High-resolution X-ray Computed Tomography Research Articles

Investigation of Organic Materials From the ‘Royal’ Burials of Xiongnu (Noin‐Ula, Mongolia) by Srxrf and XAFS Methods

The burials of famous Xiongnu people are a unique source of information about Xiongnu culture, due to the variety of organic findings. SRXRF analysis of hair, clay, bones, teeth and woollen cloth was carried out. An anomalously high copper content was observed in all hair samples, whereas the levels of copper in bone and clay were low. To define the hair morphology and the elemental distribution in the hair cross‐section, high‐resolution X‐ray computed tomography (HRXCT) and energy‐dispersive spectroscopy (EDS) with scanning electron microscopy (SEM) were used. The X‐ray absorption fine‐structure method (XAFS) was applied to determine the local copper environment. The majority of the copper species in the hair and enamel samples are present as Cu2+ cations in a distorted octahedral (4 + 2) coordination, surrounded by light ligands (oxygen/nitrogen). A similar distorted octahedral coordination is typical for both inorganic mixed oxide/hydroxide Cu nanosystems and metal–organic Cu complexes (with oxygen/nitrogen).

Analysis of Vesicular Porosity in Soils using High Resolution X‐Ray Computed Tomography

Vesicular horizons are common at the surface of arid and semiarid soils and play a critical role in regulating infiltration. Most methods for examining pore morphology in the vesicular horizon involve physical sectioning of the sample and individual measurement of pores, which is time-consuming and provides an incomplete view of the pores. The objectives of this study were to (i) develop methods for the classification and characterization of pores in the vesicular horizon using high resolution X-ray computed tomography (HRXCT) and (ii) use these methods to examine the distribution of pores within vesicular peds. Three intact peds were scanned by HRXCT and examined using Blob3D software. A subset of pores from the first scan were observed and used to develop a classification tree model based on quantitative parameters of pore shape. Five major pore classes were found: equant vesicles, non-equant vesicles, individual vughs, connected vughs, and planar voids. All pore types decreased in size with increasing depth in the samples; however, the trend in quantity of pores with depth varied between pore types. In the ped with the least vesicular porosity, there was an increase in size and decrease in number of all pore types between the ped interior and exterior, a pattern which was reduced in the peds that were more dominantly vesicular. The application of HRXCT in this study shows how pore shape and size can be quantified within the vesicular horizon and reveals considerable variation of these characteristics within and between peds.

A tomographic osteology of the taxonomically puzzling catfishKryptoglanis shajii(Siluriformes, Siluroidei,incertae sedis): description and a first phylogenetic interpretation

The recent discovery and description of an unusually puzzling catfish, Kryptoglanis shajii Vincent and Thomas (2011) from ground and surface waters in Kerala State, southwestern, peninsular India, added an unresolved taxon to the order Siluriformes. Here we use high-resolution X-ray computed tomography (HRXCT) and X-radiography to illustrate, describe and compare the bony skeleton of Kryptoglanis with the objective of determining its phylogenetic position.Several characteristics of Kryptoglanis are strongly modified and structurally complex, setting this catfish apart from other siluriforms. Striking examples are its greatly shortened mesethmoid with overlapping frontals; non-tubular nasal bone; absence of the infraorbital lateralis sensory canal and canal bones but with an apparent antorbital bone; the flat and expansive orbitosphenoid; the vaulted supraoccipital-Weberian neural arch joint; the fenestrated occipital wall; the upwardly flexed occipito-vertebral joint; three pairs of elongated accessory processes off the compound Weberian vertebra; a unique exoccipital process for attachment of the transscapular ligament; hyomandibular-sphenotic ball and socket articulation; a serially notched anterior ceratohyal; and a novel posttemporo-supracleithum joint with the fourth transverse process. Some of these apparent autapomorphic features may eventually be found in some other siluriforms and judged to be informative on phylogenetic relationships. Presently, however, we have identified a few features that support the placement of Kryptoglanis in the Siluroidei (the presence of a posterior nostril barbel and position of the pterosphenoid along the anterior margin of the trigeminofacial foramen), and therein, as the sister lineage to family Siluridae (the nodular form and small size of the autopalatine).

