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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
191

Technical note: Reliability of Suchey-Brooks and Buckberry-Chamberlain methods on 3D visualizations from CT and laser scans

Villa, C., Buckberry, J., Cattaneo, C., Lynnerup, N. January 2013 (has links)
Previous studies have reported that the ageing method of Suchey-Brooks (pubic bone) and some of the features applied by Lovejoy et al. and Buckberry-Chamberlain (auricular surface) can be confidently performed on 3D visualizations from CT-scans. In this study, seven observers applied the Suchey-Brooks and the Buckberry-Chamberlain methods on 3D visualizations based on CT-scans and, for the first time, on 3D visualizations from laser scans. We examined how the bone features can be evaluated on 3D visualizations and whether the different modalities (direct observations of bones, 3D visualization from CT-scan and from laser scans) are alike to different observers. We found the best inter-observer agreement for the bones versus 3D visualizations, with the highest values for the auricular surface. Between the 3D modalities, less variability was obtained for the 3D laser visualizations. Fair inter-observer agreement was obtained in the evaluation of the pubic bone in all modalities. In 3D visualizations of the auricular surfaces, transverse organization and apical changes could be evaluated, although with high inter-observer variability; micro-, macroporosity and surface texture were very difficult to score. In conclusion, these methods were developed for dry bones, where they perform best. The Suchey-Brooks method can be applied on 3D visualizations from CT or laser, but with less accuracy than on dry bone. The Buckberry-Chamberlain method should be modified before application on 3D visualizations. Future investigation should focus on a different approach and different features: 3D laser scans could be analyzed with mathematical approaches and sub-surface features should be explored on CT-scans.
192

Primena PET/CT pregleda u planiranju radiološke terapije kod pacijenata obolelih od Hočkinovog limfoma / The use of PET/CT in radiotherapy planning in patients with Hodgkin's lymphoma

Mitrić Ašković Milana 19 July 2016 (has links)
<p>Studija je imala za cilj da pokaže značaj primene PET/CT pregleda u planiranju radiolo&scaron;ke terapije kod pacijenata obolelih od Hočkinovog linfoma. U Vojvodini je 2009. godine prema podacima Registra za maligne neoplazme Vojvodine incidence za Hočkinov limfom iznosila 2,7 na 100 000 dok je mortalitet bio 1,1 na 100 000 stanovnika. Na osnovu dostupnih podataka Registra za maligne neoplazme Vojvodine beleži se porast incidence u protekloj deceniji. Procenat obolelih u Vojvodini u korelaciji je sa podacima koje navodi i Međunarodna agencija za istraživanje raka iz Liona (IARC). U Evropi i u Sjedinjenim Američkim Državama postoji bimodularna kriva incidence po starosti koja pokazuje maksimalne vrednosti u period između 20 i 30 godina i nakon 55. godine. S obzirom da od Hočkinovog limfoma dominantnije obolevaju mlađe osobe a da bolest ima dobru prognozu neophodno je iznaći nove načine za inicijalno određivanje stadijuma bolesti, kao i metode koje mogu da unaprede kvalitet lečenja. Jedan od načina je primena &scaron;to savremenijih dijagnostičkih metoda. PET-CT je imidžing metoda koja poslednjih godina zauzima značajno mesto u određivanju stadijuma malignih bolesti kao i u proceni odgovora na primenjenu terapiju. Fuzionisanjem skenova PET-a i CT-a dobija se PET-CT slika koja prikazuje funkcionalno stanje pojedinih tkiva i organa (PET) sa anatomskim detaljima (CT). Cilj istraživanja je bio da se utvrdi prednost PET-CT pregleda u planiranju radioterapije kod pacijenata sa supradijafragmalnom lokalizacijom bolesti. Nakon postavljanja dijagnoze Hočkinovog limfoma kod pacijenata je urađen PET-CT i planiranje radiolo&scaron;ke terapije. Zračna terapija je planirana na osnovu nalaza PET-CT-a i njegovom fuzijom sa CT-om za planiranje radiolo&scaron;kog lečenja. Dobijeni planovi su poređeni sa onim koji su rađeni standardnom 3D konformalnom tehnikom bez fuzije. Poređeni su klinički volumeni (CTV) i planirani volumen (PTV) kao i razlike u njihovoj obuhvaćenosti preskribovanom dozom. Pokazano je da postoji statistički značajna razlika u ciljnim volumenima kao i u njihovoj obuhvaćenosti. Posmatrani su takođe i rizični organi- srce, pluća, dojke, &scaron;titasta žlezda, kičmena moždina i doze koje oni prime. Dokazano je da su sa statističkom značajno&scaron;ću dozna opterećenja na navedene rizične organe manja kada se planiranje vr&scaron;i na osnovu fuzije sa PET-CT-om, te se na osnovu toga može reći da će i očekivane manifestacije kasne toksičnosti biti manje. Istraživanjem je potvrđena hipoteza da PET/CT ima veliku prednost u planiranju radioterapije jer smanjuje zapremine ciljnih volumena i doprinosi pobolj&scaron;anju kvaliteta radiolo&scaron;kog lečenja.</p> / <p>This study aimed to prove that the use of PET/CT in radiotherapy planning makes a material change in the course of the treatment of the patients with Hodgkin&#39;s lymphoma. According to the data from the Registry of malignant neoplasms in Vojvodina, incidence of Hodgkin&#39;s lymphoma in Vojvodina in 2009 was 2.7 per 100 000, while the mortality rate was 1.1 per 100 000 inhabitants. Based on the available data, the said Register recorded an increase in the incidence over the past decade. The percentage of patients who were registered in Vojvodina is in correlation with the data cited by the International Agency for Research on Cancer in Lyon (IARC).In Europe and in the United States the disease has a bi-modular distribution distribution with the highest frequency rate in persons ageing from 20-30 years and people older than 55 years. Due to the fact that the dominant Hodgkin&#39;s lymphoma affects young people and having in mind the good prognosis of the disease, it is necessary to find a new modality for the initial staging of disease and methods which can improve the quality of treatment. PET/CT is the imaging method which has in recent years had an important role in the staging of malignancies, as well in the evaluation of response to therapy. PET/CT image is obtained by fusing PET scans with CT and it show functional status of certain tissues and organs (PET) with anatomical details (CT).The object of this study was to show that PET/CT examinations are preferred imaging method in radiotherapy planning in patients with localized disease above the diaphragm. After they had been diagnosed with HL, patients underwent PET/CT scan which was later used for delineation in radiotherapy planning. In this study, radiation therapy was planned on the basis of the findings of PET /CT and its fusion with CT for planning radiological treatment. The resulting plans were compared with those made using standard 3D conformal technique without fusion. Clinical volume (CTV) and the planned volume (PTV) and the differences in their coverage with the prescription dose in both plans were also compared. The study has shown a statistically significant difference in the target volume and their coverage. In addition, the dose which receive organs at risk was also examined. It has been shown that organs at risk were exposed to lower doses when using PET/CT fusion in radiotherapy planning and consequently, less incidence of late toxicity is to be expected. The study confirmed the hypothesis that PET /CT has a great advantage in the planning of radiotherapy because it reduces the volume of the target volume and improves the quality of radiation treatment.</p>
193

