Accuracy of the DIAGNOcam and bitewing radiographs in the diagnosis of cavitated proximal carious lesions in primary molars.

AIMS: To evaluate the diagnostic abilities of near-infrared light transillumination (using the DIAGNOcam) and bitewing radiographs in detecting cavitated proximal carious lesions in primary molars. SUBJECTS AND METHODS: The study was a cross-sectional analytical, clinical study. The proximal surfaces of primary molars of healthy 5- to 8-year-old children were radiographically screened for the presence of carious lesions in the enamel or outer third of dentin (D1). Two trained and calibrated examiners evaluated the depth of caries in bitewing radiographs and DIAGNOcam images and then verified the presence of cavitation by direct visual examination using the "International Caries Detection and Assessment System" after temporary tooth separation. RESULTS: A total of 236 proximal lesions were included in the study. Most of the clinically cavitated lesions (51.9%) were D1 radiographically and in outer dentin lesions (scores 3 and 4) by the DIAGNOcam (37% and 48.1%, respectively). Although DIAGNOcam showed higher sensitivity (0.852) compared to the radiographs (0.519), it showed slightly less specificity (0.569) compared to the radiographs (0.579). However, DIAGNOcam showed higher value of the area under the curve (AUC = 0.722; P < 0.001) compared to the radiographic method (AUC = 0.561; P = 0.308). CONCLUSIONS: The DIAGNOcam showed higher sensitivity and better accuracy than bitewing radiographs in diagnosing cavitated proximal lesions in primary molars and can be generally considered as an alternative to radiographs to detect cavitation without the hazards of ionizing radiation in children.

Quantitative X-Ray Imaging of Mouse Bone by Faxitron.

This chapter describes the use of point projection digital microradiography for rapid imaging and quantitation of bone mineral content in mice.

Scanning Electron Microscopy of Bone.

This chapter describes methods for preparing samples of bone and bone cells for scanning electron microscopy (SEM). Backscattered electron (BSE) imaging is by far the most useful in the bone field, followed by secondary electrons (SE) and the energy dispersive X-ray (EDX) analytical modes. Samples may have 3D detail in a 3D surface, or be topography-free, polished or micromilled, resin-embedded block surfaces, or resin casts of space compartments surrounded by bone matrix. Methods for cells include fixation, drying, looking at undersides of bone cells, and metallic conductive coating. Maceration with alkaline bacterial pronase, hypochlorite, hydrogen peroxide, and sodium or potassium hydroxide to remove cells and unmineralized matrix is described in detail. Attention is given especially to methods for 3D BSE SEM imaging of bone samples. Recommendations are made for the types of resin embedding for BSE SEM imaging. Correlated confocal and SEM imaging of PMMA embedded bone requires the use of glycerol to coverslip. Cathodoluminescence (CL) mode SEM imaging is an alternative for visualizing fluorescent mineralizing front labels such as calcein and tetracyclines. Making spatial casts from PMMA or other resin-embedded samples is an important use of this material. Correlation with other imaging means, including microradiography and microtomography is important. Shipping wet bone samples between labs is best done in glycerol. Control of the vacuum pressure in the SEM sample chamber (now generally available) can be used to eliminate "charging" problems which were common, for example, with large, complex, cancellous bone samples.

In vitro performance of the DIAGNOcam for detecting proximal carious lesions adjacent to composite restorations.

