Abstract
Aims: Using conventional chest X-ray imaging it is hardly possible to visualize early stages of emphysema. The aim of this study was to evaluate whether mild to moderate emphysema can be diagnosed in vivo using X-ray dark-field radiography.
Materials/Methods: Female C57Bl/6N mice were used for the experiments. Emphysema was induced by orotracheal injection of elastase. Control mice received orotracheal injection of PBS. To ensure the development of different stages of emphysema anesthetized and freely breathing mice were scanned 7, 14 and 21 days after application of elastase or PBS. Images were acquired with a prototype grating-based small animal scanner and processed using Fourier decomposition to generate transmission as well as dark-field radiographs. In vivo pulmonary function tests were performed before sacrificing the animals. Lungs were obtained for further histopathological analysis (e.g. mean cord length (MCL-) quantification). Three blinded readers, all of them experienced radiologists who are familiar with dark-field imaging, were asked to stage the severity of emphysema for dark-field and transmission images.
Results: As confirmed by MCL-quantifications lungs in the elastase group had developed different stages of emphysema. Correlation of MCL and dark-field signal intensity (r=0,86) was significantly better than correlation of MCL and transmission signal intensity (r=0,37). Visual ratings for dark-field intensity correlated better with MCL (r=0,82) than those for transmission images (r=0,55).
Conclusion: Using X-ray dark-field radiography it is possible to visualize and diagnose mild to moderate emphysema in vivo with a conventional imaging method for the first time.
- © 2014 ERS
