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A number of phase based X-ray imaging methods have been developed that derive contrast from phase effects from the object which make them particularly interesting because of the ability to visualize soft tissues. Shack–Hartmann is a wave-front diagnostic technique that emerged from optics which uses ray-line beams (beamlets) to interrogate the differences in the wave-front across a beam can also be used for X-ray imaging applications with phase sensitivity. This method, which has been applied in the X-ray regime, is very simple in that it only requires a screen to prepare an array of beamlets that then pass through the object and are allowed to propagate a distance onto a pixelated detector. Absorption and refraction information can be extracted from the detected beamlets. An untapped property is the additional ability to extract scatter distribution information based on the observed width of the detected spots. This paper describes experiments done at a synchrotron facility investigating the use of a Shack–Hartmann system for biomedical applications and include our method and examples of scatter contrast extraction from the method. [ABSTRACT FROM AUTHOR]

Accurate evaluation of morphological changes in articular cartilage are necessary for early detection of osteoarthritis (OA). 3T magnetic resonance imaging (MRI) has highly sensitive contrast resolution and is widely used clinically to detect OA. However, synchrotron radiation phase-contrast imaging computed tomography (SR-PCI) can also provide contrast to tissue interfaces that do not have sufficient absorption differences, with the added benefit of very high spatial resolution. Here, MRI was compared with SR-PCI for quantitative evaluation of human articular cartilage. Medial tibial condyles were harvested from non-OA donors and from OA patients receiving knee replacement surgery. Both imaging methods revealed that average cartilage thickness and cartilage volume were significantly reduced in the OA group, compared to the non-OA group. When comparing modalities, the superior resolution of SR-PCI enabled more precise mapping of the cartilage surface relative to MRI. As a result, MRI showed significantly higher average cartilage thickness and cartilage volume, compared to SR-PCI. These data highlight the potential for high-resolution imaging of articular cartilage using SR-PCI as a solution for early OA diagnosis. Recognizing current limitations of using a synchrotron for clinical imaging, we discuss its nascent utility for preclinical models, particularly longitudinal studies of live animal models of OA. [ABSTRACT FROM AUTHOR]