A angiografia coronariana por tomografia computadorizada (ACTC) é um exame bem estabelecido no diagnóstico da doença arterial coronariana. Entretanto, segmentos coronarianos submetidos a implante de stent podem apresentar limitação na avaliação luminal. O objetivo deste estudo é avaliar o valor adicional da perfusão miocárdica por tomografia computadorizada (PMTC) à avaliação anatômica isolada pela ACTC em portadores de stent, tendo o cateterismo (CATE) como referência. Quarenta e seis pacientes (56,9±7,2 anos, 28 homens) com indicação clínica de CATE em até 60 dias foram submetidos à avaliação combinada de ACTC e PMTC, por meio de tomógrafo de 64 detectores (Aquillion 64, Toshiba). A aquisição foi iniciada com a fase de estresse (PMTC) usando-se dipiridamol a 0,56mg/kg/4min e 60ml de contraste a 3ml/s, seguido de reversão com aminofilina 240mg e metoprolol (até 20mg). Em seguida, realizou-se a ACTC com 80-90ml de constraste a 5ml/s. Os dados da PMTC, da ACTC, e do CATE foram analisados por dois observadores independentes, sem informações clínicas dos pacientes. Primariamente analisou-se a ACTC, seguida da avaliação da PMTC. Concluída esta fase, os observadores tinham a possibilidade de reclassificar os segmentos coronarianos submetidos a stent cuja avaliação estivesse limitada ou inadequada por artefatos. A dose total média de radiação foi 15,83±4,93 mSv e todos os exames foram adequados. Um total de 129 segmentos coronarianos foi avaliado na ACTC, bem como os respectivos territórios miocárdicos pela PMTC. Destes, 54 territórios (42%) eram relacionados à presença de stents, sendo 19 com stents de avaliação adequada e 23 com avaliação luminal limitada, porém possível, e 12 segmentos de avaliação inadequada (sem possibilidade de avaliação luminal). Os valores de sensibilidade, especificidade, valor preditivo positivo, valor preditivo negativo e acurácia para a ACTC isolada nos territórios com stents foram de, respectivamente: 85%, 76%, 85%, 76% e 81%, e com o uso combinado da ACTC + PMTC foram de, respectivamente 88%, 95%, 97%, 83% e 92% (p=0,0314). Nos territórios com stent e avaliação luminal prejudicada (limitada ou inadequada) os valores para análise da ACTC isolada foram de, respectivamente: 83%, 71%, 75%, 80% e 77% e após a análise da ACTC + PMTC foram de, respectivamente: 89%, 94%, 94%, 89% e 92% (p = 0,0441). A avaliação combinada da ACTC + PMTC permitiu melhorar a acurácia diagnóstica da avaliação de obstrução coronariana significativa em pacientes portadores de stents, comparativamente à avaliação isolada da ACTC / Coronary computed tomography angiography (coronary CTA) is a well established examination in the diagnosis of coronary artery disease (CAD). However, the segments with prior coronary stent implantation may have limited luminal evaluation. The aim of this study is to assess the incremental value of myocardial computed tomography perfusion (myocardial CTP) to the anatomical assessment by coronary CTA alone in patients with stents, using catheterization (CAT) as a reference method. Forty-six patients (56.9 ± 7.2 years, 28 men) referred to CAT by clinical indication within 60 days, were evaluated with combined evaluation of coronary CTA and myocardial CTP through 64-detector CT scanner (Aquillion 64, Toshiba). The acquisition protocol began with the stress phase (myocardial CTP), using dipyridamole to 0.56 mg/kg/4min and 60ml of contrast (3ml/s), followed by a bolus of aminophylline 240 mg and metoprolol (up to 20mg). After, it was performed the coronary CTA wih 80-90ml of contrast (5 ml/s). Data from the myocardial CTP, coronary CTA and CAT were analyzed by two independent observers, with no knowledge to clinical information. The observers reviewed the coronary CTA findings, and in a second time performed the evaluation of myocardial CTP. So, they had the possibility to reclassify segments with coronary stent that were considered with limited or inadequate assessment due to artifacts. Mean total dose of radiation was 15.83 ± 4.93 mSv, and all examinations were interpretable. A total of 129 coronary segments were evaluated by coronary CTA, and also were their correspondent myocardial territories by myocardial CTP. Of these, 54 territories (42%) were related to the presence of stents, 19 stents with adequate evaluation, 23 with limited evaluation, but possible, and 12 with inadequate evaluation (no luminal assessment possible). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for the coronary CTA in territories with stents were respectively: 85%, 76%, 85%, 76% and 81%, and the combined use of coronary CTA + Myocardial CTP were respectively 88%, 95%, 97%, 83% and 92% (p=0.0314). In territories with impaired luminal stent evaluation (limited or inadequate), the values for analysis of coronary CTA alone were: 83%, 71%, 75%, 80% and 77%, and after analysis of myocardial CTP were, respectively: 89%, 94%, 94%, 89% and 92% (p = 0.0441). The combined evaluation of the coronary CTA and myocardial CTP has improved the diagnostic accuracy of the evaluation of significant coronary obstruction in patients with stents, compared to the assessment of coronary CTA alone

