Oesophageal cancer is an aggressive malignancy with an overall five-year survival of 5-10% and two-thirds of patients have irresectable disease at diagnosis. Accurate staging of oesophageal cancer is important as survival closely correlates with the stage of the tumour, nodal involvement and presence of metastases (TNM staging). Endoscopic ultrasonography (EUS) is currently the most reliable modality for providing accurate T and N staging. Depending on findings of the staging, various treatment options including endoscopic, oncological, and surgical treatments may be performed. It was theorised that the development of three-dimensional radial endoscopic ultrasonography would reduce the operator dependence of EUS and provide accurate dimensional and volume measurements to aid planning and monitoring of treatment. This thesis investigates the development of a three dimensional endoscopic ultrasound technique that can be used with the radial echoendoscopes. Various agar-based tissue mimicking material (TMM) recipes were characterised using a scanning acoustic macroscope to obtain the acoustic properties of attenuation, backscatter and speed of sound. Using these results, a number of endoscopic ultrasound phantoms were developed for the in-vitro investigation and evaluation of 3D-EUS techniques. To increase my understanding of EUS equipment, the imaging and acoustic properties of the EUS endoscopes were characterised using a pipe phantom and a hydrophone. The dual ‘single element’ mechanical and ‘multi-element’ electronic echoendoscopes were investigated. Measured imaging properties included dead space, low contrast penetration, and pipe length. The measured acoustic properties included transmitted beam plots, active working frequency and peak pressures. Three-dimensional ultrasound techniques were developed for specific application to EUS. This included the study of positional monitoring systems, reconstruction algorithms and measurement techniques. A 3D-EUS system was developed using a Microscribe positional arm and frame grabber card, to acquire the 3D dataset. A Matlab 3D-EUS toolbox was written to reconstruct and analyse the volumes. The 3D-EUS systems were evaluated on the EUS phantom and in clinical cases. The usefulness of the 3D-EUS systems was evaluated in a cohort of patients, who were routinely investigated by conventional EUS for a variety of upper gastrointestinal pathology. 3D-EUS accurately staged early tumours and provided the necessary anatomical information to facilitate treatment. With regards to more advanced tumours, 3D-EUS was more accurate than EUS in T and N staging. 3D-EUS gave useful anatomical details in a variety of benign conditions such as varicies and GISTs.

Le membre fantôme correspond à la persistance de perceptions sensitives et motrices attribuées au membre amputé. Des douleurs chroniques parfois invalidantes ainsi que des capacités d’évocation de mouvements dans le membre absent sont fréquemment rapportées. Très peu connue, cette motricité résiduelle est souvent considérée comme de l’imagerie motrice. Le premier objectif de cette thèse est de réinterroger le statut psychologique des mouvements de membre fantôme. Le second objectif est d’étudier le lien entre le contrôle moteur dans le membre fantôme et les réorganisations corticales dans le cortex moteur du sujet amputé. Au moyen de tests comportementaux et d’examens en Imagerie par Résonnance Magnétique fonctionnelle (IRMf), ces travaux de thèse ont permis de dissocier expérimentalement une forme de perceptions kinesthésiques associée à de l’imagerie motrice et une autre forme associée à de l’exécution motrice dans le membre fantôme. Cette distinction repose à la fois sur des différences de performances et sur le recrutement de régions cérébrales partiellement distinctes. Au-delà de cette distinction physiologique, les résultats obtenus suggèrent que les mouvements de membre fantôme s’apparentent à une forme d’exécution motrice plutôt qu’à de l’imagerie motrice. A travers le modèle du membre fantôme, ce travail aborde donc la question de la nature des informations menant à la perception d’un mouvement comme étant « exécuté ». Les altérations du fonctionnement cortical mises en évidence chez l’amputé peuvent représenter un modèle d’étude intéressant des différents mécanismes physiopathologiques relevés dans des situations de déficiences liées à une forme de plasticité « maladaptative ». Les observations cliniques et les examens en neuroimagerie menés au cours de cette thèse dressent en effet, un modèle relativement cohérent de l’organisation fonctionnelle du cortex après amputation. En particulier, l’existence d’un lien entre les réorganisations fonctionnelles au sein du cortex moteur et la qualité du contrôle moteur résiduel dans le membre fantôme permet de mieux comprendre les mécanismes sur lesquels reposent certaines thérapies antalgiques, comme les thérapies visuomotrices / The phantom limb is a sensory experience that is perceived to originate from the missing part. Amputees report that the phantom limb had certain sensory properties like touch and pain, as well as kinesthetic properties like being able to be moved voluntarily. Phantom limb movements are little-known and generally considered to reflect motor imagery rather than motor execution. The first aim of this thesis is to investigate whether amputees distinguish between executing a movement of the phantom limb and imagining moving the missing limb. The second aim is to