Bibliographies thématiques / Tomographic sequences

Littérature scientifique sur le sujet « Tomographic sequences »

Auteur : Grafiati
Publié le 10 mars 2023

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Articles de revues sur le sujet "Tomographic sequences"

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Gravier, Erwan, Yongyi Yang et Mingwu Jin. « Tomographic Reconstruction of Dynamic Cardiac Image Sequences ». IEEE Transactions on Image Processing 16, no 4 (avril 2007) : 932–42. http://dx.doi.org/10.1109/tip.2006.891328.

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Gravier, E. J., et Yongyi Yang. « Motion-compensated reconstruction of tomographic image sequences ». IEEE Transactions on Nuclear Science 52, no 1 (février 2005) : 51–56. http://dx.doi.org/10.1109/tns.2004.843092.

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Siedlecki, Damian, Waldemar Kowalik et Henryk Kasprzak. « Optical Coherence Tomography as a Tool for Ocular Dynamics Estimation ». BioMed Research International 2015 (2015) : 1–8. http://dx.doi.org/10.1155/2015/293693.

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Purpose. The aim of the study is to demonstrate that the ocular dynamics of the anterior chamber of the eye can be estimated quantitatively by means of optical coherence tomography (OCT).Methods. A commercial high speed, high resolution optical coherence tomographer was used. The sequences of tomographic images of the iridocorneal angle of three subjects were captured and each image from the sequence was processed in MATLAB environment in order to detect and identify the contours of the cornea and iris. The data on pulsatile displacements of the cornea and iris and the changes of the depth of the gap between them were retrieved from the sequences. Finally, the spectral analysis of the changes of these parameters was performed.Results. The results of the temporal and spectral analysis manifest the ocular microfluctuation that might be associated with breathing (manifested by 0.25 Hz peak in the power spectra), heart rate (1–1.5 Hz peak), and ocular hemodynamics (3.75–4.5 Hz peak).Conclusions. This paper shows that the optical coherence tomography can be used as a tool for noninvasive estimation of the ocular dynamics of the anterior segment of the eye, but its usability in diagnostics of the ocular hemodynamics needs further investigations.
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Nielsen, Lars, Hans Thybo et Martin Glendrup. « Seismic tomographic interpretation of Paleozoic sedimentary sequences in the southeastern North Sea ». GEOPHYSICS 70, no 4 (juillet 2005) : R45—R56. http://dx.doi.org/10.1190/1.1996908.

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Seismic wide-angle data were recorded to more than 300-km offset from powerful airgun sources during the MONA LISA experiments in 1993 and 1995 to determine the seismic-velocity structure of the crust and uppermost mantle along three lines in the southeastern North Sea with a total length of 850 km. We use the first arrivals observed out to an offset of 90 km to obtain high-resolution models of the velocity structure of the sedimentary layers and the upper part of the crystalline crust. Seismic tomographic traveltime inversion reveals 2–8-km-thick Paleozoic sedimentary sequences with P-wave velocities of 4.5–5.2 km/s. These sedimentary rocks are situated below a Mesozoic-Cenozoic sequence with variable thickness: ∼2–3 km on the basement highs, ∼2–4 km in the Horn Graben and the North German Basin, and ∼6–7 km in the Central Graben. The thicknesses of the Paleozoic sedimentary sequences are ∼3–5 km in the Central Graben, more than 4 km in the Horn Graben, up to ∼4 km on the basement highs, and up to 8 km in the North German Basin. The Paleozoic strata are clearly separated from the shallower and younger sequences with velocities of ∼1.8–3.8 km/s and the deeper crystalline crust with velocities of more than 5.8–6.0 km/s in the tomographic P-wave velocity model. Resolution tests show that the existence of the Paleozoic sediments is well constrained by the data. Hence, our wide-angle seismic models document the presence of Paleozoic sediments throughout the southeastern North Sea, both in the graben structures and in deep basins on the basement highs.
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Santarelli, Chiara, Fabrizio Argenti, Francesca Uccheddu, Luciano Alparone et Monica Carfagni. « Volumetric interpolation of tomographic sequences for accurate 3D reconstruction of anatomical parts ». Computer Methods and Programs in Biomedicine 194 (octobre 2020) : 105525. http://dx.doi.org/10.1016/j.cmpb.2020.105525.

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Santarelli, Chiara, Monica Carfagni, Luciano Alparone, Alberto Arienzo et Fabrizio Argenti. « Multimodal fusion of tomographic sequences of medical images : MRE spatially enhanced by MRI ». Computer Methods and Programs in Biomedicine 223 (août 2022) : 106964. http://dx.doi.org/10.1016/j.cmpb.2022.106964.

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Puķīte, J., S. Kühl, T. Deutschmann, S. Dörner, P. Jöckel, U. Platt et T. Wagner. « The effect of horizontal gradients and spatial measurement resolution on the retrieval of global vertical NO<sub>2</sub> ; distributions from SCIAMACHY measurements in limb only mode ». Atmospheric Measurement Techniques Discussions 3, no 3 (11 mai 2010) : 2055–105. http://dx.doi.org/10.5194/amtd-3-2055-2010.

