Imaging for Physicists

What is k-space?

• ‘k’ is wave-number: number of cycles per unit distance  Spatial analogue to ‘cycles per second’ (frequency) • k-space is the raw data  An array of numbers whose FT is the MR image • Each row in k-space corresponds to the echo data obtained from a single application of the PE gradient  Rows near centre correspond to low-order PE steps (small gradients)  Rows at edges correspond to high-order steps