Final answer:
In an MRI scanner, applying an x-gradient pulse leads to linear and spatial variations in the magnetic field along a sagittal plane, which allows the scanner to produce images by varying magnetic field gradients.
Step-by-step explanation:
When applying an x-gradient pulse in an MRI scanner, there are linear and spatial variations in the magnetic field along a sagittal plane. The gradients in the magnetic field are essential for spatial encoding of the MRI signals, allowing the scanner to produce images with clear resolution. For example, the sagittal plane images are obtained by varying the gradients along the x-axis, which corresponds with the left-right direction of the body when a person is in an upright, standing position. These variations in the magnetic field strength cause differences in the precession frequency of the hydrogen protons in the body, and when detected can be used to construct a two-dimensional image slice.