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‣ Diagnostic Performance of Coronary Angiography by 64-Row CT

MILLER, Julie M.; ROCHITTE, Carlos E.; DEWEY, Marc; ARBAB-ZADEH, Armin; NIINUMA, Hiroyuki; GOTTLIEB, Ilan; PAUL, Narinder; CLOUSE, Melvin E.; SHAPIRO, Edward P.; HOE, John; LARDO, Albert C.; BUSH, David E.; ROOS, Albert de; COX, Christopher; BRINKER, Jeff
Fonte: MASSACHUSETTS MEDICAL SOC Publicador: MASSACHUSETTS MEDICAL SOC
Tipo: Artigo de Revista Científica
Português
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Background: The accuracy of multidetector computed tomographic (CT) angiography involving 64 detectors has not been well established. Methods: We conducted a multicenter study to examine the accuracy of 64-row, 0.5-mm multidetector CT angiography as compared with conventional coronary angiography in patients with suspected coronary artery disease. Nine centers enrolled patients who underwent calcium scoring and multidetector CT angiography before conventional coronary angiography. In 291 patients with calcium scores of 600 or less, segments 1.5 mm or more in diameter were analyzed by means of CT and conventional angiography at independent core laboratories. Stenoses of 50% or more were considered obstructive. The area under the receiver-operating-characteristic curve (AUC) was used to evaluate diagnostic accuracy relative to that of conventional angiography and subsequent revascularization status, whereas disease severity was assessed with the use of the modified Duke Coronary Artery Disease Index. Results: A total of 56% of patients had obstructive coronary artery disease. The patient-based diagnostic accuracy of quantitative CT angiography for detecting or ruling out stenoses of 50% or more according to conventional angiography revealed an AUC of 0.93 (95% confidence interval [CI]...

‣ 3-D volume rendering maxillofacial analysis of angular measurements by multislice CT

LOPES, Patricia M. L.; MOREIRA, Carla R.; PERRELLA, Andreia; ANTUNES, Jose L.; CAVALCANTI, Marcelo G. P.
Fonte: MOSBY-ELSEVIER Publicador: MOSBY-ELSEVIER
Tipo: Artigo de Revista Científica
Português
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Objective. This study was designed to determine the precision and accuracy of angular measurements using three-dimensional computed tomography (3D-CT) volume rendering by computer systems. Study design. The study population consisted of 28 dried skulls that were scanned with a 64-row multislice CT, and 3D-CT images were generated. Angular measurements, (n = 6) based upon conventional craniometric anatomical landmarks (n = 9), were identified independently in 3D-CT images by 2 radiologists, twice each, and were then performed by 3D-CT imaging. Subsequently, physical measurements were made by a third examiner using a Beyond Crysta-C9168 series 900 device. Results. The results demonstrated no statistically significant difference between interexaminer and intraexaminer analysis. The mean difference between the physical and 3-D-based angular measurements was -1.18% and -0.89%, respectively, for both examiners, demonstrating high accuracy. Conclusion. Maxillofacial analysis of angular measurements using 3D-CT volume rendering by 64-row multislice CT is established and can be used for orthodontic and dentofacial orthopedic applications.

‣ Otimização do co-registo metabolismo-morfologia em estudos de PET/CT com 18F-DG de nódulos pulmonares: comparação de dois protocolos - 4D vs CT lento

Matos, Patrícia Isabel Relvas de
Fonte: Instituto Politécnico de Lisboa Publicador: Instituto Politécnico de Lisboa
Tipo: Dissertação de Mestrado
Publicado em //2013 Português
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Mestrado em Medicina Nuclear - Área de especialização: Tomografia por Emissão de Positrões.; Os sistemas híbridos PET/CT oferecem a vantagem de proporcionar um melhor coregisto entre as imagens de cada uma das modalidades. O objetivo é estabelecer uma correspondência exata entre os voxels de cada uma, tornando possível uma comparação direta entre ambas. Contudo, o co-registo está sujeito a vários erros potenciais, incluindo desalinhamentos mecânicos entre a PET e a CT, diferentes parâmetros de aquisição entre modalidades, movimentos involuntários do paciente e movimentos cardíaco e respiratório. A PET é uma ferramenta precisa para diagnóstico, estadiamento e avaliação da resposta à terapêutica no carcinoma do pulmão, afirmando cada vez mais o seu potencial para auxílio ao planeamento de Radioterapia. Devido ao movimento respiratório, o incorreto co-registo de imagem entre PET e CT pode ser mais marcado na região pulmonar do que em outras zonas do corpo. Assim, persistem controvérsias acerca dos protocolos de aquisição PET/CT para lesões pulmonares, sendo que o conhecimento da amplitude do erro de registo é importante para entender as limitações da utilização desta técnica de imagem. O objetivo do estudo consistiu em avaliar o impacto das aquisições PET/CT 4D e PET/CT com CT lento no co-registo de imagens PET e CT...

