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X-ray Imaging (x-ray + imaging)
Selected AbstractsIMAGING LUNG AERATION AND LUNG LIQUID CLEARANCE AT BIRTH USING PHASE CONTRAST X-RAY IMAGINGCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1 2009Stuart B Hooper SUMMARY 1The transition to extra-uterine life at birth is critically dependent on airway liquid clearance to allow the entry of air and the onset of gaseous ventilation. We have used phase contrast X-ray imaging to identify factors that regulate lung aeration at birth in spontaneously breathing term and mechanically ventilated preterm rabbit pups. 2Phase contrast X-ray imaging exploits the difference in refractive index between air and water to enhance image contrast, enabling the smallest air-filled structures of the lung (alveoli; < 100 µm) to be resolved. Using this technique, the lungs become visible as they aerate, allowing the air,liquid interface to be observed as it moves distally during lung aeration. 3Spontaneously breathing term rabbit pups rapidly aerate their lungs, with most fully recruiting their functional residual capacity (FRC) within the first few breaths. The increase in FRC occurs mainly during individual breaths, demonstrating that airway liquid clearance and lung aeration is closely associated with inspiration. We suggest that transpulmonary pressures generated by inspiration provide a hydrostatic pressure gradient for the movement of water out of the airways and into the surrounding lung tissue after birth. 4In mechanically ventilated preterm pups, lung aeration is closely associated with lung inflation and a positive end-expiratory pressure is required to generate and maintain FRC after birth. 5In summary, phase contrast X-ray imaging can image the air-filled lung with high temporal and spatial resolution and is ideal for identifying factors that regulate lung aeration at birth in both spontaneously breathing term and mechanically ventilated preterm neonates. [source] Spatially resolved X-ray diffraction as a tool for strain analysis in laterally modulated epitaxial structuresCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2009A. Wierzbicka Abstract Spatially resolved X-ray diffraction (SRXRD) is applied for micro-imaging of strain in laterally modulated epitaxial structures. In GaAs layers grown by liquid phase epitaxial lateral overgrowth (ELO) on SiO2 -masked GaAs substrates a downward tilt of ELO wings caused by their interaction with the mask is observed. The distribution of the tilt magnitude across the wings width is determined with ,m-scale spatial resolution. This allows measuring of the shape of the lattice planes in individual ELO stripes. If a large area of the sample is studied the X-ray imaging provides precise information on the tilt of an individual wing and its distribution. In heteroepitaxial GaSb/GaAs ELO layers local mosaicity in the wing area is found. By the SRXRD the size of microblocks and their relative misorientation were analyzed. Finally, the SRXRD technique was applied to study distribution of localized strain in AlGaN epilayers grown by MOVPE on bulk GaN substrates with AlN mask. X-ray mapping proves that by mask patterning strain in AlGaN layer can be easily engineered, which opens a way to produce thicker, crack-free AlGaN layers with a higher Al content needed in GaN-based laser diodes. All these examples show that high spatial and angular resolutions offered by SRXRD makes the technique a powerful tool to study local lattice distortions in semiconductor microstructures. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] In situ investigation of the non-linear optical crystal rubidium titanyl arsenate, RbTiOAsO4, under applied electric field using X-ray imagingJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2007P. A. Thomas Recent work on the non-linear optical single-crystal rubidium titanyl arsenate (RbTiOAsO4, RTA) has shown that it exhibits behaviour consistent with a ferroelectric semiconductor under large applied electric fields, with the development of a non-uniform field in the near-surface region. To confirm aspects of the proposed model, the behaviour of 001 slices of initially single-domain RTA, patterned with periodic Ag electrodes of spacing 38,µm, as for periodic poling in non-linear optics, were investigated using synchrotron X-ray section topography with the electric field applied in situ while under X-ray illumination at the ID19 topography beamline of the ESRF, Grenoble. The results of white-beam section topography as both a function of crystal to film distance, and under DC voltage are reported, confirming that there is a bending of the planes in the near-surface region. The strain in the near-surface region was examined directly using high-resolution monochromatic