Multiple-image radiography for human soft tissue

Radiographic Measurements of the Foot and Ankle After Ankle Arthrodesis

Background

Ankle arthrodesis is an established treatment for ankle arthritis. For patients with ankle arthritis, the position of the talus during ankle arthrodesis may affect the radiographic parameters of the foot. The purpose of this study is to assess the radiographic relationship between talar alignment and the longitudinal arch of the foot before and after ankle arthrodesis.

Methods

We retrospectively reviewed a single-surgeon series of 30 patients who had undergone ankle arthrodesis. Measured parameters included the lateral tibiotalar angle (LTTA), lateral talometatarsal angle (LTMA), lateral talocalcaneal angle (LTCA), cuneiform height (CH), and calcaneal pitch (CP). Additional data collected included demographics, fusion construct type, and visual analog scale (VAS) measurements.

Results

LTTA was increased from 68.2 ± 7.4 degrees preoperatively to 75.0 ± 6.4 degrees postoperatively (P = .001), LTMA increased from -2.0 ± 10.7 degrees to 4.0 ± 10.1 degrees (P < .001), CH increased from 20.1 ± 7.5 mm to 26.1 ± 8.4 mm (P < .001), LTCA and CP had no statistically significant change. VAS score decreased from 5.7 ± 2.7 to 1.3 ± 1.9 (P < .001).

Conclusion

Correcting the talar alignment in the sagittal plane during ankle arthrodesis improved the radiographic parameters of the foot, contributing to restoration of the longitudinal arch. The clinical significance of these findings is that in patients undergoing ankle arthrodesis, the surgeon should be aware that the alignment of the foot will be altered at the time of ankle arthrodesis and should be considered in preoperative planning. Further research is needed to determine the effect of ankle arthrodesis in patients determined to have pes planus preoperatively.

Level of Evidence

Level III, retrospective cohort study.

Interobserver Reliability in the Radiological Evaluation of Flatfoot (Pes Planus) Deformity: A Cross-Sectional Study

This study was planned for analyzing the interobserver reliability on the diagnosis of flatfoot. This study aims to evaluate the interobserver reliability of the digital radiography of flatfoot patients. Eight parameters were used in digital x-rays within the as statistically in 2 groups. Study group includes 34 patients. Two groups were formed four medical specialists as 2 orthopedists and 2 radiologists. Two orthopedists made measurements on x-ray viewing as calcaneal pitch (CP) as CP floor, calcaneus-1 metatarsal angle, calcaneus-5 metatarsal angle; longitudinal arch angles (LAAs) as medial and lateral LAAs, Tomeno-Meary angle (TMA), anteroposterior and lateral CYMA line. The intraclass correlation coefficient (ICC) analysis was performed. Fleiss Kappa and Kappa was used to investigate the reliability of qualitative data between 2 observers. ICCs were in high levels for CP floor, calcaneus-1 metatarsal angle, calcaneus-5 metatarsal angle. ICCs of TMA was in high levels, also. ICCs of LAA-medial and LAA-lateral were not in high levels as other measurements. In the CYMA line (anteroposterior and lateral) Kappa was 0.140 for right feet in the quadruple group (p = .045; .458; and .314). Kappa was 0.197 for left feet in the quadruple group (p = .005; .146; .377). The ICCs was excellent for CP angles and TMA in all groups. LAAs as medial and lateral longitudinal arch angle had not high ICC's. CYMA line had significant p values in the quadruple group. But not in orthopedists and radiologists.

Developing a Microbubble-Based Contrast Agent for Synchrotron Multiple-Image Radiography

PURPOSE

Multiple-image radiography (MIR) is an analyzer-based synchrotron X-ray imaging approach capable of dissociating absorption, refraction, and scattering components of X-ray interaction with the material. It generates additional image contrast mechanisms (besides absorption), especially in the case of soft tissues, while minimizing absorbed radiation dose. Our goal is to develop a contrast agent for MIR using ultrasound microbubbles by carrying out a systematic assessment of size, shell material, and concentration.