‣ The Yield of Head CT in Syncope: A Pilot Study

Bar, J. L.; Mottley, L.; Grossman, Shamai Aaron; Fischer, Christopher M; Lipsitz, Lewis Arnold; Sands, Kenneth Eliot Frederick; Thompson, Sylvia V; Shapiro, Nathan Ivan; Zimetbaum, Peter J.; Thompson, Sally Wright
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
Português
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Although head CT is often routinely performed in emergency department (ED) patients with syncope, few studies have assessed its value. Objectives: To determine the yield of routine head CT in ED patients with syncope and analyse the factors associated with a positive CT. Methods: Prospective, observational, cohort study of consecutive patients presenting with syncope to an urban tertiary-care ED (48 000 annual visits). Inclusion criteria: age >8 and loss of consciousness (LOC). Exclusion criteria included persistent altered mental status, drug-related or post-trauma LOC, seizure or hypoglycaemia. Primary outcome was abnormal head CT including subarachnoid, subdural or parenchymal haemorrhage, infarction, signs of acute stroke and newly diagnosed brain mass. Results: Of 293 eligible patients, 113 (39%) underwent head CT and comprise the study cohort. Ninety-five patients (84%) were admitted to the hospital. Five patients, 5% (95% CI=0.8%–8%), had an abnormal head CT: 2 subarachnoid haemorrhage, 2 cerebral haemorrhage and 1 stroke. Post hoc examination of patients with an abnormal head CT revealed focal neurologic findings in 2 and a new headache in 1. The remaining 2 patients had no new neurologic findings but physical findings of trauma (head lacerations with periorbital ecchymoses suggestive of orbital fractures). All patients with positive findings on CT were >65 years of age. Of the 108 remaining patients who had head CT...

‣ Paired inspiratory-expiratory chest CT scans to assess for small airways disease in COPD

Hersh, Craig Palmer; Washko, George Richard; Estépar, Raúl San José; Lutz, Sharon; Friedman, Paul J; Han, MeiLan K; Hokanson, John E; Judy, Philip Frank; Lynch, David A; Make, Barry J; Marchetti, Nathaniel; Newell, John D; Sciurba, Frank C; Crapo, Jame
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
Português
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Background: Gas trapping quantified on chest CT scans has been proposed as a surrogate for small airway disease in COPD. We sought to determine if measurements using paired inspiratory and expiratory CT scans may be better able to separate gas trapping due to emphysema from gas trapping due to small airway disease. Methods: Smokers with and without COPD from the COPDGene Study underwent inspiratory and expiratory chest CT scans. Emphysema was quantified by the percent of lung with attenuation < −950HU on inspiratory CT. Four gas trapping measures were defined: (1) Exp−856, the percent of lung < −856HU on expiratory imaging; (2) E/I MLA, the ratio of expiratory to inspiratory mean lung attenuation; (3) RVC856-950, the difference between expiratory and inspiratory lung volumes with attenuation between −856 and −950 HU; and (4) Residuals from the regression of Exp−856 on percent emphysema. Results: In 8517 subjects with complete data, Exp−856 was highly correlated with emphysema. The measures based on paired inspiratory and expiratory CT scans were less strongly correlated with emphysema. Exp−856, E/I MLA and RVC856-950 were predictive of spirometry, exercise capacity and quality of life in all subjects and in subjects without emphysema. In subjects with severe emphysema...

‣ The current role of PET-CT in the characterization of hepatobiliary malignancies

Garcea, G.; Ong, S.; Maddern, G.
Fonte: Isis Medical Media Ltd. Publicador: Isis Medical Media Ltd.
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
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Background: Surgery has become heavily dependent on accurate imaging in the assessment and treatment of suspected or confirmed intra-abdominal malignancy. Positron emission tomographycomputed tomography (PET-CT) fuses uptake of a radiotracer combined with CT images to assess both functional tissue activity and anatomical detail. Since its introduction it has offered new ways of treating gastrointestinal cancers. Methods: The review analyses the present literature regarding the use of PET-CT in the assessment, diagnosis, staging and treatment of hepatobiliary malignancies. Results: PET-CT is widely used in pre-operative tumours staging for colorectal liver metastases. There is convincing data that it may also be applicable for neuroendocrine tumours, assessment of indeterminate pancreas lesions and clinical drug trials. PET-CT is of limited value in hepatocellular cancers, although new techniques in dual-tracer PET-CT may change this. Conclusion: Knowledge of the strengths and limitations of PET-CT is important for all surgeons managing cancer of the hepatobiliary system. More clinical data are required on PET-CT, particularly its effect on long-term survival in PET-CT-staged patients undergoing resection.; Ginseppe Garcea, Seok Ling Ong and Guy J. Maddern

