K-space filling techniques

1. How is k-space filled?
2. How many lines of k-space are filled per tr?
3. What is k-space sequence in MRI?
4. Why is k-space useful?
5. What does the center of k-space contain?
6. Why is the Centre of k-space usually the brightest?

How is k-space filled?

The easier way to fill the k-space is to use a line-by-line rectilinear trajectory. One line of k-space is fully acquired at each excitation, containing low and high-horizontal-spatial-frequency information (contrast and resolution in the horizontal direction).

How many lines of k-space are filled per tr?

Answer: We fill in eight lines of k-space with each TR, each line going to a separate slab within k-space.

What is k-space sequence in MRI?

The k-space is an extension of the concept of Fourier space well known in MR imaging. The k-space represents the spatial frequency information in two or three dimensions of an object. The k-space is defined by the space covered by the phase and frequency encoding data.

Why is k-space useful?

In practice, k-space often refers to the temporary image space, usually a matrix, in which data from digitized MR signals are stored during data acquisition. When k-space is full (at the end of the scan) the data are mathematically processed to produce a final image. Thus k-space holds raw data before reconstruction.

What does the center of k-space contain?

As an overview, the center of k-space contains low spatial frequency information, determining overall image contrast, brightness, and general shapes. The periphery of k-space contains high spatial frequency information (edges, details, sharp transitions).

Why is the Centre of k-space usually the brightest?

There are two reasons the central area of k-space is the brightest. First, the central row (ky = 0) is acquired with no phase-encoding gradient (and hence no destructive wave interference caused by phase-encoding steps). Secondly, the central column of k-space (kx = 0) coincides with the peak of the MR echo.