Premium
Advantages of parallel imaging in conjunction with hyperpolarized helium—A new approach to MRI of the lung
Author(s) -
Lee Ray F.,
Johnson Glyn,
Grossman Robert I.,
Stoeckel Bernd,
Trampel Robert,
McGuinness Georgeann
Publication year - 2006
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.20855
Subject(s) - point spread function , helium , nuclear magnetic resonance , temporal resolution , image resolution , flip angle , physics , signal to noise ratio (imaging) , magnetic resonance imaging , computational physics , chemistry , optics , atomic physics , radiology , medicine
Hyperpolarized helium ( 3 He) gas MRI has the potential to assess pulmonary function. The non‐equilibrium state of hyperpolarized 3 He results in the continual depletion of the signal level over the course of excitations. Under non‐equilibrium conditions the relationship between the signal‐to‐noise ratio (SNR) and the number of excitations significantly deviates from that established in the equilibrium state. In many circumstances the SNR increases or remains the same when the number of data acquisitions decreases. This provides a unique opportunity for performing parallel MRI in such a way that both the temporal and spatial resolution will increase without the conventional decrease in the SNR. In this study an analytical relationship between the SNR and the number of excitations for any flip angle was developed. Second, the point‐spread function (PSF) was utilized to quantitatively demonstrate the unconventional SNR behavior for parallel imaging in hyperpolarized gas MRI. Third, a 24‐channel (24ch) receive and two‐channel (2ch) transmit phased‐array system was developed to experimentally prove the theoretical predictions with 3 He MRI. The in vivo experimental results prove that significant temporal resolution can be gained without the usual SNR loss in an equilibrium system, and that the entire lung can be scanned within one breath‐hold (∼13 s) by applying parallel imaging to 3D data acquisition. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.