‣ Evaluation eines VR (Virtuelle Realität)-Systems zur CT-basierten Operationsplanung an der lateralen Schädelbasis; Evaluation of a VR (virtual reality) system used for the planning of a surgical operation at the lateral skull-base

Heinrich, Bernd Michael
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
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Gegenstand dieser Arbeit war die Bestimmung der klinischen Validität der Ergebnisse einer CT-basierten Hörgerät-Implantationsprüfung mithilfe eines bereits vorgestellten kostengünstigen und kommerziell erhältlichen VR (Virtuelle Realität)-Systems. Das System wurde bei einer Serie von 29 Felsenbeinpräparaten und 25 Patienten eingesetzt. Nach Aufbereitung der zugrundeliegenden CT-Datensätze in einer Prozesskette wurden die resultierenden 3D-Oberflächen zwei unterschiedlichen Testverfahren zugeführt. Zunächst wurde das Ausmaß der anatomischen Übereinstimmung zwischen realer und virtueller Mastoidektomie anhand des Surfacer-Tests ermittelt. Anschliessend erfolgte in der VR-Umgebung ein Fitting-Test, bei dem der Implantationsprozess durch Zusammenführen der CAD-Daten der Hörgerätemodule und der Felsenbeinkonturen nach virtueller Mastoidektomie simuliert wurde. Die Ergebnisse bezüglich der Implantierbarkeit wurde anschließend mit den Ergebnissen der realen Operation verglichen. Als Grundlage für eine qualitativ adäquate Aussagekraft des Surfacer-Tests konnte bei allen Patienten eine hohe Registrierungsqualität der virtuell mit den tatsächlich operierten Felsenbeinregionen erreicht werden. Der Test ergab dann eine ausgezeichnete Übereinstimmung zwischen virtueller und realer Mastoidektomie: in den für die Prognose der Implantationsfähigkeit relevanten Regionen der Felsenbeinhöhlen betrugen die Differenzen überwiegend maximal 1mm. Der Fitting-Test benötigte inklusive der vorab erfolgten Datenaufbereitung einen Zeitaufwand von durchschnittlich 90 Minuten. Die Implantationsprüfung selbst wurde in Echtzeit-Darstellung durchgeführt. In 94% aller Felsenbeinpräparate und Patienten war die Prognose des Fitting-Tests richtig. Schwierigkeiten beim Einbau und Gründe für ein Scheitern der Operation konnten exakt vorhergesagt werden. Das verwendete CT-basierte VR-System hat sich in dieser Arbeit als gut bedienbar und stabil erwiesen. Die Simulationsergebnisse waren in hohem Maße präzise und zeigten eine große Vorhersagegenauigkeit. Die hervorragende klinische Anwendbarkeit des Systems in einer anatomisch komplexen und interindividuell sehr variablen Körperregion zur präoperativen Planung und Simulation konnte aufgezeigt werden. Die Weiterentwicklung des VR-Systems und die Anwendung zur Operationsplanung in anderen Körperregionen erscheint deshalb empfehlenswert. Neben der Verringerung des Zeitaufwandes für die Datenaufbereitung durch Zusammenfassen einzelner Arbeitsschritte sollte künftig die Einbindung dreidimensionaler Visualisierungstechniken zur vereinfachten exakten Lokalisation der Objekte in der VR-Umgebung angestrebt werden.; The subject of this thesis was to determine the clinical validity of a CT (computer tomography)-based simulation of the implantation of an electronic hearing device in a VR surrounding with an already introduced...

