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Mandibular and medial retropharyngeal lymph nodes are routinely evaluated with CT when staging dogs with oral melanomas. While size alone is considered inadequate for detecting nodal metastasis, it is critical in evaluating treatment response, as clinical decisions are based on changes in size. It is common for different radiologists to measure the size of pre- and posttreatment lymph nodes in the same patient. The objective of this retrospective, observer agreement study was to evaluate the inter- and intraobserver agreement in measuring canine mandibular and medial retropharyngeal lymph nodes by a diverse population of veterinary radiologists and trainees. Fourteen dogs with documented oral melanoma and head CT studies identified from records of a single institution were included in this study. North American veterinary radiologists and trainees were recruited to measure the mandibular and medial retropharyngeal lymph nodes; in triplicate. Prior to performing the study measurements, participants completed a training tool demonstrating the lymph node measurements. Overall, interobserver intraclass correlation coefficient (ICC) was 0.961 (95% confidence interval [CI]: 0.946, 0.972) and intraobserver ICC was 0.977 (95% CI: 0.968, 0.983), indicating excellent agreement (ICC > 0.9 considered excellent). Similar findings were noted following sub-analysis for most variables (experience, size, laterality, axis of measurement). These results suggest that follow-up measurement of the long and short axis of the mandibular lymph nodes and short axis of the medial retropharyngeal lymph nodes in the transverse plane, performed by different veterinary radiologists using the same method of measure, should have minimal impact on clinical decision making.

The use of magnetic resonance imaging (MRI) during pregnancy is associated with concerns among patients and health professionals with regards to fetal safety. In this work, the Canadian Association of Radiologists (CAR) Working Group on MRI in Pregnancy presents recommendations for the use of MRI in pregnancy, derived from literature review as well as expert panel opinions and discussions. The working group, which consists of academic subspecialty radiologists and obstetrician-gynaecologists, aimed to provide updated, evidence-based recommendations addressing safety domains related to energy deposition, acoustic noise, and gadolinium-based contrast agent use based on magnetic field strength (1.5T and 3T) and trimester scanned, in addition to the effects of sedative use and occupational exposure.

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 × 107, 5 × 106 and 5 × 105 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 × 106 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.

Mycobacterium avium complex (MAC) is usually considered an opportunistic organism, which infects immunocompromised children or those with structural airway abnormalities. We present two cases of MAC infection affecting immune competent children, likely from hot tubs with primary involvement of pulmonary and urinary systems. These cases highlight the importance of asking about hot tub use in immune competent children with suspected or confirmed MAC infections.

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.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 × 10No 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.These data indicate that lipid microbubbles 6-10 µm are candidates as contrast agents for MIR, specifically for USAXS. A minimum concentration of 5 × 10

While next-generation sequencing has accelerated the discovery of human disease genes, progress has been largely limited to the “low hanging fruit” of mutations with obvious exonic coding or canonical splice site impact. In contrast, the lack of high-throughput, unbiased approaches for functional assessment of most noncoding variants has bottlenecked gene discovery. We report the integration of transcriptome sequencing (RNA-seq), which surveys all mRNAs to reveal functional impacts of variants at the transcription level, into the gene discovery framework for a unique human disease, microcephaly-micromelia syndrome (MMS). MMS is an autosomal recessive condition described thus far in only a single First Nations population and causes intrauterine growth restriction, severe microcephaly, craniofacial anomalies, skeletal dysplasia, and neonatal lethality. Linkage analysis of affected families, including a very large pedigree, identified a single locus on Chromosome 21 linked to the disease (LOD > 9). Comprehensive genome sequencing did not reveal any pathogenic coding or canonical splicing mutations within the linkage region but identified several nonconserved noncoding variants. RNA-seq analysis detected aberrant splicing in DONSON due to one of these noncoding variants, showing a causative role for DONSON disruption in MMS. We show that DONSON is expressed in progenitor cells of embryonic human brain and other proliferating tissues, is co-expressed with components of the DNA replication machinery, and that Donson is essential for early embryonic development in mice as well, suggesting an essential conserved role for DONSON in the cell cycle. Our results demonstrate the utility of integrating transcriptomics into the study of human genetic disease when DNA sequencing alone is not sufficient to reveal the underlying pathogenic mutation.

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.

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.

