In-vivo NMR of hyperpolarized 3He in the human lung at very low magnetic fields
Résumé
We present NMR measurements of the diffusion of hyperpolarized 3He in the human lung performed at fields much lower than those of conventional MRI scanners. The measurements were made on standing subjects using homebuilt apparatus operating at 3mT. O2-limited transverse relaxation (T2 up to 15-35 s) could be measured in-vivo. Accurate global diffusion measurements have been performed in-vivo and in a plastic bag; the average apparent diffusion coefficient (ADC) in-vivo was 14.2±0.6 mm2/s, whereas the diffusion coefficient in the bag (3He diluted in N2) was 79.5±1 mm2/s. 1D ADC mapping with high SNR (~200- 300) demonstrates the real possibility of performing quality lung imaging at extremely low fields.