‣ Funktionsdiagnostik des Herzens mittels 4-Schicht-Mehrzeilen-Computertomographie; Left ventricular functional parameters using ECG-gated multidetector spiral CT in comparison with invasive ventriculography

Trebar, Branko
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
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Ziel: Ziel der vorgestellten Arbeit ist, die Genauigkeit der Bestimmung linksventrikulärer Funktionsparameter unter Verwendung der 4-Zeilen-Mehrschicht-Computertomographie (MS-CT) mittels retrospektivem EKG-Gating zu untersuchen und mit den Ergebnissen der konventionellen Ventrikulographie zu vergleichen. Material und Methode: Bei 40 Patienten mit bekannter bzw. zum Ausschluss einer koronaren Herzerkrankung (KHK) wurde neben einer Herzdarstellung unter Verwendung der MS-CT mit retrospektivem EKG-Gating (Volume Zoom, Siemens, Forchheim) eine konventionelle Koronarangiographie mit Ventrikulographie durchgeführt. Die CT-Untersuchung (120 kV, 400 mAs) erfolgte mit einer Kollimation von 4 × 1 mm (Rotationszeit: 500 ms) und 150 ml Kontrastmittel (Fluss von 4 ml/s). Für die Bestimmung der kardialen Funktionsparameter Wandbewegungsstörung, Globalfunktion und Myokarddurchmesser wurden zu 10 Zeitpunkten innerhalb einer RR-Phase Bilddatensätze rekonstruiert, aus welchen orthogonal zur z-Achse stehende horizontale Schichten des linken Ventrikels erstellt wurden. Die Auswertung dieser Schnitte erfolgte anschließend mittels der Cine-Darstellung und dem quantitativen Vergleich mit der Ventrikulographie. Bei 26 Patienten wurde das endsystolische Volumen (ESV) und enddiastolische Volumen (EDV) sowie die Ejektionsfraktion (EF) der MS-CT bestimmt und mit den Ergebnissen der invasiven Ventrikulographie korreliert. Hierzu wurden zum endsystolischen und enddiastolischen Zeitpunkten Bilddatensätze rekonstruiert...

‣ 3D-Oberflächenvisualisierung des Gehör- und Gleichgewichtsorgans mittels Image Fusion von HR-CT- und HR-MRT-Volumendatensätzen; Image fusion of CT and MRI for the visualisation of the auditory and vestibular system

Beltle, Jens
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
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Ziel dieser Studie war es, eine realistische dreidimensionale Darstellung des Gehör- und Gleichgewichtsorgans anhand von fusionierten Volumen-Datensätzen durchzuführen. Diese wurden aus hochauflösenden Computer-Tomographieaufnahmen (HR-CT) und hochauflösenden Magnetresonanztomographieaufnahmen (HR-MRT) gewonnen. Anschließend sollte die Qualität und die Beurteilbarkeit dieser Visualisierungsform mit einer herkömmlichen axialen zweidimensionalen Darstellung verglichen werden. Bei 10 Patienten (6 Frauen und 4 Männer), die aufgrund von Schallempfindungs- und/oder Schallleitungstörungen unter partiellen oder totalen Hörverlusten (n=5), unter Schwindel (n=2) oder Tinnitus (n=3) litten, wurden ein HR-CT und ein HR-MRT des Felsenbeins durchgeführt. CT-Aufnahmen wurden mit einem 16-Zeilen Computertomographiescanner durchgeführt. MRT-Daten wurden mithilfe eines 3.0-Tesla Magnetresonanzscanners mit einer speziellen Gradientenecho-Sequenz (3D-CISS-Sequenz) und sowohl T2-gewichteten als auch unverstärkten und kontrastmittelverstärkten T1-gewichteten Turbo-Spinecho Sequenzen akquiriert. Die Segmentation der Strukturen des Mittelohrs erfolgte anhand eines im Handel erhältlichen Computerprogrammes halbautomatisiert aus den HR-CT-Volumendatensätzen...

‣ CT-Angiographie: Unterschiede in der Bildgebung von Abdominalarterien mittels verschiedener Dünnschichtrekonstruktionen und Kontrastmittelapplikationsformen an einem 16-Zeilen-Multidetektor-CT; CT Angiography: Differences in the imaging of abdominal arteries by means of various thin-slice reconstructions and forms of contrast agent application using a 16-channel Multidetector CT

