Animation 6.3 (Filling Methods)

This is an animation that supports Figure 6.19. It shows the difference between 2D sequential and 2D volumetric acquisitions (not to be confused with volume scans that are called 3D volumetric). There are three areas of k-space, or three chests of drawers or three slices to fill with data. On the bottom row, 2D volumetric acquisition fills k-space in the same sequence as demonstrated in Animation 6.1. A drawer is filled with data in chest of drawers 1, and then the same drawer is filled in chest of drawers 2 and then 3 in a TR period. In the next TR period, another drawer is filled in each chest of drawers. The scan is, therefore, not over until all the drawers filled for every chest of drawers. This is the most common type of acquisition and images are not displayed on the monitor until the scan is completely over. The scanner cannot display an image until all the lines have been filled. The top row shows a less common way of acquiring the data - 2D sequential filling. This method fills all the drawers or lines in chest of drawers 1, before moving on to chest of drawers 2, and these are all filled before moving onto chest of drawers 3. In this type of acquisition, image 1 is displayed very quickly, and the subsequent images are displayed sequentially, while the scan is running. It can do this because by acquiring all the lines for a particular k-space area, it is able to display an image of that slice on the monitor. This type of acquisition is often used in dynamic imaging.