k-space explained for MRI technologists
k-space is where the scanner collects the image data. A few facts about it explain scan time, contrast timing and several artifacts.
k-space: where the image is collected
The scanner does not collect the picture pixel by pixel. It fills a grid of raw data called k-space, one line per phase-encoding step, and converts the whole grid into the image at the end. The centre of the grid holds contrast and overall brightness. The edges hold fine detail and sharp borders. Every point of k-space contributes to every pixel.
One bad line (a spike) spoils the whole image. Skipping the edges saves time and costs sharpness. The moment the centre is collected decides the contrast: that is why bolus timing aims at the centre, and why the effective TE in FSE is the echo placed there.
This page is one entry from the MRI Technologist Reference
The full reference has 31 protocols, 9 dynamic study timelines, 19 artifacts, 16 scanner problems and 15 safety topics, as a PDF in English and Arabic plus an interactive tool.
Educational reference. It does not replace your site protocols, the radiologist's instructions, the MR safety officer, or the manufacturer's instructions for any implant, device or contrast agent. Parameter values are typical starting points at 1.5 T and must be adapted to the scanner, coil and patient.