Klinički značaj načina određivanja torakalnih indeksa u dijagnostici i terapijskom tretmanu pektus ekskavatuma kod dece / Clinical significance of the method for thoracic indices assessment in diagnosing and treatment of pectus excavatum in children

Pajić Miloš 19 September 2016 (has links)
<p>Cilj: Proveriti da li je moguće promeniti način CT verifikacije Hallerovog indeksa u okviru preoperativne pripreme pacijenata sa deformitetom grudnog ko&scaron;a po tipu pectus excavatum-a, uz utvrđivanje fiziolo&scaron;kog opsega vrednosti indeksa, njegove zavisnosti od uzrasta i pola, kao i respiratorne faze u kojoj se CT pregled izvodi. Utvrditi značaj vrednosti indeksa korekcije, indeksa asimetrije i indeksa torzije sternuma. Proveriti i mogućnost smanjivanja efektivne doze jonizujućeg zračenja kod primene CT tehnike jednog skena (single slice). Materijal i metod rada: Ispitivanje se sastojalo iz prospektivne studije koja je obuhvatila 30 pacijenata sa pektus ekskavatumom uz CT snimanje (single slice) u respiratornim fazama: ekspirijum i inspirijum. Na dobijenim snimcima su izračunati pored Halerovog indeksa i indeksi asimetrije, korekcije i sternalne torzije. Prema dobijenim rezultatima merenja i izračunavanja, dono&scaron;ena je odluka o načinu terapijskog tretmana. U retrospektivnoj studiji, urađena je analiza 100 CT pregleda grudnog ko&scaron;a kod dece gde nije verifikovan pectus excavatum, uz kalibriranje vrednosti indeksa u odnosu na uzrast i pol pacijenata. Retrospektivno istraživanje je obuhvatilo i analizu dodatnih 30 CT pregleda grudnog ko&scaron;a pacijenata sa deformitetom grudnog ko&scaron;a po tipu pectus excavatum-a, koji su dijagnostikovani i/ili operisani. Kod svih operisanih pacijenata je primenjenja Nusova operativna tehnika. U ovoj grupi pacijenata je izračunata srednja vrednost efektivne doze jonizujućeg zračenja, a dobijene vrednosti su potom komparirane sa efektivnim dozama koje su dobijene niskodoznim CT pregledima grudnog ko&scaron;a uz primenu novog protokola (&quot;single-slice&quot; tehnika u respiratornim fazama inspirijuma i ekspirijuma). Rezultati: Fiziolo&scaron;ki opseg vrednosti Haller-ovog indeksa u populaciji zdravih pacijenata se kretao od 1,47 do 3,17 i u proseku je iznosio 2,23&plusmn;0,32 (znatna pozitivna korelacija uzrasta i vrednosti HI). Na osnovu rezultata Man-Vitnijevog testa nije postojala polna razlika u posmatranoj grupi. Haller-ov indeks u grupi dijagnostikovane/operisane dece je u proseku iznosio 3,39 i kretao se u intervalu od 2,23 do 5,72 (korelacija između uzrasta ovih pacijenata i Haller-ovog indeksa je bila neznatna i negativna). Utvrđena je zavisnost veličine Haller-ovog indeksa od respiratorne faze u kojoj se CT pregled izvodi. Tako su prosečne vrednosti Haller-ovog indeksa u inspirijumu dece sa dijagnostikovanim deformitetom iznosile 2,69&plusmn;0,76. Kod dece ove grupe u ekspirijumu vrednosti Haller-ovog indeksa su iznosile 3,49&plusmn;1,19. U inspirijumu su samo 3/32 (9%) ispitanika imali vrednost HI preko 3,25 (granična vrednost za operativni tretman), dok ih je u ekspirijumu bilo znatno vi&scaron;e 13/32 (41%), &scaron;to je statistički značajna razlika (&chi;2=6,250; df =1; p=0,012). &quot;Single-slice&quot; tehnika CT pregleda u inspirijumu i ekspirijumu 20-25 puta smanjuje efektivnu dozu jonizujućeg zračenja. Zaključak: Vrednost Haller-ovog indeksa raste sa uzrastom deteta, dok nije utvrđena zavisnost Haller-ovog indeksa od pola. Moguće je promeniti načini CT verifikacije Haller-ovog indeksa u preoperativnoj pripremi za Nuss-ovu operaciju primenom &quot;single-slice&quot; tehnike u ekspiratornoj fazi. Osim Hallerovog indeksa, korisno je određivati i indeks korekcije, indeks asimetrije i indeks sternalne rotacije. Predlaže se protokol standardne preoperativne pripreme i lečenja pacijenata dečjeg uzrasta sa deformitetom grudnog ko&scaron;a po tipu pektus ekskavatuma, sa ciljem njegove primene u svakodnevnom radu u institucijama koje se bave ovim problemom, a u cilju pobolj&scaron;anja kvaliteta dijagnostikovanja i krajnjeg ishoda lečenja.</p> / <p>Aim: The aim of this study was to verify whether it is possible to change the way of CT verification of Haller index (HI), as part of preoperative preparation for patients with pectus excavatum, with the determination of the physiological range of the index value, its dependence on the age and sex, as well as the respiratory phase during which the scan is performed. Also, the aim was to determine the significance of correction, asymmetry and sternal torsion indices values. Evaluate the possibility of reduction the effective dose of ionizing radiation using a single slice CT scan technique. Materials and methods: The study consisted of prospective study that included evaluation of CT scans (single slice technique) of 30 patients with pectus excavatum in both respiratory phases: expirium and inspirium. Haller index and indices of asymmetry, correction and sternal torsion were measured. The decision for the treatment was made according to the results of measurements and calculations of these indices. In retrospective study, 100 CT scans of the chest in children without the deformity (pectus excavatum) were analyzed, and the index value was calibrated depending on the age and gender. The retrospective study also included the analysis of another 30 CT scans in patients who were operated or diagnosed with pectus excavatum. Nuss procedure was used in all operated patients. In this group of patients the median value of effective dose of ionizing radiation was calculated, and the values were compared with the effective dose obtained using low-dose CT examinations applied in the new protocol (single-slice technique in inspiratory and expiratory respiratory phases). Results: The physiological range of Haller index value in healthy patients was from 1.47 to 3.17 and average value was 2.23&plusmn;0.32 (significant positive correlation between age and the value of HI). Results of Mann- Whitney test did not demonstrate any difference between gender in the observed group. In the group of patients who were operated/diagnosed with pectus excavatum the average value of Haller index was 3.39 within the range of 2.23 to 5.72 (correlation between the age of these patients and Haller index was negative, but not significant). The dependence of the Haller index value and certain respiratory phase during which the CT scan was performed also was determined. Thus, the average value of Haller index in inspirium in children with diagnosed deformity was up to 2.69&plusmn;0.76. In the same group of patients the value of Haller index in expirium was up to 3.49&plusmn;1.19. Only 3/32 (9%) patients had HI value over 3.25 (a boundary value for surgical treatment) during inspirium, while 13/32 (41%) patients had it in expirium, this data showed statistically significant difference (&chi;2=6.250; df=1; p=0.012). Single-slice CT technique during the inspiratory and expiratory phase reduces 20-25 times the effective dose of ionizing radiation. Conclusion: The value of Haller index increases with the age, but its dependence on the gender was not determined. It is possible to change the way of CT verification of Haller index in preoperative preparation for the Nuss operation using the &quot;single-slice&quot; technique in exspiratory phase. In addition to Haller index it is useful to determine correction index, the index of asymmetry and the index of sternal rotation as well. This protocol is proposed for standard preoperative preparation and treatment of pediatric population with pectus excavatum with the aim of its application in daily work in institutions that deal with this problem, but also to improve the quality of diagnosis and treatment outcomes.</p>
194

