Purpose: To demonstrate the feasibility to quantify the lung respiratory airway in vivo with hyperpolarized xenon diffusion magnetic resonance imaging (MRI), which is able to detect mild emphysema in the rat model.
Materials and methods: The lung respiratory airways were quantified in vivo using hyperpolarized xenon diffusion MRI (7T) with eight b values (5, 10, 15, 20, 25, 30, 35, 40 s/cm2 ) in five control rats and five mild emphysematous rats, which were induced by elastase. The morphological results from histology were acquired and used for comparison.
Results: The parameters DL (longitudinal diffusion coefficient), r (internal radius), h (alveolar sleeve depth), Lm (mean linear intercept), and S/V (surface area to lung volume ratio) derived from the hyperpolarized xenon diffusion MRI in the emphysematous group showed significant differences from those in the control group (P < 0.05). Additionally, these parameters correlated well with the Lm obtained by the traditional histological sections (Pearson's correlation coefficients >0.8).
Conclusion: The lung respiratory airways can be quantified by hyperpolarized xenon diffusion MRI, showing the potential for mild emphysema diagnosis. Also, the study suggested that the hyperpolarized xenon DL is more sensitive than DT (transverse diffusion coefficient) to detect mild emphysema.
Level of evidence: 1 J. Magn. Reson. Imaging 2017;45:879-888.
Keywords: diffusion; emphysema; hyperpolarized xenon; lung; morphology; respiratory airways.
© 2016 International Society for Magnetic Resonance in Medicine.