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Abstract. Limb measurements provided by the Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on the ENVISAT satellite allow retrieving stratospheric profiles of various trace gases on a global scale. Combining measurements of the same air volume from different viewing positions along the orbit, a tomographic approach can be applied and 2-D distribution fields of stratospheric trace gases can be acquired in one inversion. With this approach, it is possible to improve the accounting for the effect of horizontal gradients in the trace gas distribution on the profile retrieval. This was shown in a previous study for the retrieval of NO2 and OClO profiles in the Arctic region near the polar vortex boundary. In this study, the tomographic retrieval is applied on measurements during special limb-only orbits performed on 14 December 2008. For these orbits the distance between consecutive limb scanning sequences was reduced to ~3.3° of the orbital circle (i.e. more than two times with respect to the nominal operational mode). Thus, the same air volumes are scanned successively by more than one scanning sequence also for midlatitudes and the tropics. It is found that the profiles obtained by the tomographic 2-D approach show significant differences to those obtained by the 1-D approach. In particular, for regions close to stratospheric transport barriers (i.e. near to the edge of the polar vortex and subtropical transport barrier) up to 50% larger or smaller NO2 number densities (depending on the sign of the gradient along the line of sight) for altitudes below the peak of the profile (around 20 km) are obtained. The limb-only measurements allow examining the systematic error if the horizontal gradient is not accounted for, and studying the impact of the gradient strength on the profile retrieval on a global scale. The findings for the actual SCIAMACHY observations are verified by sensitivity studies for simulated data for which the NO2 distributions to be retrieved are known in advance. In addition, the impact of the horizontal distance between consecutive limb scanning sequences on the quality of the tomographic 2-D retrieval is investigated and a possibility to take into account the horizontal gradients by an interpolation approach is studied.
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Puķīte, J., S. Kühl, T. Deutschmann, S. Dörner, P. Jöckel, U. Platt et T. Wagner. « The effect of horizontal gradients and spatial measurement resolution on the retrieval of global vertical NO<sub>2</sub> ; distributions from SCIAMACHY measurements in limb only mode ». Atmospheric Measurement Techniques 3, no 4 (30 août 2010) : 1155–74. http://dx.doi.org/10.5194/amt-3-1155-2010.

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Abstract. Limb measurements provided by the Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on the ENVISAT satellite allow retrieving stratospheric profiles of various trace gases on a global scale. Combining measurements of the same air volume from different viewing positions along the orbit, a tomographic approach can be applied and 2-D distribution fields of stratospheric trace gases can be acquired in one inversion. With this approach, it is possible to improve the accounting for the effect of horizontal gradients in the trace gas distribution on the profile retrieval. This was shown in a previous study for the retrieval of NO2 and OClO profiles in the Arctic region near the polar vortex boundary. In this study, the tomographic retrieval is applied on measurements during special limb-only orbits performed on 14 December 2008. For these orbits the distance between consecutive limb scanning sequences was reduced to ~3.3° of the orbital circle (i.e. more than two times with respect to the nominal operational mode). Thus, the same air volumes are scanned successively by more than one scanning sequence also for midlatitudes and the tropics. It is found that the profiles obtained by the tomographic 2-D approach show significant differences to those obtained by the 1-D approach. In particular, for regions close to stratospheric transport barriers (i.e. near to the edge of the polar vortex and subtropical transport barrier) up to 50% larger or smaller NO2 number densities (depending on the sign of the gradient along the line of sight) for altitudes below the peak of the profile (around 20 km) are obtained. The limb-only measurements allow examining the systematic error if the horizontal gradient is not accounted for, and studying the impact of the gradient strength on the profile retrieval on a global scale. The findings for the actual SCIAMACHY observations are verified by sensitivity studies for simulated data for which the NO2 distributions to be retrieved are known in advance. In addition, the impact of the horizontal distance between consecutive limb scanning sequences on the quality of the tomographic 2-D retrieval is investigated and a possibility to take into account the horizontal gradients by an interpolation approach is studied.
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Valeev, A. I., et A. A. Malov. « The role of magnetic resonance imaging in the diagnosis of malignant bone neoplasms. Current state of an issue ». Russian Journal of Pediatric Hematology and Oncology 7, no 4 (7 janvier 2021) : 77–81. http://dx.doi.org/10.21682/2311-1267-2020-7-4-77-81.

