Orthodontic plate for management of obstructive sleep apnoea in infants with Pierre Robin sequence: experience and protocol in Hong Kong.

OBJECTIVE: To present the application of the pre-epiglottic baton plate (PEBP) in infants with Pierre Robin sequence (PRS) in the Southern Chinese population (Hong Kong) and to present the diagnosis and management protocol of these infants in our centre. DESIGN: Retrospective case series of three patients with PRS. SETTING: Neonatal Intensive Care Unit in Kwong Wah Hospital and Craniofacial Orthodontic Centre in United Christian Hospital, Hong Kong. PARTICIPANTS: Three new-born infants (two girls, one boy) with PRS and upper airway obstruction due to glossoptosis. METHODS: A protocol for the diagnosis and management of these infants in the Southern Chinese population (Hong Kong) was presented. The three patients received nasal high-flow oxygen and/or continuous positive airway pressure (CPAP) as first-line respiratory support, followed by PEBP for 3-5 months. A two-stage approach was undertaken to ensure accurate positioning of the PEBP. RESULTS: All three infants had improvement in clinical signs, symptoms and polysomnography upon discharge. PEBP and other respiratory aids were weaned off at 3-6 months. CONCLUSIONS: The PEBP, combined with other respiratory support, is a useful modality in the treatment of obstructive sleep apnoea in infants with PRS.

Prognostic factors for the outcome of extracorporeal shockwave therapy for calcific tendinitis of the shoulder.

AIMS: We conducted a study to identify factors that are prognostic of the outcome of extracorporeal shockwave therapy (ESWT) for calcific tendinitis of the shoulder. PATIENTS AND METHODS: Since 1998, patients with symptomatic calcific tendinitis of the rotator cuff have been treated with ESWT using an electrohydraulic mode shockwave device. One year after ESWT, patients were grouped according to the level of resorption of calcification. RESULTS: Of 241 symptomatic shoulders, complete resorption (CR) of calcification occurred in 134 (CR group). The remaining 107 shoulders had incomplete resorption (ICR) (ICR group). Gartner type I calcification was most common (64.5%) in the ICR group. The mean duration of symptoms before ESWT was significantly longer in the ICR group. Overall, 81% of the CR group and 23.4% of the ICR group were symptom free. There was a strong relationship between subsidence of symptoms and remission of calcification. Poor prognosis was significantly related to Gartner type I calcification, calcification extent > 15 mm and duration of symptoms > 11 months. CONCLUSION: Patients with calcific tendinitis of the shoulder who have the factors identified for a poor outcome after ESWT should undergo a different procedure. Cite this article: Bone Joint J 2017;99-B:1643-50.

Unexplained childhood anaemia: idiopathic pulmonary hemosiderosis.

This report demonstrates pulmonary haemorrhage as a differential cause of anaemia. Idiopathic pulmonary hemosiderosis is a rare disease in children; it is classically described as a triad of haemoptysis, pulmonary infiltrates on chest radiograph, and iron-deficiency anaemia. However, anaemia may be the only presenting feature of idiopathic pulmonary hemosiderosis in children due to occult pulmonary haemorrhage. In addition, the serum ferritin is falsely high in idiopathic pulmonary hemosiderosis which increases the diagnostic difficulty. We recommend that pulmonary haemorrhage be suspected in any child presenting with iron-deficiency anaemia and persistent bilateral pulmonary infiltrates.

Haemodynamical stress in mouse aortic arch with atherosclerotic plaques: Preliminary study of plaque progression.

Atherosclerotic plaques develop at particular sites in the arterial tree, and this regional localisation depends largely on haemodynamic parameters (such as wall shear stress; WSS) as described in the literature. Plaque rupture can result in heart attack or stroke and hence understanding the development and vulnerability of atherosclerotic plaques is critically important. The purpose of this study is to characterise the haemodynamics of blood flow in the mouse aortic arch using numerical modelling. The geometries are digitalised from synchrotron imaging and realistic pulsatile blood flow is considered under rigid wall assumptions. Two cases are considered; arteries with and without plaque. Mice that are fed under fat diet present plaques in the aortic arch whose size is dependent on the number of weeks under the diet. The plaque distribution in the region is however relatively constant through the different samples. This result underlines the influence of the geometry and consequently of the wall shear stresses for plaque formation with plaques growing in region of relative low shear stresses. A discussion of the flow field in real geometry in the presence and absence of plaques is conducted. The presence of plaques was shown to alter the blood flow and hence WSS distribution, with regions of localised high WSS, mainly on the wall of the brachiocephalic artery where luminal narrowing is most pronounced. In addition, arch plaques are shown to induce recirculation in the blood flow, a phenomenon with potential influence on the progression of the plaques. The oscillatory shear index and the relative residence time have been calculated on the geometry with plaques to show the presence of this recirculation in the arch, an approach that may be useful for future studies on plaque progression.

