The impact of Sinogram-Affirmed Iterative Reconstruction on patient dose and image quality compared to filtered back projection: a narrative review

Objective: Summarize all relevant findings in published literature regarding the potential dose reduction related to image quality using Sinogram-Affirmed Iterative Reconstruction (SAFIRE) compared to Filtered Back Projection (FBP). Background: Computed Tomography (CT) is one of the most used radiographic modalities in clinical practice providing high spatial and contrast resolution. However it also delivers a relatively high radiation dose to the patient. Reconstructing raw-data using Iterative Reconstruction (IR) algorithms has the potential to iteratively reduce image noise while maintaining or improving image quality of low dose standard FBP reconstructions. Nevertheless, long reconstruction times made IR unpractical for clinical use until recently. Siemens Medical developed a new IR algorithm called SAFIRE, which uses up to 5 different strength levels, and poses an alternative to the conventional IR with a significant reconstruction time reduction. Methods: MEDLINE, ScienceDirect and CINAHL databases were used for gathering literature. Eleven articles were included in this review (from 2012 to July 2014). Discussion: This narrative review summarizes the results of eleven articles (using studies on both patients and phantoms) and describes SAFIRE strengths for noise reduction in low dose acquisitions while providing acceptable image quality. Conclusion: Even though the results differ slightly, the literature gathered for this review suggests that the dose in current CT protocols can be reduced at least 50% while maintaining or improving image quality. There is however a lack of literature concerning paediatric population (with increased radiation sensitivity). Further studies should also assess the impact of SAFIRE on diagnostic accuracy.

A comparison of Sinogram Affirmed Iterative Reconstruction and filtered back projection on image quality and dose reduction in paediatric head CT: a phantom study

Background: Computed tomography (CT) is one of the most used modalities for diagnostics in paediatric populations, which is a concern as it also delivers a high patient dose. Research has focused on developing computer algorithms that provide better image quality at lower dose. The iterative reconstruction algorithm Sinogram-Affirmed Iterative Reconstruction (SAFIRE) was introduced as a new technique that reduces noise to increase image quality. Purpose: The aim of this study is to compare SAFIRE with the current gold standard, Filtered Back Projection (FBP), and assess whether SAFIRE alone permits a reduction in dose while maintaining image quality in paediatric head CT. Methods: Images were collected using a paediatric head phantom using a SIEMENS SOMATOM PERSPECTIVE 128 modulated acquisition. 54 images were reconstructed using FBP and 5 different strengths of SAFIRE. Objective measures of image quality were determined by measuring SNR and CNR. Visual measures of image quality were determined by 17 observers with different radiographic experiences. Images were randomized and displayed using 2AFC; observers scored the images answering 5 questions using a Likert scale. Results: At different dose levels, SAFIRE significantly increased SNR (up to 54%) in the acquired images compared to FBP at 80kVp (5.2-8.4), 110kVp (8.2-12.3), 130kVp (8.8-13.1). Visual image quality was higher with increasing SAFIRE strength. The highest image quality was scored with SAFIRE level 3 and higher. Conclusion: The SAFIRE algorithm is suitable for image noise reduction in paediatric head CT. Our data demonstrates that SAFIRE enhances SNR while reducing noise with a possible reduction of dose of 68%.

Kinetic measurements during transient film growth on zinc

Quimica Nova, Vol. 32, Nº2

Ecoturismo e Estratégias de Comunicação – Interacções em Contexto de Experiência Pedagógica. . O Caso de El Remanso Lodge, Costa Rica

Dissertação apresentada para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Ecologia Humana, e Problemas Sociais Contemporâneos

A colecção de arte colonial do Patriarcado de Lisboa. Proposta de estudo e musealização

