Tiqiao Xiao

Measurement of the linear attenuation coefficients of breast tissues by synchrotron radiation computed tomography.

The measurement of the linear attenuation coefficients of breast tissues is of fundamental importance in the field of breast x-ray diagnostic imaging. Different groups have evaluated the linear attenuation coefficients of breast tissues by carrying out direct attenuation measurements in which the specimens were thin and selected as homogeneous as possible. Here, we use monochromatic and high-intensity synchrotron radiation computed tomography (SR CT) to evaluate the linear attenuation coefficients of surgical breast tissues in the energy range from 15 to 26.5 keV. X-ray detection is performed by a custom digital silicon micro-strip device, developed in the framework of the PICASSO INFN experiment. Twenty-three human surgical breast samples were selected for SR CT and histological study. Six of them underwent CT, both as fresh tissue and after formalin fixation, while the remaining 17 were imaged only as formalin-fixed tissues. Our results for fat and fibrous tissues are in good agreement with the published values. However, in contrast to the published data, our measurements show no significant differences between fibrous and tumor tissues. Moreover, our results for fresh and formalin-fixed tissues demonstrate a reduction of the linear attenuation coefficient for fibrous and tumor tissues after fixation.

Lung cancer and angiogenesis imaging using synchrotron radiation

Early detection of lung cancer is the key to a cure, but a difficult task using conventional x-ray imaging. In the present study, synchrotron radiation in-line phase-contrast imaging was used to study lung cancer. Lewis lung cancer and 4T1 breast tumor metastasis in the lung were imaged, and the differences were clearly shown in comparison to normal lung tissue. The effect of the object-detector distance and the energy level on the phase-contrast difference was investigated and found to be in good agreement with the theory of in-line phase-contrast imaging. Moreover, 3D image reconstruction of lung tumor angiogenesis was obtained for the first time using a contrast agent, demonstrating the feasibility of micro-angiography with synchrotron radiation for imaging tumor angiogenesis deep inside the body.

Microvascular imaging using synchrotron radiation.

In vascular diseases, the involvement of small vessels can be very crucial physiologically. Morphological changes of vasculature and alterations may be promising characteristic criteria for investigating disease progression and for evaluating therapeutic effects. Visualization of microvasculatures is an important step in understanding the mechanism of early vessel disorders and developing effective therapeutic strategies. However, the microvessels involved are beyond the detection limit of conventional angiography, i.e. 200 microm. Thus, faster and higher-resolution imaging technologies are desired to capture the early anatomical structure changes of vasculatures in study of the disease. A new angiography system, synchrotron radiation microangiography, has been developed in this study. It allows for enhanced sensitivity to contrast agents and superior image quality in spatial resolution. Iodine and barium sulfate were used as blood vessel contrast agents. Physiological features of whole-body mouse microvasculature were investigated using synchrotron radiation for the first time. The intracranial vascular network and other blood vessels were observed clearly, and the related anatomy and vessel diameters were studied. Dynamic angiography in mouse brain was performed with a high spatial image resolution of around 20-30 microm. Future research will focus on the development of novel specific targeting contrast agents for blood vessel imaging in vivo with a long half-life and fewer side effects.

X-ray Imaging for Non-Destructive Microstructure Analysis at SSRF

The X-ray imaging beamline at the Shanghai Synchrotron Radiation Facility is aimed at developing and evaluating the effectiveness of synchrotron radiation (SR)-based imaging techniques in planar or computed tomography modalities. Several X-ray imaging methods are in use and find extensive applications in many research fields. In this Essay, the status of the methodology development at the beamline is discussed and applications are reviewed.

Application of x-ray phase contrast imaging to microscopic identification of Chinese medicines

In the last decade, x-ray phase contrast imaging (XPCI) has received considerable attention as a novel imaging technique, which has proved to be suitable for weakly absorbing materials such as biomedical samples and polymers. In this paper, the microstructures of traditional Chinese medicines (TCMs), which are used as judging criteria in the identification of TCMs, were investigated by XPCI based on a nano-focus x-ray tube. The results demonstrated that XPCI is a promising new method for the identification of TCMs, with advantages such as nondestructivity, no special sample preparation and suitability for thick samples.

Development of functional in vivo imaging of cerebral lenticulostriate artery using novel synchrotron radiation angiography.

The lenticulostriate artery plays a vital role in the onset and development of cerebral ischemia. However, current imaging techniques cannot assess the in vivo functioning of small arteries such as the lenticulostriate artery in the brain of rats. Here, we report a novel method to achieve a high resolution multi-functional imaging of the cerebrovascular system using synchrotron radiation angiography, which is based on spatio-temporal analysis of contrast density in the arterial cross section. This method provides a unique tool for studying the sub-cortical vascular elasticity after cerebral ischemia in rats. Using this technique, we demonstrated that the vascular elasticity of the lenticulostriate artery decreased from day 1 to day 7 after transient middle cerebral artery occlusion in rats and recovered from day 7 to day 28 compared to the controls (pxa0<xa00.001), which paralleled with brain edema formation and inversely correlated with blood flow velocity (pxa0<xa00.05). Our results demonstrated that the change of vascular elasticity was related to the levels of brain edema and the velocity of focal blood flow, suggesting that reducing brain edema is important for the improvement of the function of the lenticulostriate artery in the ischemic brain.

High Resolution X‐Ray Microangiography of 4T1 Tumor in Mouse Using Synchrotron Radiation

Angiogenesis is very important in tumor growth and metastasis. But in clinic, only vessels lager than 200 μm in diameter, can be observed using conventional medical imaging. Synchrotron radiation (SR) phase contrast imaging, whose spatial resolution can reach as high as 1 μm, has great advantages in imaging soft tissue structures, such as blood vessels and tumor tissues. In this paper, the morphology of newly formed micro‐vessels in the mouse 4T1 tumor samples was firstly studied with contrast agent. Then, the angiogenesis in nude mice tumor window model was observed without contrast agent using the SR phase contrast imaging at the beamline for X‐ray imaging and biomedical applications, Shanghai Synchrotron Radiation Facility (SSRF). The images of tumors showed dense, irregular and tortuous tumor micro‐vessels with the smallest size of 20–30 μm in diameter.