TY  - JOUR
AU  - Acosta, R. H.
AU  - Blümler, P.
AU  - Agulles-Petrós, L.
AU  - Morbach, A. E.
AU  - Schmiedeskamp, J.
AU  - Herweling, A.
AU  - Wolf, U.
AU  - Scholz, A.
AU  - Schreiber, W. G.
AU  - Heil, W.
AU  - Thelen, M.
AU  - Spies, H.-W.
TI  - Controlling diffusion of 3He by buffer gases: a structural contrast agent in lung MRI
JO  - Journal of magnetic resonance imaging
VL  - 24
SN  - 1053-1807
CY  - New York, NY
PB  - Wiley-Liss
M1  - PreJuSER-47111
SP  - 1291 - 1297
PY  - 2006
N1  - Record converted from VDB: 12.11.2012
AB  - To study the influence of admixing inert buffer gases to laser-polarized (3)He in terms of resulting diffusion coefficients and the consequences for image contrast and resolution.The diffusion coefficient of (3)He was altered by admixing buffer gases of various molecular weights ((4)He, N(2), and SF(6)). The influence of the pulse sequence and the diffusion coefficient on the appearance of MRI of (laser-polarized) gases was analyzed by comparison of basic theoretical concepts with demonstrative experiments.Excellent agreement between theoretical description and observed signal in simple gradient echoes was observed. A maximum signal gain can be predicted and was experimentally validated. Images acquired under such conditions revealed improved resolution. The nature and concentration of the admixed gas defines a structural threshold for the observed apparent diffusion coefficient (ADC) as demonstrated with diffusion-weighted MRI on a pig's lung flooded with suitable gas mixtures.A novel procedure is proposed to control the diffusion coefficient of gases in MRI by admixture of inert buffer gases. Their molecular mass and concentration enter as additional parameters into the equations that describe structural contrast. This allows for setting a structural threshold up to which structures contribute to the image. For MRI of the lung this enables images of very small structural elements (alveoli) only, or in the other extreme, all airways can be displayed with minimal signal loss due to diffusion.
KW  - Contrast Media: chemistry
KW  - Diffusion Magnetic Resonance Imaging: instrumentation
KW  - Diffusion Magnetic Resonance Imaging: methods
KW  - Gases: chemistry
KW  - Gases: diagnostic use
KW  - Helium: chemistry
KW  - Helium: diagnostic use
KW  - Humans
KW  - Image Enhancement: methods
KW  - Isotopes: chemistry
KW  - Isotopes: diagnostic use
KW  - Lung: anatomy & histology
KW  - Lung: chemistry
KW  - Phantoms, Imaging
KW  - Reproducibility of Results
KW  - Sensitivity and Specificity
KW  - Contrast Media (NLM Chemicals)
KW  - Gases (NLM Chemicals)
KW  - Isotopes (NLM Chemicals)
KW  - Helium (NLM Chemicals)
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
C6  - pmid:17078046
UR  - <Go to ISI:>//WOS:000242562000012
DO  - DOI:10.1002/jmri.20777
UR  - https://juser.fz-juelich.de/record/47111
ER  -