Larmor frequency

low angle view of lighting equipment on shelf
  • Each MR active nucleus spins on its own axis
  • When put in an external magnetic field, it develops a secondary spin. This is called precession
  • Magnetic moments of the MR active nucleus follows a circular path around the external magnetic field
  • The speed with which the moments spin around the magnetic field is called the precessional or Larmor frequency
  • Frequency expressed in MHz
  • It is a product of gyromagnetic ratio and strength of external field
  • Gyromagnetic ratio at 1 T = 42.57 MHz/T