Trüg, Stefan
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
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CT-Angiographie: Unterschiede in der Bildgebung von Abdominalarterien mittels verschiedener Dünnschichtrekonstruktionen und Kontrastmittelapplikationsformen an einem 16-Zeilen-Multidetektor-CT Ziel: Vergleich unterschiedlicher Rekonstruktionsverfahren und Kontrastmittelapplikationsformen hinsichtlich ihrer Darstellungsqualität arterieller Abdominalgefäße bei der CT-Angiographie (CTA) des Abdomens unter Verwendung der 16-Zeilen-Multidetektor-Computertomographie (MDCT). Material und Methodik: Im Rahmen der klinischen Diagnostik wurde bei 62 Patienten eine 16-Zeilen-MDCT (Sensation 16, Siemens) des Abdomen durchgeführt (16 x 0,75 mm Kollimation, 120 KV, 120-140 mAs, 80 ml Kontrastmittel i.v.). Folgende Parameter wurden bei den unterschiedlichen axialen und MIP (Maximum Intensity Projections)-Bilddatenrekonstruktionen verwendet: 1 mm Schichtdicke (SD) / 0,7 mm Rekonstruktionsinkrement (RI), 2 mm SD / 1,5 mm RI, 4 mm SD / 3 mm RI. Als Referenz galt die MIP-Reformation mit 1 mm SD. Ausgewertet wurden die A. mesenterica superior (AMS), die Aa. renales (AR) und die A. hepatica propria (AHP) von der 0. bis zur 4. anatomischen Ordnung unter Verwendung einer 5-Punkte-Skala. Außerdem wurden den Patienten, in drei Gruppen aufgeteilt, verschiedene Kontrastmittelapplikationsprotokolle (uniphasische Injektion mit 3 ml/s...

‣ Bedeutung der Perfusions-Computertomographie beim akuten ischämischen Insult; Significance of Perfusion CT in acute management of ischemic Stroke

Erharhaghen, Jite
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
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Hintergrund. Der ischämische Insult ist ein Notfall, der nach wie vor mit sehr hoher Morbidität und Mortalität verbunden ist. Intravenöse und intraarterielle Thrombolyse innerhalb eines Zeitfensters von 4,5 bzw. 6 h ist effektiv, sicher und gilt inzwischen als Standardtherapie. Vor einer Lyse muss die intrazerebrale Blutung als wichtigste Differentialdiagnose des ischämischen Insults mittels Computertomographie (CT) oder Kernspintomographie (MRT) ausgeschlossen werden. Die CT-Agiographie und Perfusions-CT-Bildgebung (PCT) ist eine schnell verfügbare und Zusatzuntersuchung, die über den Ausschluss einer Blutung hinaus den Positivnachweis einer Ischämie erbringen kann. Ziel. Ziel unsere retrospektive Studie war es, den prädiktiven Wert der PCT für Infarktgröße, initiales Defizit, frühe Besserung und Prognose bei lysierten und nicht lysierten Patienten zu überprüfen. Methoden. Bei 92 Patienten (47 lysiert), die bei Aufnahme eine CT mit PCT sowie eine Kontroll-Bildgebung nach 24 Stunden erhalten hatten, wurden verschiedene PCT-Parameter gemessen und deren Vorhersagewert auf die initiale Symptomatik (gemessen mit dem NIHSS) und ihre Verbesserung, auf die Infarktgröße und der Grad der Behinderung nach der Entlassung aus der Rehabiliation (gemessen mittels modified Rankin Scale) ermittelt. Ergebnisse. Je größer die Fläche der Perfusionsdefizits und je älter der Patient...

‣ CT-Befunde der durch humanen Polyomavirus (BK) induzierten Zystitis beiPatienten nach allogener hämatopoietischer Stammzellentransplantation; CT Findings of Human polyomavirus BK (BKV) associated cystitis in allogeneous hematopoietic stem cell transplant recipients.

Schulze, Maximilian Michael Walther
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
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Hintergrund Über 70% der Bevölkerung weltweit besitzen positive Antikörper gegen Polyomavirus hominis Typ 1 (BKV). Polyomavirus kann bei immunkompromittierten Patienten reaktiviert werden und dadurch Infektionen des Urogenitaltraktes, einschließlich einer Zystitis, hervorrufen. Ziel CT-Befunde der humanen Polyomavirus BK (BKV) induzierten Zystitis bei erwachsenen Patienten nach allogener hämatopoietischer Stammzelltransplantation (allo-SZT) zu beschreiben. Material und Methoden Die Studienpopulation bestand aus einer Kohorte von 11 konsekutiven erwachsenen Patienten (8 Männer, 3 Frauen; Alter: 22-59 Jahre, Mean: 42,9 Jahre), die eine allogene Stammzelltransplantation zwischen Dezember 2003 und Dezember 2007 erhalten hatten und positiv für eine BKV-Infektion der ableitenden Harnwege getestet worden waren. Die CT-Befunde wurden hinsichtlich der Wanddicke der Harnblase, der mukosalen Dichteanhebung, Abgrenzbarkeit der verdickten Schichten der Blasenwand, das Vorhandensein intravesikaler Koagel oder perivesikale Dichteanhebung des Fettgewebes evaluiert. Diese Befunde wurden mit klinischen Daten korreliert. Ergebnisse Alle Patienten wiesen klinische Zeichen einer Zystitis und unterschiedliche Ausprägungen der Harnblasenwandverdickung auf. Sechs Patienten zeigten eine gute Abgrenzbarkeit Blasenwandschichten; 9/11 Patienten besaßen eine kontinuierliche Wandverdickung; 7 Patienten wiesen erhöhte Dichtewerte des intravesikalen Urins auf (4 Patienten präsentierten sich mit intraluminalen Koageln). Die Dichteanhebung des perivesikalen Fettgewebes war kein führender CT-Befund. Die klinische Klassifikation der hämorrhagischen Zystitis korrelierte nicht mit den bildgebenden Parametern. Zusammenfassung Die CT- Befunde bei Patienten mit Polyomavirus BK Zystitis bestehen aus unterschiedlichen Graden der Blasenwandverdickung...

