
- What is phase encoding direction in MRI?
- Which gradient coil is responsible for phase encoding?
- What is the frequency encoding gradient?
What is the phase encoding gradient in MRI?
The phase encoding gradient (GPE) intervenes for a limited time period. While it is applied, it modifies the spin resonance frequencies, inducing dephasing, which persists after the gradient is interrupted. This results in all the protons precessing in the same frequency but in different phases.
What is phase encoding direction in MRI?
The phase-encoding direction is usually chosen so that these artifacts do not project over the area of interest. For example, axial brain images are usually phase-encoded from left to right so that artifacts from the eyes do not spill over into the brain.
Which gradient coil is responsible for phase encoding?
The phase encoding gradient is a gradient in the magnetic field Bo. The phase encoding gradient is used to impart a specific phase angle to a transverse magnetization vector.
What is the frequency encoding gradient?
As they are of different frequencies, they will eventually become of different phases. Adding the signals together gives a large signal at the start, when they are still all in phase, but this signal drops off as the phases diverge. This gradient is called the “read out” or “frequency encoding” gradient.