X-ray section topography. This revealed an extensive strain of 3,(±1) × 10,4 at 1,kV, indicating that the electrostrictive coefficient, ,3333, in RTA is positive in sign. [source] Synchrotron X-ray imaging reveals a correlation of tumor copper speciation with Clioquinol's anticancer activityJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2009Raul A. Barrea Abstract Tumor development and metastasis depend on angiogenesis that requires certain growth factors, proteases, and the trace element copper (Cu). Recent studies suggest that Cu could be used as a novel target for cancer therapies. Clioquinol (CQ), an antibiotic that is able to form stable complexes with Cu or zinc (Zn), has shown proteasome-inhibitory, androgen receptor-suppressing, apoptosis-inducing, and antitumor activities in human cancer cells and xenografts. The mechanisms underlying the interaction of CQ with cellular Cu, the alteration of the Cu/Zn ratio and the antitumor role of CQ in vivo have not been fully elucidated. We report here that Cu accumulates in tumor tissue and that the Cu/Zn balances in tumor, but not normal, tissue change significantly after the treatment with CQ. Cu speciation analysis showed that the Cu(I) species is predominant in both normal and tumor tissues and that Cu(II) content was significantly increased in tumor, but not normal tissue after CQ treatment. Our findings indicate that CQ can interact with cellular Cu in vivo, dysregulates the Cu/Zn balance and is able to convert Cu(I) to Cu(II) in tumor tissue. This conversion of Cu(I) to Cu(II) may be associated with CQ-induced proteasome inhibition and growth suppression in the human prostate tumor xenografts. J. Cell. Biochem. 108: 96,105, 2009. © 2009 Wiley-Liss, Inc. [source] Molecular imaging in small animals,roles for micro-CTJOURNAL OF CELLULAR BIOCHEMISTRY, Issue S39 2002Erik L. Ritman Abstract X-ray micro-CT is currently used primarily to generate 3D images of micro-architecture (and the function that can be deduced from it) and the regional distribution of administered radiopaque indicators, within intact rodent organs or biopsies from large animals and humans. Current use of X-ray micro-CT can be extended in three ways to increase the quantitative imaging of molecular transport and accumulation within such specimens. (1) By use of heavy elements, other than the usual iodine, attached to molecules of interest or to surrogates for those molecules. The accumulation of the indicator in the physiological compartments, and the transport to and from such compartments, can be quantitated from the imaged spatial distribution of these contrast agents. (2) The high spatial resolution of conventional X-ray attenuation-based CT images can be used to improve the quantitative nature of radionuclide-based tomographic images (SPECT & PET) by providing correction for attenuation of the emitted gamma rays and the accurate delineation of physiological spaces known to selectively accumulate those indicators. Similarly, other imaging modalities which also localize functions in 2D images (such as histological sections subsequently obtained from the same specimen), can provide a synergistic combination with CT-based 3D microstructure. (3) By increasing the sensitivity and specificity of X-ray CT image contrast by use of methods such as: K-edge subtraction imaging, X-ray fluorescence imaging, imaging of the various types of scattered X-ray and the consequences of the change in the speed of X-rays through different tissues, such as refraction and phase shift. These other methods of X-ray imaging can increase contrast by more than an order of magnitude over that due to conventionally-used attenuation of X-ray. To fully exploit their potentials, much development of radiopaque indicators, scanner hardware and image reconstruction and analysis software will be needed. J. Cell. Biochem. Suppl. 39: 116,124, 2002. © 2002 Wiley-Liss, Inc. [source] X-RAY ASSESSMENT OF TRANSLUCENCY IN PINEAPPLEJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 5 2006R.P. HAFF ABSTRACT A nondestructive method for detection of translucency, a physiological disorder in pineapple, would be beneficial to the industry. Ninety-two pineapples were imaged with X-ray to determine whether translucency could be detected. After imaging, each pineapple was cut open to determine the true level of the disorder and rated on a scale from 1 (no translucency) to 5 (extremely translucent). The X-ray images were inspected by human subjects who evaluated them as either good or bad based on the appearance of translucent and nontranslucent pineapples in training images. The results show a high correlation (R2 = 0.96) between the likelihood of a sample being rated as good and the actual level of translucency observed. Samples with