Posture-dependent human 3He lung imaging in an open-access MRI system: initial results.
OBJECTIVE
The human lung and its functions are extremely sensitive to orientation and posture, and debate continues as to the role of gravity and the surrounding anatomy in determining lung function and heterogeneity of perfusion and ventilation. However, study of these effects is difficult. The conventional high-field magnets used for most hyperpolarized (3)He magnetic resonance imaging (MRI) of the human lung, and most other common radiologic imaging modalities including positron emission tomography and computed tomography, restrict subjects to lying horizontally, minimizing most gravitational effects.


METHODS
In this article, we review the motivation for posture-dependent studies of human lung function and present initial imaging results of human lungs in the supine and vertical body orientations using inhaled hyperpolarized (3)He gas and an open-access MRI instrument. The open geometry of this MRI system features a "walk-in" capability that permits subjects to be imaged in vertical and horizontal positions and potentially allows for complete rotation of the orientation of the imaging subject in a two-dimensional plane.


RESULTS
Initial results include two-dimensional lung images acquired with approximately 4 x 8 mm in-plane resolution and three-dimensional images with approximately 2-cm slice thickness.


CONCLUSIONS
Effects of posture variation are observed, including posture-related effects of the diaphragm and distension of the lungs while vertical.
Tsai
Leo L
LL
Harvard-Smithsonian Center for Astrophysics, 60 Garden St, MS 59, Cambridge, MA 02138, USA.
Mair
Ross W
RW
Li
Chih-Hao
CH
Rosen
Matthew S
MS
Patz
Samuel
S
Walsworth
Ronald L
RL
D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D004867:Equipment Design; D006371:Helium; D006801:Humans; D007554:Isotopes; D008168:Lung / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008875:Middle Aged; D011187:Posture / Q000502:physiology*
D007554:Isotopes; D006371:Helium