k-space and spatial frequencies. A single point in k-space defines a spatial frequency that can be represented as a wave in image space. A point close to the centre of k-space contributes a low spatial frequency, represented by a wave with broad peaks and troughs. This provides the signal content for large regions of uniform signal in the image and therefore the image contrast. A point at the edge of k-space contributes a high spatial frequency and is represented by a fine 'toothcomb' wave. The highest spatial frequency content defines the spatial resolution limit of the image.