no translucency were correctly identified 95% of the time, while those with extreme translucency were correctly identified 86% of the time. The results indicate that X-ray imaging is a useful method for selecting either pineapples that are most likely to be free of translucency or those that are most likely to be extremely translucent. [source] Image-guided and -monitored renal artery stenting using only MRIJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 5 2006Daniel R. Elgort PhD Abstract Purpose To demonstrate the ability of a unique interventional MR system to be used safely and effectively as the only imaging modality for all phases of MR-guided stent-supported angioplasty. Materials and Methods An experimental disease model of renal stenosis was created in six pigs. An interventional MR system, which employed previously reported tools for real-time catheter tracking with automated scan-plane positioning, adaptive image parameters, and radial true,FISP imaging with steady-state precession (True-FISP) imaging coupled with a high-speed reconstruction technique, was then used to guide all phases of the intervention, including: guidewire and catheter insertion, stent deployment, and confirmation of therapeutic success. Pre- and postprocedural X-ray imaging was used as a gold standard to validate the experimental results. Results All of the stent-supported angioplasty interventions were a technical success and were performed without complications. The average postoperative residual stenosis was 14.9%. The image guidance enabled the stents to be deployed with an accuracy of 0.98 ± 0.69 mm. Additionally, using this interventional MRI system to guide renal artery stenting significantly reduces the procedure time, as compared to using X-ray fluoroscopy. Conclusion This study has clearly demonstrated the first successful treatment of renal artery stenting in an experimental animal model solely under MRI guidance and monitoring. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [source] Head morphology in perinatal dolphins: A window into phylogeny and ontogenyJOURNAL OF MORPHOLOGY, Issue 11 2006Michael A. Rauschmann Abstract In this paper on the ontogenesis and evolutionary biology of odontocete cetaceans (toothed whales), we investigate the head morphology of three perinatal pantropical spotted dolphins (Stenella attenuata) with the following methods: computer-assisted tomography, magnetic resonance imaging, conventional X-ray imaging, cryo-sectioning as well as gross dissection. Comparison of these anatomical methods reveals that for a complete structural analysis, a combination of modern imaging techniques and conventional morphological methods is needed. In addition to the perinatal dolphins, we include series of microslides of fetal odontocetes (S. attenuata, common dolphin Delphinus delphis, narwhal Monodon monoceros). In contrast to other mammals, newborn cetaceans represent an extremely precocial state of development correlated to the fact that they have to swim and surface immediately after birth. Accordingly, the morphology of the perinatal dolphin head is very similar to that of the adult. Comparison with early fetal stages of dolphins shows that the ontogenetic change from the general mammalian bauplan to cetacean organization was characterized by profound morphological transformations of the relevant organ systems and roughly seems to parallel the phylogenetic transition from terrestrial ancestors to modern odontocetes. J. Morphol., 2006. © 2006 Wiley-Liss, Inc. [source] Confocal full-field X-ray microscope for novel three-dimensional X-ray imagingJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2009Akihisa Takeuchi A confocal full-field X-ray microscope has been developed for use as a novel three-dimensional X-ray imaging method. The system consists of an X-ray illuminating `sheet-beam' whose beam shape is micrified only in one dimension, and an X-ray full-field microscope whose optical axis is normal to the illuminating sheet beam. An arbitral cross-sectional region of the object is irradiated by the sheet-beam, and secondary X-ray emission such as fluorescent X-rays from this region is imaged simultaneously using the full-field microscope. This system enables a virtual sliced image of a specimen to be obtained as a two-dimensional magnified image, and three-dimensional observation is available only by a linear translation of the object along the optical axis of the full-field microscope. A feasibility test has been carried out at beamline 37XU of SPring-8. Observation of the three-dimensional distribution of metallic inclusions in an artificial diamond was performed. [source] Analyser-based tomography images of cartilageJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2008Ahi S. Issever