A number of phase based X-ray imaging methods have been developed that derive contrast from phase effects from the object which make them particularly interesting because of the ability to visualize soft tissues. Shack–Hartmann is a wave-front diagnostic technique that emerged from optics which uses ray-line beams (beamlets) to interrogate the differences in the wave-front across a beam can also be used for X-ray imaging applications with phase sensitivity. This method, which has been applied in the X-ray regime, is very simple in that it only requires a screen to prepare an array of beamlets that then pass through the object and are allowed to propagate a distance onto a pixelated detector. Absorption and refraction information can be extracted from the detected beamlets. An untapped property is the additional ability to extract scatter distribution information based on the observed width of the detected spots. This paper describes experiments done at a synchrotron facility investigating the use of a Shack–Hartmann system for biomedical applications and include our method and examples of scatter contrast extraction from the method.

The Biomedical Imaging and Therapy (BMIT) beamlines at the Canadian Light Source (CLS) comprise a multi-modality synchrotron imaging facility capable of imaging objects with 2–200 μm resolution with beam sizes up to ~200 mm wide and ~10 mm high in the experimental hutches [1–3]. BMIT hosts two beamlines, a bend magnet 05B1-1 and an insertion device 05ID-2, with capabilities to apply absorption imaging, in-line phase contrast imaging (PCI), analyzer-based imaging (ABI) or diffraction-enhanced imaging (DEI), and K-Edge Subtraction (KES) imaging. Talbot or grating interferometry is under development.

While next-generation sequencing has accelerated the discovery of human disease genes, progress has been largely limited to the “low hanging fruit” of mutations with obvious exonic coding or canonical splice site impact. In contrast, the lack of high-throughput, unbiased approaches for functional assessment of most noncoding variants has bottlenecked gene discovery. We report the integration of transcriptome sequencing (RNA-seq), which surveys all mRNAs to reveal functional impacts of variants at the transcription level, into the gene discovery framework for a unique human disease, microcephaly-micromelia syndrome (MMS). MMS is an autosomal recessive condition described thus far in only a single First Nations population and causes intrauterine growth restriction, severe microcephaly, craniofacial anomalies, skeletal dysplasia, and neonatal lethality. Linkage analysis of affected families, including a very large pedigree, identified a single locus on Chromosome 21 linked to the disease (LOD > 9). Comprehensive genome sequencing did not reveal any pathogenic coding or canonical splicing mutations within the linkage region but identified several nonconserved noncoding variants. RNA-seq analysis detected aberrant splicing in DONSON due to one of these noncoding variants, showing a causative role for DONSON disruption in MMS. We show that DONSON is expressed in progenitor cells of embryonic human brain and other proliferating tissues, is co-expressed with components of the DNA replication machinery, and that Donson is essential for early embryonic development in mice as well, suggesting an essential conserved role for DONSON in the cell cycle. Our results demonstrate the utility of integrating transcriptomics into the study of human genetic disease when DNA sequencing alone is not sufficient to reveal the underlying pathogenic mutation.

Rationale and Objectives 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. Materials and Methods 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. Results 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. Conclusions 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.

The bending magnet line (05B1-1) of the BioMedical Imaging and Therapy (BMIT) facility of the Canadian Light Source saw initial research application (Figure 1) during commissioning which began in December 2008 and continued intermittently through May 2010. Following an initial run based upon letters of intent (June-Dec. 2010), the bending magnet line is now available for regular user access. The mandate to advance research related to human and animal health, combined with an active bone imaging community at the University of Saskatchewan, has resulted in a strong representation of skeletal imaging during initial experiments at BMIT. To date, specific manifestations of bone imaging have ranged from micro-CT imaging of human cortical bone samples to in vitro diffraction enhanced imaging (DEI) of rat and pig bones and, ultimately, to in vivo DEI of bones within young chickens. In this article we focus on the diffraction enhanced imaging capabilities of BMIT and describe our efforts to apply this technology t...

We report an unusual case of chronic mesenteric ischemia presenting in a 12-year-old girl with idiopathic infantile arterial calcinosis (IIAC). This is the first reported case in the literature of chronic mesenteric ischemia in the setting of IIAC. The girl presented with a classical history of postprandial abdominal pain. Imaging demonstrated significant stenoses of the celiac axis, superior mesenteric artery (SMA) and inferior mesenteric artery (IMA). Angioplasty of the celiac axis and SMA was attempted, with successful dilation of the SMA only. At 3-, 6- and 12-month follow-ups, the child's symptoms had almost resolved. This case report has three important ramifications: chronic mesenteric ischemia is a possible clinical presentation in children with IACC, pre-angioplasty imaging is important in guiding treatment approach, and angioplasty was effective in this case of chronic mesenteric ischemia and offers hope for other similarly affected children.

Dysosteosclerosis is a rare autosomal recessive skeletal dysplasia characterized by osteosclerosis and platyspondyly. A case of dysosteosclerosis in a 17-year-old male from our institution was first published by Houston et al. 1978. This patient has survived into adulthood and to our knowledge, is the only reported adult with dysosteosclerosis. We will review the clinical and radiographic features in our patient.

