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Functional brain perfusion evaluation with Arterial Spin Labeling at 3 Tesla

Pimentel, Marco André Figueiredo
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2009 ENG
Relevância na Pesquisa
27.45%
Dissertation submitted in Faculdade de Ciências e Tecnologia of Universidade Nova de Lisboa for the degree of Master of Biomedical Engineering; Background: The new clinically available arterial spin labelling (ASL) sequences present some advantages relatively to the commonly used blood oxygenation level dependent (BOLD) method for functional brain studies using magnetic resonance imaging (MRI), namely the fact of being potentially quantitative and more reproducible. Purpose: The main aim of this work was to evaluate the functional use of a commercial ASL sequence implemented on a 3 Tesla MRI system (Siemens, Verio) in the Imaging Department of Hospital da Luz. The first aim was to obtain a functional validation of this technique by comparison with the BOLD contrast, using a number of different approaches. The second aim was to accomplish perfusion quantification, by resolving some important quantification issues. Materials and Methods: Fifteen adult volunteers participated in a single functional imaging session using three different protocols: one using BOLD and two using ASL. The subjects performed a motor finger tapping task and the data analysis was performed using Siemens Neuro3D and FSL (FMRIB’s Software Library). The location and variability of the activated areas were analysed in MNI (Montereal Neurological Institute) standard space. Results: Topographic agreement between the activated regions obtained by BOLD and ASL was found. However...

Empirical optimization of ASL data analysis using an ASL data processing toolbox: ASLtbx

Wang, Ze; Aguirre, Geoffrey K.; Rao, Hengyi; Wang, Jiongjiong; Fernández-Seara, María A.; Childress, Anna R.; Detre, John A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.41%
Arterial spin labeling (ASL) perfusion fMRI data differ in important respects from the more familiar blood oxygen level dependent (BOLD) fMRI data, and require specific processing strategies. In this paper, we examined several factors that may influence ASL data analysis, including data storage bit resolution, motion correction, preprocessing for cerebral blood flow (CBF) calculations, and nuisance covariate modeling. Continuous ASL data were collected at 3 Tesla from 10 subjects while they performed a simple sensorimotor task with an epoch length of 48 seconds. These data were then analyzed using systematic variations of the factors listed above to identify the approach that yielded optimal signal detection for task activation. Improvements in statistical power were found for use of at least 10 bits for data storage at 3T. No significant difference was found in motor cortex regarding using simple subtraction or sinc-subtraction; but the former presented minor but significantly (P<0.024) larger peak-t value in visual cortex. While artifactual head motion patterns were observed in synthetic data and background suppressed ASL data when label/control images were realigned to a common target, independent realignment of label and control images did not yield significant improvements in activation in the sensorimotor data. It was also found that CBF calculations should be performed prior to spatial normalization and that modeling of global fluctuations yielded significantly increased peak t-value in motor cortex. The implementation of all ASL data processing approaches is easily accomplished within an open source toolbox...

Estimation of Perfusion and Arterial Transit Time in Myocardium using Free-breathing Myocardial ASL with Navigator-echo

Wang, Danny J.J.; Bi, Xiaoming; Avants, Brian B.; Meng, Tongbai; Zuehlsdorff, Sven; Detre, John A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/2010 EN
Relevância na Pesquisa
27.35%
Arterial spin labeling (ASL) provides noninvasive measurement of tissue blood flow, but sensitivity to motion has limited its application to imaging of myocardial blood flow (MBF). While different cardiac phases can be synchronized using ECG triggering, breath holding is generally required to minimize effects of respiratory motion during ASL scanning, which may be challenging in clinical populations. Here a free-breathing myocardial ASL technique with the potential for reliable clinical application is presented, by combining ASL with a navigator-gated, ECG-triggered TrueFISP readout sequence. Dynamic myocardial perfusion signals were measured at multiple delay times that allowed simultaneous fitting of MBF and arterial transit time (ATT). With the assist of a non-rigid motion correction program, the estimated mean MBF was 1.00±0.55mL/g/min with a mean transit time of approximately 400ms. The intraclass correlation coefficient of repeated scans was 0.89 with a mean within subject coefficient of variation (wsCV) of 22%. Perfusion response during mild to moderate stress was further measured. The capability for non-invasive, free-breathing assessment of MBF using ASL may offer an alternative approach to first-pass perfusion MRI for clinical evaluation of patients with coronary artery disease.

The Neurospora crassa OS MAPK Pathway-Activated Transcription Factor ASL-1 Contributes to Circadian Rhythms In Pathway Responsive Clock-Controlled Genes

Lamb, Teresa M.; Finch, Katelyn E.; Bell-Pedersen, Deborah
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.35%
The OS-pathway mitogen-activated protein kinase (MAPK) cascade of Neurospora crassa is responsible for adaptation to osmotic stress. Activation of the MAPK, OS-2, leads to the transcriptional induction of many genes involved in the osmotic stress response. We previously demonstrated that there is a circadian rhythm in the phosphorylation of OS-2 under constant non-stress inducing conditions. Additionally, several osmotic stress-induced genes are known to be regulated by the circadian clock. Therefore, we investigated if rhythms in activation of OS-2 lead to circadian rhythms in other known stress responsive targets. Here we identify three more osmotic stress induced genes as rhythmic: cat-1, gcy-1, and gcy-3. These genes encode a catalase and two predicted glycerol dehydrogenases thought to be involved in the production of glycerol. Rhythms in these genes depend upon the oscillator component FRQ. To investigate how the circadian signal is propagated to these stress induced genes, we examined the role of the OS-responsive transcription factor, ASL-1, in mediating circadian gene expression. We find that while the asl-1 transcript is induced by several stresses including an osmotic shock, asl-1 mRNA accumulation is not rhythmic. However...