Esta tese procura reflectir sobre as possibilidades de constituição de uma colecção de arte colonial portuguesa (objectos artísticos híbridos resultantes da experiência ultramarina portuguesa) (Young 1995; Bhabha 2004) no contexto dos museus nacionais de arte. Recorrendo ao património da Igreja Católica em Portugal (especificamente, ao do Patriarcado de Lisboa), circunscreveu-se a análise das peças ao período Moderno. Considerando que não existem em Portugal colecções de âmbito museológico com a classificação de colonial, procurei no vasto património móvel da diocese de Lisboa (algum dele in situ e a uso) a aplicação dos parâmetros que constituiriam tal sistema (Baudrillard 1978; Foucault 1977 e 1988). A organização deste trabalho baseou-se em dois vectores fundamentais: um conceptual e metodológico que procura nos estudos teóricos e nos instrumentos da museologia as ferramentas para, primeiro, a constituição da colecção e, depois, a fundamentação documental e analítica da mesma (Impey e MacGregor 1989; Pearce 1994; Elsner e Cardinal 1997). E um segundo vector, que procura na historiografia do termo mais recuado e gregário, o “indo-português”, a fundamentação para a problematização em torno da questão mais vasta da introdução de artefactos de origem colonial na classificação de arte de acordo com os parâmetros europeus. Neste sentido, procura-se perceber como foram os artefactos coloniais recebidos – já que desde o início lhe foram conferidos valores de etnicidade –, interpretados – como “portugueses” – e (re)classificados como arte no âmbito da realização das exposições internacionais e da criação dos museus nacionais de arte. Por último, através da aplicação da ferramenta de inventário utilizada pela Rede Nacional de Museus, o Matriz3.0, a uma amostra de estudo (sete fichas de inventário correspondentes a sete casos de estudo), desenvolve-se a abordagem à ideia do inventário enquanto instrumento (isto é, a documentação de peças de arte colonial portuguesa através de um sistema criado para a arte europeia), que se propõe servir de base à narrativa da ideia de que a ferramenta inventário é o primeiro passo do(s) discurso(s) elaborado(s) sobre o objecto (dos quais fazem parte as biografias da vida cultural dos objectos) (Appadurai 2011). Problematizando este tema através de cinco v campos da ficha de inventário – “As Categorias e o Número de Inventário”; “A difícil atribuição de Autorias e a múltipla Produção”; “A Datação por aproximação”; “A Informação Técnica” e “O campo infinito da Documentação Associada” –, do acrescento de um parâmetro especificamente desenvolvido no âmbito da arte colonial – “As funções dos objectos” – e colocando em evidência a importância da análise destas peças a partir dos aspectos inerentes à sua materialidade (Miller 2005), propõe-se como resposta ao enunciado colocado no início deste resumo e possibilidades expositivas, que não é tanto o sistema de classificação que está implícito à institucionalização do objecto (ou seja, a forma como o social categoriza as coisas) que condiciona o seu entendimento, mas mais os discursos que são produzidos sobre ele (isto é, a forma como o social representa as coisas) (Vergo 2000; Macdonald 2006; Semedo e Lopes 2006).

Production and diagnostic application of recombinant domain III of West Nile envelope protein in Brazil

INTRODUCTION: West Nile virus (WNV) is a flavivirus with a natural cycle involving mosquitoes and birds. Over the last 11 years, WNV has spread throughout the Americas with the imminent risk of its introduction in Brazil. METHODS: Envelope protein domain III of WNV (rDIII) was bacterially expressed and purified. An enzyme-linked immunosorbent assay with WNV rDIII antigen was standardized against mouse immune fluids (MIAFs) of different flavivirus. RESULTS: WNV rDIII reacted strongly with St. Louis encephalitis virus (SLEV) MIAF but not with other flaviviruses. CONCLUSIONS: This antigen may be a potentially useful tool for serologic diagnosis and may contribute in future epidemiological surveillance of WNV infections in Brazil.

The effects of cultural heritage on residential property values: Evidence from Lisbon, Portugal

This paper examines the impact of historic amenities on residential housing prices in the city of Lisbon, Portugal. Our study is directed towards identifying the spatial variation of amenity values for churches, palaces, lithic (stone) architecture and other historic amenities via the housing market, making use of both global and local spatial hedonic models. Our empirical evidence reveals that different types of historic and landmark amenities provide different housing premiums. While having a local non-landmark church within 100 meters increases housing prices by approximately 4.2%, higher concentrations of non-landmark churches within 1000 meters yield negative effects in the order of 0.1% of prices with landmark churches having a greater negative impact around 3.4%. In contrast, higher concentration of both landmark and non-landmark lithic structures positively influence housing prices in the order of 2.9% and 0.7% respectively. Global estimates indicate a negative effect of protected zones, however this significance is lost when accounting for heterogeneity within these areas. We see that the designation of historic zones may counteract negative effects on property values of nearby neglected buildings in historic neighborhoods by setting additional regulations ensuring that dilapidated buildings do not damage the city’s beauty or erode its historic heritage. Further, our results from a geographically weighted regression specification indicate the presence of spatial non-stationarity in the effects of different historic amenities across the city of Lisbon with variation between historic and more modern areas.

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