Biomedical research at synchrotron facilities may involve imaging live animals that must remain motionless for extended periods of time to obtain quality images. Even breathing movements reduce image quality but on the other hand excessive restraint of animals increases morbidity and mortality. We describe a humane animal restraint designed to eliminate head movements while promoting animal survival. This paper describes how an animal restraint that conforms to the shape of an animal's head was fabricated by a 3D prototyper. The method used to translate medical computed tomography (CT) data to a 3D stereolithography format is described and images of its use at the Canadian Light Source (CLS) are shown. This type of restraint holds great promise in improving image quality and repeatability while reducing stress on experimental animals.

Survivors of childhood Wilms tumors are at an increased risk of second malignant neoplasms. Recently, it has been postulated that renal cell carcinoma is among the malignancies for which this population is at risk. We present the unique case of an adult Wilms tumor survivor with non-syndromic hemihypertrophy (NSHH) who developed renal cell carcinoma. This case highlights the need for close follow-up in two populations: adults who have survived Wilms tumor and those with NSHH.

In mechanically ventilated neonates it is not uncommon to observe obstructive atelectasis from various causes. However it is extremely rare to see mucous plugging and massive pulmonary atelectasis in the absence of infection, aspiration, and respiratory distress syndrome in the first couple of days of life. In this report we describe a neonate born with cystic fibrosis (CF) who presented to us with hypoxic respiratory failure, pulmonary hypertension, and hypercarbia without lactic acedemia from sticky mucous plugging and massive lung collapse. Neonatal respiratory distress and wide spread pulmonary atelectasis has not been reported in infants born with CF. Pediatr Pulmonol. 2012; 47:620–622. © 2012 Wiley Periodicals, Inc.

Detection and visualization of lung tissue structures is impaired by predominance of air. However, by using synchrotron x-rays, refraction of x-rays at the interface of tissue and air can be utilized to generate contrast which may in turn enable quantification of lung optical properties. We utilized multiple image radiography, a variant of diffraction enhanced imaging, at the Canadian light source to quantify changes in unique x-ray optical properties of lungs, namely attenuation, refraction and ultra small-angle scatter (USAXS or width) contrast ratios as a function of lung orientation in free-breathing or respiratory-gated mice before and after intra-nasal bacterial endotoxin (lipopolysaccharide) instillation. The lung ultra small-angle scatter and attenuation contrast ratios were significantly higher 9 h post lipopolysaccharide instillation compared to saline treatment whereas the refraction contrast decreased in magnitude. In ventilated mice, end-expiratory pressures result in an increase in ultra small-angle scatter contrast ratio when compared to end-inspiratory pressures. There were no detectable changes in lung attenuation or refraction contrast ratio with change in lung pressure alone. In effect, multiple image radiography can be applied towards following optical properties of lung air-tissue barrier over time during pathologies such as acute lung injury.

OBJECTIVE. In our pediatric interventional practice, we have found that occasionally a loop of bowel is interposed between the stomach and the anterior wall of the abdomen, preventing safe needle access for procedures such as placement of a gastrostomy tube. The use of a small-caliber needle to aspirate air from the colon or small bowel, for bowel decompression, may be a safe way to aid in establishing a safe access route for the subsequent percutaneous introduction of larger needles or tubes.CONCLUSION. Our retrospective review of patients who have undergone bowel-gas aspiration during an interventional procedure shows that the aspiration of air from the colon with a small-caliber needle is technically easy and may permit completion of an abdominal procedure.

The purpose of this pilot study was to evaluate lymph node enhancement with an indirect magnetic resonance (MR) lymphography technique using 2 different contrast agents in the head and neck region of healthy dogs. Five dogs were imaged at various times after intradermal injection of gadoversetamide and Gadofluorine M (minimum of 1 week apart) in the right and left mandibular, temporal, and lateral neck regions. We observed consistent progressive enhancement with time in the mandibular, retropharyngeal, and superficial cervical lymph nodes. The node enhancement was comparable for both contrast agents. Contrast enhancement of the parotid lymph nodes was not seen. We conclude that this technique of indirect MR lymphography using either agent could be used to identify those lymph nodes at highest risk of metastatic disease in dogs with cancer, and to guide staging and treatment.

Moire 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 Moire pattern noise during the image data acquisition stage. In this paper, we introduce a post-processing method for filtering Moire 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.

