Table 1.

NMR properties and predicted sensitivity of ²³Na MRI in tissue relative to ¹H.

	1H MRI in tissue	23Na MRI in tissue
Magnetic moment (in nuclear magnetons)	2.7927	2.2161
Spin quantum number	1/2	3/2
NMR frequency @ 1 Tesla	42.577	11.262
Sensitivity* @ constant field per nucleus ∝ υ3I(I+1)	1	0.0925
Relative SNR at constant B0/nucleus*	1	0.35
In vivo concentration (mol/kg)	42.8	0.04
In vivo conc. of nucleus (mol/kg)	85.6	0.04
SNR of moiety in tissue	85.6	0.014
SNR relative to 1H of tissue water†	1	1.64 × 10−4

^*υ =NMR frequency,

I =nuclear spin quantum number.

^†Assumes SNR ∝ υ¹.