Single-cell resolution in high-resolution synchrotron X-ray CT imaging with gold nanoparticles

Gold nanoparticles are excellent intracellular markers in X-ray imaging. Having shown previously the suitability of gold nanoparticles to detect small groups of cells with the synchrotron-based computed tomography (CT) technique both exvivo and in vivo, it is now demonstrated that even single-cell resolution can be obtained in the brain at least ex vivo. Working in a small animal model of malignant brain tumour, the image quality obtained with different imaging modalities was compared. To generate the brain tumour, 1 × 10(5) C6 glioma cells were loaded with gold nanoparticles and implanted in the right cerebral hemisphere of an adult rat. Raw data were acquired with absorption X-ray CT followed by a local tomography technique based on synchrotron X-ray absorption yielding single-cell resolution. The reconstructed synchrotron X-ray images were compared with images obtained by small animal magnetic resonance imaging. The presence of gold nanoparticles in the tumour tissue was verified in histological sections.

Monitoring of Stainless-Steel Slag Carbonation Using X-ray Computed Microtomography

Steel production is one of the largest contributors to industrial CO2 emissions. This industry also generates large amounts of solid byproducts, such as slag and sludge. In this study, fine grained stainless-steel slag (SSS) is valorized to produce compacts with high compressive strength without the use of a hydraulic binder. This carbonation process is investigated on a pore-scale level to identify how the mineral phases in the SSS react with CO2, where carbonates are formed, and what the impact of these changes is on the pore network of the carbonated SSS compact. In addition to conventional research techniques, high-resolution X-ray computed tomography (HRXCT) is applied to visualize and quantify the changes in situ during the carbonation process. The results show that carbonates mainly precipitate at grain contacts and in capillary pores and this precipitation has little effect on the connectivity of the pore space. This paper also demonstrates the use of a custom-designed polymer reaction cell that allows in situ HRXCT analysis of the carbonation process. This shows the distribution and influence of water and CO2 in the pore network on the carbonate precipitation and, thus, the influence on the compressive strength development of the waste material.

New constraints on the origin of the Skaergaard intrusion Cu–Pd–Au mineralization: Insights from high-resolution X-ray computed tomography

This contribution presents the first detailed three-dimensional (3D) in situ analysis of samples from the Platinova Reef using high-resolution X-ray computed tomography (HRXCT) and 3D image processing and quantification coupled with microscopic and mineralogical investigations. Our HRXCT analyses reveal the complex textural relationships between Cu-rich sulfides (bulk composition close to bornite), skaergaardite (PdCu), Au-rich phases, silicates and Fe–Ti oxides and provide unequivocal textural evidences, not observed previously. The association in 3D between Cu-rich sulfide globules, PdCu alloy and ilmenite is inconsistent with a hydrothermal origin of the Cu–Pd mineralization. In contrast, our results combined with phase diagrams strongly support a primary magmatic origin for the Cu–Pd mineralization where Cu and Pd-rich, Fe-poor sulfide liquid represents a cumulus phase that forms by in-situ nucleation. These sulfide droplets and attached skaergaardite grains were trapped during the formation and crystallization of the Fe–Ti oxides. Subsequent, post-cumulus processes led to the partial to total dissolution of the sulfide not entirely enclosed by the Fe–Ti oxides (i.e., not protected from reaction) leading to the observed variability in Cu and Pd composition at the aggregate (sulfide+PdCu) scale and to the occurrence of free PdCu alloys. In contrast to the PdCu alloy, gold-bearing minerals are never observed entirely enclosed within the Fe–Ti oxide. Two hypotheses can be envisaged for the formation of the gold enriched layer in the upper part of the section. Gold may have either precipitated from high-temperature late magmatic Cl-rich fluids. Alternatively, gold may have been enriched during fractional crystallization after sulfide had been suppressed from the liquidus after the Pd layer crystallized and then deposited along redox barriers.

