Evaluation of phase-contrast CT of breast tissue at conventional X-ray sources - presentation of selected findings

Background: Grating-based phase contrast computed tomography (PC-CT) at synchrotron radiation sources has been shown to provide improved visualization of breast tumors. However, broad clinical application of phase-contrast imaging will likely depend on transferring the technology to standard polychromatic X-ray sources. On the basis of selected findings, we demonstrate the potential of grating-based PC-CT using a conventional X-ray source.

Materials and methods: Grating-based PC-CT of two ex-vivo formalin fixed breast specimens containing lobular carcinoma was conducted using a Talbot Lau interferometer run at a polychromatic X-ray source of 40kVp. Phase-contrast and absorption-based 3D-datasets of both specimens were simultaneously recorded. Radiological images were manually matched with corresponding histological sections. The visualization of selected histological findings in phase contrast was compared to absorption contrast.

Results: Grating-based PC-CT was able to depict the 3-dimensional structure of dilated ducts and high phase contrast was found as a correlate to thickened fibrous ductal walls. Differences in contrast between fibrous and less fibrous breast tissue were observed in phase- but not in absorption-contrast images. Furthermore, regions of low phase contrast correlated with the extension of compact tumor components.

Conclusions: On the basis of selected findings, we show that grating-based PC-CT at a polychromatic X-ray source provides complementary information to conventional absorption contrast; albeit at lower spatial resolution than synchrotron-based imaging.