Andre Yaroshenko, Presenter: Nothing to Disclose

Astrid Velroyen, Abstract Co-Author: Nothing to Disclose

Martin Bech, Abstract Co-Author: Nothing to Disclose

Katharina Hellbach MD, Abstract Co-Author: Nothing to Disclose

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

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

Franz Pfeiffer, Abstract Co-Author: Nothing to Disclose

Recently first in vivo x-ray differential phase-contrast and dark-field radiographic images of a mouse were reported. It was noticed that the dark field yields much stronger signal for the lung tissue than the conventional absorption. The purpose of this study was to analyze how the lung dark-field signal depends on the scanning parameters like x-ray spectrum, detector pixel size and how much animal breathing affects the results.

A compact small-animal preclinical scanner, which acquires conventional x-ray absorption simultaneously with phase-contrast and dark-field images, was used to acquire projection images of an in vivo 10-week-old C57BL/6N mouse. The measurements were performed for three different spectra (35 kVp, 45 kVp and 50 kVp) and processed using different detector binning modes. During image acquisition the mouse was breathing freely. Subsequently, the mouse was sacrificed and the measurements were repeated introducing different air volumes to the lung.

The processed dark-field images revealed that the best contrast-to-noise ratio was achieved for the 35 kVp spectrum, though other spectra also yielded significant signal. The lung could be clearly visualized for all three source settings. 200 x 200 µm pixel size was considered, applying a 4 x 4 detector binning. Hereby obtained images demonstrate that dark field gives a strong signal also for clinically compatible pixel sizes. Finally, comparison of the data acquired in vivo and ex vivo showed that breathing introduces only insignificant feature blurring due to motion.

This study analyzes different acquisition parameters for lung dark-field radiographic imaging. The results show that the high contrast for lung tissue can be achieved also for higher source voltages and clinically compatible pixel sizes. Furthermore, it is demonstrated that the animal breathing affects the image quality only negligibly. The results of this study provide a rule of thumb for future choice of acquisition parameters for preclinical dark-field studies.

The results of this study give an overview of how different acquisition parameters influence the imaging results for x-ray phase-contrast and dark-field radiographs. These results are of importance for future preclinical studies.

Yaroshenko, A, Velroyen, A, Bech, M, Hellbach, K, Meinel, F, Reiser, M, Pfeiffer, F, Influence of Acquisition Parameters on in Vivo X-ray Phase-contrast and Dark-field Radiographic Imaging of Mice.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045700.html