OBJECTIVES: To assess the accuracy of near-infrared-light transillumination (DIAGNO) compared to visual-tactile (VT) and radiographic (RA) evaluation of proximal carious lesions adjacent to composite restorations in vitro. METHODS: Two hundred extracted posterior permanent human teeth with occluso-proximal composite restorations were allocated to 50 groups of four posterior teeth, and mounted in a pilot-tested diagnostic model in a dummy head. The teeth were independently assessed by two examiners. Transverse microradiography and visual assessment served as reference tests to detect any lesions (prevalence 24%) and cavitated lesions (18%), respectively, adjacent to restorations. Sensitivity, specificity, positive and negative predictive values and the area under the receiver-operating-characteristics curve (AUC) were calculated. RESULTS: To detect any proximal carious lesions adjacent to composite, the mean sensitivity/specificity were 0.63/0.95 for DIAGNO, 0.70/0.88 for RA when lesions radiographically extending into enamel and dentin were considered, 0.26/0.98 for RA when only lesions extending into dentin were considered, and 0.31/0.96 for VT. For cavitated lesions adjacent to proximal composite restorations, these values were RA (enamel and dentin) 0.84/0.88, RA (dentin) 0.34/0.99, DIAGNO 0.69/0.94 and VT 0.40/0.97. AUC did not differ significantly between RA and DIAGNO, while VT showed significantly lower values (p < 0.05). CONCLUSION: Within the limitations of this study, DIAGNO seems useful for detecting proximal carious lesions adjacent to restorations. CLINICAL RELEVANCE: Near-infrared-light transillumination could be used as a radiation-free adjunct or alternative to RA for detecting carious lesions adjacent to composite restorations.

Sub-micrometer resolution proximity X-ray microscope with digital image registration.

A compact laboratory proximity soft X-ray microscope providing submicrometer spatial resolution and digital image registration is described. The microscope consists of a laser-plasma soft X-ray radiation source, a Schwarzschild objective to illuminate the test sample, and a two-coordinate detector for image registration. Radiation, which passes through the sample under study, generates an absorption image on the front surface of the detector. Optical ceramic YAG:Ce was used to convert the X-rays into visible light. An image was transferred from the scintillator to a charge-coupled device camera with a Mitutoyo Plan Apo series lens. The detector's design allows the use of lenses with numerical apertures of NA = 0.14, 0.28, and 0.55 without changing the dimensions and arrangement of the elements of the device. This design allows one to change the magnification, spatial resolution, and field of view of the X-ray microscope. A spatial resolution better than 0.7 µm and an energy conversion efficiency of the X-ray radiation with a wavelength of 13.5 nm into visible light collected by the detector of 7.2% were achieved with the largest aperture lens.

Validation of a novel microradiography device for characterization of bone mineralization.

In order to simplify bone mineralization measurements, a system using radiographic films has been updated with a digital detector. The objective of this paper was to validate this new device. Technologies and physical phenomena involved in both systems (radiographic films and digital detector) are different. The methodology used to compare the two systems was based on image quality and assessed on two main parameters: contrast to noise ratio and spatial resolution. Results showed that the contrast to noise ratio was similar between the two systems, provided that acquisition parameters were optimized. With regard to spatial resolution, a magnification factor of at least 4 or more was required to achieve the same resolution as films. A final validation was also shown on a real image of a bone sample. The results showed that both systems have similar image quality performances, and the system using digital detector has several advantages (easier to use than films, no consumables and faster acquisition time).

Imaging cells and sub-cellular structures with ultrahigh resolution full-field X-ray microscopy.

Our experimental results demonstrate that full-field hard-X-ray microscopy is finally able to investigate the internal structure of cells in tissues. This result was made possible by three main factors: the use of a coherent (synchrotron) source of X-rays, the exploitation of contrast mechanisms based on the real part of the refractive index and the magnification provided by high-resolution Fresnel zone-plate objectives. We specifically obtained high-quality microradiographs of human and mouse cells with 29 nm Rayleigh spatial resolution and verified that tomographic reconstruction could be implemented with a final resolution level suitable for subcellular features. We also demonstrated that a phase retrieval method based on a wave propagation algorithm could yield good subcellular images starting from a series of defocused microradiographs. The concluding discussion compares cellular and subcellular hard-X-ray microradiology with other techniques and evaluates its potential impact on biomedical research.

Complete microscale profiling of tumor microangiogenesis: a microradiological methodology reveals fundamental aspects of tumor angiogenesis and yields an array of quantitative parameters for its characterization.

Complete profiling would substantially facilitate the fundamental understanding of tumor angiogenesis and of possible anti-angiogenesis cancer treatments. We developed an integrated synchrotron-based methodology with excellent performances: detection of very small vessels by high spatial resolution (~1 µm) and nanoparticle contrast enhancement, in vivo dynamics investigations with high temporal resolution (~1 ms), and three-dimensional quantitative morphology parametrization by computer tracing. The smallest (3-10 µm) microvessels were found to constitute >80% of the tumor vasculature and exhibit many structural anomalies. Practical applications are presented, including vessel microanalysis in xenografted tumors, monitoring the effects of anti-angiogenetic agents and in vivo detection of tumor vascular rheological properties.

