Lung Morphometry Using Hyperpolarized 129Xe Apparent Diffusion Coefficient Anisotropy in Chronic Obstructive Pulmonary Disease

PurposeThe goal of this work was to investigate lung morphological changes associated with chronic obstructive pulmonary disease (COPD) using hyperpolarized Xe-129 diffusion-weighted MRI. MethodsHyperpolarized Xe-129 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 (L-m), and depth of alveolar sleeve (h). ResultsLongitudinal (D-L) and transverse (D-T) 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 mu m vs. 95 +/- 710 mu m, respectively, P = 0.019) and increases in L-m (352 +/- 57 mu m vs. 253 +/- 37 mu m, respectively, P = 0.002) consistent with values obtained previously using hyperpolarized He-3 MRI in similar subjects. ConclusionsDiffusion-weighted hyperpolarized Xe-129 MRI is a promising technique for mapping changes in human lung morphology and may be useful for early detection of emphysema associated with COPD. Magn Reson Med 70:1699-1706, 2013. (c) 2013 Wiley Periodicals, Inc.