Orientador: Carlos Alberto Hussni / Resumo: A venografia é um exame radiográfico contrastado utilizado para identificar ou avaliar a função venosa de membros, órgãos ou região anatômica. A lidocaína é um anestésico local que possui efeito vasodilatador. O objetivo do trabalho foi avaliar o efeito da lidocaína (2%), na venografia distal do membro torácico de equinos hígidos, por meio da descrição e contagem dos vasos contrastados distalmente ao membro, comparou-se a aplicação de 40 mL de contraste diatrizoato de meglumina 60% associado à lidocaína 2% com a associação de solução salina 0,9% e os volumes entre 40 e 60 mL de solução, questionando-se se a variação de volume ou a associação com a lidocaína pela vasodilatação podem diferir sobre no preenchimento venoso. Em cinco equinos adultos hígidos procedeu-se a venografia em ambos os membros torácicos com estase a partir de torniquete aplicado na região distal do rádio, aplicando-se para cada membro torácico os protocolos 40S (20 mL de meio de contraste + 20 mL de solução salina 0,9%), 40L (20 mL de meio de contraste + 20 mL de lidocaína 2%) e 60S (30 mL de meio de contraste + 30 mL de solução salina 0,9%) com intervalo de cinco dias entre cada exame. Os exames radiográficos foram realizados nas projeções dorso-palmar (DPa) e látero-medial (LM) (70 kV, 8 mAs e 70 cm distância foco-filme). As medianas foram calculadas a partir da contagem de vasos nas duas posições radiográficas e nas regiões distal de metacarpo e média das falanges proximal e média. Foi observado a distr... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Venography is a contrasted radiographic examination used to identify or evaluate venous function in limbs, organs or other anatomic regions. Lidocaine is a local anesthetic that has a vasodilator effect. The aim of this study was to evaluate the effect of lidocaine (2%), in the distal venography of the distal forelimb of horses, through the description and counting of regional distal vessels, comparing the application of contrast solution associated with lidocaine and saline solution in total volumes of 40 or 60 mL, aiming to evaluate whether the volume variation or the association with lidocaine would interfere in the results. Venography was performed on both forelimbs of five adult horses, with stasis from a tourniquet applied to the distal radius, applying three different combinations of fluids: group 40S received 20 mL of contrast + 20 mL of saline solution 0,9%; group 40L received 20 mL of contrast + 20 mL of lidocaine 2% and group 60S received 30 mL de contrast + 30 mL of solution saline 0,9%. An interval of five days between every utilization was respected. The radiographs were made in the dorsopalmar and lateromedial projections (70kV, 8 mA and 70 cm of distance). The medians were calculated using the vessel count of both radiographic projections, in the distal metacarpal and middle regions of the proximal and middle phalanges. Axial distribution to the distal phalanx was observed in all protocols, with more evidence of the larger caliber of the vessels when lidocaine... (Complete abstract click electronic access below) / Mestre

Automatic and semi-automatic magnetic resonance angiography (MRA)s segmentation techniques can potentially save radiologists larges amounts of time required for manual segmentation and cans facilitate further data analysis. The proposed MRAs segmentation method uses a mathematical modeling technique whichs is well-suited to the complicated curve-like structure of bloods vessels. We define the segmentation task as ans energy minimization over all 3D curves and use a level set methods to search for a solution. Ours approach is an extension of previous level set segmentations techniques to higher co-dimension.

