3D Diffraction Tomography for Visualization of Contrast Media

摘要

In x-ray CT, the ability to selectively isolate a contrast agent signal from the surrounding soft tissue and bone can greatly enhance contrast visibility and enable quantification of contrast concentration. We present here a 3D diffraction tomography implementation for selectively retaining volumetric diffraction signal from contrast agent particles that are within a banded size range while suppressing the background signal from soft tissue and bone. For this purpose, we developed a CT implementation of a single-shot x-ray diffraction imaging technique utilizing gratings. This technique yields both diffraction and absorption images from a single grating-modulated projection image through analysis in the spatial frequency domain. A solution of iron oxide nano-particles, having very different x-ray diffraction properties from tissue, was injected into ex vivo chicken wing and in vivo rat specimens respectively and imaged in a 3D diffraction CT setup. Following parallel beam reconstruction, it is noted that while the soft tissue, bone and contrast media are observed in the absorption volume reconstruction, only the contrast media is observed in the diffraction volume reconstruction. This 3D diffraction tomographic reconstruction permits the visualization and quantification of the contrast agent isolated from the soft tissue and bone background.