For obtaining DWI images, which sequences are typically employed?

The correct answer indicates that both echo-planar (EP) and fast gradient echo (GRE) sequences are commonly employed to obtain diffusion-weighted imaging (DWI) images. The reason for this involves the unique capabilities of these sequences to effectively capture the movement of water molecules within tissues.

Echo-planar imaging is particularly advantageous for DWI because it allows for rapid image acquisition, which is crucial in minimizing motion artifacts and capturing transient changes in the diffusion of water molecules. This is important in clinical scenarios such as assessing acute ischemic strokes, where time is critical, and the rapid imaging contributes to better patient outcomes.

Fast GRE sequences can also be used in DWI, particularly when there is a need for high-resolution images or specific contrasts. They provide a balance between acquisition speed and image quality, making them useful for certain clinical applications where diffusion characteristics of the tissue need to be evaluated.

In summary, the use of both EP and fast GRE sequences for DWI enhances the ability to visualize diffusion changes effectively, which is critical in various diagnostic situations.