Alignment - Video Lesson

Hey, everybody. Welcome to today's lesson about the basic principles of MRI. This lesson focuses on nuclear alignment, how the magnetic moments of hydrogen nuclei create the net magnetization vector or NMV, and how thermal equilibrium and alignment work together to generate the signal read by the MRI scanner. Outside of an MRI scanner, the magnetic moments of hydrogen nuclei in your body are oriented in random directions. However, when placed inside of an MRI scanner and exposed to the static magnetic field b sub zero, these magnetic moments will align with the magnetic field. There are only two directions the magnetic moments can go when exposed to b sub zero. Some of the magnetic moments will align in the same direction as b sub zero, and some will align in the opposite direction. The magnetic moments that align with b sub zero are said to be in parallel alignment. These magnetic moments belong to low energy nuclei, also called spin up.