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The review article is about clinical experience in the use of modern tomographic methods (magnetic resonance imaging (MRI) and X-ray computed tomography (CT)) in the diagnosis and assessment of the progression of malignant bone neoplasms, summarizing the results of the largest studies demonstrating the comparative characteristics of the methods. Numerous data demonstrate high sensitivity of MRI and form the following diagnostic tasks that can be solved by this method: the involvement degree of soft tissues in the pathological process, damage to the neurovascular bundle, the articular surface, assessment of the extent of tumor in the bone marrow canal. At the same time, CT shows a higher sensitivity in assessing cortical destruction and the degree of matrix mineralization. The article discusses the variety of program sequences and modes of MRI scanning, the prospects of the method in assessing the prevalence, staging, and differential diagnosis of bone tumors.
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BAIMPAS, NIKOLAOS, MENGYIN XIE, XU SONG, FELIX HOFMANN, BRIAN ABBEY, JAMES MARROW, MAHMOUD MOSTAFAVI, JIAWEI MI et ALEXANDER M. KORSUNSKY. « RICH TOMOGRAPHY TECHNIQUES FOR THE ANALYSIS OF MICROSTRUCTURE AND DEFORMATION ». International Journal of Computational Methods 11, no 03 (juin 2014) : 1343006. http://dx.doi.org/10.1142/s0219876213430068.

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Until very recently, the three-dimensionality of the material world presented numerous challenges in terms of characterization, data handling, visualization, and modeling. For this reason, 2D representation of sections, projections, or surfaces remained the mainstay of most popular imaging techniques, such as optical and electron microscopy and X-ray radiography. However, the advent of faster computers with greater memory capacity ensured that large 3D matrices can now not only be stored and manipulated efficiently, but also that advanced algorithms such as algebraic reconstruction techniques (ART) can be used to interpret redundant datasets containing multiple projections or averages across the object obtained by some suitable analytical measurement technique. These tools open up unprecedented opportunities for numerical simulation. Model formulation can be accomplished semi-automatically on the basis of microstructurally-informed 3D imaging, while model validation can be achieved by direct comparison of 3D maps of complex quantities, such as displacement vectors or strain tensor components. In this paper, we review several modalities of what can be referred to as "rich" tomography: strain tomography in the bulk of a load bearing structural component; Laue orientation tomography for nondestructive mapping of grain orientation within a polycrystal, and the use of sequences of tomographic reconstructions for digital volume correlation (DVC) analysis of in situ deformation.
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Thèses sur le sujet "Tomographic sequences"

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Berglund, Karin. « Seismic tomography in the source region of the May 29th 2008 earthquake-aftershock-sequence in southwest Iceland ». Thesis, Uppsala universitet, Geofysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-187589.

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On May 29th 2008 two earthquakes with moment magnitude of Mw ~6 occurred in the southwestern part of Iceland. The second earthquake struck within only seconds after the first, on a fault ~5 km west from the first fault. The aftershock sequence was recorded by 14 seismic stations during the subsequent 34 days. The recorded earthquakes were detected and located with a Coalesence Microseismic Mapping (CMM) technique. The output data from this program has been used as basis for the tomography algorithm PStomo_eq, which simultaneously inverts for both P- and S-wave velocities and relocates the events. Within the study area of 46×36 km the three-dimensional velocity structure has, successfully but not conclusively, been modeled to depths of ~10 km. The Vp/Vs ratio varies from 1.74 to 1.82 within the study area. The velocity increases with depth starting from 2 km where the P-wave velocity is 4.6 km/s and the S-wave velocity is 2.7 km/s, at a depth of 10 km the P-wave velocity is 6.9 km/s and S-wave velocity is 4.0 km/s. In the horizontal slices a high velocity area is seen in the northwestern part of model. This is interpreted to be caused by a magma body rising up from below and lithifying at high pressure. From cross-sections a large low velocity zone is seen in the western part of model area concentrated above the seismicity. The low velocity anomaly is found between depths of 2 km to 4 km, stretching from 21.5° to 21.2° W. It is interpreted to be caused by high porosity within the area. The depth to the brittle crust is increasing from the western part of the model towards the eastern part, right in the middle of the model it abruptly decreases again. The depth to the base of the brittle crust is increasing from 7 km in west to 9 km in the middle of model.
Den 29:e maj 2008 inträffade två jordbävningar med magnitud Mw ~6 på sydvästra Island. Den första jordbävningen följdes tätt av en andra jordbävning på en förkastning ~5 km väster om den första. Påföljande efterskalvssekvens registrerades av 14 seismiska stationer under 34 dagar efter huvudskalven. De registrerade skalven har detekterats och lokaliserats med en Coalesence Microseismic Mapping (CMM) teknik. Utdata från detta program har använts som grund för tomografin som genomförts med PStomo_eq, en algoritm som inverterar oberoende för både P- och S-vågs hastigheter och samtidigt omlokaliserar eventen. Inom det undersökta området på 46×36 km har en tredimensionell hastighetsmodell, om än inte slutgiltigt, modellerats för djup ned till 10 km. Vp/Vs kvoten varierar mellan 1.74 och 1.82 inom studieområdet. Hastigheterna ökar med ökande djup, på ett djup av 2 km är P-vågs hastigheten 4.6 km/s och S-vågs hastigheten 2.7 km/s och vid 10 km är P-vågs hastigheten 6.9 km/s och S-vågs hastigheten 4.0 km/s. I den nordvästra delen av modellen återfinns en höghastighetszon. Denna tolkas vara orsakad av en magma kropp som stigit och kristalliserat under högt tryck. De vertikala tvärsnitten visar en låghastighetsanomali i västra delen av modellen, koncentrerat ovan seismiciteten. Denna anomali sträcker sig från ett djup på 2 km ned till 4 km, från 21.5° till 21.2° V. Den tolkas vara orsakad av en hög grad av porositet. Djupet för den bräckliga jordskorpan ökar från väster till öster i modellen, för att i mitten abrupt minska igen. Basen av den bräckliga skorpan ökar från 7 km i väst till 9 km i mitten av modellen.
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Uyeno, Theodore Akira. « Comparative morphology and evolutionary trends in the class Gastropoda through three-dimensional tomography and DNA sequence analysis ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0021/MQ49660.pdf.