PROCEDURES

Microbubbles were synthesized with two different shell materials: phospholipid and polyvinyl-alcohol. Polydisperse perfluorobutane-filled lipid microbubbles were divided into five size groups using centrifugation. Two distributions of air-filled polymer microbubbles were generated: 2-3 µm and 3-4 µm. A subset of polymer microbubbles 3-4 µm had iron oxide nanoparticles incorporated into their shell or coated on their surface. Microbubbles were immobilized in agar with different concentrations: 5 × 10⁷, 5 × 10⁶, and 5 × 10⁵ MBs/ml. MIR was conducted on the BioMedical Imaging and Therapy beamline at the Canadian Light Source. Three images were generated: Gaussian amplitude, refraction, and ultra-small-angle X-ray scattering (USAXS). The contrast signal was quantified by measuring mean pixel values and comparing them with agar.

RESULTS

No difference was detected in absorption or refraction images of all tested microbubbles. Using USAXS, a significant signal increase was observed with lipid microbubbles 6-10 µm at the highest concentration (p = 0.02), but no signal was observed at lower concentrations.

CONCLUSIONS

These data indicate that lipid microbubbles 6-10 µm are candidates as contrast agents for MIR, specifically for USAXS. A minimum concentration of 5 × 10⁷ microbubbles (lipid-shell 6-10 µm) per milliliter was needed to generate a detectable signal.

Clinical utility of postprocessed low-dose radiographs in skeletal imaging

OBJECTIVES

Radiography remains the mainstay of diagnostic and follow-up imaging. In view of the risks and the increasing use of ionizing radiation, dose reduction is a key issue for research and development. The introduction of digital radiography and the associated access to image postprocessing have opened up new opportunities to minimize the radiation dosage. These advances are contingent upon quality controls to ensure adequate image detail and maintenance of diagnostic confidence. The purpose of this study was to investigate the clinical applicability of postprocessed low-dose images in skeletal radiography.

METHODS

In our study setting, the median radiation dose for full dose X-rays was 9.61 dGy*cm2 for pelvis, 1.20 dGy*cm2 for shoulder and 18.64 dGy*cm2 for lumbar spine exams. Based on these values, we obtained 200 radiographs for each anatomic region in four consecutive steps, gradually reducing the dose to 84%, 71%, 60% and 50% of the baseline using an automatic exposure control (AEC). 549 patients were enrolled for a total of 600 images. All X-rays were postprocessed with a spatial noise reduction algorithm. Two radiologists assessed the diagnostic value of the radiographs by rating the visualization of anatomical landmarks and image elements on a five-point Likert scale. A mean-sum score was calculated by averaging the two reader's total scores. Given the non-parametric distribution, we used the Mann-Whitney U test to evaluate the scores.

RESULTS

Median dosage at full dose accounted for 38.4%, 48 and 53.2% of the German reference dose area product for shoulder, pelvis and lumbar spine, respectively. The applied radiation was incrementally reduced to 21.5%, 18.4% and 18.7% of the respective reference value for shoulder, pelvis and lumbar spine. Throughout the study, we observed an estimable tendency of superior quality at higher dosage in overall image quality. Statistically significant differences in image quality were restricted to the 50% dose groups in shoulder and lumbar spine images. Regardless of the applied dosage, 598 out of 600 images were of sufficient diagnostic value.

CONCLUSION

In digital radiography image postprocessing allows for extensive reduction of radiation dosage. Despite a trend of superior image detail at higher dose levels, overall quality and, more importantly, diagnostic utility of low-dose images was not significantly affected. Therefore, our results not only confirm the clinical utility of postprocessed low-dose radiographs, but also suggest a widespread deployment of this advanced technology to ensure further dose limitations in clinical practice.

ADVANCES IN KNOWLEDGE

The diagnostic image quality of postprocessed skeletal radiographs is not significantly impaired even after extensive dose reduction by up to 20% of the reference value.