Current status of developments and applications of micro-CT.

Use of microscopic computed-tomography (micro-CT) scanning continues to grow in biomedical research. Laboratory-based micro-CT scanners, laboratory-based nano-CT scanners, and integrated micro-CT/SPECT and micro-CT/PET scanners are now manufactured for "turn-key" operation by a number of commercial vendors. In recent years a number of technical developments in X-ray sources and X-ray imaging arrays have broadened the utility of micro-CT. Of particular interest are photon-counting and energy-resolving detector arrays. These are being explored to maximize micro-CT image grayscale dynamic range and to further increase image contrast by utilizing the unique spectral attenuation characteristics of individual chemical elements. X-ray phase-shift images may increase contrast resolution and reduce radiation exposure. Although radiation exposure is becoming a concern with the drive for increased spatial and temporal resolution, especially for longitudinal studies, gated scans and limited scan-data-set reconstruction algorithms show great potential for keeping radiation exposure to a minimum.

Micro-computed tomography: a method for the non-destructive evaluation of the three-dimensional structure of biological specimens.

The large increase in interest in micro-computed tomography (micro-CT) over the last decade reflects the+ need for a method able to non-destructively visualize the internal three-dimensional structure of an object. Thereby, the real beauty of computed tomography lies in the fact that it is available for a large range of nominal resolutions, which allows hierarchical imaging from whole bodies down to the tissue level. Although micro-CT is currently mainly used for imaging of hard tissue (i.e., bone and tooth), future developments might also allow high soft tissue contrast either using appropriate contrast agents or x-ray contrast mechanisms. This chapter aims to review the steps necessary for a successful micro-CT measurement. Although the actual measurement is often machine dependent, the chapter does not describe a specific system but rather lists all steps that eventually have to be considered to set up a measurement, run the measurement, process the image data, and get morphometric indices as a result. The chapter provides an easy understandable manual that should allow newcomers to perform successful measurements and hence to best profit from this powerful technique.

Phase contrast X-ray synchrotron imaging: opening access to fossil inclusions in opaque amber.

A significant portion of Mesozoic amber is fully opaque. Biological inclusions in such amber are invisible even after polishing, leading to potential bias in paleoecological and phylogenetic studies. Until now, studies using conventional X-ray microtomography focused on translucent or semi-opaque amber. In these cases, organisms of interest were visualized prior to X-ray analyses. It was recently demonstrated that propagation phase contrast X-ray synchrotron imaging techniques are powerful tools to access invisible inclusions in fully opaque amber. Here we describe an optimized synchrotron microradiographic protocol that allowed us to investigate efficiently and rapidly large amounts of opaque amber pieces from Charentes (southwestern France). Amber pieces were imaged with microradiography after immersion in water, which optimizes the visibility of inclusions. Determination is not accurate enough to allow precise phylogenetic studies, but provides preliminary data on biodiversity and ecotypes distribution; phase contrast microtomography remains necessary for precise determination. Because the organisms are generally much smaller than the amber pieces, we optimized local microtomography by using a continuous acquisition mode (sample moving during projection integration). As tomographic investigation of all inclusions is not practical, we suggest the use of a synchrotron for a microradiographic survey of opaque amber, coupled with microtomographic investigations of the most valuable organisms.

The 3DX multi image micro-CT device in clinical dental practice.