Утврђивање морфолошких типова пинеалне жлезде хистолошком и методом компјутеризоване томографије / Utvrđivanje morfoloških tipova pinealne žlezde histološkom i metodom kompjuterizovane tomografije / Pineal Gland Morphology Types Determined with Histology and Computed Tomography Method

Munteanu Valerija 19 September 2016 (has links)
<p>Увод: Пинеална жлезда је неуроендокрини, циркумвентрикуларни орган филогенетски пореклом органа вида. Калцификације пинеалне жлезде су чест налаз приликом радиолошких претрага, без још увек довољно доказа да ли су оне нормалан налаз. Магнетна резонанца описује три морфолошка типа пинеалне жлезде. Циљеви: Утврдити степен корелације морфолошких типова пинеалне жлезде утврђених патохистолошким налазом са налазом компјутеризоване томографије, као и степен корелације присуства калцификација у пинеалној жлезди утврђених патохистолошким налазом и налазом компјутеризоване томографије. Утврдити степен калцификације пинеалне жлезде патохистолошким налазом у зависности од старости. Материјал и методе: Макроскопском морфолошком и микроскопском, хистолошком анализом обухваћено је 111 изолованих пинеалних жлезди осoба оба пола, не млађих од 18 година од којих је 27 снимљено апаратом Somatom Sensation 64 са дебљинама реконструисаних пресека 5 и 1mm, а још 9 апаратом Somatom Emotion 16. Резултати: Постоји статистички значајна разлика у одређивању сва три дијаметра епифизе петомилиметарским реконструкцијама, и при утврђивању два дијаметра једномилиметарским реконструкцијама. Постоји статистички значајна разлика у утврђивању морфолошких типова хистолошком и методом компјутеризоване томографије. Присутна је позитивна корелација калцификованости жлезде одређене мерењем њене густине у Хаунсфилдовим јединицама и утврђене микроскопски. Калцификованост пинеалног паренхима не корелира старости. Закључак: Наша студија је показала да су једномилиметарске реконструкције тачније у одређивању дијаметара жлезде. Макроскопским и микроскопским мерењем утврђена су сва три типа пинеалне жлезде описана магнетнорезонантним осликавањем. Утврђена је статистички значајна повезаност густине пинеалне жлезде измерене у Хаунсфилдовим јединицама на једномилиметарским реконструкцијама и степена калцификованости израженог у процентима. Није утврђена повезаност калцификованости епифизе мерене микроскопски и старости.</p> / <p>Uvod: Pinealna žlezda je neuroendokrini, cirkumventrikularni organ filogenetski poreklom organa vida. Kalcifikacije pinealne žlezde su čest nalaz prilikom radioloških pretraga, bez još uvek dovoljno dokaza da li su one normalan nalaz. Magnetna rezonanca opisuje tri morfološka tipa pinealne žlezde. Ciljevi: Utvrditi stepen korelacije morfoloških tipova pinealne žlezde utvrđenih patohistološkim nalazom sa nalazom kompjuterizovane tomografije, kao i stepen korelacije prisustva kalcifikacija u pinealnoj žlezdi utvrđenih patohistološkim nalazom i nalazom kompjuterizovane tomografije. Utvrditi stepen kalcifikacije pinealne žlezde patohistološkim nalazom u zavisnosti od starosti. Materijal i metode: Makroskopskom morfološkom i mikroskopskom, histološkom analizom obuhvaćeno je 111 izolovanih pinealnih žlezdi osoba oba pola, ne mlađih od 18 godina od kojih je 27 snimljeno aparatom Somatom Sensation 64 sa debljinama rekonstruisanih preseka 5 i 1mm, a još 9 aparatom Somatom Emotion 16. Rezultati: Postoji statistički značajna razlika u određivanju sva tri dijametra epifize petomilimetarskim rekonstrukcijama, i pri utvrđivanju dva dijametra jednomilimetarskim rekonstrukcijama. Postoji statistički značajna razlika u utvrđivanju morfoloških tipova histološkom i metodom kompjuterizovane tomografije. Prisutna je pozitivna korelacija kalcifikovanosti žlezde određene merenjem njene gustine u Haunsfildovim jedinicama i utvrđene mikroskopski. Kalcifikovanost pinealnog parenhima ne korelira starosti. Zaključak: Naša studija je pokazala da su jednomilimetarske rekonstrukcije tačnije u određivanju dijametara žlezde. Makroskopskim i mikroskopskim merenjem utvrđena su sva tri tipa pinealne žlezde opisana magnetnorezonantnim oslikavanjem. Utvrđena je statistički značajna povezanost gustine pinealne žlezde izmerene u Haunsfildovim jedinicama na jednomilimetarskim rekonstrukcijama i stepena kalcifikovanosti izraženog u procentima. Nije utvrđena povezanost kalcifikovanosti epifize merene mikroskopski i starosti.</p> / <p>Introduction: Pineal gland is a small neuroendocrine, circumventricular organ wich evolved from the eye. Calcifications were incidentally discovered and frequently without a proof whether they were normal or abnormal. Magnetic resonance imaging describes three morphological types. Aim: To determine if there is a correlation between pineal gland morphology types and calcifications established with histology and with computed tomography (CT) and if there is the correlation between calcifications and age. Method of work and material: Macroscopic and mycroscopic analysis encounted 111 isolated pineal glands of both sexes, no younger than 18, from wich 27 was examed with Somatom Sensation 64 and 9 with Somatom Emotion 16 with 5mm and 1mm reformated pictures. Results: All three diameters measured on 5mm reformated pictures and two measured on 1mm reformated pictures differed statistically compared to diameters measured macroscopically. There was siginificant difference between morphological types established on computed tomography and macroscopically. Pineal gland calcifications measured microscopically and with CT correlated positivelly. Pineal gland calcifications were not dependant on the patients age. Conclusion: Allthough 1mm reformated pictures are more accurate than 5mm, the pineal gland morpholgy types determined macroscopically and with CT are not correlated. However, calcification measurement with CT correlates with the microscopic measurement. Calcifications measured microscopically are not correlated with age.</p>