examine the link between the quality of the motor control in the phantom limb and cortical reorganizations in the motor cortex of amputees. Behavioral tests and functional Magnetic Resonance Imaging (fMRI) results reveal the ability of amputees to make the distinction between execution and motor imagery in the phantom limb. This distinction is based both on differences in performances associated with the two tasks and the recruitment of partially distinct brain regions. Beyond this physiological distinction, this result suggests that phantom limb movements are similar to executed movements and differ from imagined movements. This raises important questions about the very nature of the processes underlying the awareness of a movement as being executed or imagined. The functional alterations in the motor cortex of amputees are somewhat similar to the pathophysiological mechanisms of maladaptative plasticity. Amputation could be a great model for its study. Indeed, the clinical and neuroimaging examinations conducted during this thesis led to a relatively coherent model of the functional reorganizations in the motor cortex after a limb-amputation and their relationships with behavioral variables. In particular, the relationship between functional reorganizations in the motor cortex and the quality of residual motor control in the phantom limb helps to understand the mechanisms underlying some analgesic therapies, such as the “visuomotor therapy”

A radiocirurgia estereotáxica é um procedimento que trata principalmente lesões intracranianas para destruir células tumorais inacessíveis cirurgicamente. O Gamma Knife® é uma unidade de radiocirurgia estereotáxica que trata lesões exclusivamente cerebrais com feixes de 60Co de forma não-invasiva. De forma a garantir a acurácia na entrega da dose, esse tipo de equipamento necessita de detectores adequados para determinar a dose a ser entregue com exatidão. O protocolo da IAEA, TRS 483, é um guia padronizado para procedimentos dosimétricos e indicação de detectores relativos à dosimetria de referência de campos pequenos usados em feixes de radioterapia. Este trabalho seguiu as recomendações do TRS 483 na dosimetria do Gamma Knife® e foram realizadas medições utilizando duas câmaras de ionização, Exradin A16 e PTW Pinpoint 3D 31016, a alanina como detector de referência e os objetos simuladores indicados pela Elekta, fabricante do Gamma Knife®, sendo um de ABS e outro de Solid Water®. Um objeto simulador de acrílico foi construído, com as mesmas dimensões dos indicados pela Elekta, e implementado na dosimetria de equipamentos Gamma Knife®. A calibração das câmaras de ionização utilizadas foi realizada em um laboratório padrão primário e o coeficiente de calibração obtido foi utilizado no cálculo da dose absorvida na água dessas câmaras. Os estudos e testes dosimétricos realizados com o objeto simulador construído demonstraram resultados próximos aos simuladores existentes. Todos os fatores de correção indicados pelo TRS 483 foram considerados para o cálculo da dose absorvida. Foi constatado que o novo objeto simulador pode ser utilizado na dosimetria de Gamma Knife® e também para calibração de câmaras de ionização de volume pequeno, garantindo uma configuração de dosimetria e calibração similares e proporcionando ao usuário uma calibração próxima à configuração da dosimetria clínica. O projeto e a execução do objeto simulador utilizado neste trabalho visa contribuir para o TRS 483, de forma que seja utilizado na aplicação da dosimetria de Gamma Knife® e na calibração de câmaras de ionização de volume pequeno. / Stereotactic radiosurgery is a procedure that primarily treats intracranial lesions to destroy tumor cells that are inaccessible surgically. Gamma Knife® is a stereotactic radiosurgery unit that treats exclusively cerebral lesions using 60Co beams non-invasively. In order to ensure accurate dose delivery, this type of equipment requires adequate detectors to determine the dose is delivered accurately. The IAEA TRS 483 protocol is a standardized guide for dosimetric procedures and indication of detectors for reference dosimetry of small fields used in radiotherapy beams. Following TRS 483 recommendations in Gamma Knife® dosimetry, the measurements performed in this work used two ionization chambers; Exradin A16 and PTW Pinpoint 3D 31016, alanine as reference detector and phantoms indicated by Elekta, Gamma Knife\'s® manufacturer, which are made of ABS and Solid Water®. An acrylic phantom was built with the same dimensions as those indicated by Elekta, and implemented for the Gamma Knife® dosimetry. The calibration of the ionization chambers used was performed in a primary standard laboratory and the calibration coefficient obtained was used to calculate the absorbed dose in the water for these chambers. The dosimetry and tests performed with the acrylic phantom showed results close to the existing phantoms. All the correction factors indicated by TRS 483 were considered for the absorbed dose to water calculation. The new phantom can be used in Gamma Knife® dosimetry and also for calibration of small volume ionization chambers, assuring a similar dosimetry and calibration configuration and providing a calibration close to the clinical dosimetry configuration for the user. The design and implementation of the simulator object used in this work aims to contribute to the TRS 483, for the use in Gamma Knife® dosimetry and in the calibration of small volume ionization chambers.