High-Resolution X-Ray Computed Tomography and Its Application to Ore Deposits: From Data Acquisition to Quantitative Three-Dimensional Measurements with Case Studies from Ni-Cu-PGE Deposits

High-resolution X-ray computed tomography (HRXCT) is a nondestructive technique that allows exploration of the three-dimensional distribution of minerals and pore space in natural and synthetic rock samples. Recent technological developments allow the characterization of samples (up to few centimeters in diameter) at a resolution down to 0.7 μ m. This, combined with the development of dedicated workflows, algorithms, and softwares, is opening new doors for the quantitative three-dimensional characterization of ores at the sample scale. When combined with three-dimensional image analysis, HRXCT provides quantitative three-dimensional mineralogical and textural measurements (volume, shape, three-dimensional relationship) that are impossible to assess accurately by any other method. This manuscript describes the principles of HRXCT and presents dedicated methodologies from data acquisition throught to quantitative three-dimensional measurements. These methodologies are applied to Ni-Cu-PGE ore samples but are suitable for a range of geologic materials. The combination of HRXCT with quantitative three-dimensional image analysis applied to geologic materials hosting ore deposits provides a better understanding of ore mineralogy, ore-forming processes, and parameters required for mineral or metallurgical processing, with benefit for both academic studies and mineral industry applications.

Using High Resolution Computed Tomography to Visualize the Three Dimensional Structure and Function of Plant Vasculature

High resolution x-ray computed tomography (HRCT) is a non-destructive diagnostic imaging technique with sub-micron resolution capability that is now being used to evaluate the structure and function of plant xylem network in three dimensions (3D) (e.g. Brodersen et al. 2010; 2011; 2012a,b). HRCT imaging is based on the same principles as medical CT systems, but a high intensity synchrotron x-ray source results in higher spatial resolution and decreased image acquisition time. Here, we demonstrate in detail how synchrotron-based HRCT (performed at the Advanced Light Source-LBNL Berkeley, CA, USA) in combination with Avizo software (VSG Inc., Burlington, MA, USA) is being used to explore plant xylem in excised tissue and living plants. This new imaging tool allows users to move beyond traditional static, 2D light or electron micrographs and study samples using virtual serial sections in any plane. An infinite number of slices in any orientation can be made on the same sample, a feature that is physically impossible using traditional microscopy methods. Results demonstrate that HRCT can be applied to both herbaceous and woody plant species, and a range of plant organs (i.e. leaves, petioles, stems, trunks, roots). Figures presented here help demonstrate both a range of representative plant vascular anatomy and the type of detail extracted from HRCT datasets, including scans for coast redwood (Sequoia sempervirens), walnut (Juglans spp.), oak (Quercus spp.), and maple (Acer spp.) tree saplings to sunflowers (Helianthus annuus), grapevines (Vitis spp.), and ferns (Pteridium aquilinum and Woodwardia fimbriata). Excised and dried samples from woody species are easiest to scan and typically yield the best images. However, recent improvements (i.e. more rapid scans and sample stabilization) have made it possible to use this visualization technique on green tissues (e.g. petioles) and in living plants. On occasion some shrinkage of hydrated green plant tissues will cause images to blur and methods to avoid these issues are described. These recent advances with HRCT provide promising new insights into plant vascular function.

Using X-ray computed tomography in pore structure characterization for a Berea sandstone: Resolution effect

Summary X-ray computed tomography (XCT) is a powerful tool for detecting the micro-scale pore structure and has been applied to many natural and synthetic porous media. However, due to the resolution limitations, either non-representative view of the sample or inaccurate results can be produced from the XCT image processing. In this paper, two XCT (micro-CT and CT with synchrotron radiation) with different resolutions of 12.7 μm and 0.35 μm, as well as mercury intrusion porosimetry (MIP) with a minimum detection limit of 3 nm, were used for Berea sandstone to investigate the effect of detecting resolution on the pore structure. Several key pore structure parameters, including porosity, pore size distribution, pore connectivity, surface area, hydraulic radius, and aspect ratio were analyzed in a manner of quantitative comparison between different resolutions of XCT and MIP. The low resolution XCT can capture the large-pore porosity, while overestimates the pore size and pore connectivity. The high resolution XCT is more accurate in describing the pore shape, porosity, pore size; however, it is not representative since narrower detecting pore size range and small volume represented. A representative element volume related to large-pore porosity and probably large-pore connectivity with diameter and height of 2.8 mm is obtained through scale effect analysis. Therefore, selecting an appropriate resolution should be a compromise between the pore size and the representative element volume for the specific property or process of interest.