195

Damage mechanisms in SiC/SiC composite tubes : three-dimensional analysis coupling tomography imaging and numerical simulation / Mécanismes d'endommagement des tubes composites SiC/SiC : analyse tridimensionnelle couplée par imagerie tomographique et simulation numérique

Chen, Yang 22 November 2017 (has links)
Du fait de leurs propriétés physiques et chimiques exceptionnelles à haute température par rapport aux métaux, les composites de carbure de silicium (SiC) sont étudiés comme éventuel matériau de gainage du combustible nucléaire dans les réacteurs de fusion ou fission avancée futurs, ainsi que, depuis plus récemment, dans les réacteurs à eau légère existants. Les tubes composites SiC/SiC tressés en 2D, fabriqués par procédé d'infiltration chimique en phase vapeur (CVI), présentent un comportement mécanique anisotrope, faiblement déformable (~ 1%). La maîtrise des relations entre la microstructure, l’endommagement et le comportement macroscopique est essentielle pour optimiser précisément le dimensionnement structurel de ce matériau pour les applications envisagées. Un paramètre de fabrication important est l'angle de tressage, angle entre les torons de fibres et l'axe du tube. L'objectif de ce travail est de fournir une compréhension détaillée de la relation endommagement-microstructure, en particulier des effets de l'angle de tressage sur les mécanismes d’endommagement. Dans ce but, une étude combinant observations expérimentales à macro et micro-échelle et simulations numériques est menée. Les tubes composites sont d’abord étudiés par des essais de traction in situ sous tomographie par rayons X. Les expériences ont été réalisées sur la ligne PSICHE du synchrotron SOLEIL sous faisceau rose polychromatique. Les images tridimensionnelles sont analysées par la technique de corrélation d’image volumique (DVC), complétée par une série d'algorithmes de traitement d'image originaux, développés spécifiquement pour analyser les microstructures 3D, mesurer les déformations à travers l'épaisseur du tube, détecter et caractériser quantitativement le réseau de microfissures créées par le chargement mécanique. De plus, les microstructures réelles, décrites par les images de haute résolution issues des tests in situ, sont utilisées dans les simulations numériques multi-échelle. Les champs de contrainte à l’échelle microstructurale sont calculés en régime élastique par une technique utilisant la transformée de Fourier rapide (FFT). Ils permettent de mieux comprendre l'initiation des fissures et d’interpréter les observations expérimentales par une comparaison directe. Ces approches expérimentales et numériques sont appliquées à trois tubes présentant différents angles de tressage (30 °, 45 ° et 60 °). L’influence de l'angle de tressage sur l'initiation et l'évolution de l’endommagement à cœur des composites est ainsi mise en évidence / Because of their outstanding physical and chemical properties at high temperature, in comparison with metals, silicon carbide (SiC) composite materials are studied as possible nuclear fuel cladding materials either for future advanced fission/fusion reactors, or more recently, for the currently existing light water reactors. 2D-braided SiC/SiC composite tubes, manufactured by chemical vapor infiltration (CVI), exhibit an anisotropic, hardly deformable (~1%) mechanical behavior. Understanding the relations between the microstructure, the damage mechanisms and the macroscopic behavior is essential to optimize the structural design of this material for the considered applications. One important manufacturing parameter is the braiding angle, i.e. the angle between the fiber tows and the tube axis. The objective of this work is to provide a comprehensive understanding of the damage-microstructure relations, in particular of the effects of the braiding angle on the damage mechanisms. For this purpose, an investigation combining experimental observations at macro and micro-scale and numerical simulations is developed. The composite tubes are first studied through in situ tensile testing under X-ray computed tomography. Experiments were carried out on the PSICHE beamline at synchrotron SOLEIL using a pink polychromatic beam. The recorded 3D images are processed using the digital volume correlation (DVC) technique, extended by a series of advanced image processing algorithms specifically developed in order to analyze the 3D microstructures, to measure the deformations through the tube thickness, and to detect and quantitatively characterize the network of micro-cracks created by the mechanical loading. In addition, numerical simulations are performed on the real microstructures as observed in the high-resolution images recorded during the in situ tests. Stress fields are calculated at the microstructural scale in the elastic regime using a numerical tool based on the Fast Fourier Transform (FFT). They help to better understand crack initiation and interpret the experimental observations within one-to-one comparisons. Both the experimental and numerical approaches are applied to three tubes with different braiding angles (30°, 45° and 60°). The effect of the braiding angle on the initiation and evolution of damage in the bulk of the composite materials can thus be highlighted
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Avaliação da hiperinsuflação pulmonar em felinos domésticos submetidos à ventilação por pressão controlada analisados por meio da tomografia  computadorizada helicoidal / Evaluation of hyperinflation in domestic cats undergoing pressure-controlled ventilation analyzed with helicoidal CT

