RESUMEN

Stereomicroscopic observations of thick sections, or three-dimensional (3-D) reconstructions from serial sections, have provided insights into histopathology. However, they generally require time-consuming and laborious procedures. Recently, we have developed a new algorithm for refraction-based X-ray computed tomography (CT). The aim of this study is to apply this emerging technology to visualize the 3-D structure of a high-grade ductal carcinomas in situ (DCIS) of the breast. The high-resolution two-dimensional images of the refraction-based CT were validated by comparing them with the sequential histological sections. Without adding any contrast medium, the new CT showed strong contrast and was able to depict the non-calcified fine structures such as duct walls and intraductal carcinoma itself, both of which were barely visible in a conventional absorption-based CT. 3-D reconstruction and virtual endoscopy revealed that the high-grade DCIS was located within the dichotomatous branches of the ducts. Multiple calcifications occurred in the necrotic core of the continuous DCIS, resulting in linear and branching (casting type) calcifications, a hallmark of high-grade DCIS on mammograms. In conclusion, refraction-based X-ray CT approaches the low-power light microscopic view of the histological sections. It provides high quality slice data for 3-D reconstruction and virtual ductosocpy.

Asunto(s)

Asunto(s)

RESUMEN

Diabetes mellitus increases the risk of cerebrovascular disease, the effects of hypercapnia on CBF (cerebral blood flow) and cerebrovascular reactivity during diabetes are still inconsistent. Here, we have established a new microangiographic technique using synchrotron radiation (SPring-8, Japan), which enabled us to visualize rat cerebral vessels with high spatial resolution in real time. The goal of the study presented here was to identify the effects of chronic hyperglycemia on hypercapnia-induced vascular responses (endothelium-dependent vasodilatation) and nitric oxide (NO) donor- induced vascular responses (endothelium-independent) of perforating arteries and of the deeply located large cerebral arteries. We found a significant vasodilatation of rat perforating arteries after hypercapnia with a maximum diameter of approximately 140% of baseline in normal Wistar rats. Chronic hyperglycemia impaired vasodilatation of perforating arteries in genetically diabetic GK rats. SNP (sodium nitroprusside) caused a similar vasodilatation of perforating vessels in normal and chronic hyperglycemia, indicating that endothelium-dependent vasodilatation of perforating arteries may be specifically impaired in chronic hyperglycemia. Possible impairment of endothelium-dependent vasodilatation in perforating vessels during chronic hyperglycemia may cause decreased vascular reserve capacity of perforating artery, resulting in the increased ischemic insults and cerebrovascular diseases in diabetes.

Asunto(s)

RESUMEN

We simulated refraction contrast imaging in overlapping objects using the ray tracing method. The easiest case, in which two columnar objects (blood vessels) with a density of 1.0 [g/cm3], run at right angles in air, was calculated. For absorption, we performed simulation using the Snell law adapted to the object's boundary. A pair of bright and dark spot results from the interference of refracted X-rays where the blood vessels crossed. This has the possibility of increasing the visibility of the image.

Asunto(s)

RESUMEN

PURPOSE: We discuss the usefulness of the refraction contrast method using highly parallel X-rays as a new approach to minute lung cancer detection. The advantages of refraction contrast images are discussed in terms of contrast, and a comparison is made with absorption images. MATERIALS AND METHODS: We simulated refraction contrast imaging using globules with the density of water in air as models for minute lung cancer detection. The contrast intensified by bright and dark lines was compared on a globule with the contrast of absorption images. We adopted the Monte Carlo simulation to determine the strength of the profile curve of the photon counts at the detector. RESULTS: The obtained contrasts were more intense by two to three digits than those obtainable with the absorption contrast imaging method. CONCLUSION: The contrast in refraction contrast imaging was more intense than that obtainable with absorption contrast imaging. A two to three digit improvement in contrast means that it is possible to greatly reduce the exposure dose necessary for imaging. Therefore, it is expected to become possible to detect the interfaces of soft tissues, which are difficult to capture with conventional absorption imaging, at low dosages and high resolution.

Asunto(s)

RESUMEN

In this study, we observed bone specimens of the mouse using a very high coherence beam and high spatial resolution detector (zooming tube: approximately 0.7 micron resolution) and successfully obtained images of the Haversian canal, osteocytes, and osteoclasts.

Asunto(s)

RESUMEN

We developed micro blood vessel diameter measurement algorithm for angiography using refraction contrast by monochromatic X-ray of the 3rd generation synchrotron radiation with the high degree parallel beam. The accuracy is evaluated using the actually obtained image.

Asunto(s)