chapter  14
Optical Pumping and MRI of Hyperpolarized Spins
ByXizeng Wu, Thomas Nishino, Hong Liu
Pages 32

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.