Martins, Alessandro Rodrigues de Carvalho 12 August 2014 (has links)
É sabido que a ventilação mecânica é essencial para oxigenação do sangue e remoção de dióxido de carbono, sendo realizada sobre sedação ou anestesia geral. Contudo, durante à ventilação mecânica, podem ocorrer alterações na estrutura pulmonar caracterizadas por aparecimento de colapso ao final da expiração e zonas de hiperinsuflação alveolar durante a fase inspiratória, podendo levar ao aparecimento de lesão pulmonar associada à ventilação mecânica. Como não existe consenso sobre a melhor estratégia para ventilação mecânica intraoperatória em pequenos animais submetidos a procedimentos cirúrgicos sobre anestesia geral, o objetivo desse estudo foi avaliar a hiperinsuflação pulmonar em diferentes níveis pressóricos nas vias aéreas por meio de tomografia computadorizada em gatos submetidos à anestesia geral. Foram utilizados 17 gatos machos adultos, submetidos à ventilação mecânica a pressão controlada, iniciando a uma pressão de pico de 5cmH2O em \"ZEEP\", subindo escalonadamente 2 cmH2O a cada 5 minutos, até chegar a 15 cmH2O, em seguida, descendo escalonadamente 2 cmH2O a cada 5 minutos, até chegar a 5 cmH2O. A frequência respiratória foi mantida em 15 movimentos por minuto e o tempo inspiratório em um segundo, independente de seu EtCO2. Imediatamente a cada aumento de pressão, foi realizada uma pausa inspiratória de 4 segundos para realização da imagem tomográfica; dados de mecânica respiratória e gasometria arterial. A pressão inspiratória de 5cmH2O apresentou menores áreas hiperinsufladas (4,68±4,7%) e maiores áreas normoaredas (83,6%±6,24%) em comparação aos outros momentos de subida. A pressão de 5cmH2O demostrou ser a ventilação mais protetora para felinos com pulmão íntegro, pois apresentou a maior área normoaerada com boa oxigenação apesar de apresentar acidemia por acidose respiratória. Fato este que pode ser controlado aumentando a freqüência respiratória e/ou diminuindo o tempo inspiratório / Mechanical ventilation is crucial to blood oxygenation and carbon dioxide removal during sedation or general anesthesia. However, lung structure alterations may occur during anesthesia induction period, characterized by emergence of end-expiration collapse and alveolar overinsuflation zones during the inspiratory period, leading to lung injury associated to mechanical ventilation. Since there is no consensus on the best strategy to intraoperative mechanical ventilation in small animals undergoing surgery and general anesthesia, the aim of this study was to evaluate pulmonary hyperinflation at different pressure levels in the airways by computed tomography in cats undergoing general anesthesia. There were used 17 male adult cats undergoing controlled pressure mechanical ventilation, starting at a peak pressure of 5 cmH2O at \"ZEEP\", rising steeply 2 cmH2O every 5 minutes until reaching 15 cmH2O and then descending steeply each 2 cmH2O 5 minutes until it reached 5 cmH2O. The respiratory rate was maintained at 15 movements per minute and inspiratory time on 1 second, regardless of EtCO2. Immediately each pressure increase, it was performed an inspiratory pause of 4 seconds to perform the tomographic image, collect respiratory mechanic\'s data and arterial blood gases. inspiratory pressure 5cmH2O had shown lower hyperinflated areas (4,68±4,7%) and larger normoaerated areas (83,6%±6,24%) compared to other times of ascension. The pressure of 5cmH2O demonstrated to be the most protective ventilation for cats with intact lung, because it showed the largest normoaerated area with good oxygenation despite presenting acidemia by respiratory acidosis. This fact can be controlled by increasing or decreasing respiratory rate and inspiratory time
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Torus Palatinus: estudo por Tomografia Computadorizada\". / Cranial computed tomography in children and adolescents vertically infected with the human immunodeficiency virus