X-ray velocimetry within the ex vivo carotid artery.

X-ray velocimetry offers a non-invasive method by which blood flow, blood velocity and wall shear stress can be measured in arteries prone to atherosclerosis. Analytical tools for measuring haemodynamics in artificial arteries have previously been developed and here the first quantification of haemodynamics using X-ray velocimetry in a living mammalian artery under physiologically relevant conditions is demonstrated. Whole blood seeded with a clinically used ultrasound contrast agent was pumped with a steady flow through live carotid arterial tissue from a rat, which was kept alive in a physiological salt solution. Pharmacological agents were then used to produce vascular relaxation. Velocity measurements were acquired with a spatial resolution of 14 µm × 14 µm and at a rate of 5000 acquisitions per second. Subtle velocity changes that occur are readily measurable, demonstrating the ability of X-ray velocimetry to sensitively and accurately measure haemodynamics ex vivo. Future applications and possible limitations of the technique are discussed, which allows for detailed living tissue investigations to be carried out for various disease models, including atherosclerosis and diabetic vasculopathy.

Synchrotron phase-contrast X-ray imaging reveals fluid dosing dynamics for gene transfer into mouse airways.

Although airway gene transfer research in mouse models relies on bolus fluid dosing into the nose or trachea, the dynamics and immediate fate of delivered gene transfer agents are poorly understood. In particular, this is because there are no in vivo methods able to accurately visualize the movement of fluid in small airways of intact animals. Using synchrotron phase-contrast X-ray imaging, we show that the fate of surrogate fluid doses delivered into live mouse airways can now be accurately and non-invasively monitored with high spatial and temporal resolution. This new imaging approach can help explain the non-homogenous distributions of gene expression observed in nasal airway gene transfer studies, suggests that substantial dose losses may occur at deliver into mouse trachea via immediate retrograde fluid motion and shows the influence of the speed of bolus delivery on the relative targeting of conducting and deeper lung airways. These findings provide insight into some of the factors that can influence gene expression in vivo, and this method provides a new approach to documenting and analyzing dose delivery in small-animal models.

Interface-specific x-ray phase retrieval tomography of complex biological organs.

We demonstrate interface-specific propagation-based x-ray phase retrieval tomography of the thorax and brain of small animals. Our method utilizes a single propagation-based x-ray phase-contrast image per projection, under the assumptions of (i) partially coherent paraxial radiation, (ii) a static object whose refractive indices take on one of a series of distinct values at each point in space and (iii) the projection approximation. For the biological samples used here, there was a 9-200 fold improvement in the signal-to-noise ratio of the phase-retrieved tomograms over the conventional attenuation-contrast signal. The ability to 'digitally dissect' a biological specimen, using only a single phase-contrast image per projection, will be useful for low-dose high-spatial-resolution biomedical imaging of form and biological function in both healthy and diseased tissue.

Classification of breast tissue using a laboratory system for small-angle x-ray scattering (SAXS).

Structural changes in breast tissue at the nanometre scale have been shown to differentiate between tissue types using synchrotron SAXS techniques. Classification of breast tissues using information acquired from a laboratory SAXS camera source could possibly provide a means of adopting SAXS as a viable diagnostic procedure. Tissue samples were obtained from surgical waste from 66 patients and structural components of the tissues were examined between q = 0.25 and 2.3 nm(-1). Principal component analysis showed that the amplitude of the fifth-order axial Bragg peak, the magnitude of the integrated intensity and the full-width at half-maximum of the fat peak were significantly different between tissue types. A discriminant analysis showed that excellent classification can be achieved; however, only 30% of the tissue samples provided the 16 variables required for classification. This suggests that the presence of disease is represented by a combination of factors, rather than one specific trait. A closer examination of the amorphous scattering intensity showed not only a trend of increased scattering intensity with disease severity, but also a corresponding decrease in the size of the scatterers contributing to this intensity.

Assessment of the use of a diffuser in propagation-based x-ray phase contrast imaging.