Analyser-based imaging expands the performance of X-ray imaging by utilizing not only the absorption properties of X-rays but also the refraction and scatter rejection (extinction) properties. In this study, analyser-based computed tomography has been implemented on imaging an articular cartilage sample, depicting substructural variations, without overlay, at a pixel resolution of 3.6,µm. [source] In situ observation of water distribution and behaviour in a polymer electrolyte fuel cell by synchrotron X-ray imagingJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2008Taihei Mukaide In situ visualization of the distribution and behaviour of water in a polymer electrolyte fuel cell during power generation has been demonstrated using a synchrotron X-ray imaging technique. Images were recorded using a CCD detector combined with a scintillator (Gd2O2S:Tb) and relay lens system, which were placed at 2.0,m or 2.5,m from the fuel cell. The images were measured continuously before and during power generation, and data on cell performance was recorded. The change of water distribution during power generation was obtained from X-ray images normalized with the initial state of the fuel cell. Compared with other techniques for visualizing the water in fuel cells, this technique enables the water distribution and behaviour in the fuel cell to be visualized during power generation with high spatial resolution. In particular, the effects of the specifications of the gas diffusion layer on the cathode side of the fuel cell on the distribution of water were efficiently identified. This is a very powerful technique for investigating the mechanism of water flow within the fuel cell and the relationship between water behaviour and cell performance. [source] Silicon drift and pixel devices for X-ray imaging and spectroscopyJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2006G. Lutz Starting from the basic photon detection process in semiconductors, the function, principles and properties of sophisticated silicon detectors are discussed. These detectors are based on, or inspired by, the semiconductor drift detector. They have already shown their potential in X-ray astronomy (pn-CCD) and in X-ray spectroscopy (silicon drift diode), and further detector types (DEPFET pixel detector and macro-pixel detector) are under development for several other future experiments. The detectors seem to be very well suited for synchrotron radiation experiments. [source] Large-area phase-contrast X-ray imaging using a two-crystal X-ray interferometerJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2002Akio Yoneyama Large-area (25,×,20,mm) phase-contrast X-ray imaging was attained by using a skew-symmetric two-crystal X-ray interferometer. The sub-nrad angular control required to operate the X-ray interferometer was achieved with a sleeve bearing and a feedback-positioning system. As a demonstration, measurements of a phase map of a rat's liver and a phase-contrast tomographic three-dimensional image of a piece of a rabbit's liver were performed at the Photon Factory using 0.07,nm synchrotron radiation X-rays. [source] Phase-contrast X-ray imaging with a large monolithic X-ray interferometerJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2000Tohoru Takeda To increase the field of view for large objects in phase-contrast X-ray imaging, a large monolithic X-ray interferometer has been fabricated using an available silicon ingot of diameter 10,cm. A performance study of this interferometer has been carried out using a synchrotron X-ray source. The view size of the interference pattern obtained with this interferometer was 25,mm wide and 15,mm high and its visibility was 79%. Various structures of a sliced human hepatocellular carcinoma were identified as necrosis, hemorrhagic necrosis, normal liver tissue and blood vessel. The performance of this interferometer was sufficient for phase-contrast X-ray imaging. [source] Maintenance of bone mass and architecture in denning black bears (Ursus americanus)JOURNAL OF ZOOLOGY, Issue 4 2004Connor K. Pardy Abstract Bone mass is dramatically compromised during periods of weightlessness, inactivity, or bed rest. Animals that hibernate reduce their body temperature, heart rate and metabolic activity, and likewise lower bone turnover activity during their immobile state. Black bears Ursus americanus, however, do not hibernate, but rather overwinter by denning during which they maintain a nearly normal functional heart rate, cardiac output and temperature. Furthermore, markers of bone turnover in black bears are maintained during denning periods. Thus, the purpose of this work was to determine if the denning state of relative immobility in black bears results in changes in bone mass and bone architectural