How many TR periods occur in a spin echo pulse sequence if 200 phase encoding steps are selected?

How many TR periods occur in a spin echo pulse sequence if 200 phase encoding steps are selected?

• A. 100
• B. 200
• C. 300
• D. 400

Answer: (B)

In a spin echo pulse sequence, the time between successive radiofrequency (RF) pulse applications is defined as the repetition time (TR). Each TR period typically corresponds to a full cycle of image acquisition for one slice of the anatomy being imaged. When 200 phase encoding steps are utilized, each step is associated with a unique phase shift that allows for the reconstruction of an image with higher resolution along one axis. In general, each phase encoding step necessitates a complete TR period to acquire that particular piece of data while maintaining other parameters consistent. Therefore, for 200 distinct phase encoding steps, there will typically be one TR period for each of these steps, leading to a direct correlation where the number of TR periods equals the number of phase encoding steps. This results in a total of 200 TR periods required to adequately capture the necessary data for the image being generated.

In a spin echo pulse sequence, the time between successive radiofrequency (RF) pulse applications is defined as the repetition time (TR). Each TR period typically corresponds to a full cycle of image acquisition for one slice of the anatomy being imaged.

When 200 phase encoding steps are utilized, each step is associated with a unique phase shift that allows for the reconstruction of an image with higher resolution along one axis. In general, each phase encoding step necessitates a complete TR period to acquire that particular piece of data while maintaining other parameters consistent.

Therefore, for 200 distinct phase encoding steps, there will typically be one TR period for each of these steps, leading to a direct correlation where the number of TR periods equals the number of phase encoding steps. This results in a total of 200 TR periods required to adequately capture the necessary data for the image being generated.