OBJECTIVES: To evaluate the usefulness of 3DX multi-image micro-CT device in clinical dental practice. METHODS: Images of 198 examinations performed with a 3DX device during a 6 month period in a private dental practice were evaluated retrospectively for the benefit of additional information compared with panoramic or intraoral radiographs. RESULTS: The main indication for the use of 3DX micro-CT was planning of dental implant placement in 49% of the examinations. Diagnosis or exclusion of dental infection or peri-implantitis represented 28% of the examinations and tooth, root or foreign body localization represented 13%. Temporomandibular joint (TMJ) imaging and cyst or tumour diagnosis represented 7.5% and 2.5% of the examinations, respectively. In implant planning and tooth, root or foreign body localization examinations, the required information was obtained in every case except three implant planning examinations, in which the exact measurements were hampered by artefacts caused by root fillings and retrograde fillings or metal posts. When compared with conventional radiography, additional radiographic information was obtained in 51% of the micro-CT examinations performed to confirm or exclude dental infection or peri-implantitis. Micro-CT also showed the bone structure of TMJs precisely. CONCLUSIONS: The 3DX micro-CT device visualizes bony anatomical structures precisely, which makes it a reliable tool for, for example, planning of implant treatment. The device is highly suitable for diagnosing dental infections. Dental restorations may cause disturbing artefacts and in 4.5% of the examinations the small imaging area resulted in re-examination.

Effect of voxel size on 3D micro-CT analysis of cortical bone porosity.

This study examines the impact of voxel size on 3D micro-CT analysis of human cortical bone porosity. The study is based on computed microtomography scans of 10 human anterior femoral midshaft specimens acquired at 5, 10, and 15 microm voxel sizes. Artificial voxel sizes (10, 20, and 40 microm) were generated from the smallest scan voxel size (5 microm) in order to compare actual scanning with artificial degradation, a method employed in other similar studies. Canal volume fraction (CaV/TV), canal surface to volume ratio (CaS/CaV), mean canal diameter (CaDm), mean canal separation (CaSp), canal number (CaN), degree of anisotropy (DA), and canal connectivity density (CaConnD) were calculated from matching volumes of interest for all datasets. Qualitatively, the clarity of the actual scan datasets deteriorated rapidly as voxel size increased. In contrast, within the artificially generated datasets, the clarity of cortical pores was better maintained until the largest voxel size (40 microm). Mean absolute percent error values, correlation coefficients, and paired t-tests revealed a pattern of increasing, and generally significant, differences between the smallest and progressively larger voxel sizes (both scanned and artificial). Relative to the actual scans, however, the artificial datasets were less sensitive to changing voxel size. These findings indicated that subtle changes in voxel size, within the range examined, have a considerable effect on human cortical porosity structural parameters. Additionally, the use of artificially increased voxel sizes should be viewed with caution as they may not reflect what can actually be obtained by scanning.

[Characteristics and applications of a flat panel computer tomography system]. / Eigenschaften und Anwendungen der Flächendetektor-basierten Volumen-Computertomographie.

PURPOSE: To assess a new flat panel volume computed tomography (FP-VCT) with very high isotropic spatial resolution as well as high Z-axis coverage. MATERIALS AND METHODS: The prototype of an FP-VCT scanner with a detector cell size of 0.2 mm was used for numerous phantom studies, specimen examinations, and animal research projects. RESULTS: The high spatial resolution of the new system can be used to accurately determine solid tumor volume, thus allowing for earlier assessment of the therapeutic response. In animal experimentation, whole-body perfusion mapping of mice is feasible. The high spatial resolution also improves the classification of coronary artery atherosclerotic plaques in the isolated post mortem human heart. With the depiction of intramyocardial segments of the coronary arteries, investigations of myocardial collateral circulation are feasible. In skeletal applications, an accurate analysis of the smallest bony structures, e. g., petrous bone and dental preparations, can be successfully performed, as well as investigations of repetitive studies of fracture healing and the treatment of osteoporosis. CONCLUSION: The introduction of FP-VCT opens up new applications for CT, including the field of molecular imaging, which are highly attractive for future clinical applications. Present limitations include limited temporal resolution and necessitate further improvement of the system.

Synchrotron microradiography study on acute lung injury of mouse caused by PM(2.5) aerosols.

