Variable Flip Angle - Video Lesson

Hey, everybody. Welcome to today's lesson on pulse sequences. This lesson will focus on the differences between spin echo and gradient echo pulse sequences, in particular, the variable flip angle. Understanding the differences between pull sequences is key for knowing the parameters to set during a given scan. Let's get started with the differences between spin echo and gradient echo pull sequences. The biggest difference between spin echo pull sequences and gradient echo pull sequences is length. Gradient echo pulse sequences are much shorter than spin echo pulse sequences. Let's find out why. Remember, spin echo pulse sequences are characterized by the use of a ninety degree excitation RF pulse and a one hundred eighty degree rephrasing RF pulse to generate an echo, which is the signal read out to create the MRI image. The one hundred eighty degree rephrasing RF pulse rephrases the magnetic moments of the hydrogen nuclei and is useful for when we need to correct inhomogeneities within the magnetic