In 2DFT imaging, what does each horizontal row in k-space represent?

In 2DFT (two-dimensional Fourier Transform) imaging, each horizontal row in k-space corresponds to the echo data collected from a single acquisition. This is because k-space is a representation of spatial frequency data, where each point in k-space corresponds to a specific phase and frequency of the signals received during the MR imaging process.

When an MR scan is performed, the signals emitted by the tissues are collected and encoded into k-space through a series of gradient fields. The horizontal rows represent the data obtained at different times during the acquisition process, aligned according to their spatial frequencies. This is crucial for reconstructing the final image, as each row contributes to specific spatial frequency information, allowing the transformation back to image space through the Fourier transform.

This concept is fundamental to understanding how MRI data is processed and how image quality can be affected by the collection of echo data during each part of the scan. The other options do not accurately describe the structure of k-space in the context of 2DFT imaging.