In order to investigate FeSO(4), ZnSO(4) (the two of main metal compositions of Shanghai PM(2.5) (particle matter with those aerodynamical diameter <2.5 microm)) effects on acute lung injury, six solutions contained PM(2.5) aerosol particles, FeSO(4), ZnSO(4) and their mixtures were instilled intratracheally into mouse lungs for experiment. By 2 days after instillation, the live mice were checked in vivo by synchrotron refractive index microradiography. In addition after extracted and examined by dissection, the right lobes of lung were fixed by formalin, then imaged by synchrotron microradiography again. Corresponding parts of those lung tissues were embedded in paraffin for histopathologic study. The synchrotron X-ray microradiographs of live mouse lung showed different lung texture changes after instilled with different toxic solutions. Hemorrhage points in lung were observed more from those mice instilled by FeSO(4) contained toxin solutions groups. Bronchial epithelial hyperplasia can be observed in ZnSO(4) contained solution-instilled groups from histopathologic analysis. It was found that the acute lung injury of mice caused by solution of PM(2.5)+FeSO(4)+ZnSO(4) was more serious than other toxin solutions. Results suggested that FeSO(4) mainly induced hemorrhage and ZnSO(4) mainly induced inflammation and bronchiolar epithelial hyperplasia in the early toxicological effects of PM(2.5).

Synchrotron radiation in radiology: radiology techniques based on synchrotron sources.

The characteristics of synchrotron X-ray sources--quite different from those of conventional sources--are exploited by several new imaging techniques. These techniques expand the capabilities of conventional radiology and find interesting application in special cases. We briefly review the basic principle, applications and limitations of the most important of them: monochromatic mammography, two-wavelength digital subtraction angiography, phase-contrast/edge-enhancement imaging, diffraction-enhanced imaging and microtomography.

High-resolution imaging of osteoarthritis using microcomputed tomography.

Three-dimensional imaging of osteoarthritis is so far limited to late stages of the disease. In this chapter we introduce microcomputed tomography (microCT) as a new imaging tool that offers exciting features for diagnosis of earlier disease stages and for disease monitoring. microCT provides spatial resolution better than 100 microm, but the size of the objects that can be scanned is restricted to several centimeters. The strength of X-ray-based techniques like micro CT is the excellent visualization of bone. Therefore, the main application of microCT in osteoarthritis (OA) will be the analysis of bone in small-animal models or of human bone biopsies. As an example, we will exemplarily describe the application of microCT for the examination of knee joints of male STR1N mice. This inbred strain spontaneously develops OA that carries many characteristics of the human disease. With microCT it is possible to monitor the prominent bony alterations such as osteophyte formation, trabecular remodeling, subchondral bone plate thickening, and subchondral sclerosis. We discuss sample preparation, scanning procedures, data processing, and analysis as well as implications and restrictions for in vivo and in vitro applications.

Micro-computed tomography-current status and developments.

The recent rapid increase in interest in tomographic imaging of small animals and of human (and large animal) organ biopsies is driven largely by drug discovery, cancer detection/monitoring, phenotype identification and/or characterization, and development of disease detection methods and monitoring efficacies of drugs in disease treatment. In biomedical applications, micro-computed tomography (CT) scanners can function as scaled-down (i.e., mini) clinical CT scanners that provide a three-dimensional (3-D) image of most, if not the entire, torso of a mouse at image resolution (50-100 microm) scaled proportional to that of a human CT image. Micro-CT scanners, on the other hand, image specimens the size of intact rodent organs at spatial resolutions from cellular (20 microm) down to subcellular dimensions (e.g., 1 microm) and fill the resolution-hiatus between microscope imaging, which resolves individual cells in thin sections of tissue, and mini-CT imaging of intact volumes.

Image analysis of X-ray microtomograms of soft materials during convective drying.

X-ray microtomography is used to explore the textural evolution that soft materials undergo during a drying treatment. An original image processing algorithm is applied to vertical projections and reconstructed cross-section images in order to quantify the texture at different stages of drying. Measurements are performed both on grey-level and on binary images. It is shown that X-ray microtomography is a very promising tool in the field of drying investigations. It can be used to determine internal moisture profiles, and to follow crack development and shrinkage in an accurate and non-destructive way. This information is crucial to validate drying models. Waste-water sludges are used as test materials to assess the validity of the proposed methodology. The management of these sludges, often including a drying stage, will become a challenge in the forthcoming years in accordance with environmental regulations. Samples collected in two waste-water treatment plants are investigated. Their analysis by X-ray microtomography brings to the fore two different drying behaviours, illustrating that sludge drying is a complex unit operation very sensitive to the way the material is produced.