Comparison of Tracheal Diameter Measurements on Radiograph Versus Computed Tomography at a Tertiary Care Hospital in Pune, Central India

Background

Variations in tracheal diameter with respect to factors like age and gender are one of the major factors affecting the size of the endotracheal tube (ETT) preferred in a patient. It is important to pre-determine this figure because a tube of a larger size predisposes the patient for tracheal mucosal ischemia, while one of a smaller size may not ensure adequate oxygen saturation in the patient.

Purpose

We undertook this study to assess the accuracy of radiograph versus computed tomography (CT) and comment on whether a CT should be carried out mandatorily in all patients where intubation is needed.

Materials and methods

The study was undertaken at Dr DY Patil Medical College, Hospital, and Research Center, a tertiary care institute in Pune, India. A total of 217 patients in whom both chest radiograph and chest CT were performed were enrolled in the study and measurements were performed at suitable landmarks which correspond to the position of endotracheal tubes.

Results

The males had a mean age of 44.2 years and females of 41.7 years. The mean X-ray transverse diameter was 15.4 ± 3.2 (SD) mm, mean CT axial transverse diameter was 15.3 ± 3.4 (SD) mm, mean CT sagittal diameter was 14.8 ± 3.7 (SD) mm, and the mean CT coronal diameter was 15.2 ± 3.5(SD)mm.

Conclusions

There was a significant difference in mean X-ray transverse diameter (Low kV), CT axial transverse diameter, CT sagittal diameter, and CT coronal diameter between males and females. Mean values were significantly higher in males as compared to females. There was a significant difference in tracheal diameters for different age groups, irrespective of the modality. Bland-Altman analysis revealed no significant difference between chest radiograph and CT for tracheal diameter measurement.

X-ray Dark-Field Imaging (XDFI)-a Promising Tool for 3D Virtual Histopathology

X-ray dark-field imaging (XDFI) utilizing a thin silicon crystal under Laue case enables visualizing three-dimensional (3D) morphological alterations of human tissue. XDFI uses refraction-contrast derived from phase shift rather than absorption as the main X-ray image contrast source to render 2D and 3D images of tissue specimens in unprecedented detail. The unique features of XDFI are its extremely high sensitivity (approximately 1000:1 compared to absorption for soft tissues under X-ray energy of around 20 keV, theoretically) and excellent resolution (8.5 μm) without requiring contrast medium or staining. Thus, XDFI-computed tomography can generate 3D virtual histological images equivalent to those of stained histological sections pathologists observe under low-power light microscopy as far as organs and tissues selected as samples in preliminary studies. This paper reviews the fundamental principles and the potential of XDFI, describes two optical setups for XDFI with examples, illustrates features of XDFI that are salient for histopathology, and presents XDFI examples of refraction-contrast images of atherosclerotic plaques, musculoskeletal tissue, neuronal tissue, and breast cancer specimens. Availability of this X-ray imaging in routine histopathological evaluations of tissue specimens would help guide clinical decision making by highlighting suspicious areas in unstained, thick sections for further sampling and analysis using conventional histopathological techniques. XDFI is a promising tool for 3D virtual histopathology.