‣ Contributions to the improvement of image quality in CBCT and CBμCT and application in the development of a CBμCT system

Sisniega Crespo, Alejandro
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado
Português
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During the last years cone-beam x-ray CT (CBCT) has been established as a widespread imaging technique and a feasible alternative to conventional CT for dedicated imaging tasks for which the limited flexibility offered by conventional CT advises the development of dedicated designs. CBCT systems are starting to be routinely used in image guided radiotherapy; image guided surgery using C-arms; scan of body parts such as the sinuses, the breast or extremities; and, especially, in preclinical small-animal imaging, often coupled to molecular imaging systems. Despite the research efforts advocated to the advance of CBCT, the challenges introduced by the use of large cone angles and two-dimensional detectors are a field of vigorous research towards the improvement of CBCT image quality. Moreover, systems for small-animal imaging add to the challenges posed by clinical CBCT the need of higher resolution to obtain equivalent image quality in much smaller subjects. This thesis contributes to the progress of CBCT imaging by addressing a variety of issues affecting image quality in CBCT in general and in CBCT for small-animal imaging (CBμCT). As part of this work we have assessed and optimized the performance of CBμCT systems for different imaging tasks. To this end...

‣ PET/CT com 18-fluor-fluorodeoxiglucose no seguimento do melanoma maligno cutâneo; PET/CT with 18-fluor-fluorodeoxyglucose in the follow-up of the cutaneous malignant melanoma

Batanete, Sofia; Infante, J. R.; Rayo, J. I.; Vieira, Lina
Fonte: Escola Superior de Tecnologia da Saúde de Lisboa Publicador: Escola Superior de Tecnologia da Saúde de Lisboa
Tipo: Artigo de Revista Científica
Publicado em /05/2015 Português
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Introdução – O melanoma maligno cutâneo (MMC) é considerado uma das mais letais neoplasias e no seu seguimento recorre-se, para além dos exames clínicos e da análise de marcadores tumorais, a diversos métodos imagiológicos, como é o exame Tomografia por Emissão de Positrões/Tomografia Computorizada (PET/CT, do acrónimo inglês Positron Emission Tomography/Computed Tomography) com 18fluor-fluorodeoxiglucose (18F-FDG). O presente estudo tem como objetivo avaliar a utilidade da PET/CT relativamente à análise da extensão e à suspeita de recidiva do MMC, comparando os achados imagiológicos com os descritos em estudos CT. Metodologia – Estudo retrospetivo de 62 estudos PET/CT realizados em 50 pacientes diagnosticados com MMC. Excluiu-se um estudo cujo resultado era duvidoso (nódulo pulmonar). As informações relativas aos resultados dos estudos anatomopatológicos e dos exames imagiológicos foram obtidas através da história clínica e dos relatórios médicos dos estudos CT e PET/CT. Foi criada uma base de dados com os dados recolhidos através do software Excel e foi efetuada uma análise estatística descritiva. Resultados – Dos estudos PET/CT analisados, 31 foram considerados verdadeiros positivos (VP), 28 verdadeiros negativos (VN)...

