Human pulmonary imaging and spectroscopy with hyperpolarized 129Xe at 0.2T.
OBJECTIVE
Using a novel (129)Xe polarizer with high throughput (1-2 L/hour) and high polarization (approximately 55%), our objective was to demonstrate and characterize human pulmonary applications at 0.2T. Specifically, we investigated the ability of (129)Xe to measure the alveolar surface area per unit volume of gas, S(A)/V(gas).


METHODS
Variable spin echo time (TE) gradient and radiofrequency (RF) echoes were used to obtain estimates of the lung's contribution to both T(2)* and T(2). Standard multislice ventilation images were obtained and signal-to-noise ratio (SNR) determined. Whole-lung, time-dependent measurements of (129)Xe diffusion from gas to septal tissue were obtained with a chemical shift saturation recovery (CSSR) method. Four healthy subjects were studied, and the Butler et al CSSR formalism (J Phys Condensed Matter 2002; 14:L297-L304) was used to calculate S(A)/V(gas). A single-breath version of the xenon transfer contrast (SB-XTC) method was implemented and used to image (129)Xe diffusion between alveolar gas and septal tissue. A direct comparison of CSSR and SB-XTC was performed.


RESULTS
T(2)*=135+/-29 ms amd T(2)=326.2+/-9.5 ms. Maximum SNR=36 for ventilation images from inhalation of 1L 86% (129)Xe and voxel volume =0.225 mL. CSSR analysis showed S(A)/V(gas) decreased with increasing lung volume in a manner very similar to that observed from histology measurements; however, the absolute value of S(A)/V(gas) was approximately 40% smaller than histology values. SB-XTC images in different postures demonstrate gravitationally dependent values. Initial comparison of CSSR with XTC showed fairly good agreement with expected ratios.


CONCLUSIONS
Hyperpolarized (129)Xe human imaging and spectroscopy are very promising methods to provide functional information about the lung.
Patz
Samuel
S
Center for Pulmonary Functional Imaging, 221 Longwood Avenue, Brigham and Women's Hospital, Boston, MA 02115, USA. patz@bwh.harvard.edu
Muradian
Iga
I
Hrovat
Mirko I
MI
Ruset
Iulian C
IC
Topulos
George
G
Covrig
Silviu D
SD
Frederick
Eric
E
Hatabu
Hiroto
H
Hersman
F W
FW
Butler
James P
JP
D000280:Administration, Inhalation; D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008168:Lung / Q000502:physiology*; D011653:Pulmonary Diffusing Capacity / Q000502:physiology; D014979:Xenon Isotopes / Q000737:chemistry
D014979:Xenon Isotopes