Analyzer-based phase-contrast imaging system using a micro focus X-ray source

Here we describe a new in-laboratory analyzer based phase contrast-imaging (ABI) instrument using a conventional X-ray tube source (CXS) aimed at bio-medical imaging applications. Phase contrast-imaging allows visualization of soft tissue details usually obscured in conventional X-ray imaging. The ABI system design and major features are described in detail. The key advantage of the presented system, over the few existing CXS ABI systems, is that it does not require high precision components, i.e., CXS, X-ray detector, and electro-mechanical components. To overcome a main problem introduced by these components, identified as temperature stability, the system components are kept at a constant temperature inside of three enclosures, thus minimizing the electrical and mechanical thermal drifts. This is achieved by using thermoelectric (Peltier) cooling/heating modules that are easy to control precisely. For CXS we utilized a microfocus X-ray source with tungsten (W) anode material. In addition the proposed system eliminates tungsten's multiple spectral lines by selecting monochromator crystal size appropriately therefore eliminating need for the costly mismatched, two-crystal monochromator. The system imaging was fine-tuned for tungsten Kα1 line with the energy of 59.3 keV since it has been shown to be of great clinical significance by a number of researchers at synchrotron facilities. In this way a laboratory system that can be used for evaluating and quantifying tissue properties, initially explored at synchrotron facilities, would be of great interest to a larger research community. To demonstrate the imaging capability of our instrument we use a chicken thigh tissue sample.

Microcomputed tomography with diffraction-enhanced imaging for morphologic characterization and quantitative evaluation of microvessel of hepatic fibrosis in rats

Backgroud

Hepatic fibrosis can lead to deformation of vessel morphology and structure. In the present feasibility study, high-resolution computed tomography (CT) using diffraction-enhanced imaging (DEI) was used to represent three-dimensional (3D) vessel microstructures of hepatic fibrosis in rats and to differentiate different stages of hepatic fibrosis using qualitative descriptions and quantitative measurement of microvessels.

Material and Methods

Three typical specimens at different stages, i.e., mild, moderate and severe hepatic fibrosis, were imaged using DEI at 15 keV without contrast agents. The correspondence between DEI-CT images and histopathological findings was determined. The 3D visualizations from different stages of hepatic fibrosis were presented using DEI-CT. Additionally, Qualitative descriptions and quantitative evaluation of vessel features, such as vessel trend, vascular distortion deformation, thrombus formation and texture features on the inner wall of the vessel, were performed.

Results

DEI-CT produced high-resolution images of the vessel microstructures in hepatic fibrosis that corresponded to information on actual structures observed from the histological sections. Combined with the 3D visualization technique, DEI-CT enabled the acquisition of an accurate description of the 3D vessel morphology from different stages of hepatic fibrosis. Qualitative descriptions and quantitative assessment of microvessels demonstrated clear differences between the different stages of hepatic fibrosis. The thrombus inside the vessel of severe liver fibrosis was accurately displayed, and corresponding analysis can provide an exact measurement of vessel stenosis rate.

Conclusions

DEI-CT may allow morphologic descriptions and quantitative evaluation of vessel microstructures from different stages of hepatic fibrosis and can better characterize the various stages of fibrosis progression using high-resolution 3D vessel morphology.

Potential for imaging engineered tissues with X-ray phase contrast

As the field of tissue engineering advances, it is crucial to develop imaging methods capable of providing detailed three-dimensional information on tissue structure. X-ray imaging techniques based on phase-contrast (PC) have great potential for a number of biomedical applications due to their ability to provide information about soft tissue structure without exogenous contrast agents. X-ray PC techniques retain the excellent spatial resolution, tissue penetration, and calcified tissue contrast of conventional X-ray techniques while providing drastically improved imaging of soft tissue and biomaterials. This suggests that X-ray PC techniques are very promising for evaluation of engineered tissues. In this review, four different implementations of X-ray PC imaging are described and applications to tissues of relevance to tissue engineering reviewed. In addition, recent applications of X-ray PC to the evaluation of biomaterial scaffolds and engineered tissues are presented and areas for further development and application of these techniques are discussed. Imaging techniques based on X-ray PC have significant potential for improving our ability to image and characterize engineered tissues, and their continued development and optimization could have significant impact on the field of tissue engineering.