‣ Repeatability of quantitative FDG-PET/CT and contrast enhanced CT in recurrent ovarian carcinoma: test retest measurements for tumor FDG uptake, diameter and volume

Rockall, Andrea G.; Avril, Norbert; Lam, Raymond; Iannone, Robert; Mozley, P. David; Parkinson, Christine; Bergstrom, Donald; Sala, Evis; Sarker, Shah-Jalal; McNeish, Iain A.; Brenton, James D.
Fonte: American Association for Cancer Research. Publicador: American Association for Cancer Research.
Tipo: Article; accepted version
Português
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This version is the author accepted manuscript. The OnlineFirst version of this article can be found on the publisher's website at: http://clincancerres.aacrjournals.org/content/20/10/2751.full.pdf+html; Purpose - Repeatability of baseline FDG-PET/CT measurements has not been tested in ovarian cancer. This dual-center, prospective study assessed variation in tumor FDG uptake, tumor diameter (TD) and tumor volume (TV) from sequential FDG-PET/CT and contrast-enhanced CT (CECT) in patients with recurrent platinum-sensitive ovarian cancer. Methods - Patients underwent two pre-treatment baseline FDG-PET/CT (n=21) and CECT (n=20) at 2 clinical sites with different PET/CT instruments. Patients were included if they had at least one target lesion (TL) in the abdomen with an SUV maximum (SUVmax) of ?2.5 and a long axis diameter of ?15mm. Two independent reading methods were used to evaluate repeatability of TD and SUV uptake: on site and at an imaging clinical research organization (CRO). TV reads were only performed by CRO. In each reading set, TLs were independently measured on sequential imaging. Results - Median time between FDG-PET/CT was 2 days (range 1-7). For site reads, concordance correlation coefficient (CCC) for SUVmean, SUVmax and TD were 0.95...

‣ Prospective study evaluating the relative sensitivity of 18F-NaF PET/CT for detecting skeletal metastases from renal cell carcinoma in comparison to multidetector CT and 99mTc-MDP bone scintigraphy, using an adaptive trial design

Gerety, Emma-Louise; Lawrence, Edward; Wason, James; Yan, Haixi; Hilborne, Sarah; Buscombe, John; Cheow, Heok; Shaw, Ashley; Bird, Nick; Fife, Kate; Lomas, David; Matakidou, Athena; Soloviev, Dmitry; Eisen, Tim
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Article; published version
Português
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This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/annonc/mdv289; Background: The detection of occult bone metastases is a key factor in determining the management of patients with renal cell carcinoma (RCC), especially when curative surgery is considered. This prospective study assessed the sensitivity of 18F-labelled sodium fluoride in conjunction with Positron Emission Tomography/Computed Tomography (18F-NaF PET/CT) for detecting RCC bone metastases, compared to conventional imaging with bone scintigraphy or CT. Patients and methods: An adaptive 2-stage trial design was utilized, which was stopped after the first stage due to statistical efficacy. Ten patients with Stage IV RCC and bone metastases were imaged with 18F-NaF PET/CT and 99mTc-labelled methylene diphosphonate (99mTc-MDP) bone scintigraphy including pelvic Single Photon Emission Computed Tomography (SPECT). Images were reported independently by experienced radiologists and nuclear medicine physicians using a 5-point scoring system. Results: 77 lesions were diagnosed as malignant: 100% were identified by 18F-NaF PET/CT, 46% by CT and 29% by bone scintigraphy/SPECT. Standard-of-care imaging with CT and bone scintigraphy identified 65% of the metastases reported by 18F-NaF PET/CT. On an individual patient basis...

‣ Investigation of Improved Quantification Techniques in Dedicated Breast SPECT-CT

Mann, Steve Dean
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2015 Português
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The work presented in this dissertation focuses on evaluation of absolute quantification accuracy in dedicated breast SPECT-CT. The overall goal was to investigate through simulations and measurements the impact and utilization of various correction methods for scattered and attenuated photons, characterization of incomplete charge collection in Cadmium Zinc Telluride detectors as a surrogate means of improving scatter correction, and resolution recovery methods for modeling collimator blur during image reconstruction. The quantification accuracy of attenuation coefficients in CT reconstructions was evaluated in geometric phantoms, and a slice-by-slice breast segmentation algorithm was developed to separate adipose and glandular tissue. All correction and segmentation methods were then applied to a pilot study imaging parathyroid patients to determine the average uptake of Tc-99m Sestamibi in healthy breast tissue, including tissue specific uptake in adipose and glandular tissue.

Monte Carlo methods were utilized to examine the changes in incident scatter energy distribution on the SPECT detector as a function of 3D detector position about a pendant breast geometry. A simulated prone breast geometry with torso, heart, and liver was designed. An ideal detector was positioned at various azimuthal and tilted positions to mimic the capabilities of the breast SPECT subsystem. The limited near-photopeak scatter energy range in simulated spectra was linearly fit and the slope used to characterize changes in scatter distribution as a function of detector position. Results show that the detected scatter distribution changes with detector tilt...

