Visualization of microvascular proliferation as a tumor infiltration structure in rat glioma specimens using the diffraction-enhanced imaging in-plane CT technique.

In order to study potent microenvironments of malignant gliomas with a high- resolution x-ray imaging technique, an injection orthotopic glioma model was made using the Sprague-Dawley rat. Total brain tissue, taken out as an ex vivo model, was examined with diffraction-enhanced imaging (DEI) computed tomography (CT) acquired with a 35 keV monochromatic x-ray. In the convolution-reconstructed 2D/3D images with a spatial resolution of 12.5 × 12.5 × 25 µm, distinction among necrosis, typical ring-shaped viable tumors, edemas and healthy tissues was clearly observed near the frontal lobe in front of the rat's caudate nucleus. Multiple microvascular proliferations (MVPs) were observed surrounding peritumoral edemas as a tumor infiltration structure. Typical dimensions of tubular MVPs were 130 (diameter) ×250 (length) µm with a partial sprout structure revealed in the 3D reconstructed image. Hyperplasia of cells around vessel walls was revealed with tumor cell infiltration along the perivascular space in microscopic observations of mild MVP during histological analysis. In conclusion, DEI-CT is capable of imaging potent tumor-infiltrating MVP structures surrounding high-grade gliomas.

Convolution reconstruction algorithm for refraction-contrast computed tomography using a Laue-case analyzer for dark-field imaging.

We derive a reconstruction algorithm for refraction-contrast computed tomography (CT) using dark-field imaging (DFI) optics, which can extract refraction information by a single shot, from the ray equation in geometrical optics. The proposed algorithm is similar to the convolution reconstruction technique widely used in conventional CT. Thus, this algorithm can be implemented simply while also being fast and stable. To demonstrate its validity, we constructed the imaging system based on DFI optics composed of a transmission Laue-type angular analyzer at the vertical wiggler beamline BL-14C in KEK and performed a preliminary imaging experiment using a physical phantom to successfully obtain the DFI-CT image using the proposed algorithm.

X-ray fluorescent CT imaging of cerebral uptake of stable-iodine perfusion agent iodoamphetamine analog IMP in mice.

Using X-ray fluorescent computed tomography (XFCT), the in vivo and ex vivo cerebral distribution of a stable-iodine-labeled cerebral perfusion agent, iodoamphetamine analog (127I-IMP), has been recorded in the brains of mice. In vivo cerebral perfusion in the cortex, hippocampus and thalamus was depicted at 0.5 mm in-plane spatial resolution. Ex vivo XFCT images at 0.25 mm in-plane spatial resolution allowed the visualisation of the detailed structures of these regions. The quality of the XFCT image of the hippocampus was comparable with the 125I-IMP autoradiogram. These results highlight the sensitivity of XFCT and its considerable potential to evaluate cerebral perfusion in small animals without using radioactive agents.

Sheet-beam geometry for in vivo fluorescent x-ray computed tomography: proof-of-concept experiment in molecular imaging.

We propose a fluorescent x-ray computed tomography method using an array of detectors with an incident sheet beam, aimed at providing molecular imaging with high sensitivity and good spatial resolution. In this study, we prove the feasibility of this concept and investigate its imaging properties, including spatial and contrast resolutions and quantitativeness, by imaging an acrylic phantom and a normal mouse brain using a preliminary imaging system with monochromatic synchrotron x rays.

Visualization of age-dependent myocardial metabolic impairment in cardiomyopathic model hamster obtained by fluorescent X-ray computed tomography using I-127 BMIPP.

Fluorescent X-ray computed tomography (FXCT) enables visualization of myocardial fatty acid metabolism by using non-radio-iodinated I-5-(p-iodophenyl)-3-(R,S)-methylpentadecanoice acid (BMIPP). In this experiment, age-dependent myocardial metabolic impairment was successfully imaged and analyzed quantitatively in J2N-k cardiomyopathic hamster using FXCT.

Preliminary quantitative analysis of myocardial fatty acid metabolism from fluorescent X-ray computed tomography imaging.

Fluorescent X-ray computed tomography (FXCT) using synchrotron radiation reveals the cross-sectional distribution of specific elements in biomedical objects. The aim of this study was to investigate the feasibility of FXCT imaging to assess the myocardial metabolic state quantitatively. Hearts labelled with non-radioactive iodine myocardial fatty acid agent 15-p-(iodophenyl)-3-methylpentadecanoic acid (BMIPP) from cardiomyopathic and normal hamsters were imaged. FXCT images were compared with optical microscope images. Myocardial fatty acid metabolism enhanced with BMIPP was clearly depicted by FXCT, which showed an almost homogeneous image for normal and a heterogeneous image for cardiomyopathic hearts. Morphological structures of the heart such as the left ventricle and myocardial wall were also visualized by FXCT. Optical microscopy showed no fibrosis in normal and slight interstitial fibrosis in cardiomyopathic hearts. In the case of cardiomyopathy, the area of significantly reduced BMIPP uptake was 39% in the short axis of the mid-left ventricle in the FXCT image, whereas a slight interstitial fibrosis of around 12% was recognized by optical microscopy for the same slice. This result indicated that reduced BMIPP uptake was caused by the myocardial fatty acid metabolic abnormality, not by the fibrosis in cardiomyopathy. Thus, FXCT images might be used to assess the quantitative metabolic analysis in small animal models of heart diseases.