MR Signal - Video Lesson

Hey, everybody. Welcome to today's lesson on the basic principles of MRI. This lesson focuses on how the MR signal is generated using Faraday's and Lenz's laws to explain the phenomenon. These terms sound complex, but we will break them down to make them easier to understand. Let's dive in. First, let's discuss how an MR signal is generated. When placed inside an MRI scanner, the magnetic moments of a patient's hydrogen nuclei align either with or against the magnetic field b sub zero in the longitudinal plane. The magnetic moments also precess around b sub zero. Alignment and precession are covered in detail in other lessons. A radio frequency or RF pulse set at the Larmor frequency of some of these hydrogen nuclei is applied, flipping the hydrogen nuclei into the transverse plane, causing them to precess in phase or in sync with each other. This process is called excitation.