X-ray phase-contrast imaging: from pre-clinical applications towards clinics

Abstract

Phase-contrast x-ray imaging (PCI) is an innovative method that is sensitive to the refraction of the x-rays in matter. PCI is particularly adapted to visualize weakly absorbing details like those often encountered in biology and medicine. In past years, PCI has become one of the most used imaging methods in laboratory and preclinical studies: its unique characteristics allow high contrast 3D visualization of thick and complex samples even at high spatial resolution. Applications have covered a wide range of pathologies and organs, and are more and more often performed in vivo. Several techniques are now available to exploit and visualize the phase-contrast: propagation- and analyzer-based, crystal and grating interferometry and non-interferometric methods like the coded aperture. In this review, covering the last five years, we will give an overview of the main theoretical and experimental developments and of the important steps performed towards the clinical implementation of PCI.

Clinical study in phase- contrast mammography: image-quality analysis

“…Multiple abnormalities in the same patient were evaluated independently. According to the BI-RADS classes for breast density [9], the radiologists associated each patient with a breast density score: (1) almost entirely fatty breast, (2) scattered fibroglandular densities, (3) heterogeneous dense and (4) extremely dense.…”

“…PPCI technique meets this requirement because it does not need multiple image acquisitions, as typically happens in grating-based differential phase-contrast imaging or diffraction-enhanced imaging [7]. Analyser-based imaging can be applied in single acquisition mode, but the stability constraints and the temperature drifts of the crystal analyser increase the complexity of the instrumentation and of the patient safety system [9].…”

Image-based modelling of skeletal muscle oxygenation

“…All of the mentioned experiments have been carried out ex vivo. Other experimental set-ups for grating-based interferometry and other phase-contrast imaging techniques have been reviewed by Bravin et al [115]. For ex vivo imaging with the purpose of providing image datasets for mathematical modelling on the whole-organ scale, phase-contrast SR CT can be considered as an optimal technique if access to a synchrotron facility can be obtained, due to the easy experimental set-up and simple specimen preparation requirements (fixation and potentially embedding).…”

A continuous sampling scheme for edge illumination x-ray phase contrast imaging

“…Local variations in this phase shift translate into small deviations of x-rays from their path (x-ray refraction). This can offer a promising alternative to conventional, attenuation-based x-ray imaging for the visualization of weakly attenuating specimens, due to the fact that phase effects are often stronger in this case 1 . To date, several XPCi modalities have been developed [2][3][4][5][6][7] .…”