structure. Harvested forelimbs (ulna and radius) were compared between pre- and post-denning black bears using X-ray imaging, dual energy X-ray absorptiometry, and micro-computed tomography to quantify total distal forelimb bone mineral density, cancellous bone mineral density, bone mineral content, bone volume fraction, degree of anisotropy, structure model index, and trabecular thickness. No significant differences in any of the measured parameters were found in comparing radius and ulna from autumn and spring bears in this cross-sectional sample, suggesting that black bears did not experience a significant change in bone mass or architecture during denning. The statistical power for detecting a significant difference (P, 0.05) for this sample was 0.8. The specific mechanism by which the preservation of bone was attained may be related to skeletal muscle interaction or circulating systemic hormones. [source] X-ray imaging of various biological samples using a phase-contrast hard X-ray microscopeMICROSCOPY RESEARCH AND TECHNIQUE, Issue 9 2008Guk Bae Kim Abstract In this study, we visualized the internal structures of various bio-samples and found the optimum conditions of test samples for the 7 keV hard X-ray microscope of the Pohang light source. From the captured X-ray images, we could observe the intercellular and intracellular structures of dehydrated human cells and mouse tumor tissues without using any staining materials in a spatial resolution better than 100 nm. The metastasized lung tissue, which was several tens of micrometers in thickness, was found to be very well suited to this hard X-ray microscope system, because it is nearly impossible to observe such a nontransparent and thick sample with a high spatial resolution better than 100 nm using any microscopes such as a soft X-ray microscope, an optical microscope, or an electron microscope. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc. [source] Mapping the intake of different elements in vegetal tissues by dual-energy X-ray imaging at Da,ne synchrotron light sourceMICROSCOPY RESEARCH AND TECHNIQUE, Issue 3 2008L. Reale Abstract This article reports on the first utilization of the soft X-ray beamline at the Da,ne synchrotron light source for mapping the intake of different elements in plant tissues. As a test, the method of dual-energy X-ray microradiography was applied to the investigation of the natural sulfur content in dried leaf and root samples. Our ultimate goal was to monitor the pollutant lead and its intake, which was added in controlled doses to the hydroponic medium of laboratory-controlled samples of vegetal species. The results obtained by the nondestructive X-ray radiographic analysis are compared to the values of concentrations determined by a standard chemical analysis utilizing atomic absorption spectroscopy. From this comparison the validity of the X-ray detection of heavy metals in biological samples has been confirmed. The superposition of the dual energy results on the simple planar radiography shows the representation of the pollutant intake directly on the sample structures. It should be pointed out that this method, developed here for plant root and leaves could be applied to any biological sample of interest, but the preparation and observation conditions necessitate different strategies according to the type of sample under analysis. Microsc. Res. Tech., 2008. © 2007 Wiley-Liss, Inc. [source] Multiwavelength study of the nuclei of a volume-limited sample of galaxies , II.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007Optical, infrared, radio observations ABSTRACT We present optical and infrared broad-band images, radio maps, and optical spectroscopy for the nuclear region of a sample of nearby galaxies. The galaxies have been drawn from a complete volume-limited sample for which we have already presented X-ray imaging. We modelled the stellar component of the spectroscopic observations to determine the star formation history of our targets. Diagnostic diagrams were used to classify the emission-line spectra and determine the ionizing mechanism driving the nuclear regions. All those sources classified as active galactic nuclei present small Eddington ratios (,10,3,10,6), implying a very slow growth rate of their black holes. We finally investigate the relative numbers of active and normal nuclei as a function of host galaxy luminosity and find that the fraction of active galaxies slowly rises as a function of host absolute magnitude in the MB,,12 to ,22 range. [source] Deep radio imaging of the SCUBA 8-mJy survey fields: submillimetre source identifications and redshift distributionMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2002R. J. Ivison Abstract The SCUBA 8-mJy survey is the largest submillimetre (submm) extragalactic mapping survey undertaken to date, covering 260 arcmin2 to a 4 , detection limit of ,8 mJy at 850 ,m, centred on the Lockman Hole and ELAIS N2 regions. Here, we present the results of new 1.4-GHz imaging of these fields, of the depth and resolution necessary to reliably identify radio counterparts for 18 of 30 submm sources, with possible detections of a further 25 per cent. Armed with this greatly improved positional information, we present and analyse new optical, near-infrared (near-IR) and XMM,Newton X-ray imaging to identify optical/IR host galaxies to half of the submm-selected sources in those fields. As many as 15 per cent of the submm sources detected at 1.4 GHz are resolved by the 1.4-arcsec beam and a further 25 per cent have more than one radio counterpart, suggesting that radio and submm emission arise from extended starbursts and that interactions are common. We note that less than a quarter of the submm-selected sample would have been recovered by targeting optically faint radio sources, underlining the selective nature of such surveys. At least 60 per cent of the radio-confirmed optical/IR host galaxies appear to be morphologically distorted; many are composite systems , red galaxies with relatively blue companions; just over one half are found to be very red (I , K > 3.3) or extremely red (I , K > 4); contrary to popular belief, most are sufficiently bright to be tackled with spectrographs on 8-m telescopes. We find one submm source which is associated with the steep-spectrum lobe of a radio galaxy, at least two more with flatter radio spectra typical of radio-loud active galactic nuclei (AGN), one of them variable. The latter is amongst four sources (,15 per cent of the full sample) with X-ray emission consistent with obscured AGN, though the AGN would need to be Compton thick to power the observed far-IR luminosity. We exploit our well-matched radio and submm data to estimate the median redshift of the S850,m , 8 mJy submm galaxy population. If the radio/far-IR correlation holds at high redshift, and our sample is unbiased, we derive a conservative limit of ,z, ,2.0, or ,2.4 using spectral templates more representative of known submm galaxies. [source] Phase contrast X-ray imaging of large samples using an incoherent laboratory sourcePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2007C. Kottler Abstract An interferometric method to record quantitative X-ray phase contrast images has been developed that can be used at polychromatic and incoherent X-ray sources such as laboratory tubes. With respect to previously presented results, in this work we report on recent developments and results that have been achieved in view of potential future applications such as in medicine or biology. In particular, due to improvements in the fabrication process large area diffraction gratings with high aspect ratio were achieved. Thereby, the field of view of the interferometer has been drastically increased to 64 × 64 mm2 and the design value of the photon energy for the gratings could be increased up to 28 keV. Moreover, the use of a Medipix2 single photon-counting pixel detector shows a considerable improvement in image quality and sensitivity over the integrating detector used so far. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Hydrogen diffusion in titanium-hydride observed by the diffraction-enhanced X-ray imaging methodPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2007K. Mizuno Abstract The X-ray refraction imaging technique was applied to the quantitative study of hydrogen diffusion in titanium-hydride. Diffusivity and activation energy of hydrogen diffusion were determined by direct observation of the hydride. The hydride was formed on the surface of titanium by electrolytic-charging at 31, 63 and 98 °C. The specimens were cut into 1 mm thick slices for cross-sectional observations. The hydride layer was observed using the diffraction-enhanced X-ray imaging (DEI) method. Boundaries between titanium and the hydride were observed as thick black or white lines parallel to the specimen surface in the DEI images similar to previously reported results. Hydride distribution caused by hydrogen diffusion from the surface was calculated using an assumed hydrogen diffusivity value and from the solution of the appropriate diffusion equation. The results were converted to the intensity profiles of refraction images of the hydride using the measured rocking curve from an analyzer. The calculated intensity profiles were compared to those obtained from the experimental results and the fitted diffusivity was determined by trial and error. The activation energy of hydrogen in titanium-hydride thus obtained, 0.55 ± 0.07 eV, showed good agreement with the widely accepted value obtained by the internal friction. