ABSTRACT
Ironically, the nuclear spin polarizations at these high magnetic elds are really tiny because thermal spin polarizations are determined by the Boltzmann factor e-hµ/kBT, where T is the temperature and ν the magnetic transition frequency. Here h (6.6266 × 10−34 J/s) is Planck’s constant and kB (1.38 × 10−23 J/K) is Boltzmann’s constant. e magnetic transition frequencies are radio frequencies (RF) and range from 108 to 109 Hz in MRI. e resulting polarizations are approximately 10−6 to 10−5 only.