A high percentage of unrecognized myocardial infarctions (UMIs) seen at delayed-enhanced magnetic resonance imaging (DE-MRI) are not detected by ECG. DE-MRI-detected UMIs are independent predictors of cardiovascular events in patients with coronary artery disease. In an elderly population, subjects with DE-MRI-detected UMIs do not have increased Framingham risk score or increased prevalence of artery stenosis in whole-body MR angiography as patients with recognized myocardial infarctions (RMI). Further investigation on the pathogenesis of DE-MRI-detected UMIs focus on the need to decide the management of these subjects. From the Prospective Investigation of the Vasculature in Uppsala Seniors, 248 subjects underwent cardiac MRI at age 70 and from these, 185 underwent a 5-year follow-up MR. DE-MRI-detected UMIs had lower signal intensity than RMIs probably reflecting different composition of their tissues. Subjects with UMI scar had increased levels of NT-proBNP, a predictor of increased risk of cardiovascular events. After 5 years, UMI scars were in their majority seen on the same location and with the same size, and their prevalence increased. Subjects with an UMI did not differ from subjects without a scar in terms of coronary stenosis assessed by computed tomography angiography or signs of ischemia on exercise test. In conclusion, DE-MRI-detected UMI scars are a frequent finding in an elderly population and its prevalence increases with age. The increased levels of NT-proBNP indicate that subjects with an UMI might have an increased rate of future cardiovascular events but the findings that these scars might have a different contrast distribution volume on MRI and that they are not related to CAD are indicators that they probably have a different etiology from RMIs. The prognosis of DE-MRI detected UMI scars in the general population is still unknown and therefore the clinical management of these individuals is yet to be defined.

The aim of this study was to describe peripheral vascular patients´experiences of quality of care in connection whith ambulatory care, and to identify if ambulatory treatment responded to patients´expectations. / Syftet med studien var att beskriva perifert kärlsjuka patienters erfarenheter av vårdkvalitet i samband med dagkirurgisk vård och identifiera om dagkirurgisk behandling motsvarade patienters förväntningar. Detta mättes med hjälp av frågeformuläret Kvalitet Ur Patientens Perspektiv - KUPP. Designen var en beskrivande empirisk studie med kvantitativ ansats. Patienterna valdes konsekutivt och bestod av 47 respondenter (22 män och 25 kvinnor). Samtliga patienter vårdades elektivt där intentionen varit dagsjukvård. Resultatet visade att patienterna generellt varit nöjda med vårdkvaliteten. Balans eller övergod kvalitet skattades på frågor inom dimensionen fysiskt - tekniska förutsättningar och inom dimensionen kontextspecifik där påståenden om dagsjukvård besvarats. Vårdkvaliteten bedömdes även hög vad gäller medicinsk vård och väntetid, läkarens och sjuksköterskans engagemang och visad respekt och att patienterna fått tillräcklig information om själva ingreppet före behandlingen. Brister identifierades vad gäller patienternas erfarenheter av information om resultatet efter behandling. På frågor som berörde läkares och sjukaköterskors empatieka kvaliteter bedömdes vårdkvaliteten vara hög men på andra frågor inom dimensionen identitetsorienterat förhållningssätt bedömdes vårdkvaliteten bristande. detta gällde frågor som berörde information om ansvarig person, delaktighet och information/undervisning i egenvård. Slutsatsen blev att patienterna generellt var nöjda med vårdkvaliteten men att det fanns frågor där kvalitetsförbättrande åtgärder bör ges prioritet.

Medical imaging has known great advances over the past decades to become a powerful tool for the clinical practice. It has led to the tremendous growth of interventional radiology, in which medical devices are inserted and manipulated under image guidance through the vascular system to the pathology location and then used to deliver the therapy. In these minimally-invasive procedures, X-ray guidance is carried out with C-arm systems through two-dimensional real-time projective low-dose images. More recently, three-dimensional visualization via tomographic acquisition has also become available. This work tackles tomographic reconstruction in the aforementioned context. More specifically, it deals with the correction of motion artifacts that originate from the temporal variations of the contrast-enhanced vessels and thus tackles a central aspect of tomography: data (angular) sampling. The compressed sensing theory identifies conditions under which subsampled data can be recovered through the minimization of a least-square data fidelity term combined with sparse constraints. Relying on this theory, an original reconstruction framework is proposed based on iterative filtered backprojection, proximal splitting, '1-minimization and homotopy. This framework is derived for integrating several spatial and temporal penalties. Such a strategy is shown to outperform the analytical filtered backprojection algorithm that is used in the current clinical practice by reducing motion and sampling artifacts in well-identified clinical cases, with focus on cerebral and abdominal imaging. The obtained results emphasize one of the key contributions of this work that is the importance of homotopy in addition to regularization, to provide much needed image quality improvement in the suggested domain of applicability.

No description available.