Glioblastoma multiforme (GBM) is one of the most malignant human tumors, with a uniformly poor outcome. One obstacle in curing malignant brain tumors is the limitation of conventional light microscopy in detecting microscopic residual tumor in biopsy samples from the perimeter of the surgically resected tumor. We further refined the identification of GBM tumor tissue at the sub-cellular level, utilising the technique of Synchrotron, sourced mid-infrared (mid-IR) spectromicroscopy. Paired, thin (5 μm) cryosections of snap-frozen human GBM tumor samples removed at elective surgery were mounted on glass slides (hematoxylin and eosin-stained tissue section) and calcium fluoride (CaF 2 ) windows (unstained tissue section for transmission spectromicroscopy), respectively. Concordance of tumor bearing areas identified in the stained section with the unstained IR tissue section was confirmed by the pathologist of the study. Compared with molecular signatures obtained from normal control brain tissue, unique spectroscopic patterns were detected in GBM tumor samples from 6 patients. The identifying features of GBM were: i) high protein-to-lipid ratios (amide I+II/CH 2 symmetric stretch; amide I+II/CH 2 +CH 3 symmetric and asymmetric stretch), and ii) considerable enhancement of the intensities of characteristic peaks at 2,957 and 2,871 cm -1 representing CH 3 asymmetric and symmetric stretch, respectively. Spectral data sets were subjected to Ward's algorithm for assignment to similar groups, and then subjected to hierarchical cluster analysis (HCA) by means of false color digital maps. False color images of 5 clusters obtained by HCA identified dominant clusters corresponding to tumor tissue. Corroboration of these findings in a larger number of GBM may allow for more precise identification of these and other types of brain tumors.

Sandhoff ’s disease is a rare autosomal recessive disorder of sphingolipid metabolism that results from deficiency of the lysosomal enzymes, β-hexosaminidase A and B. The resultant accumulation of GM2 ganglioside within both grey matter nuclei and myelin sheaths of the white matter results in eventual severe neuronal dysfunction and neurodegeneration. Disease progression is rapid, resulting in early death. Currently, there is no curative treatment, with therapy remaining primarily supportive. This case report is of a 13-month-old aboriginal Canadian boy who was referred for further investigations related to global developmental delay and loss of developmental milestones, at which time the diagnosis was discovered.

Short stature is a frequent presenting problem in the pediatric population. Various causes including endocrinopathies, skeletal dysplasias, dysmorphic syndromes and malabsorption have been implicated. In girls with short stature, Turner syndrome is frequently considered in the differential diagnosis and can easily be ruled out with chromosome analysis. However, it is not uncommon for a child to have no identifiable cause of their short stature. ?FOR Advances in the field of genetics have estimated that about 2% of idiopathic short stature is related to haploinsufficiency of the Short stature homeobox (SHOX) gene, which is found on the short arm of the X and Y chromosomes in the pseudoautosomal region. Heterozygous carriers of SHOX mutations may be minimally affected or may present with disproportionate short stature, Madelung deformity and other radiographic findings as in Leri-Weill dyschondrosteosis (LWD). In this article, we report on a 14-year old girl with mesomelic short stature and bilateral Madelung deformities caused by LWD and describe the radiographic findings.

No Abstract South African Journal of Radiology Vol. 11 (2) 2007: pp. 32-35

Physiologic changes in renal transplant patients, such as transiently low central venous pressure, may be related to increased intra-abdominal pressure, from the volume of the transplanted kidney itself. Using intraoperative and postoperative Doppler ultrasound of the transplant renal vessels, we identified changes in flow dynamics following closure of the abdomen and reversal of the changes when the abdomen was reopened. This was attributed to abdominal compartment syndrome and a fasciotomy was created in the abdominal wall to accommodate the transplanted kidney. The findings in this case, in keeping with abdominal compartment syndrome, are not often considered in transplant recipients, but may explain some of the postsurgical physiology in some patients, particularly in the pediatric population.

Bronchial varices, which have rarely been described in the radiology literature, can be the result of pulmonary venous obstruction and may present with hemoptysis. This case is an illustration of this rare condition, which correlates CT findings with bronchoscopic findings. We also describe the findings on phase-contrast MR that demonstrated reversed diastolic flow in the branch pulmonary artery supplying the affected lung.