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Achieving super-resolution X-ray imaging with mobile C-arm devicesTHE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Issue 3 2009C. Bodensteiner Abstract Background The term super-resolution refers to the process of combining a set of low-resolution images into a high-resolution image using image processing methods. This work is concerned with the reconstruction of high-resolution X-ray images. Specifically, we address the problem of acquiring X-ray images from multiple, very close view points. Methods We propose to use a novel experimental robotic C-arm device to create high-resolution X-ray images. For this purpose, we suggest different strategies for acquiring multiple low-resolution images, and we provide the steps to achieve acquisition-error compensation. Compared to visible light images, X-ray images have the particularity that parallax effects render super-resolution very difficult. Using the acquired multi-frame data, we evaluate recent well-known super-resolution reconstruction algorithms. The same algorithms are evaluated based on synthetic 3D phantom data and real X-ray images. Results In experiments with both synthetic and real projection data, we successfully reconstruct up to four times higher-resolution images. These images reveal structures and details which are not perceivable in the low-resolution images. Conclusions The advantage of super-resolution techniques for X-ray is the potential reduction of radiation dose for patients and medical personnel. Potential medical applications include the diagnosis of early-stage osteoporosis and the detection of very small calcifications. Copyright © 2009 John Wiley & Sons, Ltd. [source] Image-guided reconstruction of the anterior cruciate ligamentTHE INTERNATIONAL JOURNAL OF MEDICAL ROBOTICS AND COMPUTER ASSISTED SURGERY, Issue 1 2004J Sabczynski Abstract The replacement of the ruptured Anterior Cruciate Ligament (ACL) of the knee is a biomechanically difficult task. The correct placement of the graft, especially the isometry of the tibial and femoral insertion points, is critically to the success of the procedure. However, during arthroscopy, the planning of the insertion points and accurate execution of the plan is difficult. This paper reports an X-ray based system for navigation of the ACL graft implant. The system integrates arthroscopy and intra-operative X-ray imaging to identify the correct insertion points of the graft. Furthermore, it allows testing the isometry of these points before drilling of the femoral and tibial tunnel, and guides the drilling itself. Copyright © 2004 Robotic Publications Ltd. [source] Bilateral tentorial sinus drainage of the basal vein (of Rosenthal)CLINICAL ANATOMY, Issue 3 2003Diego San Millįn Ruķz Abstract We report a case of bilateral collateral tentorial venous sinus drainage of the basal vein (of Rosenthal) (BV). The observation was made on a corrosion cast of the cerebral venous system obtained from a fresh cadaver. Radiographic correlation was obtained by performing standard X-ray imaging of the corrosion cast. Embryologic and clinical considerations are discussed. Clin. Anat. 16:264,268, 2003. © 2003 Wiley-Liss, Inc. [source] IMAGING LUNG AERATION AND LUNG LIQUID CLEARANCE AT BIRTH USING PHASE CONTRAST X-RAY IMAGINGCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 1 2009Stuart B Hooper SUMMARY 1The transition to extra-uterine life at birth is critically dependent on airway liquid clearance to allow the entry of air and the onset of gaseous ventilation. We have used phase contrast X-ray imaging to identify factors that regulate lung aeration at birth in spontaneously breathing term and mechanically ventilated preterm rabbit pups. 2Phase contrast X-ray imaging exploits the difference in refractive index between air and water to enhance image contrast, enabling the smallest air-filled structures of the lung (alveoli; < 100 µm) to be resolved. Using this technique, the lungs become visible as they aerate, allowing the air,liquid interface to be observed as it moves distally during lung aeration. 3Spontaneously breathing term rabbit pups rapidly aerate their lungs, with most fully recruiting their functional residual capacity (FRC) within the first few breaths. The increase in FRC occurs mainly during individual breaths, demonstrating that airway liquid clearance and lung aeration is closely associated with inspiration. We suggest that transpulmonary pressures generated by inspiration provide a hydrostatic pressure gradient for the movement of water out of the airways and into the surrounding lung tissue after birth. 4In mechanically ventilated preterm pups, lung aeration is closely associated with lung inflation and a positive end-expiratory pressure is required to generate and maintain FRC after birth. 