Talbot phase-contrast x-ray imaging for the small joints of the hand

A high-resolution radiographic method for soft tissues in the small joints of the hand would aid in the study and treatment of rheumatoid arthritis (RA) and osteoarthritis (OA), which often attacks these joints. Of particular interest would be imaging with <100 µm resolution the joint cartilage, whose integrity is a main indicator of disease. Differential phase-contrast (DPC) or refraction-based x-ray imaging with Talbot grating interferometers could provide such a method, since it enhances soft tissue contrast and can be implemented with conventional x-ray tubes. A numerical joint phantom was first developed to assess the angular sensitivity and spectrum needed for a hand DPC system. The model predicts that, due to quite similar refraction indexes for joint soft tissues, the refraction effects are very small, requiring high angular resolution. To compare our model to experiment we built a high-resolution bench-top interferometer using 10 µm period gratings, a W anode tube and a CCD-based detector. Imaging experiments on animal cartilage and on a human finger support the model predictions. For instance, the estimated difference between the index of refraction of cartilage and water is of only several percent at ∼25 keV mean energy, comparable to that between the linear attenuation coefficients. The potential advantage of DPC imaging thus comes mainly from the edge enhancement at the soft tissue interfaces. Experiments using a cadaveric human finger are also qualitatively consistent with the joint model, showing that refraction contrast is dominated by tendon embedded in muscle, with the cartilage layer difficult to observe in our conditions. Nevertheless, the model predicts that a DPC radiographic system for the small hand joints of the hand could be feasible using a low energy quasi-monochromatic source, such as a K-edge filtered Rh or Mo tube, in conjunction with a ∼2 m long 'symmetric' interferometer operated in a high Talbot order.

Development of microperiodic mirrors for hard x-ray phase-contrast imaging

Differential phase-contrast imaging with hard x rays can have important applications in medicine, material sciences, and energy research. Phase-contrast methods based on microperiodic optics, such as shearing interferometry, are particularly attractive because they allow the use of conventional x-ray tubes. To enable shearing interferometry with x rays up to 100?keV, we propose using grazing-incidence microperiodic mirrors. In addition, a simple lithographic method is proposed for the production of the microperiodic x-ray mirrors, based on the difference in grazing-incidence reflectivity between a low-Z substrate and a high-Z film. Using this method, we produced prototype mirrors with 5-100?mum periods and 90?mm active length. Experimental tests with x rays up to 60?keV indicate good microperiodic mirror reflectivity and high-contrast fringe patterns, encouraging further development of the proposed imaging concept.

Synchrotron X-ray imaging via ultra-small-angle scattering: principles of quantitative analysis and application in studying bone integration to synthetic grafting materials

Optimized experimental conditions for extracting accurate information at subpixel length scales from analyzer-based X-ray imaging were obtained and applied to investigate bone regeneration by means of synthetic beta-TCP grafting materials in a rat calvaria model. The results showed a 30% growth in the particulate size due to bone ongrowth/ingrowth within the critical size defect over a 1-month healing period.

The design and application of an in-laboratory diffraction-enhanced x-ray imaging instrument

We describe the design and application of a new in-laboratory diffraction-enhanced x-ray imaging (DEXI) instrument that uses a nonsynchrotron, conventional x-ray source to image the internal structure of an object. In the work presented here, a human cadaveric thumb is used as a test-sample to demonstrate the imaging capability of our instrument. A 22 keV monochromatic x-ray beam is prepared using a mismatched, two-crystal monochromator; a silicon analyzer crystal is placed in a parallel crystal geometry with the monochromator allowing both diffraction-enhanced imaging and multiple-imaging radiography to be performed. The DEXI instrument was found to have an experimentally determined spatial resolution of 160+/-7 mum in the horizontal direction and 153+/-7 mum in the vertical direction. As applied to biomedical imaging, the DEXI instrument can detect soft tissues, such as tendons and other connective tissues, that are normally difficult or impossible to image via conventional x-ray techniques.

Diffraction-enhanced imaging of musculoskeletal tissues using a conventional x-ray tube

RATIONALE AND OBJECTIVES

In conventional projection radiography, cartilage and other soft tissues do not produce enough radiographic contrast to be distinguishable from each other. Diffraction-enhanced imaging (DEI) uses a monochromatic x-ray beam and a silicon crystal analyzer to produce images in which attenuation contrast is greatly enhanced and x-ray refraction at tissue boundaries can be detected. The aim of this study was to test the efficacy of conventional x-ray tube-based DEI for the detection of soft tissues in experimental samples.

