Katharina Hellbach MD, Presenter: Nothing to Disclose

Andre Yaroshenko, Abstract Co-Author: Nothing to Disclose

Oliver Eickelberg, Abstract Co-Author: Nothing to Disclose

Martin Bech, Abstract Co-Author: Nothing to Disclose

Maximilian F. Reiser MD, Abstract Co-Author: Nothing to Disclose

Ali Onder Yildirim, Abstract Co-Author: Nothing to Disclose

Franz Pfeiffer, Abstract Co-Author: Nothing to Disclose

Felix G. Meinel MD, Abstract Co-Author: Nothing to Disclose

The aim of this study was to evaluate whether it is possible to visualize pulmonary fibrosis in vivo using X-ray dark-field imaging and whether dark-field radiography has incremental diagnostic value in diagnosing fibrosis compared to conventional transmission images.

Pulmonary fibrosis was induced by orotracheal injection of bleomycin (2.5U/kg BW, n=6). Control mice (n=5) received orotracheal injection of PBS. All mice (female C57Bl/6N) were examined 14 days after application of bleomycin or PBS. A prototype grating-based small animal scanner was used for image acquisition. Images were processed using Fourier decomposition thus generating transmission as well as dark-field radiographs. Mice were breathing freely during image acquisition. Before sacrificing the animals pulmonary function tests were performed. Lungs were obtained for further histopathological analysis (e.g. tissue ratio).

As confirmed by histopathological analysis and pulmonary function tests mice in the bleomycin group had developed fibrosis: Tissue ratio was significantly higher for fibrotic (51.8% ± 9.6) than for control lungs (37.7% ± 1.7; p < 0.05). Dynamic compliance was significantly lower for the bleomycin (0.0121 ml/cmH2O ± 0.0022) than for the PBS group (0.0214 ml/cmH2O ± 0.0003; p < 0.001). Correspondingly, tissue elastance was significantly higher for mice suffering from fibrosis (85.0 cm H2O/ml ± 15.7) compared to healthy mice (37.7 cm H2O/ml ± 9.6; p < 0.01). Fibrotic areas within the lungs resulted in a strong decrease in dark-field signal intensity (figure1). This change in signal intensity was easier to detect in dark-field than in transmission images.

With this study we were able to show for the first time that in vivo visualization of pulmonary fibrosis is feasible using dark-field radiography. Moreover, changes in dark-field signal intensity can be detected more readily than corresponding changes in transmission signal strength.

Dark-field imaging yields a stronger contrast for lung imaging than conventional absorption and has, therefore, a high potential for pulmonary imaging. This study reveals that it is easier to detect pulmonary fibrosis relying on dark-field images, when compared to conventional absorption-based imaging. With further technical development this implies that fibrosis could be detected at early stages without the use of CT.

Hellbach, K, Yaroshenko, A, Eickelberg, O, Bech, M, Reiser, M, Yildirim, A, Pfeiffer, F, Meinel, F, In Vivo Proof of Principle: X-ray Dark-field Radiography for Diagnosis of Lung Fibrosis.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045634.html