Biomedical imaging using hyperpolarized noble gas MRI: pulse sequence considerations.
Hyperpolarized noble gas MRI is a new technique for imaging of gas spaces and tissues that have been hitherto difficult to image, making it a promising diagnostic tool. The unique properties of hyperpolarized species, particularly the non-renewability of the large non-equilibrium spin polarization, raises questions about the feasibility of hyperpolarized noble gas MRI methods. In this paper, the critical issue of T1 relaxation is discussed and it is shown that a substantial amount of polarization should reach the targets of interest for imaging. We analyse various pulse sequence designs, and point out that total scan times can be decreased so that they are comparable or shorter than tissue T1 values. Pulse sequences can be optimized to effectively utilize the non-renewable hyperpolarization, to enhance the SNR, and to eliminate image artifacts. Hyperpolarized noble gas MRI is concluded to be quite feasible.
Zhao
L
L
Department of Radiology, Harvard Medical School, Boston, MA 02115, USA. malbert@bwh.harvard.edu
Albert
M S
MS
D017352:Echo-Planar Imaging; D005240:Feasibility Studies; D006371:Helium / Q000097:blood / Q000493:pharmacokinetics; D006801:Humans; D007089:Image Enhancement; D007554:Isotopes; D008168:Lung / Q000033:anatomy & histology / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000379:methods*; D005741:Noble Gases / Q000097:blood / Q000493:pharmacokinetics; D013997:Time Factors; D014978:Xenon / Q000097:blood / Q000493:pharmacokinetics; D014979:Xenon Isotopes
D007554:Isotopes; D005741:Noble Gases; D014979:Xenon Isotopes; D006371:Helium; D014978:Xenon