MATERIALS AND METHODS

Cadaveric human tali (normal and degenerated) and a knee and thumb were imaged with DEI using a conventional x-ray tube and DEI setup that included a double-silicon crystal monochromator and a silicon crystal analyzer positioned between the imaged object and the detector.

RESULTS

Diffraction-enhanced images of the cadaveric tali allowed the visualization of cartilage and its specific level of degeneration for each specimen. There was a significant correlation between the grade of cartilage integrity as assessed on the tube diffraction-enhanced images and on their respective histologic sections (r = 0.97, P = .01). Images of the intact knee showed the articular cartilage edge of the femoral condyle, even when superimposed by the tibia. In the thumb image, it was possible to visualize articular cartilage, tendons, and other soft tissues.

CONCLUSION

DEI based on a conventional x-ray tube allows the visualization of skeletal and soft tissues simultaneously. Although more in-depth testing and optimization of the DEI setup must be carried out, these data demonstrate a proof of principle for further development of the technology for future clinical imaging.

Comparison of refraction information extraction methods in diffraction enhanced imaging

Diffraction enhanced imaging (DEI) is a powerful phase-sensitive technique that generates the improved contrast of weakly absorbing samples compared to conventional radiography. The x-ray refraction contrast of the sample is an important contrast in DEI, and it vastly exceeds the absorption contrast for weakly absorbing samples imaging, which makes it hold great promise for medical, biological and material applications. In order to effectively utilize the refraction contrast, the key procedure is first to obtain the refraction information expressed as the refraction image. By comparing the signal-to-noise ratio (SNR) of the refraction image, x-ray radiation dose of the sample and the range of obtained refraction angles, the different refraction information extraction methods are investigated in this paper, and the experimental results confirm the conclusion.

Spatial harmonic imaging of X-ray scattering--initial results

Coherent X-ray scattering is related to the electron density distribution by a Fourier transform, and therefore a window into the microscopic structures of biological samples. Current techniques of scattering rely on small-angle measurements from highly collimated X-ray beams produced from synchrotron light sources. Imaging of the distribution of scattering provides a new contrast mechanism which is different from absorption radiography, but is a lengthy process of raster or line scans of the beam over the object. Here, we describe an imaging technique in the spatial frequency domain capable of acquiring both the scattering and absorption distributions in a single exposure. We present first results obtained with conventional X-ray equipment. This method interposes a grid between the X-ray source and the imaged object, so that the grid-modulated image contains a primary image and a grid harmonic image. The ratio between the harmonic and primary images is shown to be a pure scattering image. It is the auto-correlation of the electron density distribution at a specific distance. We tested a number of samples at 60-200 nm autocorrelation distance, and found the scattering images to be distinct from the absorption images and reveal new features. This technique is simple to implement, and should help broaden the imaging applications of X-ray scattering.

Anatomic relationship of heel spur to surrounding soft tissues: greater variability than previously reported

The stimulating factor for the development of heel spur (calcaneal exostosis) is controversial. In a sample of elderly cadaveric specimens, using radiographic, gross morphological, and histological investigation, we demonstrate that heel spurs are generally not found in the trajectory of traction from the plantar aponeurosis enthesis or plantar muscles. Rather, they are variably associated with soft tissues including loose connective tissue, fibrocartilage, muscle, and aponeurosis. Furthermore, the bony trabeculae of the spur are not aligned in the direction of soft tissue traction, but rather in the direction of stress on the calcaneus during walking and standing. These results substantiate the view that the heel spur may be a skeletal response to stress and may serve to protect the bone against the development of microfractures.