A rotating random-phase-screen diffuser is sometimes employed on synchrotron x-ray imaging beamlines to ameliorate field-of-view inhomogeneities due to electron-beam instabilities and beamline optics phase artifacts. The ideal result is a broader, more uniformly illuminated beam intensity for cleaner coherent x-ray images. The spinning diffuser may be modeled as an ensemble of transversely random thin phase screens, with the resulting set of intensity maps over the detector plane being incoherently averaged over the ensemble. Whilst the coherence width associated with the source is unaffected by the diffuser, the magnitude of the complex degree of second-order coherence may be significantly reduced [K. S. Morgan, S. C. Irvine, Y. Suzuki, K. Uesugi, A. Takeuchi, D. M. Paganin, and K. K. W. Siu, Opt. Commun. 283, 216 (2010)]. Through use of a computational model and experimental data obtained on x-ray beamline BL20XU at SPring-8, Japan, we investigate the effects of such a diffuser on the quality of Fresnel diffraction fringes in propagation-based x-ray phase contrast imaging. We show that careful choice of diffuser characteristics such as thickness and fiber size, together with appropriate placement of the diffuser, can result in the ideal scenario of negligible reduction in fringe contrast whilst the desired diffusing properties are retained.

The projection approximation and edge contrast for x-ray propagation-based phase contrast imaging of a cylindrical edge.

We examine the projection approximation in the context of propagation-based phase contrast imaging using hard x-rays. Specifically, we consider the case of a cylinder or a rounded edge, as a simple model for the edges of many biological samples. The Argand-plane signature of a propagation-based phase contrast fringe from the edge of a cylinder is studied, and the evolution of this signature with propagation. This, along with experimental images obtained using a synchrotron source, reveals how propagation within the scattering volume is not fully described in the projection approximation's ray-based approach. This means that phase contrast fringes are underestimated by the projection approximation at a short object-to-detector propagation distance, namely a distance comparable to the free-space propagation within the volume. This failure of the projection approximation may become non-negligible in the detailed study of small anatomical features deep within a large body. Nevertheless, the projection approximation matches the exact solution for a larger propagation distance typical of those used in biomedical phase contrast imaging.

Towards the clinical application of X-ray phase contrast imaging.

Synchrotron-based propagation-based imaging, a type of phase contrast imaging, produces better soft tissue image contrast than conventional radiography. To determine whether the technique is directly transferable to the clinical environment for routine diagnostic or screening imaging, a micro-focus (100 microm spot-size) Molybdenum X-ray source with 0.03 mm molybdenum filtration was installed at a local hospital. Breast tissue samples, excised masses and mastectomies, were obtained directly from surgery and imaged at three geometries. The first geometry was optimised for visualizing phase contrast effects using a ray-line argument, the second was the same as that employed by Konica-Minolta in their commercial phase contrast system, and the third was the conventional contact arrangement. The three images taken of each tissue sample were comparatively scored in a pair-wise fashion. Scoring was performed by radiologist expert in mammography, general radiologists, associated clinicians and radiographers on high-resolution mammography rated monitors at two separate locations. Scoring indicated that the optimised and Konica geometries both outperformed the conventional mammographic geometry. An unexpected complication within the trial was the effect that the scoring platform and the associated display tools had on some of the scorer's responses. Additionally, the trial revealed that none of the conventional descriptors for image quality were adequate in the presence of phase contrast enhancements.

Dynamic measures of regional lung air volume using phase contrast x-ray imaging.

Phase contrast x-ray imaging can provide detailed images of lung morphology with sufficient spatial resolution to observe the terminal airways (alveoli). We demonstrate that quantitative functional and anatomical imaging of lung ventilation can be achieved in vivo using two-dimensional phase contrast x-ray images with high contrast and spatial resolution (<100 microm) in near real time. Changes in lung air volume as small as 25 microL were calculated from the images of term and preterm rabbit pup lungs (n = 28) using a single-image phase retrieval algorithm. Comparisons with plethysmography and computed tomography showed that the technique provided an accurate and robust method of measuring total lung air volumes. Furthermore, regional ventilation was measured by partitioning the phase contrast images, which revealed differences in aeration for different ventilation strategies.

Phase contrast X-ray imaging for the non-invasive detection of airway surfaces and lumen characteristics in mouse models of airway disease.

