Accurate evaluation of morphological changes in articular cartilage are necessary for early detection of osteoarthritis (OA). 3T magnetic resonance imaging (MRI) has highly sensitive contrast ...resolution and is widely used clinically to detect OA. However, synchrotron radiation phase-contrast imaging computed tomography (SR-PCI) can also provide contrast to tissue interfaces that do not have sufficient absorption differences, with the added benefit of very high spatial resolution. Here, MRI was compared with SR-PCI for quantitative evaluation of human articular cartilage. Medial tibial condyles were harvested from non-OA donors and from OA patients receiving knee replacement surgery. Both imaging methods revealed that average cartilage thickness and cartilage volume were significantly reduced in the OA group, compared to the non-OA group. When comparing modalities, the superior resolution of SR-PCI enabled more precise mapping of the cartilage surface relative to MRI. As a result, MRI showed significantly higher average cartilage thickness and cartilage volume, compared to SR-PCI. These data highlight the potential for high-resolution imaging of articular cartilage using SR-PCI as a solution for early OA diagnosis. Recognizing current limitations of using a synchrotron for clinical imaging, we discuss its nascent utility for preclinical models, particularly longitudinal studies of live animal models of OA.
Congenital lung malformations are a constellation of pathologies that can be diagnosed antenatally by ultrasound and fetal MRI. Ultrasound is considered the modality of choice for a routine ...assessment of second-trimester scans worldwide. Bronchopulmonary sequestration (BPS) and congenital pulmonary airway malformation (CPAM) are the 2 most common echogenic chest masses discovered incidentally during routine ultrasound scans in the second trimester. This paper describes BPS and differentiates it from CPAM sonographically in utero. An extensive literature search involving antenatal ultrasound is undertaken to review the most up-to-date understanding of the BPS. Furthermore, a case study at our institution and the literature review will help better describe the salient features of BPS. A 41-year-old female G3P1 visits our department for a routine second-trimester ultrasound. An echogenic lesion with a cystic component is visualized in this scan. Based on the grayscale and color imaging, this complex echogenic lesion was reported as CPAM and was referred to fetal assessment for confirmation. The fetal assessment diagnosed the lesion as BPS because of the pathognomonic feeding vessel from the thoracic aorta. Regardless of the congenital lung mass, any large mass compromising fetal well-being is an indication for intervention. The prognosis of BPS in the absence of fetal hydrops is excellent. A robust collaboration among radiologists, obstetricians, and pediatricians is required for the best outcome for the pregnancy and the neonate.
► Moiré pattern noise has occasionally been observed in Scanning Transmission X-ray Microscopy (STXM) images. ► The STXM images with the noise introduce significant errors in image analysis for ...chemical speciation and quantification of the specimen composition. ► Due to the complex origination of the noise, it is difficult to avoid the Moiré pattern noise during the data acquisition stage. ► In this study, we investigate the feasibility to apply a post-processing method to remove the noise from STXM images.
Moiré pattern noise in Scanning Transmission X-ray Microscopy (STXM) imaging introduces significant errors in qualitative and quantitative image analysis. Due to the complex origin of the noise, it is difficult to avoid Moiré pattern noise during the image data acquisition stage. In this paper, we introduce a post-processing method for filtering Moiré pattern noise from STXM images. This method includes a semi-automatic detection of the spectral peaks in the Fourier amplitude spectrum by using a local median filter, and elimination of the spectral noise peaks using a Gaussian notch filter. The proposed median-Gaussian filtering framework shows good results for STXM images with the size of power of two, if such parameters as threshold, sizes of the median and Gaussian filters, and size of the low frequency window, have been properly selected.
The objective of this project was to develop and test a new technology for imaging growing joints by means of diffraction-enhanced imaging (DEI) combined with CT and using a synchrotron radiation ...source. DEI-CT images of an explanted 4-wk-old piglet stifle joint were acquired
by using a 40-keV beam. The series of scanned slices was later 'stitched' together, forming a 3D dataset. High-resolution DEI-CT images demonstrated fine detail within all joint structures and tissues. Striking detail of vasculature traversing between bone and cartilage, a characteristic of
growing but not mature joints, was demonstrated. This report documents for the first time that DEI combined with CT and a synchrotron radiation source can generate more detailed images of intact, growing joints than can currently available conventional imaging modalities.