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León-Ríos, Sergio [Verfasser], et A. [Akademischer Betreuer] Rietbrock. « 3D Tomography based on the aftershock sequence of the 2016 Mw 7.8 Pedernales, Ecuador earthquake / Sergio León-Ríos ; Betreuer : A. Rietbrock ». Karlsruhe : KIT-Bibliothek, 2021. http://d-nb.info/1227451350/34.

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Bauch, Steffen [Verfasser], et Katharina [Akademischer Betreuer] Fischbach. « Evaluation MR kompatibler Nadeln und interaktiver Sequenzen zur interventionellen Bildgebung an einem offenen 1.0 Tesla MR-Tomographen (Panorama-HFO) / Steffen Bauch. Betreuer : Katharina Fischbach ». Magdeburg : Universitätsbibliothek, 2014. http://d-nb.info/105463856X/34.

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Waldenström, Erik. « Genetical and Clinical Studies in Wilson's Disease ». Doctoral thesis, Uppsala University, Department of Medical Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7779.

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Wilson’s disease is a rare inborn error of metabolism caused by a defect in ATP7B, a protein necessary for proper copper excretion into bile. It is characterised by copper accumulation with hepatic and central nervous system dysfunction.

We investigated 24 Swedish families with Wilson’s disease by sequencing the entire coding sequence using a new technique called manifold sequencing. Disease causing mutations were found in 44 out of 48 alleles.

From data obtained in the first study, the two most common mutations (C3207A and C2930T) were sought in 2640 anonymous DNA samples from a Swedish population, using a pooling strategy and solid-phase minisequencing. Four C3207A and one C2930T were found. From the number of C3207A, a prevalence of Wilson’s disease in Sweden of about 1 in 110,000 could be estimated.

Four groups with three patients each had four different genotypes concerning mutations in ATP7B. The patients’ psychopathological symptoms were investigated, using the Karolinska Scales of Personality rating (KSP) and Comprehensive Psychopathological Rating Scale (CPRS). A trend towards lower CPRS scores was seen in the groups with mutations known to render ATP7B completely without activity.

Using 61Cu liver PET in patients homozygous for mutations in ATP7B, heterozygotes, normal individuals and two patients with alcoholic liver cirrhosis, significantly slower uptake was seen in the homozygotes as compared to the heterozygotes and normal individuals. The patients with cirrhosis had values in between. This implies that 61Cu liver PET might be used as an additional rapid and little invasive diagnostic tool in Wilson’s disease.

In a retrospectively studied cohort consisting of 363 patients followed in Sweden and the UK, nine cases of aggressive intra-abdominal malignancies were seen, which is more than expected. Caution should be taken in the follow-up of Wilson’s disease patients.

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Wang, Qian. « Characterizing InternetWorm Spatial-Temporal Infection Structures ». FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/294.

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Since the Morris worm was released in 1988, Internet worms continue to be one of top security threats. For example, the Conficker worm infected 9 to 15 million machines in early 2009 and shut down the service of some critical government and medical networks. Moreover, it constructed a massive peer-to-peer (P2P) botnet. Botnets are zombie networks controlled by attackers setting out coordinated attacks. In recent years, botnets have become the number one threat to the Internet. The objective of this research is to characterize spatial-temporal infection structures of Internet worms, and apply the observations to study P2P-based botnets formed by worm infection. First, we infer temporal characteristics of the Internet worm infection structure, i.e., the host infection time and the worm infection sequence, and thus pinpoint patient zero or initially infected hosts. Specifically, we apply statistical estimation techniques on Darknet observations. We show analytically and empirically that our proposed estimators can significantly improve the inference accuracy. Second, we reveal two key spatial characteristics of the Internet worm infection structure, i.e., the number of children and the generation of the underlying tree topology formed by worm infection. Specifically, we apply probabilistic modeling methods and a sequential growth model. We show analytically and empirically that the number of children has asymptotically a geometric distribution with parameter 0.5, and the generation follows closely a Poisson distribution. Finally, we evaluate bot detection strategies and effects of user defenses in P2P-based botnets formed by worm infection. Specifically, we apply the observations of the number of children and demonstrate analytically and empirically that targeted detection that focuses on the nodes with the largest number of children is an efficient way to expose bots. However, we also point out that future botnets may self-stop scanning to weaken targeted detection, without greatly slowing down the speed of worm infection. We then extend the worm spatial infection structure and show empirically that user defenses, e.g., patching or cleaning, can significantly mitigate the robustness and the effectiveness of P2P-based botnets. To counterattack, we evaluate a simple measure by future botnets that enhances topology robustness through worm re-infection.
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Prakosa, Adityo. « Analysis and simulation of multimodal cardiac images to study the heart function ». Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00837857.