Computational modeling offers better insight into a wide range of bioelectrical and biomechanical problems with improved tools for the design of medical devices and the diagnosis of pathologies. Electromagnetic modeling at low and high frequencies is particularly necessary. Modeling electromagnetic, structural, thermal, and acoustic response of the human body to different internal and external stimuli is limited by the availability of numerically efficient computational human models. This study describes the development to date of a computational full-body human model - Visible Human Project (VHP) - Female Model. Its unique feature is full compatibility both with MATLAB and specialized FEM computational software packages such as ANSYS HFSS/Maxwell 3D. This study also describes progress made to date in using the newly developed tools for segmentation. A visualization tool is implemented within MATLAB and is based on customized version of the constrained 2D Delaunay triangulation method for intersecting objects. This thesis applies a VHP - Female Model to a specific application, transcranial Direct Current Stimulation (tDCS). Transcranial Direct Current Stimulation has been beneficial in the stimulation of cortical activity and treatment of neurological disorders in humans. The placement of electrodes, which is cephalic versus extracephalic montages, is studied for optimal targeting of currents for a given functional area. Given the difficulty of obtaining in vivo measurements of current density, modeling of conventional and alternative electrode montages via the FEM has been utilized to provide insight into the tDCS montage performance. An insight into future work and potential areas of research, such as study of bone quality have been presented too.

A radiocirurgia estereotáxica é um procedimento que trata principalmente lesões intracranianas para destruir células tumorais inacessíveis cirurgicamente. O Gamma Knife® é uma unidade de radiocirurgia estereotáxica que trata lesões exclusivamente cerebrais com feixes de 60Co de forma não-invasiva. De forma a garantir a acurácia na entrega da dose, esse tipo de equipamento necessita de detectores adequados para determinar a dose a ser entregue com exatidão. O protocolo da IAEA, TRS 483, é um guia padronizado para procedimentos dosimétricos e indicação de detectores relativos à dosimetria de referência de campos pequenos usados em feixes de radioterapia. Este trabalho seguiu as recomendações do TRS 483 na dosimetria do Gamma Knife® e foram realizadas medições utilizando duas câmaras de ionização, Exradin A16 e PTW Pinpoint 3D 31016, a alanina como detector de referência e os objetos simuladores indicados pela Elekta, fabricante do Gamma Knife®, sendo um de ABS e outro de Solid Water®. Um objeto simulador de acrílico foi construído, com as mesmas dimensões dos indicados pela Elekta, e implementado na dosimetria de equipamentos Gamma Knife®. A calibração das câmaras de ionização utilizadas foi realizada em um laboratório padrão primário e o coeficiente de calibração obtido foi utilizado no cálculo da dose absorvida na água dessas câmaras. Os estudos e testes dosimétricos realizados com o objeto simulador construído demonstraram resultados próximos aos simuladores existentes. Todos os fatores de correção indicados pelo TRS 483 foram considerados para o cálculo da dose absorvida. Foi constatado que o novo objeto simulador pode ser utilizado na dosimetria de Gamma Knife® e também para calibração de câmaras de ionização de volume pequeno, garantindo uma configuração de dosimetria e calibração similares e proporcionando ao usuário uma calibração próxima à configuração da dosimetria clínica. O projeto e a execução do objeto simulador utilizado neste trabalho visa contribuir para o TRS 483, de forma que seja utilizado na aplicação da dosimetria de Gamma Knife® e na calibração de câmaras de ionização de volume pequeno. / Stereotactic radiosurgery is a procedure that primarily treats intracranial lesions to destroy tumor cells that are inaccessible surgically. Gamma Knife® is a stereotactic radiosurgery unit that treats exclusively cerebral