Search results for "tomography"
showing 10 items of 2332 documents
Augmented Reality of the Middle Ear Combining Otoendoscopy and Temporal Bone Computed Tomography
2018
International audience; HYPOTHESIS:Augmented reality (AR) may enhance otologic procedures by providing sub-millimetric accuracy and allowing the unification of information in a single screen.BACKGROUND:Several issues related to otologic procedures can be addressed through an AR system by providing sub-millimetric precision, supplying a global view of the middle ear cleft, and advantageously unifying the information in a single screen. The AR system is obtained by combining otoendoscopy with temporal bone computer tomography (CT).METHODS:Four human temporal bone specimens were explored by high-resolution CT-scan and dynamic otoendoscopy with video recordings. The initialization of the system…
Changes in visual function and retinal structure in the progression of Alzheimer's disease
2019
Background Alzheimer's Disease (AD) can cause degeneration in the retina and optic nerve either directly, as a result of amyloid beta deposits, or secondarily, as a result of the degradation of the visual cortex. These effects raise the possibility that tracking ophthalmologic changes in the retina can be used to assess neurodegeneration in AD. This study aimed to detect retinal changes and associated functional changes in three groups of patients consisting of AD patients with mild disease, AD patients with moderate disease and healthy controls by using non-invasive psychophysical ophthalmological tests and optical coherence tomography (OCT). Methods We included 39 patients with mild AD, 2…
Naming People Ignoring Semantics in a Patient with Left Frontal Damage
1999
Studies about proper name anomia generally assume that persons' names are harder to recall than other semantic information one knows about them and that name retrieval is not possible without biographical knowledge. We describe a patient, SB, who, after a left frontal haemorrhage, was unable to recall any biographical information about people she could name. Moreover, she had a normal score in an Object Picture Naming Test, but gave confabulatory answers in a Semantic Questionnaire involving the same items. The role of frontal function in producing this pattern of impairment is discussed, together with the possible existence of a direct route from visual perception to proper name retrieval.
Effects of functional endoscopic sinus surgery on the acoustics of the sinonasal tract
2017
Background: Nasal and paranasal cavities are supposed to contribute substantially to the vocal tract resonator properties. However, their acoustical effects as well as the effects of sinus surgery on the voice remain unclear. In this work we investigate resonance phenomena of paranasal sinuses prior to and after various rhinosurgical procedures in cadaveric human sinonasal tracts and corresponding 3D casts. Methodology: Nasal and paranasal cavities of formalin-preserved cadavers and corresponding 3D replicas were excited by sine tone sweeps from an earphone placed in the epipharynx.The response was picked up by a microphone at the nostrils. Different FESS procedures were performed and the a…
Porous structure of fibre networks formed by a foaming process: a comparative study of different characterization techniques
2016
Recent developments in making fibre materials using the foam-forming technology have raised a need to characterize the porous structure at low material density. In order to find an effective choice among all structure-characterization methods, both two-dimensional and three-dimensional techniques were used to explore the porous structure of foam-formed samples made with two different types of cellulose fibre. These techniques included X-ray microtomography, scanning electron microscopy, light microscopy, direct surface imaging using a CCD camera and mercury intrusion porosimetry. The mean pore radius for a varying type of fibre and for varying foam properties was described similarly by all …
Pharmacokinetics of the cannabinoid receptor ligand [18 F]MK-9470 in the rat brain - Evaluation of models using microPET
2018
PURPOSE The positron emission tomography ligand [18 F]MK-9470 is an inverse agonist that binds reversibly and with high affinity to the cannabinoid type 1 receptor. Due to its slow brain kinetics, care is required in the definition of its dissociation rates from the receptor. The goal of this study was to investigate pharmacokinetic analysis methods using an arterial input function. METHODS Five Sprague-Dawley rats received injections of 13 to 25 MBq of [18 F]MK-9470 and were scanned over a period of 90 min. Arterial blood samples were collected throughout the scan. Data were analyzed using four different compartmental models: a reversible one-tissue model, reversible two tissue models with…
Classification of diabetes-related retinal diseases using a deep learning approach in optical coherence tomography
2019
Background and objectives: Spectral Domain Optical Coherence Tomography (SD-OCT) is a volumetric imaging technique that allows measuring patterns between layers such as small amounts of fluid. Since 2012, automatic medical image analysis performance has steadily increased through the use of deep learning models that automatically learn relevant features for specific tasks, instead of designing visual features manually. Nevertheless, providing insights and interpretation of the predictions made by the model is still a challenge. This paper describes a deep learning model able to detect medically interpretable information in relevant images from a volume to classify diabetes-related retinal d…
How and why does willow biochar increase a clay soil water retention capacity?
2018
Addition of biochar into a soil changes its water retention properties by modifying soil textural and structural properties. In addition, internal micrometer-scale porosity that is able to directly store readily plant available water affects soil water retention properties. This study shows how precise knowledge of the internal micrometer-scale pore size distribution of biochar can deepen the understanding of the biochar-water interactions in soils. The micrometer-scale porosity of willow biochar was quantitatively and qualitatively characterized using X-ray tomography, 3D image analysis and Helium ion microscopy. The effect of biochar application on clay soil water retention was studied by…
Localized potentials in electrical impedance tomography
2008
In this work we study localized electric potentials that have an arbitrarily high energy on some given subset of a domain and low energy on another. We show that such potentials exist for general L ∞ -conductivities in almost arbitrarily shaped subregions of a domain, as long as these regions are connected to the boundary and a unique continuation principle is satisfied. From this we deduce a simple, but new, theoretical identifiability result for the famous Calderon problem with partial data. We also show how to con- struct such potentials numerically and use a connection with the factorization method to derive a new non-iterative algorithm for the detection of inclusions in electrical imp…
Reclaimed asphalt test specimen preparation assisted by image analysis
2015
This paper presents a laboratory investigation aimed at establishing a protocol for the production of homogeneous asphalt mixtures test specimens, incorporating reclaimed asphalt by using a gyratory compactor with coring and trimming works. Stone mastic asphalt specimens were compacted at the previously identified target densities with the final aim of obtaining specimens with a fixed and homogeneous air void distribution. A microstructural study was conducted to characterize the homogeneity in the air void distribution using X-ray computed tomography (CT) combined with image analysis techniques. The study concluded that the gyratory compactor is suitable for producing homogeneous test spec…