Valente, Marcelo 14 December 1999 (has links)
Estudou-se prospectivamente o comportamento das calcificações, da atrofia, das alterações da substância branca e alterações vasculares nas imagens de tomografia computadorizada de crânio de 162 crianças e adolescentes infectados pelo vírus da imunodeficiência humana (HIV) por transmissão vertical e que estavam ou estiveram em acompanhamento clínico no Ambulatório de Infectologia Pediátrica do Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, entre 1992 e 2002. Analisaram-se as possíveis correlações entre estas alterações e seu aspecto evolutivo. Para tal finalidade, foram avaliadas 606 tomografias computadorizadas de crânio (média de 3,74 exames por paciente), as quais constituíram o grupo de estudo. Após a caracterização quanto à presença ou não das alterações supracitadas, e suas possíveis inter-relações, realizou-se a análise estatística dos resultados obtidos através do teste exato de Fisher com nível de significância de 5%. Posteriormente, os mesmo aspectos foram avaliados em função do seu comportamento evolutivo em um subgrupo de 61 pacientes (média, 4,18 exames por paciente, totalizando 321 exames tomográficos). Estes pacientes tinham, pelo menos, quatro estudos tomográficos seriados (com intervalo mínimo de noventa dias entre os exames subseqüentes e pelo menos dois anos de intervalo total entre o primeiro e o último exame). As alterações tomográficas foram abordadas individual e qualitativamente segundo o critério de presença e intensidade. Inicialmente, o conjunto dos resultados foi tratado de forma individual (para cada paciente) e, depois, em relação à totalidade do grupo em questão. As calcificações foram encontradas em 46,30% dos pacientes; a atrofia, em 37,65%; as alterações da substância branca, em 25,93%; as anomalias vasculares, em 25,19%. Constatou-se uma correlação significativa entre as alterações de substância branca e a atrofia, bem como entre as calcificações e as alterações vasculares. A análise evolutiva destas características demonstrou haver um acréscimo significativo das alterações entre o momento inicial e o quarto momento no conjunto das alterações, sobretudo para as calcificações e para as alterações vasculares. Concluiu-se que as calcificações e a atrofia foram as alterações mais freqüentes nesta série de crianças e adolescentes com HIV adquirido por transmissão vertical. A atrofia e as alterações da substância branca apresentaram uma inter-relação importante na amostra descritiva, assim como as alterações vasculares e as calcificações mostraram uma associação evolutiva significativa em relação à sua progressão / We prospectively studied the behavior of calcifications, atrophy, white matter and vascular abnormalities on the images of computed tomography (CT) of 162 children and adolescents infected with the human immunodeficiency virus (HIV) acquired by vertical transmission, who are or were clinically followed in the Ambulatory of Pediatric Infectology of the Children Institute at the Clinics Hospital of University of São Paulo Medical School, from 1992 to 2002. We analyzed the possible correlation between these abnormalities, as well as, their evolutive aspects. For this purpose, we evaluated 606 CT scans (mean 3.74 exams per patient), which composed the group of study. After the characterization according to the presence or not of the anomalies mentioned above, and their possible inter-relations, we performed a statistical analysis of the obtained results with the Fisher test with a level of significance below 5%. Later, these aspects were evaluated regarding its evolutive behavior in a subgroup of 61 patients (mean, 4.18 exams per patient, summing 321 exams). These patients had, at least, four serial cranial CT (with minimum interval of ninety days between the subsequent exams and, at least, two years of total interval between the first and the fourth exam). The cranial CT abnormalities presented were assessed individually as absent or present. Initially, the set results were assessed individually (for each patient) and, later in relation to the totality of the group. Calcifications were found in 46.30% of all patients, atrophy in 37.65%, white matter abnormalities in 25.93% and vascular anomalies in 25.19%. We found a significant correlation between white matter abnormalities and atrophy, as well as, between calcifications and vascular anomalies. Evolutive analysis of these characteristics demonstrated a significant increase of the abnormalities between the first and the fourth moment, with emphasis to the calcifications and vascular anomalies. We concluded that, calcifications and atrophy were the most frequent abnormalities in this series of children and adolescents with HIV acquired by vertical transmission. Atrophy and white matter abnormalities presented a significant correlation in the descriptive sample, as well as, vascular anomalies and calcifications that also demonstrated a significant evolutive association regarding its progression
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Avaliação da correlação entre a tomografia de impedância elétrica e o volume corrente aplicado durante o suporte ventilatório mecânico invasivo / Evaluation of the correlation between electrical impedance tomography and tidal volume applied during mechanical invasive ventilatory support