Precision assembly of a miniaturized wire deflector for electron-beam lithography

The fast and precise deflection of electron-beams is mandatory for common electron beam tools and next generation multi-beam lithography systems. Electrostatic fields generated by an arrangement of electrodes with several electric potentials are used to control the electron beam. The miniaturization of such a beam-deflection system facilitates its integration at a favorable place within the electron-optical column. An efficient and accurate beam deflection with high sensitivity and low aberrations is consequently possible. The novel wire-based electrostatic deflector for electron-beam Lithography Tools presented in this paper strictly pursues this approach. Design investigations as well as manufacturing and alignment procedures are reported. 24 wire electrodes are arranged in a circular FEA-optimized pattern and kinematically well-defined mounted to a supporting structure using the Solderjet Bumping technique [2,3]. This flux free solder technique ensures vacuum compatible joints free of hydrocarbons and with an excellent long-term stability. A prototype of the wire deflector is measured by means of a high resolution X-ray computer tomography scanner (CT) [4]. The single wire elements of the wire deflector are symmetrically arranged to each other within an accuracy of a few microns.

Soil pore characteristics assessed from X-ray micro-CT derived images and correlations to soil friability

X-ray computed tomography (CT) scanning technology has, in recent decades, been shown to be a very powerful technique to visualize and quantify soil structure. The objective of this project was to quantify soil pore characteristics, on undisturbed field moist soil, using a high resolution X-ray CT scanner and link then these results to soil friability assessed using the drop shatter method. Minimally disturbed soil cores were taken from selected treatments in a long-term rotation and tillage treatment experiment located on a silt loam at the Elora Research Station near Elora, Ontario, Canada. Soil cores varied in porosity and pore characteristics. A drop shatter test was used as a reference procedure to quantify soil friability. The top 40mm of the 80mm high soil samples were scanned using a X-ray micro-CT scanner. The selected region of interest (36×36×36mm) was reconstructed with a voxel size of 60μm. Estimated surface area, produced from the drop-shatter test, varied between 0.2 and 1.62m2kg−1, and an average of 0.79m2kg−1. Total and air-filled porosity was determined on the soil cores using traditional methods. Total porosity ranged from 41 to 60m3100m−3, and an average of 49m3100m−3. The air-filled porosity, at sampling/testing, ranged between 5 and 32m3100m−3, with an average of 15m3100m−3. The porosity determined from CT imagery ranged between 1 and 31m3100m−3, with an average of 4.5m3100m−3. The number of branches, junctions and end points averaged 298, 117 and 198 per cm3, respectively. We found significant and strong correlations between the soil pore characteristics assessed on the whole soil cores and the characteristics of the air-filled pores determined using high-resolution X-ray computer tomography (CT). Our study confirmed a significant correlation between soil friability, expressed by surface area produced by standardized drop-shatter, and soil pore characteristics. The strongest correlations were found with porosity, surface area and number of junctions per cm3.

SU-F-BRA-08: Development of Novel 1H Magnetic Resonance Imaging Methods to Map Lung Structure and Function