We seek to establish non-invasive imaging able to detect and measure aspects of the biology and physiology of surface fluids present on airways, in order to develop novel outcome measures able to validate the success of proposed genetic or pharmaceutical therapies for cystic fibrosis (CF) airway disease. Reduction of the thin airway surface liquid (ASL) is thought to be a central pathophysiological process in CF, causing reduced mucociliary clearance that supports ongoing infection and destruction of lung and airways. Current outcome measures in animal models, or humans, are insensitive to the small changes in ASL depth that ought to accompany successful airway therapies. Using phase contrast X-ray imaging (PCXI), we have directly examined the airway surfaces in the nasal airways and tracheas of anaesthetised mice, currently to a resolution of approximately 2 microm. We have also achieved high resolution three-dimensional (3D) imaging of the small airways in mice using phase-contrast enhanced computed tomography (PC-CT) to elucidate the structure-function relationships produced by airway disease. As the resolution of these techniques improves they may permit non-invasive monitoring of changes in ASL depth with therapeutic intervention, and the use of 3D airway and imaging in monitoring of lung health and disease. Phase contrast imaging of airway surfaces has promise for diagnostic and monitoring options in animal models of CF, and the potential for future human airway imaging methodologies is also apparent.

Analyser-based phase contrast image reconstruction using geometrical optics.

Analyser-based phase contrast imaging can provide radiographs of exceptional contrast at high resolution (<100 microm), whilst quantitative phase and attenuation information can be extracted using just two images when the approximations of geometrical optics are satisfied. Analytical phase retrieval can be performed by fitting the analyser rocking curve with a symmetric Pearson type VII function. The Pearson VII function provided at least a 10% better fit to experimentally measured rocking curves than linear or Gaussian functions. A test phantom, a hollow nylon cylinder, was imaged at 20 keV using a Si(1 1 1) analyser at the ELETTRA synchrotron radiation facility. Our phase retrieval method yielded a more accurate object reconstruction than methods based on a linear fit to the rocking curve. Where reconstructions failed to map expected values, calculations of the Takagi number permitted distinction between the violation of the geometrical optics conditions and the failure of curve fitting procedures. The need for synchronized object/detector translation stages was removed by using a large, divergent beam and imaging the object in segments. Our image acquisition and reconstruction procedure enables quantitative phase retrieval for systems with a divergent source and accounts for imperfections in the analyser.

Dynamic imaging of the lungs using x-ray phase contrast.

High quality real-time imaging of lungs in vivo presents considerable challenges. We demonstrate here that phase contrast x-ray imaging is capable of dynamically imaging the lungs. It retains many of the advantages of simple x-ray imaging, whilst also being able to map weakly absorbing soft tissues based on refractive index differences. Preliminary results reported herein show that this novel imaging technique can identify and locate airway liquid and allows lung aeration in newborn rabbit pups to be dynamically visualized.

Effect of sildenafil citrate (Viagra) on the ocular circulation.

PURPOSE: Sildenafil citrate induces vasodilation by enhancing the smooth muscle relaxant effects of nitric oxide. We have previously reported that nitrate compounds, a different group of nitric oxide-mediated vasodilators used mainly for the treatment of ischemic cardiac diseases, produce an increase in optic nerve head circulation and retinal venous vasodilation. The purpose of the present investigation was to evaluate the effect of sildenafil on ocular circulation. METHODS: In a double-blind, randomized, crossover trial, 15 healthy male volunteers received 100-mg doses of sildenafil citrate (Viagra; Pfizer, Inc, New York, New York) or matching placebo on 2 separate days. Laser Doppler flowmetry was used to assess foveolar choroidal and optic nerve rim circulatory parameters. Measurements were obtained in one eye at baseline, 1 hour, and 5 hours after dosing. Blood pressure and intraocular pressure were monitored, and perfusion pressure was calculated. RESULTS: Mean optic nerve head blood flow measurements at baseline, 1 hour, and 5 hours were 11.6 +/- 2.2 arbitrary units (+/- SD), 12.5 +/- 2.8, and 12.1 +/- 2.4 after sildenafil and 11.9 +/- 2.5, 12.6 +/- 3.1, and 13.0 +/- 3.0 after placebo, respectively. When compared with placebo, no significant change in mean blood pressure, intraocular pressure, perfusion pressure, or choroidal or optic nerve circulatory parameters were observed after sildenafil treatment. The power to detect a 20% change in optic nerve head and choroidal blood flow after sildenafil was approximately 90%. CONCLUSIONS: In comparison with placebo, no significant change in optic nerve rim or foveolar choroidal blood flow was observed after treatment with sildenafil. This suggests that nitrate compounds and sildenafil may differentially affect ocular circulation. Furthermore, no significant effects on intraocular pressure, systemic blood pressure, or ocular perfusion pressure were detected after sildenafil treatment.