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This thesis focuses on the analysis of the cardiac electrical and kinematic function for heart failure patients. An expected outcome is a set of computational tools that may help a clinician in understanding, diagnosing and treating patients suffering from cardiac motion asynchrony, a specific aspect of heart failure. Understanding the inverse electro-kinematic coupling relationship is the main task of this study. With this knowledge, the widely available cardiac image sequences acquired non-invasively at clinics could be used to estimate the cardiac electrophysiology (EP) without having to perform the invasive cardiac EP mapping procedures. To this end, we use real clinical cardiac sequence and a cardiac electromechanical model to create controlled synthetic sequence so as to produce a training set in an attempt to learn the cardiac electro-kinematic relationship. Creating patient-specific database of synthetic sequences allows us to study this relationship using a machine learning approach. A first contribution of this work is a non-linear registration method applied and evaluated on cardiac sequences to estimate the cardiac motion. Second, a new approach in the generation of the synthetic but virtually realistic cardiac sequence which combines a biophysical model and clinical images is developed. Finally, we present the cardiac electrophysiological activation time estimation from medical images using a patient-specific database of synthetic image sequences.
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Vondra, Petr. « Vliv vodivých vzorků na vznik deformací vf magnetického pole ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217784.

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The work analyses formation of deformations of RF magnetic field within the environment of electrically and magnetically conductive materials. An analytic solution of the problem is created and the problems of numerical modeling are solved. In theoretical way, the work also familiarize with the use of magnetic resonance imaging method - the spin echo method (SE), with its features and possibilities of its use within the aim of the project. This method is used for experimental measurements of electrically conductive materials in the NMR laboratory in ISI AV Czech Republic. Results of the simulation are compared with results of the experimental measurement.
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Wei, Wen. « Apprentissage automatique des altérations cérébrales causées par la sclérose en plaques en neuro-imagerie multimodale ». Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4021.

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La sclérose en plaques (SEP) est la maladie neurologique évolutive la plus courante chez les jeunes adultes dans le monde et représente donc un problème de santé publique majeur avec environ 90 000 patients en France et plus de 500 000 personnes atteintes de SEP en Europe. Afin d'optimiser les traitements, il est essentiel de pouvoir mesurer et suivre les altérations cérébrales chez les patients atteints de SEP. En fait, la SEP est une maladie aux multiples facettes qui implique différents types d'altérations, telles que les dommages et la réparation de la myéline. Selon cette observation, la neuroimagerie multimodale est nécessaire pour caractériser pleinement la maladie. L'imagerie par résonance magnétique (IRM) est devenue un biomarqueur d'imagerie fondamental pour la sclérose en plaques en raison de sa haute sensibilité à révéler des anomalies tissulaires macroscopiques chez les patients atteints de SEP. L'IRM conventionnelle fournit un moyen direct de détecter les lésions de SEP et leurs changements, et joue un rôle dominant dans les critères diagnostiques de la SEP. De plus, l'imagerie par tomographie par émission de positons (TEP), une autre modalité d'imagerie, peut fournir des informations fonctionnelles et détecter les changements tissulaires cibles au niveau cellulaire et moléculaire en utilisant divers radiotraceurs. Par exemple, en utilisant le radiotraceur [11C]PIB, la TEP permet une mesure pathologique directe de l'altération de la myéline. Cependant, en milieu clinique, toutes les modalités ne sont pas disponibles pour diverses raisons. Dans cette thèse, nous nous concentrons donc sur l'apprentissage et la prédiction des altérations cérébrales dérivées des modalités manquantes dans la SEP à partir de données de neuroimagerie multimodale
Multiple Sclerosis (MS) is the most common progressive neurological disease of young adults worldwide and thus represents a major public health issue with about 90,000 patients in France and more than 500,000 people affected with MS in Europe. In order to optimize treatments, it is essential to be able to measure and track brain alterations in MS patients. In fact, MS is a multi-faceted disease which involves different types of alterations, such as myelin damage and repair. Under this observation, multimodal neuroimaging are needed to fully characterize the disease. Magnetic resonance imaging (MRI) has emerged as a fundamental imaging biomarker for multiple sclerosis because of its high sensitivity to reveal macroscopic tissue abnormalities in patients with MS. Conventional MR scanning provides a direct way to detect MS lesions and their changes, and plays a dominant role in the diagnostic criteria of MS. Moreover, positron emission tomography (PET) imaging, an alternative imaging modality, can provide functional information and detect target tissue changes at the cellular and molecular level by using various radiotracers. For example, by using the radiotracer [11C]PIB, PET allows a direct pathological measure of myelin alteration. However, in clinical settings, not all the modalities are available because of various reasons. In this thesis, we therefore focus on learning and predicting missing-modality-derived brain alterations in MS from multimodal neuroimaging data
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Santarelli, Chiara. « Advanced methods for volumetric interpolation and multimodal fusion of tomographic sequences with application to 3D reconstruction in biomedicine ». Doctoral thesis, 2021. http://hdl.handle.net/2158/1238978.

