K space

K space is an abstract concept and refers to a data matrix containing the raw MRI data. This data is subjected to mathematical function or formula called a transform to generate the final image. A discrete Fourier or fast Fourier transform 1-3 is generally used though other transforms such as the Hartley 4 can also work.

Discussion

A single slice corresponds to a k space plane acquired in real-time. Each point on the k space contains specific frequency, phase (x,y coordinates) and signal intensity information (brightness). Inverse FT is applied after k space acquisition to derive the final image. Each pixel in the resultant image is the weighted sum of all the individual points in the k-space. Hence, disruption of any point in the k-space translates into some form of final image distortion, determined by the frequency- and phase-related data stored in that particular point.  In general:

  • central regions of the k space encode contrast information
  • peripheral regions of the k space encode spatial resolution

Relevance

Knowledge of the k space is essential as it relates to different techniques of image acquisition and explains several MRI artifacts.


MRI physics
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Article Information

rID: 18820
Section: Physics
Tag: mri
Synonyms or Alternate Spellings:
  • K-Space

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