lesions using 60Co beams non-invasively. In order to ensure accurate dose delivery, this type of equipment requires adequate detectors to determine the dose is delivered accurately. The IAEA TRS 483 protocol is a standardized guide for dosimetric procedures and indication of detectors for reference dosimetry of small fields used in radiotherapy beams. Following TRS 483 recommendations in Gamma Knife® dosimetry, the measurements performed in this work used two ionization chambers; Exradin A16 and PTW Pinpoint 3D 31016, alanine as reference detector and phantoms indicated by Elekta, Gamma Knife\'s® manufacturer, which are made of ABS and Solid Water®. An acrylic phantom was built with the same dimensions as those indicated by Elekta, and implemented for the Gamma Knife® dosimetry. The calibration of the ionization chambers used was performed in a primary standard laboratory and the calibration coefficient obtained was used to calculate the absorbed dose in the water for these chambers. The dosimetry and tests performed with the acrylic phantom showed results close to the existing phantoms. All the correction factors indicated by TRS 483 were considered for the absorbed dose to water calculation. The new phantom can be used in Gamma Knife® dosimetry and also for calibration of small volume ionization chambers, assuring a similar dosimetry and calibration configuration and providing a calibration close to the clinical dosimetry configuration for the user. The design and implementation of the simulator object used in this work aims to contribute to the TRS 483, for the use in Gamma Knife® dosimetry and in the calibration of small volume ionization chambers.

Magnetic Resonance Electrical Impedance Mammography (MREIM) is a new imaging technique under development by Wollin Ventures, Inc. in conjunction with the H. Lee Moffitt Cancer Center & Research Institute. MREIM addresses the problem of low specificity of magnetic resonance mammography and high false-positive rates, which lead to unnecessary biopsies. Because cancerous tissue has a higher electrical conductivity than benign tissue, it may serve as a biomarker for differentiation between malignant and benign lesions. The MREIM principle is based on measuring both magnetic resonance and electric properties of the breast by adding a quasi-steady-state electric field to the standard magnetic resonance breast image acquisition. This applied electric field produces a current density that creates an additional magnetic field that in turn alters the native magnetic resonance signal in areas of higher electrical conductivity, corresponding to cancerous tissue. This work comprises MREIM theory, computer simulations, and experimental developments. First, a general overview and background review of tissue modeling and electrical-impedance imaging techniques are presented. The experimental part of this work provides a description of the MREIM apparatus and the imaging results of a custom-made breast phantom. This phantom was designed and developed to mimic the magnetic resonance and electrical properties of the breast. The theoretical part of this work provides an extension to the initial MREIM theoretical developments to further understand the MREIM effects. MREIM computer simulations were developed for both idealized and realistic tumor models. A method of numerical calculation of electric potential and induced magnetic field distribution in objects with irregular boundaries and anisotropic conductivity was developed based on the Finite Difference Method. Experimental findings were replicated with simulations. MREIM effects were analyzed with contrast diagrams to show the theoretical perceptibility as a function of the acquisition parameters. An important goal was to reduce the applied current. A new protocol for an MREIM sequence is suggested. This protocol defines parameters for the applied current synchronized to a specific magnetic resonance imaging sequence. A simulation utilizing this protocol showed that the MREIM effect is detectable for a 3-mm-diameter tumor with a current density of 0.5 A/m², which is within acceptable limits.