Purpose: Our objective was to develop novel non‐invasive pulmonary protonmagnetic resonance imaging (1H MRI) for simultaneous regional evaluation of lung function and structure in smoking‐related lung disease. Currently there is no pulmonary structure/function 1H MRI technique that can be made universally available for conventional clinical MRI systems. We focused on short echo time (TE) and Fourier‐decomposition (FD) methods providing critical technological steps required to develop lung 1H MRI for therapy guidance. Methods: In this pilot study, nine healthy never‐smokers and 11 COPD subjects underwent same‐day plethysmography, spirometry, short echo time ((TE) =1.2ms) 1H and hyperpolarized 3HeMRI at 3.0T. High resolution x‐ray computed tomography (HRCT) was also performed to measure the relative area less than 950 Houndsfield units (HU) (RA950) and lung density at the 15th percentile (HU15%). Results: We showed the feasibility of FD 1H MRI to obtain lung ventilation maps and also showed that 1H MRI signal intensity (SI) was significantly correlated with 3He apparent diffusion coefficients ADC (r=−.58, p=.008), CT measurements of emphysema (RA950 r=−.69, p=.02 and HU15%, r=.66, p=.03) and conventional measurements of pulmonary function. Conclusions: These findings suggest 1H MRI can be developed as a non‐invasive structure/function imaging tool for monitoring lung disease. Pulmonary lung structure/function 1H MRI requires minimal patient compliance, can be accomplished in less than 5 minutes of image acquisition time and is not dependent on gating techniques, creating an opportunity for serial studies of lung functional changes in lung cancer and COPD.

Use of X-ray computed tomography to investigate crack distribution and mineral dissemination in sphalerite ore particles

As the trends in mineral processing move towards the beneficiation of finer grained and more complex ore bodies, so too do the methods needed to understand and model these processes. During the heap leaching of low-grade ore bodies, the crack distribution and mineral dissemination in ore particles are important characteristics that determine the performance of sub-processes, such as the diffusion of reagents in and out of particle pores. Recent developments in X-ray computed tomography (CT) as an advanced diagnostic and nondestructive technique have indicated the potential for the technology to become a tool for the acquisition of 3-D mineralogical and structural data. The spatial distribution of cracks and mineral dissemination in particles derived from a sphalerite ore in the Northern Cape, South Africa, was characterized using a high-resolution industrial X-ray CT system. This paper describes the use of image analysis techniques including image segmentation, which uses a combination of thresholding and other methods to characterize and quantify crack and mineral dissemination in the sphalerite particles. The results are validated with those obtained using traditional techniques such as physical gas (with N 2) adsorption, mercury intrusion porosimetry, SEM and QEMSCAN. A comparison of the effect of different comminution devices (HPGR and Cone crusher) on crack generation is also given.

3D characterization of sandstone by means of X-ray computed tomography

Due to technological development, stateof-the-art high-resolution X-ray computed tomography (CT) systems can be developed, enabling the internal visualization of geomaterials in three dimensions. However, in order to obtain structural information one also needs proper three-dimensional (3D) analysis software. In this paper, the potential for petrographic purposes of high-resolution X-ray CT in combination with the 3D analysis software Morpho+ is explored for a Belgian sandstone sample. The advantage of the CT technique is the fact that it is an ideal tool to characterize the internal structure of a rock in three dimensions in a nondestructive way while a limitation of this CT technique is that only small samples can be combined with a high spatial resolution and therefore often many samples will need to be scanned in order to obtain representative volumes. The relationship between sample size and obtained spatial resolution are discussed as well as the infl uence on the spatial resolution exerted by some important technical aspects like the used X-ray source and detector. This paper focuses in detail on the structures that can be determined by means of micro- and high-resolution X-ray CT in combination with 3D algorithms.

Three-Dimensional Analysis of High-Resolution X-Ray Computed Tomography Data with Morpho+

Three-dimensional (3D) analysis is an essential tool to obtain quantitative results from 3D datasets. Considerable progress has been made in 3D imaging techniques, resulting in a growing need for more flexible, complete analysis packages containing advanced algorithms. At the Centre for X-ray Tomography of the Ghent University (UGCT), research is being done on the improvement of both hardware and software for high-resolution X-ray computed tomography (CT). UGCT collaborates with research groups from different disciplines, each having specific needs. To meet these requirements the analysis software package, Morpho+, was developed in-house. Morpho+ contains an extensive set of high-performance 3D operations to obtain object segmentation, separation, and parameterization (orientation, maximum opening, equivalent diameter, sphericity, connectivity, etc.), or to extract a 3D geometrical representation (surface mesh or skeleton) for further modeling. These algorithms have a relatively short processing time when analyzing large datasets. Additionally, Morpho+ is equipped with an interactive and intuitive user interface in which the results are visualized. The package allows scientists from various fields to obtain the necessary quantitative results when applying high-resolution X-ray CT as a research tool to the nondestructive investigation of the microstructure of materials.