Grating interferometer based scanning setup for hard X-ray phase contrast imaging

In x-ray radiography, particularly for technical and industrial applications, a scanning setup is very often favorable when compared to a direct two-dimensional image acquisition. Here, we report on an efficient scanning method for grating based x-ray phase contrast imaging with tube based sources. It uses multiple line detectors for staggered acquisition of the individual phase-stepping images. We find that the total exposure time does not exceed the time needed in an equivalent scanning setup for absorption radiography. Therefore, we conclude that it should be possible to implement the method into a scanning system without affecting the scanning speed or significant increase in cost but with the advantage of providing both the phase contrast and the absorption information at once.

An extended diffraction-enhanced imaging method for implementing multiple-image radiography

Diffraction-enhanced imaging (DEI) is an analyser-based x-ray imaging method that produces separate images depicting the projected x-ray absorption and refractive properties of an object. Because the imaging model of DEI does not account for ultra-small-angle x-ray scattering (USAXS), the images produced in DEI can contain artefacts and inaccuracies in medical imaging applications. In this work, we investigate an extended DEI method for concurrent reconstruction of three images that depict an object's projected x-ray absorption, refraction and USAXS properties. The extended DEI method can be viewed as an implementation of the recently proposed multiple-image radiography paradigm. Validation studies are conducted by use of computer-simulated and synchrotron measurement data.

Non-destructive diffraction enhanced imaging of seeds

Techniques that make possible the non-destructive continuous observation of plant anatomy and developmental processes provide novel insights into these phenomena. Non-destructive imaging of seeds was demonstrated using the synchrotron-based X-ray imaging technique, diffraction enhanced imaging (DEI). The seed images obtained had good contrast and definition, allowing anatomical structures and physiological events to be observed. Structures such as hypocotyl-root axes, cotyledons, seed coats, air cavities, and embryo-less Brassica napus L. seeds were readily observed using DEI. Embryo axes, scutella, pericarp furrows, coleoptiles, and roots were observable over a time-course in individual germinating Triticum aestivum L. caryopses. Novel anatomical and physiological observations were also made that would have been difficult to make continuously using other techniques. The physical principles behind DEI make it a unique imaging technique. Contrast in DEI is the result of X-ray refraction at the density differences occurring at tissue boundaries, scatter caused by regions containing ordered molecules such as cellulose fibres, and attenuation. Sectioning of samples and the infusion of stains or other contrast agents are not necessary. Furthermore, as high-energy X-rays are used (30-40 keV), little X-ray absorption occurs, resulting in low levels of radiation damage. Consequently, studies of developmental processes may be performed on individuals. Individual germinating B. napus and T. aestivum seeds were imaged at several time points without incurring any apparent radiation damage. DEI offers a unique way of examining plant anatomy, development, and physiology, and provides images that are complementary to those obtained through other techniques.

Do we really need plain and soft-tissue radiographies to detect radiolucent foreign bodies in the ED?

OBJECTIVE

The objective of this study was to compare 3 imaging techniques-plain radiography, soft-tissue radiography, and ultrasonography-in detecting nonradiopaque foreign bodies in soft tissue.

METHODS

In this randomized, blinded, and descriptive in vitro study, 40 chicken thighs with 2 types of nonradiopaque foreign bodies (wood and rubber) and 40 chicken thighs as part of a control group were evaluated to detect soft-tissue foreign bodies with plain radiography, soft-tissue radiography, and high-frequency ultrasonography.

RESULTS

The overall sensitivity, specificity, as well as positive predictive and negative predictive values of plain radiography for both nonradiopaque foreign bodies were 5%, 90%, 33%, and 48%, respectively; those of soft-tissue radiography for both nonradiopaque foreign bodies were 5%, 90%, 33%, and 48%, respectively; and those of ultrasonography for both nonradiopaque foreign bodies were 90%, 80%, 81%, and 89%, respectively.

CONCLUSIONS

In this experimental model, the results show that high-frequency ultrasonography is superior to plain and soft-tissue radiographies and that the latter 2 techniques are similarly poor at detecting nonradiopaque foreign bodies.