[Truncated abstract] Areal bone mineral density (BMD) is measured routinely in the clinic by a quantitative radiological technique, dual-energy X-ray absorptiometry (DXA). BMD is used widely to assess non-invasively but indirectly the mechanical fragility of bone and consequently is able to predict fracture risk. While BMD correlates well with in vitro measurements of bone strength it does not directly measure a mechanical property; half of incident minimally traumatic fractures in women occur with BMD values above the World Health Organisation defined threshold for osteoporosis. This arises partly because the mechanical strength of bone is dependent on its structural geometry and material strength as well as bone mineral mass. Essentially, bones fracture when load stresses exceed the mechanical capacity of the material to withstand them. The structural geometry (i.e., the amount of bone tissue and its complex three-dimensional arrangement within the macroscopic bone envelope) defines the stresses produced by a given load, while the intrinsic load capacity of the material is defined by the composition and microstructure of the bone tissue itself. Hip structural analysis (HSA) is a technique that elucidates the structural geometric component of bone strength; essentially combining information available from conventional DXA images of the proximal femur with a biomechanical beam model based on the stresses arising in a combination of pure bending and axial compression. A version of HSA has recently been released commercially, and has obtained US Food and Drug Administration approval for its clinical application. ... Given the acknowledged limitations of the HSA method when applied to 2-D projection images, a 3-D approach to structural geometry, using imaging modalities such as pQCT and QCT or a recently introduced version of DXA that mimics QCT, is indicated for the future. With that in mind and the possibility of the anthropometric phantom being adopted for future accuracy and precision assessments, improvements in the design of this phantom are recommended. Studies to better understand and verify Contents v the relevance of the 'local buckling' phenomenon as a structural geometric factor in the genesis of macro-fractures are also recommended. In summary, it is essential that superior (compared to BMD) non-invasively determined clinical predictors of bone fragility leading to fracture be investigated. Structural geometric variables are potential candidates. This has led to consideration of; (i) the need to progress beyond BMD for a more sensitive and specific bone strength measurement; (ii) theoretical advantages of structural geometry over BMD; (iii) limitations of the current HSA technique based on DXA, including those introduced by its restrictive assumptions; (iv) the value of HSA in longitudinal studies, exemplified by the 'normal' but rapid skeletal changes seen in human lactation, with possible implications for an analogous study of the menopause; and (v) an investigation, using a custom-designed anthropometric phantom, of the adaptation of HSA to certain emerging imaging modalities and methods able to resolve bone structural geometry in three dimensions.

The objectives of this study were: 1) to compare and contrast the effects of variations in natural densities of two common freshwater predators of crustacean zooplankton, Chaoborus spp. and Mysis relicta; and 2) to determine whether the combined impacts of these predators together differed from their effects when alone. In deep (>10m) mesocosms, additions of Chaoborus and Mysis at natural densities did not result in large changes in zooplankton abundances, lengths, or biomass. Significant decreases in abundance were observed only for Bosmina longirostris and Daphnia spp. In small (~20L) enclosures, higher predator densities caused zooplankton declines over three days. Strong interactive effects between Chaoborus and Mysis were not detected in either the large or small enclosures. This suggests that the combined effects of these two predators can be predicted from their effects determined in isolation.

Tyrimo objektas: fantominio skausmo ir raumenų jėgos pokytis po kineziterapijos ir grįžtamojo ryšio. Tyrimo tikslas: įvertini kineziterapijos ir grįžtamojo ryšio poveikį fantominiams skausmams ir šlaunies raumenų jėgai po šlaunies amputacijos. Hipotezė: manome, kad taikant kineziterapiją ir grįžtamąjį ryšį po šlaunies amputacijos, fantominių skausmų intensyvumas sumažės ir šlaunies raumenų jėga padidės labiau, nei taikant kineziterapiją be grįžtamojo ryšio. Uždaviniai: 1. Palyginti fantominių skausmų intensyvumą ir šlaunies raumenų jėgą po šlaunies amputacijos kineziterapijos pradžioje ir po įprastinės be grįžtamojo ryšio kineziterapijos. 2. Palyginti fantominių skausmų intensyvumą ir šlaunies raumenų jėgą po šlaunies amputacijos kineziterapijos pradžioje ir po kineziterapijos kartu su grįžtamuoju ryšiu. 