In this thesis a recently developed energy resolving x-ray detector (Medipix) is used to investigate potential medical applications of spectral x-ray imaging. Computed Tomography (CT) is one of the most important medical imaging modalities. Recent developments in CT techniques include dual-energy CT, where images are taken with two different x-ray spectra by either using two x-ray tubes operated at different voltages, or modulating the operating voltage of a single tube. These techniques provide spectral information in the CT dataset but are limited to what can be achieved by manipulating the x-ray source, since the detectors used in current CT systems are unable to provide spectral information about the detected x-rays. A preliminary investigation of the use of the Medipix detectors for two different medical applications is presented. The first, applications is imaging of blood vessels for diagnosis of vascular diseases, and the second, characterising and measuring the energy dependence of x-ray attenuation in fat and liver tissue using the Medipix2 detector. This second investigation is part of work towards (eventually) quantifying the fat content of liver tissue in vivo, which is important for the early diagnosis of fatty liver disease. While an early attempt to identify iron fluorescence x-rays in a Monte-Carlo simulation of blood vessel x-ray image was not successful, the potential for improving image contrast using the changes in x-ray attenuation at the iodine k-edge iodine have been investigated in a series of further simulations and appears to be feasible. The potential use of spectral imaging to differentiate and quantify tissues without the need for added contrast material has been investigated by using a Medipix2 detector to measure the energy dependence of x-ray absorption in fat and liver tissue. The results of this experimental work show significant differences in x-ray attenuation between these two tissues that suggest this form of spectral imaging may be useful in practice.

Coronary magnetic resonance angiography (CMRA) is a potential diagnostic tool for coronary artery disease (CAD). Compared to the current gold standard, x-ray angiography, CMRA provides three-dimensional visualization of coronary vessel lumens without the use of catheters and ionizing radiation. CMRA, however, requires long acquisition times that span multiple heartbeats. Typically, to reduce cardiac motion artifacts, electrocardiogram (ECG) gating is used to synchronize data acquisition windows to diastasis periods. Gating errors may cause vessel blurring by unintentionally triggering the scanner to acquire image data during periods of significant cardiac motion. This is particularly problematic for CMRA because of the associated fine spatial resolution requirement for diagnosing CAD. This thesis presents and tests the novel idea of determining the timing of global epicardial diastasis periods from the motion of the basal ventricular septum. An experiment involving a small patient cohort undergoing elective diagnostic angiography revealed a significant correlation between the beat-to-beat diastasis periods of the ventricular septum and the coronary vasculature. This motivated the ii development and testing of the hypothesis that suggests sharper coronary artery images may be obtained by using cardiac gating windows determined by septal motion. A preliminary study involving a small volunteer cohort provided encouraging results, but also revealed limitations of using ultrasound to measure septal motion during a pre- scan prior to an MRA exam. This led to the major technical development of this thesis, which is a magnetic resonance imaging (MRI) method called the Septal Scout for monitoring septal motion at a very high temporal resolution. The technique was applied to a volunteer cohort which showed that cardiac gating windows as determined by the Septal Scout provided sharper coronary images compared with conventional ECG gating. The scientific knowledge and technical developments presented in this thesis are intended to improve CMRA as a non-invasive diagnostic tool of CAD. In the future, I intend to integrate the concepts presented here into a functioning MRI-based cardiac gating system. As well, I intend to validate the Septal Scout in a patient cohort study.

A high speed, high resolution spectral domain optical coherence tomography (SD-OCT) system was used to study in-vivo early morphological changes and optical nerve head (ONH) blood flow in the Long Evans rat retina, induced by administration of sodium iodate (NaIO3). Linear and circular scanned OCT images were acquired at the same location in the retina from healthy control rats and from rats injected with 40mg/kg of NaIO3 solution at 1, 3, 6 12, 24, 72 and 168 hours post drug administration. Morphological OCT images showed changes in the optical reflectance and layer thickness of the photoreceptor IS and OS. The formation of a new low reflective layer between the photoreceptor OS and the RPE was observed in all tested rats. This new layer appeared as early as 1 hour, increased in thickness after 6 hours, and disappeared by 12 hours post NaIO3 injection. The low optical reflectance and the dynamics of this new layer suggest that it was most likely fluid accumulation. Comparison with H&E stained histological sections and IgG immunohistochemistry revealed minimal photoreceptor OS cell swelling at hour 1, detachment of the OS from the RPE by hour 3, and breaking of the blood-retina barrier with significant fluid accumulation by hour 6 post NaIO3 injection. The Doppler Optical Micro-Angiography (DOMAG) algorithm was used to carry out quantitative analysis of the ONH blood flow. Estimation of flow rate on each ONH vessel was done by measurements of the Doppler angle, vessel size and the axial velocity. This study has demonstrated that the capability of UHR-OCT to study optical reflectance and layer thickness changes, rearrangement and detachment of the photoreceptor OS and RPE layers, together with flow rate estimation of retinal blood vessels. Therefore, it can serve as markers in future non-invasive, in-vivo studies of disease or drug induced retinal degeneration in ophthalmic research.