What is the term used to describe the speed at which the NMV rotates around B0?

The term that describes the speed at which the net magnetization vector (NMV) rotates around the magnetic field (B0) is known as the Larmor frequency. The Larmor frequency is an important concept in magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) because it provides information about how the spins of nuclei precess in a magnetic field.

In a magnetic field, the magnetic moments of the nuclei experience torque, which causes them to precess at a specific frequency. This frequency depends on the strength of the magnetic field and the gyromagnetic ratio of the specific nuclei being examined. When a proton, for instance, is placed in a magnetic field, its precession speed is determined by these factors, and this is what we refer to as the Larmor frequency.

Understanding the Larmor frequency is crucial for the manipulation of magnetic resonance signals during MRI, as it helps define the timing of radiofrequency pulses needed to excite the protons and subsequently measure the emitted signals. This concept plays a foundational role in both the theory and practice of MRI, making it essential knowledge for anyone involved in the field.