3. Palyginti įprastinės kineziterapijos ir kineziterapijos kartu su grįžtamuoju ryšiu poveikį fantominių skausmų intensyvumui ir šlaunies raumenų jėgai. Rezultatai: Tyrimo pradžioje, kontrolinės grupės tiriamieji fantominį skausmą įvertino 6,17±0,75, tiriamosios grupės tiriamieji – 6,83±0,75 balais. Tyrimo pabaigoje, kontrolinė grupė – 5,86±0,75, tiriamoji grupė – 5,17±0,75 balais. Prieš kineziterapiją kontrolinėje grupėje, po amputacijos, šlaunį tiesiančių raumenų jėga buvo 3,00±0,00, lenkiančių – 3,33±0,52, pritraukiančių – 2,83±0,51 ir atitraukiančių – 2,50±0,55 balų; tiriamojoje grupėje, šlaunį lenkiančių raumenų jėga buvo 3,17±0,47, tiesiančių – 3,00±0,00... [toliau žr. visą tekstą] / The object: effects of physiotherapy with mirror therapy for phantom pain and thigh muscle strength after transfemoral. The objective: the alteration of phant pain and thigh muscle after physiotherapy and mirror therapy. Hyptohesis: We consider, that the application of physiotherapy with mirror therapy helps to reduce phantom pain and improve muscle strenght better than physiotherapy without mirror therapy. The aims: 1. To compare phantom pain and muscle force in the beginning of physiotherapy and after physiothepy. 2. To compare phantom pain and muscle force in the beginning of physiotherapy and after physiotherapy with mirrot therapy. 3. To compare physiotherapy with mirror therapy and physiotherapy without mirror therpy for phantom pain and muscle force. Results: Beginning of the study, the control group subjects phantom pain score 6.17 ± 0.75, experimental group subjects - 6.83 ± 0.75 points. End of the study, the control group - 5.86 ± 0.75, experimental group - 5.17 ± 0.75 points. Before physical therapy in the control group after the amputation, the thigh muscle stretching force was 3.00 ± 0.00, flexion - 3.33 ± 0.52, attracting - 2.83 ± 0.51 and distracting - 2.50 ± 0.55 scores, the experimental group, the thigh, the muscle strength was 3.17 ± 0.47, stretching - 3.00±0.00, attracting - 2.67±0.47 and distracting-2.83±0.37 points. Application of physical therapy procedures, after 3 weeks, the control group, after the amputation, the thigh flexion strength was 4.33 ± 0... [to full text]

Ultrasound is one of the most widely used modalities in medical imaging because of its high cost-effectiveness, wide availability in hospitals, generation of real-time images, and use of nonionizing radiation. However, the image quality can be insufficient in some patients. Introducing a contrast agent (CA), which comprises a suspension of 2–6 mm-sized microbubbles, improves the image quality and thus the image analysis. At present, contrast-enhanced ultrasound is frequently used during standard clinical procedures such as kidney, liver, and cardiac (echocardiography) imaging. Multimodality and targeted imaging are future areas for ultrasound CAs. Multimodality imaging may improve diagnostics by simultaneously providing anatomical and functional information. Targeted imaging may allow for identification of particular diseases. The work within this thesis focused mainly on a novel multimodal polymer-shelled CA with the potential to be target specific. In Study I, the acoustic response was determined in a flow phantom by evaluating the contrast-to-tissue-ratio when using contrast sequences available in clinical ultrasound systems. This study showed that a high acoustic pressure is needed for optimal visualization of the polymer-shelled CA. In Study II, the in vivo performance of this CA was evaluated in a rat model, and the blood elimination time and subcellular distribution were determined. In Study III, the efficiency in endocardial border delineation was assessed in a pig model. The polymer-shelled CA had a significantly longer blood circulation time than the commercially available CA SonoVue, which is favorable for target-specific CA, in which a long circulation time increases the probability of target-specific binding. Transmission electron microscopic analysis of tissue sections from liver, kidney, spleen and lungs, obtained at different time points after CA injection showed that macrophages were responsible for the elimination of the polymer-shelled CA. A higher dose of the polymer-shelled CA was needed to obtain similar endocardial border delineation efficiency as that obtained using SonoVue. The results of Studies I–III demonstrate that the polymer-shelled CA has potential applicability in medical imaging. Current guidelines for contrast-enhanced echocardiography are limited to cases of suboptimal image quality or when there is a suspicion of structural abnormalities within the left ventricle. It may be hypothesized that the wider use of contrast-enhanced echocardiography may help to detect some diseases earlier. Study IV assessed the diagnostic outcomes after contrast administration in patients without indications for CA use. The myocardial wall motion score index and ejection fraction were evaluated by experienced and inexperienced readers, and a screening for left ventricular structural abnormalities was performed. More cases of wall motion and structural abnormalities were detected in the contrast-enhanced analysis. Intra- and interobserver variability was lower with the use of CAs. This study suggests that the more widespread use of CAs instead of the current selective approach may contribute to earlier detection of cardiovascular disease. / <p>QC 20150401</p>