Ring artifacts can occur in reconstructed images from x-ray Computerized Tomography (CT) as full or partial concentric rings superimposed on the scanned structures. Due to the data corruption by those ring artifacts in CT images, qualitative and quantitative analysis of these images are compromised. In this paper, we propose to correct the ring artifacts on the reconstructed synchrotron radiation (SR) CT image slices. The proposed correction procedure includes the following steps: (1). transform the reconstructed CT images into polar coordinates; (2) apply discrete two-dimensional (2D) wavelet transform to the polar image to decompose it into four image components: low pass band image component, as well as the components from horizontal, vertical and diagonal details bands; (3). apply 2D Fourier transform to the vertical details band image component only, since the ring artifacts become vertical lines in the polar coordinates; (4). apply Gaussian filtering in Fourier domain along the abscissa direction to suppress the vertical lines, since the information of the vertical lines in Fourier domain is completely condensed to that direction; (5). perform inverse Fourier transform to get the corrected vertical details band image component; (6). perform inverse wavelet transform to get the corrected polar image; (7). transform the corrected polar image back to Cartesian coordinates to get the CT image slice with reduced ring artifacts. This approach has been successfully used on CT data acquired from the Biomedical Imaging and Therapy (BMIT) beamline in Canadian Light Source (CLS), and the results show that the ring artifacts in original SR CT images have been effectively suppressed with all the structure information in the image preserved.

Refraction x-ray contrast is an imaging modality used primarily in a research setting at synchrotron facilities, which have a biomedical imaging research program. The most common method for exploiting refraction contrast is by using a technique called Diffraction Enhanced Imaging (DEI). The DEI apparatus allows the detection of refraction between two materials and produces a unique ''edge enhanced'' contrast appearance, very different from the traditional absorption x-ray imaging used in clinical radiology. In this paper we aim to explain the features of x-ray refraction contrast as a typical clinical radiologist would understand. Then a discussion regarding what needs to be considered in the interpretation of the refraction image takes place. Finally we present a discussion about the limitations of planar refraction imaging and the potential of DEI Computed Tomography. This is an original work that has not been submitted to any other source for publication. The authors have no commercial interests or conflicts of interest to disclose.

Objective: We performed experimental synchrotron radiation (SR) imaging techniques on the leporine optic nerve to see if high resolution, detailed images of optic nerve microstructure could reliably be obtained. Our long term objective is to pursue safe in vivo imaging for the development of animal models for the study of optic neuropathies. Background There are no previous SR imaging studies of the optic nerve in either humans or animals. SR imaging techniques including diffraction enhanced imaging (DEI), and CT planar imaging have been successfully used to image biological tissues including the porcine eye, murine internal organs, canine articular cartilage, and human breast cancer tissue. Design/Methods: Specimen preparation included previously frozen dissected rabbit globes, optic nerves and chiasm, and one whole rabbit head. These samples were preserved and imaged in 10% formalin. A double crystal monochromator was used to select a very small energy band from the polychromatic synchrotron beam. The monochromatic beam passed through samples, with an analyzer crystal similar to that in the monochromator placed after the sample. Results: The analyzer crystal was sensitive to the refractive effects within the samples. In addition, absorption and scattering effects were used to create images with differing contrast properties. By moving the analyzer crystal various images of the optic nerve and ocular structures that showed apparent absorption and refraction properties were obtained. Conclusions: By using an intense monochromatic radiation beam from a synchrotron, we were able to image microscopic structures of the leporine optic nerve and surrounding tissues using both diffraction enhanced and CT planar imaging techniques. As far as we know, we are the only synchrotron research group in the world attempting to image the optic nerve, and the work is highly experimental and preliminary. We will continue to refine our methods and techniques of image acquisition. Supported by: Saskatchewan Health Research Foundation. Disclosure: Dr. Atkins has nothing to disclose. Dr. de Jager has nothing to disclose. Dr. Wiebe has nothing to disclose. Dr. Grahn has nothing to disclose. Dr. Chapman has nothing to disclose.

In Canada, osteoporotic fractures result in direct health care costs that exceed CAD$1.3 billion annually [1]. Fractures are related to compromised bone strength, a parameter that reflects both density (quantity) and architecture (quality) [2]. The current clinical standard for bone assessment, dual energy x-ray absorptiometry, provides only a 2-dimensional areal measurement of density and no architectural information [3]; therefore, the development of improved methods for visualizing and quantifying of bone architecture remains an important goal with respect to improving detection and treatment of osteoporosis. Advances are currently being sought in the development of new technologies [3], such as high-resolution peripheral quantitative tomography [4], and through texture-based analysis of trabecular structure from radiographs [5]. In this pictorial essay, we explore the use of x-rayebased diffraction enhanced imaging (DEI) by using synchrotron radiation [6] as a novel means of visualizing the internal architecture of the human distal radius, a clinically significant fracture site. Imaging for this study was conducted at the Canadian Light Source (CLS) synchrotron during commissioning of the BioMedical Imaging and Therapy (BMIT) bending magnet beam line [7]. As such, our goal here is 2-fold: (1) establishment of proof-of-principle