5In summary, phase contrast X-ray imaging can image the air-filled lung with high temporal and spatial resolution and is ideal for identifying factors that regulate lung aeration at birth in both spontaneously breathing term and mechanically ventilated preterm neonates. [source] Technical note: Terahertz imaging of ancient mummies and boneAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010Lena Öhrström Abstract Ancient mummified soft-tissues are a unique source to study the evolution of disease. Diagnostic imaging of such historic tissues is of foremost interest in paleoanthropology or paleopathology, with conventional x-ray and computed tomography (CT) being the gold-standard. Longer wavelength radiation in the far-infrared or Terahertz region allows diagnostic close-to-surface tissue differentiation of bone morphology while being harmless to human cells. The aim of this study is to show the feasibility and the morpho-diagnostic impact of THz imaging of historic remains. Images of an artificially embalmed ancient Egyptian human mummy hand, an artificially embalmed ancient Egyptian mummified fish and a macerated human lumbar vertebra were obtained by THz-pulse imaging and compared with conventional X-ray and CT images. Although conventional x-ray imaging provides higher spatial resolution, we found that THz-imaging is well-suited for the investigation of ancient mummified soft tissue and embalming-related substances / wrappings. In particular, bone and cartilaginous structures can be well differentiated from surrounding soft-tissues and bandage-wrappings by THz imaging. Furthermore, THz-pulse imaging also measures the time-delay of the pulsed signal when passing through the sample, which provides supplementary information on the optical density of the sample that is not obtained by X-ray and CT. Terahertz radiation provides a completely non-invasive diagnostic imaging modality for historic dry specimens. We anticipate this modality also to be used for detection of hidden objects in historic samples such as funerary amulets still in situ in wrapped mummies, as well as potentially for the identification of spectral signatures from chemical substances, e.g., in embalming essences.. Am J Phys Anthropol, 2010. © 2010 Wiley-Liss, Inc. [source] Vulnerability of the superficial zone of immature articular cartilage to compressive injuryARTHRITIS & RHEUMATISM, Issue 10 2010Bernd Rolauffs Objective The zonal composition and functioning of adult articular cartilage causes depth-dependent responses to compressive injury. In immature cartilage, shear and compressive moduli as well as collagen and sulfated glycosaminoglycan (sGAG) content also vary with depth. However, there is little understanding of the depth-dependent damage caused by injury. Since injury to immature knee joints most often causes articular cartilage lesions, this study was undertaken to characterize the zonal dependence of biomechanical, biochemical, and matrix-associated changes caused by compressive injury. Methods Disks from the superficial and deeper zones of bovine calves were biomechanically characterized. Injury to the disks was achieved by applying a final strain of 50% compression at 100%/second, followed by biomechanical recharacterization. Tissue compaction upon injury as well as sGAG density, sGAG loss, and biosynthesis were measured. Collagen fiber orientation and matrix damage were assessed using histology, diffraction-enhanced x-ray imaging, and texture analysis. Results Injured superficial zone disks showed surface disruption, tissue compaction by 20.3 ± 4.3% (mean ± SEM), and immediate biomechanical impairment that was revealed by a mean ± SEM decrease in dynamic stiffness to 7.1 ± 3.3% of the value before injury and equilibrium moduli that were below the level of detection. Tissue areas that appeared intact on histology showed clear textural alterations. Injured deeper zone disks showed collagen crimping but remained undamaged and biomechanically intact. Superficial zone disks did not lose sGAG immediately after injury, but lost 17.8 ± 1.4% of sGAG after 48 hours; deeper zone disks lost only 2.8 ± 0.3% of sGAG content. Biomechanical impairment was associated primarily with structural damage. Conclusion The soft superficial zone of immature cartilage is vulnerable to compressive injury, causing superficial matrix disruption, extensive compaction, and textural alteration, which results in immediate loss of biomechanical function. In conjunction with delayed superficial sGAG loss, these changes may predispose the articular surface to further softening and tissue damage, thus increasing the risk of development of secondary osteoarthritis. [source] | |||||||||||||||||||