What step is performed prior to frequency encoding in MRI?

Before frequency encoding is initiated in MRI, a crucial step is the application of a gradient magnetic field that is oriented along the frequency encoding direction. This step ensures that the magnetic field strength varies across the imaging volume, which allows for the differentiation of signals emitted from different locations within the body based on their frequency.

In frequency encoding, each location in the imaged area produces signals at specific frequencies corresponding to their positions. By establishing a gradient beforehand, the MRI system can assign different frequencies to different spatial locations, enabling the creation of clear and distinct images. This parameter is essential in reconstructing the image during the signal processing stage.

Other steps or phases occurring during the process either do not relate to the preparation for frequency encoding or occur afterward and would not contribute to the necessary phase of ensuring location-specific frequency differentiation. This foundational knowledge is key in understanding the sequence of operations that form successful MRI imaging techniques.