Cranial osteology and preliminary phylogenetic assessment of Plectrurus aureus Beddome, 1880 (Squamata: Serpentes: Uropeltidae)

Uropeltid snakes are among the most poorly understood clades within Alethinophidia. Their small size, limited geographic distribution, high incidence of endemism, and fossorial behaviour all contribute to the general paucity of systematic collections of these snakes, especially of adequate skeletal preparations, in most museum collections. Their hypothesized position within the higher-order phylogeny of alethinophidian snakes calls attention to the need for additional morphological work on the group. Hypotheses of uropeltid phylogenetic relationships based on morphological analyses are few, and continue to be hampered by limited taxon-sampling and character matrices that rely predominantly on features that are visible on articulated skulls. We utilized high-resolution X-ray computed tomography (HRCT) to investigate the cranial osteology of Plectrurus aureus Beddome, 1880, a species for which no osteological data were previously available. We provide a detailed description of the skull and mandible, and comment on morphological characters and potential phylogenetic relationships. Clarity in character descriptions is of paramount importance, and additional morphological characters are desirable. HRCT provides a nondestructive way to identify new systematically informative morphological characters from digitally disarticulated specimens. The small size of many uropeltid species, including P. aureus, will help to frame a greater appreciation of the limitations of traditional HRCT protocols for revealing detailed anatomical features of small vertebrates.

Plant structure visualization by high-resolution X-ray computed tomography

New developments in high-resolution X-ray computed tomography (HRXCT) are promising for the broader application of this non-destructive imaging method in plant sciences. Here, we demonstrate how detailed three-dimensional morphological traits can be extracted rapidly from in vivoArabidopsis thaliana seedlings without sample manipulation. Furthermore, ex vivo scanning at sub-micron resolution allows the quantification and visualization of the cellular organization of plant tissue samples, making HRXCT a desired tool in developmental plant biology.

Non-destructive Analysis of Oil-Contaminated Soil Core Samples by X-ray Computed Tomography and Low-Field Nuclear Magnetic Resonance Relaxometry: a Case Study

Non-destructive measurements of contaminated soil core samples are desirable prior to destructive measurements because they allow obtaining gross information from the core samples without touching harmful chemical species. Medical X-ray computed tomography (CT) and time-domain low-field nuclear magnetic resonance (NMR) relaxometry were applied to non-destructive measurements of sandy soil core samples from a real site contaminated with heavy oil. The medical CT visualized the spatial distribution of the bulk density averaged over the voxel of 0.31 × 0.31 × 2 mm3. The obtained CT images clearly showed an increase in the bulk density with increasing depth. Coupled analysis with in situ time-domain reflectometry logging suggests that this increase is derived from an increase in the water volume fraction of soils with depth (i.e., unsaturated to saturated transition). This was confirmed by supplementary analysis using high-resolution micro-focus X-ray CT at a resolution of ∼10 μm, which directly imaged the increase in pore water with depth. NMR transverse relaxation waveforms of protons were acquired non-destructively at 2.7 MHz by the Carr–Purcell–Meiboom–Gill (CPMG) pulse sequence. The nature of viscous petroleum molecules having short transverse relaxation times (T2) compared to water molecules enabled us to distinguish the water-saturated portion from the oil-contaminated portion in the core sample using an M 0–T2 plot, where M 0 is the initial amplitude of the CPMG signal. The present study demonstrates that non-destructive core measurements by medical X-ray CT and low-field NMR provide information on the groundwater saturation level and oil-contaminated intervals, which is useful for constructing an adequate plan for subsequent destructive laboratory measurements of cores.

