In the first studies in humans, the 3He gas was Helium is an inert, non-radioactive, noble gas. directly inhaled from the glass cell or via a mouth 3He is a rare isotope with a nuclear spin c. As it tip or plastic bag [2, 3]. The estimated inhaled is derived from tritium decay, it is quite expensive. volume in our studies was 400–500 ml. Recently, Non-polarized 3He costs 100–150 US$. Advanwe developed a computer-assisted application tages for applications in humans are: negligible system which is compatible with spontaneous solubility in water or blood, no adverse effects — breathing, assisted or mechanical ventilation. The widely used in deep-sea diving (80% He, 20% lungs can be flushed with 4He or 2 to avoid 2 risk of asphyxia due to lack of oxygen direct contact between the hyperpolarized 3He and when pure 3He is used. 2 , and exact volumes of the hyperpolarized 3He Hyperpolarization of 3He is an elegant approach can be administered. to overcome the difficulties of low spin density in 3He imaging has been implemented on a comthe airspaces when administered as an ‘‘inhalant mercially available MR scanner (Magnetom contrast agent’’ [1]. The non-equilibrium polarizVision, 1.5 T, Siemens Medical Systems, Erlangen, ation of 3He, five magnitudes above the Boltzmann Germany). Since the magnetization available for equilibrium, compensates for the 2500 times lower image formation or spectroscopy is independent of density of 3He compared with hydrogen concenthe field strength, 3He MRI will also be possible trations in tissue. Hyperpolarization of 3He is on low field systems. The broadband amplifier and achieved by direct optical pumping inducing multhe spectroscopy option are used. The Larmor tiple spin exchange collisions at low pressure (1 frequency of 3He is about 48.4 MHz at 1.5 T. The mb). For this procedure a neodynium-doped gyromagnetic moment of 3He is 1.074 compared La-Mg-Al laser (6–10 W, l=1083 nm) is used [1]. with 1.411 for protons. A dedicated coil, like a 3He absorbs the circularly polarized laser light transmit–receive Helmholtz coil (twin ring design), whereby the nuclear spin coupled by hyperfine operating at the He-frequency is necessary. The interaction to the electronic spin becomes hypersequence design deserves special attention. polarized. The degree of light utilization is about Standard automatic radiofrequency calibration 10%. The maximum polarization rate—obtained and localization protocols must be avoided. Low