Hirota, Adriana Sayuri 12 December 2018 (has links)
Introdução: A tomografia de impedância elétrica (TIE) é uma técnica de imagem não invasiva que mensura o potencial elétrico na superfície torácica através de eletrodos colocados ao redor do tórax. Essas medidas são transformadas em uma imagem bidimensional da distribuição da impedância elétrica no tórax. Esse instrumento detecta modificações da densidade pulmonar e distribuição do volume corrente. Entretanto, é necessário melhor avaliação da sua eficiência em estimar o volume corrente (VT) a cada ciclo ventilatório. O objetivo do estudo é avaliar a correlação do volume estimado pela TIE com o VT aplicado durante o suporte ventilatório mecânico. Métodos: Inicialmente, foram estudados cinco suínos da raça Landrace. Os animais foram sedados, intubados e monitorados com a TIE. Foram aplicados volumes incrementais (100, 250, 500, 750 e 1000 mL) com a seringa de precisão em ZEEP e com PEEP de 5, 10 e 20 cmH2O, antes e depois da promoção de lesão pulmonar com lavagem com solução salina. Posteriormente, outros cinco animais foram monitorados com a tomografia computadorizada de tórax por raios X (TC) e a TIE. Foram aplicados volumes incrementais (250, 500 e 1000 mL) com a seringa de precisão em ZEEP e com PEEP de 10 e 20 cmH2O, também antes e depois da promoção de lesão pulmonar. A amplitude da variação de impedância mensurada pela TIE foi convertida em volume e foi calculado o volume de ar na TC. Análises de correlação e concordância foram realizadas com o programa \"R\" (© R Foundation for Statistical Computing). Resultados: Em ZEEP, o coeficiente de correlação entre os volumes estimado pela TIE e calculado pela TC foram, respectivamente, 0,90 e 0,96 na comparação com a seringa de precisão. O coeficiente de determinação entre a TIE e a seringa de precisão foi progressivamente reduzindo (0,90; 0,89 e 0,81 com PEEP de 5; 10 e 20, respectivamente) com o aumento do volume pulmonar promovido pela elevação da PEEP. A TC mostrou um deslocamento progressivo do conteúdo aéreo no sentido caudal com o aumento do volume pulmonar. Conclusões: Há uma boa correlação entre o volume estimado pela TIE e o VT aplicado durante o suporte ventilatório mecânico quando utilizados volumes e pressões usuais na prática clínica / Rationale: Electrical impedance tomography (EIT) is a noninvasive imaging tool that reconstructs a cross-sectional image of the lung\'s regional conductivity using electrodes placed circumferentially around the thorax. It is able to detect changes of lung air content and tidal volume (VT) distribution. However, better evaluation of its capacity to quantify VT variations is necessary. The aim of our study was to assess the correlation between volume estimated by EIT and tidal volume applied at different positive end-expiratory pressures (PEEP). Methods: Initially, in an experimental study five mechanically ventilated pigs monitored by EIT were studied. VT increments (100, 250, 500, 750 and 1000 mL) were applied with a calibrated syringe at zero end-expiratory pressure (ZEEP) and PEEP levels of 5, 10 and 20 cmH2O before and after lung-injury (induced by saline lavage). Another five pigs was monitored by EIT and x-ray computed tomography (CT). VT increments (250, 500 and 1000 mL) were applied with a calibrated syringe at zero end-expiratory pressure (ZEEP) and PEEP levels of 10 and 20 cmH2O before and after lung-injury. Lung air volume was calculated at CT scan and the amplitude of impedance change measured by EIT was converted to volume (mL). Correlation and agreement analysis was performed at \"R\" program (© R Foundation for Statistical Computing). Results: At ZEEP, volume estimated by EIT and volume calculated at CT obtained r2 = 0.90 and 0.96 respectively, when compared to calibrated syringe. The coefficient of correlation between EIT and calibrated syringe impaired (0.90; 0.89 and 0.81 with PEEP of 5; 10 and 20, respectively) with increase of the lung volume due to increased PEEP. CT showed a progressive displacement of the air content to the caudal thoracic levels with the increase of the lung volume. Conclusion: EIT is able to estimate tidal volume during mechanical ventilatory support when used volumes and pressures usually applied at bedside
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Frequência da doença arterial coronariara (DAC) e características das placas ateroscleróticas avaliadas pela angiotomografia computadorizada multislice em pacientes diabéticos tipo 2 assintomáticos relacionado ao controle glicêmi / Frequency of coronary artery disease (cad) and atherosclerotic plaque characteristics assessed by multislice computed angiotomography in asymptomatic type 2 diabetic patients related to glycemic control

Tavares, Carlos Augusto Fernandes 18 June 2013 (has links)
O número de pacientes com diagnóstico de diabetes aumenta a cada dia. Infarto agudo do miocárdio (IAM) e acidente vascular cerebral (AVC) constituem as principais causas de óbito neste grupo. Ruptura da placa aterosclerótica coronariana é o mecanismo fisiopatológico para (IAM) em 2 a cada 3 casos e as características destas placas mais vulneráveis e propensas a ruptura como:remodelamento positivo do segmento vascular afetado e placa não calcificada com baixa atenuação podem ser avaliadas pela Angiotomografia. Objetivo: Avaliar a frequência de doença arterial coronariana e as principais características de vulnerabilidade dessas placas ateroscleróticas em diabéticos assintomáticos considerando o grau de controle glicêmico através da Angiotomografia Computadorizada Multislice. Desenho do estudo e Métodos: 90 pacientes diabéticos tipo 2 assintomáticos, avaliados,entre junho de 2011 a setembro de 2012, entre 40 e 65 anos de idade, tempo de duração do diabetes inferior a 10 anos, submetidos a avaliação clínica, laboratorial e Angiotomografia Computadorizada de artérias coronárias com 320 colunas de detectores. Resultados: Dos 90 pacientes, 42,2% (n=38) apresentaram doença arterial coronariana a Angiotomo sendo n=11 no grupo A1c < 7% e n=27 no grupo A1c >=7% com diferença estatística (p=0,0006). 14 indivíduos apresentaram doença arterial coronariana significativa (obstrução do lúmen superior a 50%), n=3 no grupo A1c<7% e n=11 no A1c>=7% (p=0,02). O tipo de placa não calcificada predominou no grupo A1c>=7% (p=0,005) e 29% dos diabéticos com doença coronária apresentaram lesões ateroscleróticas classificadas como mais vulneráveis que predominaram no grupo A1c>=7% (p=0,04). Conclusão: O paciente diabético assintomático apresenta além de elevada frequência de doença arterial coronariana possui grande número de placas classificadas como vulneráveis pela Angiotomo e portanto predispostas a ruptura e evento coronariano agudo, principalmente no grupo A1c > =7% / The number of diabetic patients increase every day. Acute myocardial infarction (AMI) and Stroke are the leading causes of death in this group. Coronary atherosclerotic plaque rupture is the pathophysiologic mechanism for (AMI) in 2 every 3 cases and the characteristics of these plaques more vulnerable and prone to rupture as positive remodeling of the vascular segment affected and non-calcified plaque with low attenuation can be evaluated by Angiotomography. Objective: To evaluate the frequency of coronary artery disease and the main characteristics of these vulnerable atherosclerotic plaques in asymptomatic diabetic considering the degree of glycemic control by Multislice Computed Angiotomography. Study Design and Methods: 90 asymptomatic type 2 diabetic patients, evaluated between June 2011 and September 2012, between 40 and 65 years of age, duration of diabetes less than 10 years, underwent clinical, laboratory and Angiotomography Computed coronary arteries with 320 columns of detectors. Results: Of 90 patients, 42.2% (n = 38) had coronary artery disease being the Angiotomo n = 11 in group A1c <7% and n = 27 in group A1c> = 7% with statistical difference (p = 0.0006 ). 14 individuals showed significant coronary artery disease (obstruction of the lumen than 50%), n = 3 in the A1c <7% and n = 11 in A1c> = 7% (p = 0.02). The type of noncalcified plaque predominated in A1c> = 7% (p = 0.005) and 29% of diabetics with coronary disease showed atherosclerotic lesions classified as most vulnerable group that predominated in A1c> = 7% (p = 0.04) . Conclusion: Diabetic patients asymptomatic features besides high frequency of coronary artery disease has a large number of plaques classified as vulnerable by Angiotomo and therefore prone to rupture and acute coronary event, especially in the group A1c> = 7%
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Avaliação da gordura visceral e subcutânea em pacientes portadores de doença gordurosa não alcoólica do fígado (DHGNA): correlação com a resistência insulínica, medidas antropométricas, síndrome plurimetabólica e hábitos alimentares / Visceral and subcutaneous fat in patients with NAFL: correlation with insulin resistance, presence of metabolic syndrome, anthropometric measurements and dietary intake