Metasomatic origin of diamonds in the world's largest diamondiferous eclogite

The world's largest diamondiferous eclogite (8.8 kg, UD-111/02) from the Udachnaya kimberlite, Siberia, is the subject of this investigation. High-resolution X-ray computed tomography (HRXCT), chemistry of host minerals and diamond inclusions, stratigraphy of the diamonds (cathodoluminescence zoning), and carbon isotopes have been obtained. HRXCT images, 3-d models, and subsequent detailed dissection of this Group B eclogite revealed linear distributions of diamonds along alteration zones. Both unusual multiple-diamond clusters with dodecahedral morphologies, and distinctive internal zoning recorded by cathodoluminescence analyses are indicative of multiple stages of diamond growth and resorption in UD-111-02. Carbon-isotope ratios ( δ 13C) of 16 diamonds have a total range of ~ 7‰ (− 2.0 to − 9.2‰), with the majority at − 5.4‰. Diamond core values are variable and include the lightest (− 9.2‰) and heaviest δ 13C (− 2.0‰) values, suggesting that cores formed from distinct carbon sources, or grew under different conditions. In contrast, the rims of all diamonds have similar δ 13C values (average − 5.2‰ with a 2SD of 1.2‰), suggesting that they formed under uniform conditions. Mineral inclusions in diamonds display compositional variations. These lines of evidence, considered together, indicate that diamonds in this eclogite were formed by several events, most likely from multiple metasomatic fluids. Furthermore, it is becoming increasingly evident that in most diamondiferous eclogites, diamonds are not synchronously formed with their host eclogites.

CAT Scan-Based Images of the Skeleton of the Asian CatfishCranoglanis(Siluriformes: Cranoglanididae)

Figured on the following two pages are 3D models of the bony skeleton of the Asian catfish Cranoglanis bouderius, produced with High Resolution X-ray Com puted Tomography (HRXCT) imaging methods. The scanned specimen is from China, Guangdong Province Guangzhou city, and is deposited at the Academy of Natrual Sciences: ANSP 164978, Standard Length = 125 mm. Additional images and animations of this specimen are publicly available at the CatfishBones website, http:// catfishbone.acnatsci.org/. The specimen was scanned at the High-Resolution X ray CT Facility, The University of Texas, Austin. The scan ning parameters are as follows. A Feinfocus microfocal X-ray source operating at 180 kV and 0.133 mA with no X ray prefiltering. For each slice, 1600 views were taken with two samples per view. The field of image reconstruction was 40 mm, corresponding to a resolution of 39.1 microns per pixel for the 1024 by 1024 pixel slices. The specimen was scanned in multi-slice mode, in which 15 slices were collected simultaneously during a single specimen rota tion resulting in a total of 645 transverse (=coronal) CT slices. The scan was taken along the long axis of the speci men from the tip of the snout to the middle of the dorsal fin base. Visualizations were produced in the commercial software package VG Studio Max?. Although the render ings appear similar to photographs, they represent the den sity differences of the biological materials as reflected in their X-ray opacity. Preparation of the figures utilized still frames captured from digital animations of HRXCT and were prepared using Adobe?Photoshop?CS. The genus Cranoglanis, with three species, is placed in its own family Cranoglanididae. These catfishes are endemic to southern mainland China, Hainan Island and Viet Nam. The relationship of Cranoglanis to other cat fishes has long been uncertain due to its generalized mor phology. Cranoglanis has been variously thought related to Asian Bagridae, Pangasiidae or Schilbidae. However, one morphological study by Diogo et al. (2002) and recent molecular-based phylogenetic studies by Hardman (2005) and Sullivan et al. (2006) indicate a sistergroup relation ship between Cranoglanididae and the North American catfish family Ictaluridae. This discovery confirms the long-standing supposition of close evolutionary relation ship between North American and some Asian catfishes. Lundberg et al. (2007) applied fossil-calibrated molecu lar dating analyses to chart the time course of catfish di versification. They estimated the age of the phylogenet ic split between Cranoglanididae and Ictaluridae to have been roughly 85 million years ago in the Late Cretaceous when the early Bering land bridge between eastern Asian and western North America provided a migration path for biotic exchange.