Oct 10, 2021 · With every cycle the amplitude of the phase encoding gradient is changed so that the phase of the MR signal at a certain y-axis position changes each time. If we look at a single point in …

Below is a 2x3 array of pixels (A-F) at the center of a brain image with frequency- and phase-encoding directions as designated. In this simple experiment we again play out only two phase-encoding …

In fact it is necessary to apply this gradient several times, each time increasing the gradient by an equidistant amount. In a MRI sequence diagram this procedure is indicated by the phase encoding …

The phase encoding gradient is applied after slice selection and excitation (before the frequency encoding gradient), orthogonally to the other two gradients. The spatial resolution is directly related …

The phase-encoding direction is associated with two major artifacts: wrap-around and flow/motion. Wrap-around (also called aliasing) occurs when the size of the body part imaged exceeds the …

Even the simplest MRI methods have considerable alteration of the gradients during this period, so we explicitly include the time dependence of the applied gradient in the equation for phase.

Phase-contrast velocity mapping Consider a single slice acquired at a single cardiac phase. To obtain the velocity map (i.e., an image where pixel intensity is proportional to v⊥i), a flow-encoding gradient …

Frequency-encoding of spatial position is accomplished through the use of supplemental magnetic field gradients. Gradients mildly distort the main magnetic field in a predictable pattern, causing the …

In 2DFT imaging, each row in k -space corresponds to the echo data obtained from a single application of the phase-encoding gradient. By convention, rows near the center of the k -space grid are defined …

The frequency-encoding gradient thus uniquely identifies a slice using center frequency (F c) to determine slice position and frequency span (ΔF) to determine slice thickness (Δz). The next step is …