Lung morphometry using hyperpolarized (129) Xe apparent diffusion coefficient anisotropy in chronic obstructive pulmonary disease.
OBJECTIVE
The goal of this work was to investigate lung morphological changes associated with chronic obstructive pulmonary disease (COPD) using hyperpolarized (129) Xe diffusion-weighted MRI.


METHODS
Hyperpolarized (129) Xe MRI was performed at three different nonzero diffusion sensitizations (b-value = 12, 20, and 30 s/cm(2) ) in the lungs of four subjects with COPD and four healthy volunteers. The image signal intensities were fit as a function of b-value to obtain anisotropic diffusion coefficient maps for all subjects. The image signal intensities were also fit to a morphological model allowing extraction of length scales associated with the terminal airways: external radius (R), internal radius (r), mean airspace chord length (Lm ), and depth of alveolar sleeve (h).


RESULTS
Longitudinal (DL ) and transverse (DT ) anisotropic diffusion coefficients were both significantly increased (both P= 0.004) in the COPD subjects (0.102 ± 0.02 cm(2) /s and 0.072 ± 0.02 cm(2) /s, respectively) compared with the healthy subjects (0.083 ± 0.011 cm(2) /s and 0.046 ± 0.017 cm(2) /s, respectively). Significant morphological differences were observed between the COPD subjects and healthy volunteers, specifically decreases in h (68 ± 36 µm vs. 95 ± 710 µm, respectively, P = 0.019) and increases in Lm (352 ± 57 µm vs. 253 ± 37 µm, respectively, P = 0.002) consistent with values obtained previously using hyperpolarized (3) He MRI in similar subjects.


CONCLUSIONS
Diffusion-weighted hyperpolarized (129) Xe MRI is a promising technique for mapping changes in human lung morphology and may be useful for early detection of emphysema associated with COPD.
Ph.D., Imaging Research Laboratories, Robarts Research Institute, Western University, London, Ontario, Canada.
Alexei
A
Ouriadov
Adam
A
Farag
Miranda
M
Kirby
David G
DG
McCormack
Grace
G
Parraga
Giles E
GE
Santyr
D000368:Aged; D000465:Algorithms; D016880:Anisotropy; D003287:Contrast Media; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008168:Lung / Q000473:pathology*; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014979:Xenon Isotopes
D003287:Contrast Media; D014979:Xenon Isotopes
ADC; anisotropy; hyperpolarized; lung; morphometry; xenon-129