X-ray specks: low dosein vivoimaging of lung structure and function

Abstract

Respiratory health is directly linked to the structural and mechanical properties of the airways of the lungs. For studying respiratory development and pathology, the ability to quantitatively measure airway dimensions and changes in their size during respiration is highly desirable. Real-time imaging of the terminal airways with sufficient contrast and resolution during respiration is currently not possible. Herein we reveal a simple method for measuring lung airway dimensions in small animals during respiration from a single propagation-based phase contrast x-ray image, thereby requiring minimal radiation. This modality renders the lungs visible as a speckled intensity pattern. In the near-field regime, the size of the speckles is directly correlated with that of the dominant length scale of the airways. We demonstrate that Fourier space quantification of the speckle texture can be used to statistically measure regional airway dimensions at the alveolar scale, with measurement precision finer than the spatial resolution of the imaging system. Using this technique we discovered striking differences in developmental maturity in the lungs of rabbit kittens at birth.

CT dose reduction factors in the thousands using X-ray phase contrast

“…Image dimensions: 3.83 mm × 3.83 mm. Dark regions are cross-sections through the airways including large bronchioles and alveoli (~160 μm diameter 28 ). TIE-Hom retrieval has been employed for all but the top row of data.…”

High-resolution short-exposure small-animal laboratory x-ray phase-contrast tomography

“…Such data is valuable for improved multiscale lung modelling30 and quantitative measures of, e.g., surface areas and alveolar density may be extracted for a better understanding of the state of the healthy and diseased lung without the need for classical histology31. It also allows for a detailed assessment of the structural changes associated with, e.g., pathological states or lung development, as presently demonstrated by synchrotron-based experiments with high dose263233. In addition, CO 2 angiography of tumor microvasculature may become important in angiogenesis research34.…”

Laryngeal closure impedes non-invasive ventilation at birth

“…High-resolution PC X-ray imaging was used to visualise the larynx 15 using an ORCA Flash 4.0 Hamamatsu C11440-22C (effective pixel size 15.3 µm, 2048×2048 pixels) located 2 m downstream of the pups. 16 17 …”