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Recently, anatomical 3D models, thanks also to the increased diffusion of 3D printing technologies, have been successfully introduced in the clinical field as innovative tools to support the medical team in several tasks. Advances in 3D technology now provide a realistic representation of complex anatomies that can be used as an aid for diagnosis, surgical planning and training. In general, 3D reconstructions are more accurate when they are the outcome of the processing of high-resolution image sequences. On the other hand, if a sequence is characterized by few tomographic sections, only a coarse reconstruction is achievable and the artifacts that are produced impair the usefulness as a tool to support the physician. The study carried out during this thesis work has two objectives. The first is to provide axial interpolation methods that, applied to low-resolution sequences, allow a refined 3D reconstruction of the anatomical model to be obtained. The methods are inspired by compensated frame interpolation techniques (MCFI) developed for video processing applications and produce an estimate of the displacement vector field (DVF). The DVF is then processed and used to estimate intermediate ones. The performance of the proposed methods has been quantitatively assessed using sequences with simulated axial low resolution. The experimental results show that the proposed methods allow an effective sliced interpolation and the 3D models obtained clearly benefit from the increased axial resolution. The second objective is studying image fusion methods specific for biomedical images obtained from different acquisition methods, also termed as multimodal image fusion. More specifically, in this thesis magnetic resonance imaging (MRI) and magnetic resonance elastography (MRE) sequences have been taken into account. The objective of the processing is achieving a fused image containing the structural information from the MRI and the mechanical (tissue stiffness) information from the MRE. The proposed method is based on multiresolution analysis (MRA). The fused MRE image is obtained by adding the geometric details, extracted from the MRI, after being modulated by a suitable injection gain. This gain is based on a correlation coefficient between the two images. The results show its effectiveness in providing in an unique image both the geometric information and elastic properties of the investigated tissues.
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Chapitres de livres sur le sujet "Tomographic sequences"

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Santarelli, Chiara, Francesca Uccheddu, Fabrizio Argenti, Luciano Alparone, Monica Carfagni et Lapo Governi. « Shift-Compensated Volumetric Interpolation of Tomographic Sequences for Accurate 3D Reconstruction ». Dans IFMBE Proceedings, 312–21. Cham : Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-31635-8_38.

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Williams, Helena, Laura Cattani, Tom Vercauteren, Jan Deprest et Jan D’hooge. « Automatic Tomographic Ultrasound Imaging Sequence Extraction of the Anal Sphincter ». Dans Simplifying Medical Ultrasound, 35–44. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-87583-1_4.

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Brlek, Srecko, et Andrea Frosini. « A Tomographical Interpretation of a Sufficient Condition on h-Graphical Sequences ». Dans Discrete Geometry for Computer Imagery, 95–104. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-32360-2_7.

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Blondel, Christophe, Grégoire Malandain, Régis Vaillant, Frédéric Devernay, Ève Coste-Manière et Nicholas Ayache. « 4-D Tomographic Representation of Coronary Arteries from One Rotational X-Ray Sequence ». Dans Lecture Notes in Computer Science, 416–23. Berlin, Heidelberg : Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-540-39899-8_52.

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Kartikasari, Yeti, Darmini, Siti Masrochah et Dwi Rochmayanti. « Comparison of Radiation Dose and Image Noise in Head Computed Tomography with Sequence and Spiral Techniques ». Dans Proceedings of the 1st International Conference on Electronics, Biomedical Engineering, and Health Informatics, 557–66. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-6926-9_49.

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Griebel, J., C. F. Hess et B. Kurtz. « Magnetic Resonance Imaging of Focal Lesions of Liver and Spleen Using Gradient-Echo Sequences at 1.5 Tesla : A Comparison with Ultrasound and Sequential Computerized Tomography ». Dans Frontiers in European Radiology, 1–33. Berlin, Heidelberg : Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-74233-0_1.

