Final answer:
Slice-selection and phase-encoding sequences are important steps in MRI imaging, used to select specific slices and encode spatial information, respectively.
Step-by-step explanation:
In magnetic resonance imaging (MRI), slice-selection and phase-encoding sequences are crucial steps in the imaging process.
Slice-selection is the process of selecting a specific slice of an object to be imaged. It involves applying a magnetic field gradient to excite protons in a particular plane, while suppressing those in other planes.
Phase-encoding is a technique used to encode spatial information in the phase of the MRI signal. It involves applying another magnetic field gradient to cause a phase shift in the signal of each pixel along a particular direction. By varying the strength of this gradient, different slices or sections of the object can be distinguished.