As I started drafting my narrative this week, I mind kept drifting to last week’s dance class. We had just begun learning a new thillana, a highly rhythmic classical piece that demands precise timing and synchronization. What’s fascinating about these kinds of pieces is that they demand a level of stamina where we live in between moments of control and abandon.
Driven to better understand this “in between” state in physics, I delved a bit more into the role of radio frequency pulses, which are short bursts of energy sent to disturb the precessing protons, once the patient is in the scanner. Yet, only certain radio frequency pulses excite, or rather perturb, the alignment of the protons - that is, there needs to be an exchange of energy between the pulse and the proton(s) of interest. It’s the difference between exchanging glances with someone and pushing someone to the point where they lose their balance. In the latter case, your alignment would be disturbed. However, for any energy exchange to occur, the pulse and the precessing protons must have the same frequency. When this happens, some of these protons are taken to a higher energy level (facing down, as opposed to facing up), and now, the longitudinal magnetization along the z-axis decreases.
So, in my piece, I would have one arm of the dancer represent the longitudinal magnetization (z-axis), while the other representing the transversal magnetization (x-y axis) in their invisible Cartesian coordinate system - and to show that there are multiple protons, I may have the dancer change the positioning of their arms.