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Köhler, L., N. Rilinger, A. Hewett, H. Niemann et P. Jensch. « Exact Planning of Surgical Interventions Based on Three-Dimensional Correlation Between Metastases and Liver Segments by Integration of Computed Tomography and Digital Subtraction Angiography Sequences ». Dans Tumor Response Monitoring and Treatment Planning, 601–5. Berlin, Heidelberg : Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/978-3-642-48681-4_99.

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Deschamps, Alexis. « Analytical Techniques for Aluminum ». Dans Encyclopedia of Aluminum and Its Alloys. Boca Raton : CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000393.

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This article provides a guideline for selection of analytical methodologies for aluminum precipitates. These methodologies include: crystallographic structure, precipitate size, volume fraction, atom probe tomography, compositional chemistry, precipitation sequence, second phase particle characterization, and geometrical information analysis.
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« Imaging of brain tumours ». Dans Paediatric Haemotology and Oncology, sous la direction de Simon Bailey, Rod Skinner, Simon Bailey et Rod Skinner, 81–84. Oxford University Press, 2022. http://dx.doi.org/10.1093/med/9780198779186.003.0008.

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Imaging for brain tumours is vital not only for making the initial diagnosis but also guides future management. This chapter describes the two main modalities in computerised tomography (CT) and magnetic resonance imaging (MRI). The most common sequences are described as well as what questions are likely to be answered by brain tumour imaging.
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Wang, Lang, Gabriel Murray, Jeff Field et Randy A. Bartels. « Three Dimensional Widefield Imaging with Coherent Nonlinear Scattering Optical Tomography ». Dans Holography - Recent Advances and Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107837.

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A full derivation of the recently introduced technique of Harmonic Optical Tomography (HOT), which is based on a sequence of nonlinear harmonic holographic field measurements, is presented. The rigorous theory of harmonic holography is developed and the image transfer theory used for HOT is demonstrated. A novel treatment of phase matching of homogeneous and in-homogeneous samples is presented. This approach provides a simple and intuitive interpretation of coherent nonlinear scattering. This detailed derivation is aimed at an introductory level to allow anyone with an optics background to be able to understand the details of coherent imaging of linear and nonlinear scattered fields, holographic image transfer models, and harmonic optical tomography.
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Actes de conférences sur le sujet "Tomographic sequences"

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Jin, Mingwu, Miles N. Wernick, Yongyi Yang, Jovan G. Brankov, Erwan Gravier, Bing Feng et Micheal A. King. « 5D Image Reconstruction for Tomographic Image Sequences ». Dans 2006 Fortieth Asilomar Conference on Signals, Systems and Computers. IEEE, 2006. http://dx.doi.org/10.1109/acssc.2006.355110.

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Satriano, Alessandro, Simone Rivolo et Elena S. Di Martino. « A Feature-Based Morphing Methodology for In-Vivo Strain Assessment in Biological Structures ». Dans ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14820.

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It is often important, for diagnostic purposes, to evaluate quantitatively the motion undergone by a biological structure, starting from a viable tomographic imaging technique, such as Computed Tomography (CT) or Magnetic Resonance (MR). This is often associated with the need of the clinical personnel to perform an evaluation of a risk factor associated with pathology, e.g. ventricle performance [1]. As of today, the problem has been approached by using the magnetic resonance (MR) tagging technique [2] or experimentally by determining the location of a series of surgically implanted markers in each temporal phase [3]. The latter procedure is naturally very invasive, while MR tagging requires the use of sophisticated MR sequences that are rarely employed in standard care. Multi-detector row computer tomography (CT) scanners (routinely used in cardiac pathology diagnosis) as well as routine cine-MR sequences, on the other hand, allow dynamic imaging of the heart and large vessels with cardiac gating. In order to exploit these dynamic sequences, we have developed a tag-less method to estimate local strains from dynamic tomography gated images.
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Wang, A., J. Eggermont, N. Dekker, H. M. Garcia-Garcia, R. Pawar, J. H. C. Reiber et J. Dijkstra. « A robust automated method to detect stent struts in 3D intravascular optical coherence tomographic image sequences ». Dans SPIE Medical Imaging, sous la direction de Bram van Ginneken et Carol L. Novak. SPIE, 2012. http://dx.doi.org/10.1117/12.911572.

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Milner, Thomas E., Sergey A. Telenkov, B. Samuel Tanenbaum, J. Stuart Nelson et Dennis M. Goodman. « Non-Invasive Evaluation of Biological Materials Using Pulsed Photothermal Tomography ». Dans ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0817.