Vilar, Lisis Karine 12 January 2007 (has links)
Introdução: O aumento alarmante da obesidade em todo mundo é um fator independente para o aumento da prevalência de doenças crônicas, como diabetes, hipertensão arterial e doença hepática gordurosa não alcoólica (DHGNA). A DHGNA engloba um amplo espectro de doença desde esteatose simples sem sinais inflamatórios, evoluindo para esteatohepatite (ENA) e até cirrose. Por ser uma patologia multifatorial sua patogênese e terapêutica ainda apresentam pontos obscuros. A resistência à insulina é um dos fatores que já foram determinados como importantes na fisiopatogênese da DHGNA e, está diretamente relacionado ao estilo de vida e hábitos alimentares. Objetivo: Avaliar a correlação entre a presença da gordura visceral e subcutânea à resistência insulínica, síndrome metabólica, medidas antropométricas e hábitos alimentares em pacientes portadores DHGNA. Resultados: Sessenta por cento dos pacientes com DHGNA apresentavam Síndrome Plurimetabólica de acordo com os critérios do ATP III. Dentre os critérios mais prevalentes da síndrome metabólica, níveis baixos HDL e circunferência de cintura (CC) aumentada ocorreram em 56%. Ao dividirmos os pacientes em grupos, os critérios se modificaram. Nos pacientes portadores de esteatose simples, o critério mais prevalente foi CC 77%. Já naqueles com ENA o aumento do nível de triglicérides ocorreu em 68% dos pacientes, sendo o de maior prevalência. As correlações entre CT e IMC (p=0,001), CC (p=0,003) e percentual de massa gorda (p=0,031), apresentam significância estatística negativa entre os pacientes com DHGNA. Não houve significância estatística entre CT e HOMA, ingestão total de energia, proteínas, carboidratos e lipídios nestes pacientes mesmo quando foram divididos de acordo com o grau de inflamação, esteatose e ENA. Por outro lado, a CC ao ser correlacionada com IMC (p=0,000), HOMA (p=0,049), ingestão total de energia (p=0,043), lipídios e dos ácidos graxos mono (p=0,020) e poliinsaturados (0,045) apresentaram significância estatística nos pacientes com DHGNA. Quando divididos segundo o grau de esteatose houve correlação positiva entre CC e HOMA (p=0,045) nos pacientes com esteatose simples. Já nos pacientes portadores de ENA houve correlação positiva entre CC e ingestão total de calorias (p=0,031). Houve diferença estatística positiva quanto ao consumo de lipídios totais (p=0,005) entre o grupo de esteatose e ENA, onde os pacientes com ENA, tinham um maior consumo de lipídios. Conclusões: A circunferência de cintura se mostrou melhor parâmetro de diagnóstico complementar ao ser comparado com a tomografia computadorizada em pacientes com DHGNA. Ao associarmos o IMC com a CC conseguimos obter uma avaliação nutricional mais fidedigna dos riscos de doenças decorrentes da síndrome metabólica. O alto consumo de lipídios apresentou correlação positiva com maior grau de inflamação em pacientes com DHGNA. / Introduction: The dramatic increasing of obesity in the world is a predictive factor to increase the prevalence of chronic diseases, as type II diabetes, hypertension and Nonalcoholic fatty liver disease (NAFLD). It is part of large spectrum of liver damage ranging from simple steatosis and cirrhosis. The pathogenesis of NAFLD is multifactorial and some points in the mechanisms and therapeutic still unknown. The insulin resistance is the major risk factors, recognized in the pathophysiology of NAFLD and it is strongly related with life style and diet. Objective: Evaluate the correlation between visceral and subcutaneous fat with insulin resistance, presence of metabolic syndrome, anthropometric measurements and dietary intake in patients with NAFLD. Results: Sixty percent of patients with NAFLD, classified by ATPIII criteria, had the metabolic syndrome. Waist circumference and low HDL -C were the most positive criteria, observed in 56% of total cases. However the criteria modifies when the group were divided. In patients with simple steatosis WC was the most prevalent criteria 77%, where as in NASH patients the high level of TGL 68%, was the most prevalent. Correlations between CT and BMI (p=0,001), WC (p=0,033) and fat mass (p =0,031) had a negative statistic significant correlation in all cases of NAFLD. No significant associations were found between CT (umbilical circumference) and fat mass, WC, HOMA, Intake of calories, carbohydrates, proteins, lipids and fat acids in patients divided in steatosis and NASH patients. The correlation between Waist circumference (WC) with BMI (p=0,000), HOMA (p:0,049), total of energy intake (p=0,043) , monounsaturated (p:0,020) and polyunsaturated (p:0,045) fat acids intake showed a statistic significance in all cases of NAFLD. Significant different correlations were found as the group were divided in steatosis and NASH cases. The values of fat mass correlated with WC was (p: 0,045) in the steatosis group where as in NASH patients the only correlation found was WC and total consumption of daily energy (p=0,031). NASH patients showed a statistic higher intake of lipids (p=0,005), compared with steatosis patients. Conclusions: CT measurement of visceral fat did not contribute to differential diagnosis as much as WC in patients with NAFLD. The use of both measurements BMI and WC showed to be a better predictor of the risks of Metabolic Syndromes. NASH subjects had a higher intake o total fat as well as of lipid fractions.

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