Precession and Precessional Frequency - Video Lesson

Hey, everybody. Welcome to today's lesson about the basic principles of MRI. This lesson focuses on precession, the gyromagnetic ratio, the Larmor equation, and the Larmor frequency. Understanding these concepts will allow you to understand how we are able to specifically target hydrogen nuclei as opposed to other MR active nuclei during an MRI scan. First, let's discuss precession. We know that hydrogen nuclei spin on their axis. When exposed to b sub zero, the magnetic moments of the hydrogen nuclei have an additional motion. They wobble around b sub zero. This wobbling motion is called precession. The precession of the magnetic moment is a secondary motion to the spinning of the hydrogen nucleus. The path of the wobble or precession is called the precessional path. When exposed to b sub zero, none of the magnetic moments are in the same place along their precessional paths. This means