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Abstract Progress is reported on the development of pulsed photothermal tomography (PPT) for determination of the initial three-dimensional temperature increase in biological materials immediately following pulsed laser irradiation. PPT uses a fast infrared focal plane array (IR-FPA) to detect temperature rises in a substrate, induced by pulsed radiation. The temperature rise, due to the selective optical absorption of pulsed laser light, creates an increase in infrared emission that is measured by a fast IR-FPA. A tomographic reconstruction algorithm computes the initial space-dependent temperature increase in subsurface chromophores from a time sequence of recorded infrared emission images. We present tomographic reconstructed images of laser heated blood vessels in the in-vivo chick chorioallantoic membrane (CAM) model.
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Mahgoub, Mohamed, Guillaume Cambois, James Cowell et Suaad Khoori. « Benefits of Ultra-Dense 3D Spatial Sampling for Seismic Processing and Interpretation ». Dans Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207719-ms.

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Abstract The advances in seismic acquisition systems, especially onshore nodes, have made it possible to acquire ultra-dense 3D surveys at a reasonable cost. This new design enables accurate processing sequences that deliver higher resolution images of the subsurface. These images in turn lead to enhanced structural interpretation and better prediction of rock properties. In 2019, ADNOC and partners acquired an 81 square kilometer ultra-high density pilot survey onshore Abu Dhabi. The receivers were nimble nodes laid out on a 12.5x12.5m grid, which recorded continuously and stored the data on a memory chip. The sources were heavy vibrators sweeping the 2-110 Hz frequency range in 14 seconds on a 12.5x100m grid. 184 million traces per square kilometers did make such small area, the densest 3D seismic survey ever recorded. The single sensor data were expectedly very noisy and the unconstrained simultaneous shooting required elaborate deblending, but we managed these steps with existing tools. The dense 3D receiver grid actually enabled the use of interferometry-based ground-roll attenuation, a technique that is rarely used with conventional data due to inadequate sampling, but that resulted in increased signal-to-noise ratio. The data were migrated directly to depth using a velocity model derived after five iterations of tomographic inversion. The final image gathers were made of 18 reciprocal azimuths with 12.5m offset increment, resulting in 5,000 fold on a 6.25x6.25m grid. The main structural interpretation was achieved during the velocity model building stage. Key horizons were picked after the tomographic iterations and the velocity model was adjusted so that their depth matched the well markers. Anisotropic parameters were adjusted to maintain gather flatness and the new model was fed to the next iteration. This ultimately resulted in flat image gathers and horizons that tied to the wells. The final high-resolution data provided a much crisper image of the target clinoforms and faults. This resulted in a more detailed interpretation of the reservoirs. The data was subjected to pre-stack stratigraphic inversion. The availability of low frequency signal (down to 3 Hz) means that less well constraints are needed for the inversion. Preliminary results are particularly encouraging. Amplitude variations with azimuth have yet to be analyzed but data density bodes very well for the process. Ultra-dense 3D seismic acquisition is feasible and results in a step change in image quality. Structural and stratigraphic interpretation provided a more detailed image of faults and clinoforms. Stratigraphic inversion benefited from the low frequencies of the vibrator source and the increased spatial resolution.
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Barber, Quinn, et Roger J. Zemp. « S-sequence enhanced synthetic aperture ultrasound scattering tomography ». Dans 2016 IEEE International Ultrasonics Symposium (IUS). IEEE, 2016. http://dx.doi.org/10.1109/ultsym.2016.7728858.

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Hyka, Oleksii, Andres Vejar et Tomasz Rymarczyk. « Pseudo Random Binary Sequence Excitation for Electrical Impedance Tomography ». Dans SenSys '21 : The 19th ACM Conference on Embedded Networked Sensor Systems. New York, NY, USA : ACM, 2021. http://dx.doi.org/10.1145/3485730.3492889.

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Chowdhury, A. S., S. M. Bhandarkar, R. W. Robinson et J. c. Yu. « Virtual Craniofacial Reconstruction from Computed Tomography Image Sequences Exhibiting Multiple Fractures ». Dans 2006 International Conference on Image Processing. IEEE, 2006. http://dx.doi.org/10.1109/icip.2006.312766.

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Hsu, Chih-Yu, Yeong-Lin Lai, Chih-Cheng Chen et Yu-Tzu Lee. « Image Segmentation Method with Positron Emission Tomography Time Sequence Images ». Dans 2011 2nd International Conference on Innovations in Bio-Inspired Computing and Applications (IBICA). IEEE, 2011. http://dx.doi.org/10.1109/ibica.2011.96.

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Klein, R., R. S. Beanlands, A. Adler et R. deKemp. « Model-based factor analysis of dynamic sequences of cardiac positron emission tomography ». Dans 2008 IEEE Nuclear Science Symposium and Medical Imaging conference (2008 NSS/MIC). IEEE, 2008. http://dx.doi.org/10.1109/nssmic.2008.4774406.

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Rapports d'organisations sur le sujet "Tomographic sequences"

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Cumbest, R. J. Evaluation of Cross-Hole Seismic Tomography for Imaging Low Resistance Intervals and Associated Carbonate Sediments in Coastal Plain Sequences on the Savannah River Site, South Carolina. Office of Scientific and Technical Information (OSTI), janvier 1999. http://dx.doi.org/10.2172/4847.

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