This article presents the data of using three phase-based X-ray imaging techniques to characterize biomaterial scaffold and soft tissues in situ, as reported in our study “Low-dose phase-based X-ray ...imaging techniques for in situ soft tissue engineering assessments” 1. The examined parameters include the radiation dose, scan time, and image quality, which are all critical to longitudinal in situ live animal assessments. The data presented were obtained from three dimensional imaging of scaffolds in situ cartilage by means of synchrotron-based computed tomography-diffraction enhanced imaging (CT-DEI), analyzer based imaging (CT-ABI), and in-line phase contrast imaging (CT-PCI) at standard and low dose imaging modalities.
Diffraction-enhanced imaging (DEI) is a type of phase contrast x-ray imaging that has improved image contrast at a lower dose than conventional radiography for many imaging applications, but no ...studies have been done to determine if DEI might be useful for diagnosing lung injury. The goals of this study were to determine if DEI could differentiate between healthy and injured lungs for a rat model of gastric aspiration and to compare diffraction-enhanced images with chest radiographs.
Radiographs and diffraction-enhanced chest images of adult Sprague Dawley rats were obtained before and 4 hours after the aspiration of 0.4 mL/kg of 0.1 mol/L hydrochloric acid. Lung damage was confirmed with histopathology.
The radiographs and diffraction-enhanced peak images revealed regions of atelectasis in the injured rat lung. The diffraction-enhanced peak images revealed the full extent of the lung with improved clarity relative to the chest radiographs, especially in the portion of the lower lobe that extended behind the diaphragm on the anteroposterior projection.
For a rat model of gastric acid aspiration, DEI is capable of distinguishing between a healthy and an injured lung and more clearly than radiography reveals the full extent of the lung and the lung damage.
Objective: X-ray phase contrast imaging generates contrast from refraction of X-rays, enhancing soft tissue contrast compared to conventional absorption-based imaging. Our goal is to develop a ...contrast agent for X-ray in-line phase contrast imaging (PCI) based on ultrasound microbubbles (MBs), by assessing size, shell material, and concentration. Methods: Polydisperse perfluorobutane-core lipid-shelled MBs were synthesized and size separated into five groups between 1 and 10 μm. We generated two size populations of polyvinyl-alcohol (PVA)-MBs, 2-3 μm and 3-4 μm, whose shells were either coated or integrated with iron oxide nanoparticles (SPIONs). Microbubbles were then embedded in agar at three concentrations: 5 × 10 7 , 5 × 10 6 and 5 × 10 5 MBs/ml. In-line phase contrast imaging was performed at the Canadian Light Source with filtered white beam micro-computed tomography. Phase contrast intensity was measured by both counting detectable MBs, and comparing mean pixel values (MPV) in minimum and maximum intensity projections of the overall samples. Results: Individual lipid-MBs 6-10 μm, lipid-MBs 4-6 μm and PVA-MBs coated with SPIONs were detectable at each concentration. At the highest concentration, lipid-MBs 6-10 μm and 4-6 μm showed an overall increase in positive contrast, whereas at a moderate concentration, only lipid-MBs 6-10 μm displayed an increase. Negative contrast was also observed from two largest lipid-MBs at high concentration. Conclusion: These data indicate that lipid-MBs larger than 4 μm are candidates for PCI, and 5 × 10 6 MBs/ml may be the lowest concentration suitable for generating visible phase contrast in vivo. Significance: Identifying a suitable MB for PCI may facilitate future clinical translation.
Abstract In tissue engineering, non-invasive imaging of biomaterial scaffolds and tissues in living systems is essential to longitudinal animal studies for assessments without interrupting the repair ...process. Conventional X-ray imaging is inadequate for use in soft tissue engineering due to the limited absorption difference between the soft tissue and biomaterial scaffolds. X-ray phase-based imaging techniques that derive contrast from refraction or phase effects rather than absorption can provide the necessary contrast to see low-density biomaterial scaffolds and tissues in large living systems. This paper explores and compares three synchrotron phase-based X-ray imaging techniques—computed tomography (CT)-diffraction enhanced imaging (DEI), -analyzer based imaging (ABI), and -phase contrast imaging (PCI)—for visualization and characterization of low-density biomaterial scaffolds and tissues in situ for non-invasive soft tissue engineering assessments. Intact pig joints implanted with polycaprolactone scaffolds were used as the model to assess and compare the imaging techniques in terms of different qualitative and quantitative criteria. For long-term in vivo live animal imaging, different strategies for reducing the imaging radiation dose and scan time—reduced number of CT projections, region of interest, and low resolution imaging—were examined with the presented phase-based imaging techniques. The results demonstrated promising capabilities of the phase-based techniques for visualization of biomaterial scaffolds and soft tissues in situ . The low-dose imaging strategies were illustrated effective for reducing the radiation dose to levels appropriate for live animal imaging. The comparison among the imaging techniques suggested that CT-DEI has the highest efficiency in retaining image contrast at considerably low radiation doses.