‣ CT Radiation Dosimetry Study using Monte Carlo Simulation and Computational Anthropomorphic Phantoms

Zhang, Yakun
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Tese de Doutorado
Publicado em //2012 Português
Relevância na Pesquisa
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There are three main x-ray based modalities for imaging the thorax: radiography, tomosynthesis, and computed tomography (CT). CT perhaps provides the highest level of feature resolution but at notably higher radiation dose, which has increased the concern among radiation protection professionals. Being able to accurately assess the radiation dose patients receive during CT procedures is a crucial step in the management of CT dose. To identify the best imaging modality for patients, the American College of Radiology published the guiding principle of "The right exam, for the right reason, at the right time". To implement this principle in making an appropriate choice between standard chest projection imaging, tomosynthesis, and CT, the organ and effective dose for each modality should be accurately known. This thesis work attempted to explain the effect on dose results when choosing different types of computational phantoms used in CT dosimetry; this work also compared radiation dose across three main x-ray based modalities on one common platform for different body shape adults.

The first part of this thesis compared organ doses, effective doses, and risk indices from 13 representative adult CT protocols using four types of reference phantoms (XCAT...

‣ Investigation of High Resolution 3D Rodent-morphic Dosimetry, and Cost-Effective Optical-CT using Fresnel Lenses

Bache, Steven
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Tese de Doutorado
Publicado em //2014 Português
Relevância na Pesquisa
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Micro-irradiators enable exploration of the efficacy of novel radiation treatment approaches by providing the capability to reproduce realistic treatment delivery in small animal models. An approach of current topical interest is hypofractionated stereotactic body radiation therapy (SBRT), and the study of associated tumor and normal tissue radio-biology. Rodent SBRT is extremely challenging, requiring the precise delivery of radiation beams on the order of several millimeters. At present there are no methods to comprehensively verify these delivery techniques due to the requirements for ultra-high resolution and ability to measure the dose in 3 dimensions (3D).

This work introduces a potential solution to the rodent SBRT verification challenge: radiochromic rodent-morphic 3D dosimeters compatible with ultra-high resolution optical computed tomography (optical-CT) dose read-out. Rodent-morphic dosimeters were produced by 3D-printing molds of rodent anatomy directly from X-ray CT data, and using these molds to create tissue-equivalent phantoms both with and without high-Z spinal inserts for cone-beam CT targeting. Feasibility was evaluated through a series of irradiations, including a 180-degree spinal arc treatment. Dose distributions were measured in high-resolution (0.5mm isotropic voxels) with an in-house built optical-CT system...

‣ Patterns of extension of gastrointestinal stromal tumors (GIST) treated with imatinib (Gleevec®) by 18F-FDG PET/CT

Valls-Ferrusola,Eulalia; García-Garzón,Juan Ramón; Ponce-López,Ana; Soler-Peter,Marina; Fuertes-Cabero,Silvia; Moragas-Solanes,Merce; Riera-Gil,Eduard; Carrió-Gasset,Ignasi; Lomeña-Caballero,Francisco
Fonte: Revista Española de Enfermedades Digestivas Publicador: Revista Española de Enfermedades Digestivas
Tipo: info:eu-repo/semantics/article; journal article; info:eu-repo/semantics/publishedVersion Formato: text/html; application/pdf
Publicado em 01/07/2012 Português
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Background and aim: currently it is recognized the usefulness of 18F-FDG PET in assessing response to therapy with imatinib (Gleevec®) in the gastrointestinal tract sarcomas (GIST). To facilitate the follow-up of these studies is important to know the patterns of metastatic spread. The aim of this paper is to describe patterns observed in the 18F-FDG PET/CT. Method: retrospective study included 29 patients who underwent 18F-FDG PET/CT after being diagnosed with unresectable or metastatic GIST. In total, 87 PET/CT studies were performed (1-6 controls per patient) with a mean time of follow-up 6-36 months. We analyzed the location of the lesions evidenced in PET, CT and fusion. Images were evaluated visually and semiquantitatively (SUV). In cases in which has been considered necessary, additional images have been undertaken: PET delayed imaging, intravenous contrast CT and inspiratory chest CT. Results: the most common primary site was the stomach (41%), small bowel (35%), and rectum (24%). Significant changes in the location of metastatic disease between pre-treatment and the monitoring were observed, with the appearance of more extra-abdominal disease. Conclusions: individualization of protocol studies and interpretation of PET, CT and fused images were required for evaluation of treatment response to imatinib. Hybrid 18F-FDG PET/CT provides an accurate determination of the extent of GIST. While the most common metastatic site is the liver and peritoneum...