Clinical diagnostic quality digital radiographs of 20 radii were acquired by using a Philips Medio (Philips Healthcare, Andover, MA) 50 CP-H in the Department of Medical Imaging, Royal University ...Hospital in Saskatoon. From the total sample of 20, 1 0 specimens that reflected a broad range of apparent trabecular morphologies were selected for DEI at the CLS synchrotron by using the 05B1-1 beam line at 41 keV, with a surface exposure typically of 2 mGy. The monochromator and analyser used single crystal silicon crystals with the (3, 3, 3) lattice planes. The DEI technique has been described previously 6, and thus we provide only a general summary here. Briefly, a single energy beam is extracted from a polychromatic synchrotron x-ray beam by using a double crystal monochromator. The high flux (intensity) of the synchrotron source ensures that sufficient photons remain after selection of a single energy. This beam passes through the target sample and is reflected off the third crystal known as the "analyser" before arriving at the detector. The placement of the analyser crystal between the sample and the detector is a defining feature of DEI. The condition for x-ray diffraction from the analyser crystal is met only when the incident beam makes the correct angle to the atomic lattice planes in the crystal for a given x-ray energy or wavelength. When this condition is met, the beam diffracts from the analyser over a very narrow range of incident angles. As the analyser is rotated, the intensity variation observed is referred to as the rocking curve. Because the range of angles that can be accepted by the analyser is only a few microradians (I microradian = 57 microdegrees = 0.21 arc-seconds), the analyser provides scatter rejection at the microradian level, which is below the capabilities of conventional antiscatter techniques, such as slit collimation and grids. Small angle scattering arises from diffraction from structures with dimensions up to micron sizes. This scattering intensity, which would normally appear in the image, is missing and appears in the same way as absorption in the image. This scatter rejection contrast is called extinction contrast. Therefore, in DEI, the image that represents the absorption of the object by x-rays is referred to as the apparent absorption image because it has contrast derived from both absorption and scatter rejection. Notably, DEI provides particular improvement with respect to resolving pixel-sized objects 8. Refraction images have a high sensitivity for defining the boundaries between areas with differing refractive indices. It is this property of DEI that provides improved visualization of trabecular bone, which consists of a lattice-like solid structure surrounded by soft tissue (marrow). Although, in the past, DEI has been applied to bone 9-11, the potential to better visualize bone microarchitecture with the aim of improving the assessment of human bone at a clinically relevant fracture site has not yet been explored.
Objective: The aim of this study was to determine the 95% confidence interval (CI) cutoff for sonographic renal artery stenosis (RAS) parameters. A secondary objective was to determine the diagnostic ...accuracy parameters of peak systolic velocity (PSV), renal aortic ratio (RAR), acceleration index (AI), and acceleration time (AT) for diagnosing RAS. Materials and Methods: Diagnostic test accuracy (DTA) parameters and 95% CIs were evaluated for the sonographic cutoff values. A total of 31 articles were extracted and subjected to statistical analysis. Results: The mean 95% CI cutoff for PSV, RAR, AI, and AT were 192.50 (175.16, 209.84), 3.10 (2.83, 3.38), 3.39 (2.51, 4.27), and 80.78 (68.56, 93.01), respectively. The pooled mean 95% CI sensitivity of PSV, RAR, AI, and AT were 85.90% (79.84, 91.97), 82.34% (77.58, 87.11), 74.92% (64.53, 85.33), and 73.57% (63.01, 84.13), respectively, whereas the pooled mean specificity of the same parameters was 82.52% (75.78, 89.25), 86.97% (83.12, 90.82), 78.93% (66.34, 91.52), and 82.57% (70.70, 94.44), respectively. Conclusion: The pooled mean 95% CI for sensitivity and specificity of the sonographic parameters was concordant with the literature. Based on this higher level of evidence, except RAR, the mean 95% CI cutoff for PSV, AI, and AT were consistent with the cutoff values encountered in the published literature.
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