Bilingual processing of ASL-English code-blends: The consequences of accessing two lexical representations simultaneously

Emmorey, Karen; Petrich, Jennifer; Gollan, Tamar H.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.41%
Bilinguals who are fluent in American Sign Language (ASL) and English often produce code-blends - simultaneously articulating a sign and a word while conversing with other ASL-English bilinguals. To investigate the cognitive mechanisms underlying code-blend processing, we compared picture-naming times (Experiment 1) and semantic categorization times (Experiment 2) for code-blends versus ASL signs and English words produced alone. In production, code-blending did not slow lexical retrieval for ASL and actually facilitated access to low-frequency signs. However, code-blending delayed speech production because bimodal bilinguals synchronized English and ASL lexical onsets. In comprehension, code-blending speeded access to both languages. Bimodal bilinguals’ ability to produce code-blends without any cost to ASL implies that the language system either has (or can develop) a mechanism for switching off competition to allow simultaneous production of close competitors. Code-blend facilitation effects during comprehension likely reflect cross-linguistic (and cross-modal) integration at the phonological and/or semantic levels. The absence of any consistent processing costs for code-blending illustrates a surprising limitation on dual-task costs and may explain why bimodal bilinguals code-blend more often than they code-switch.

Arterial Spin Labeling (ASL) fMRI: Advantages, Theoretical Constrains and Experimental Challenges in Neurosciences

Borogovac, Ajna; Asllani, Iris
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.45%
Cerebral blood flow (CBF) is a well-established correlate of brain function and therefore an essential parameter for studying the brain at both normal and diseased states. Arterial spin labeling (ASL) is a noninvasive fMRI technique that uses arterial water as an endogenous tracer to measure CBF. ASL provides reliable absolute quantification of CBF with higher spatial and temporal resolution than other techniques. And yet, the routine application of ASL has been somewhat limited. In this review, we start by highlighting theoretical complexities and technical challenges of ASL fMRI for basic and clinical research. While underscoring the main advantages of ASL versus other techniques such as BOLD, we also expound on inherent challenges and confounds in ASL perfusion imaging. In closing, we expound on several exciting developments in the field that we believe will make ASL reach its full potential in neuroscience research.

Resting State Brain Function Analysis Using Concurrent BOLD in ASL Perfusion fMRI

Zhu, Senhua; Fang, Zhuo; Hu, Siyuan; Wang, Ze; Rao, Hengyi
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/06/2013 EN
Relevância na Pesquisa
27.35%
The past decade has seen astounding discoveries about resting-state brain activity patterns in normal brain as well as their alterations in brain diseases. While the vast majority of resting-state studies are based on the blood-oxygen-level-dependent (BOLD) functional MRI (fMRI), arterial spin labeling (ASL) perfusion fMRI can simultaneously capture BOLD and cerebral blood flow (CBF) signals, providing a unique opportunity for assessing resting brain functions with concurrent BOLD (ccBOLD) and CBF signals. Before taking that benefit, it is necessary to validate the utility of ccBOLD signal for resting-state analysis using conventional BOLD (cvBOLD) signal acquired without ASL modulations. To address this technical issue, resting cvBOLD and ASL perfusion MRI were acquired from a large cohort (n = 89) of healthy subjects. Four widely used resting-state brain function analyses were conducted and compared between the two types of BOLD signal, including the posterior cingulate cortex (PCC) seed-based functional connectivity (FC) analysis, independent component analysis (ICA), analysis of amplitude of low frequency fluctuation (ALFF), and analysis of regional homogeneity (ReHo). Consistent default mode network (DMN) as well as other resting-state networks (RSNs) were observed from cvBOLD and ccBOLD using PCC-FC analysis and ICA. ALFF from both modalities were the same for most of brain regions but were different in peripheral regions suffering from the susceptibility gradients induced signal drop. ReHo showed difference in many brain regions...

Detecting Static and Dynamic Differences between Eyes-Closed and Eyes-Open Resting States Using ASL and BOLD fMRI

Zou, Qihong; Yuan, Bin-Ke; Gu, Hong; Liu, Dongqiang; Wang, Danny J. J.; Gao, Jia-Hong; Yang, Yihong; Zang, Yu-Feng
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 27/03/2015 EN
Relevância na Pesquisa
27.27%
Resting-state fMRI studies have increasingly focused on multi-contrast techniques, such as BOLD and ASL imaging. However, these techniques may reveal different aspects of brain activity (e.g., static vs. dynamic), and little is known about the similarity or disparity of these techniques in detecting resting-state brain activity. It is therefore important to assess the static and dynamic characteristics of these fMRI techniques to guide future applications. Here we acquired fMRI data while subjects were in eyes-closed (EC) and eyes-open (EO) states, using both ASL and BOLD techniques, at two research centers (NIDA and HNU). Static brain activity was calculated as voxel-wise mean cerebral blood flow (CBF) using ASL, i.e., CBF-mean, while dynamic activity was measured by the amplitude of low frequency fluctuations (ALFF) of BOLD, i.e., BOLD-ALFF, at both NIDA and HNU, and CBF, i.e., CBF-ALFF, at NIDA. We showed that mean CBF was lower under EC than EO in the primary visual cortex, while BOLD-ALFF was higher under EC in the primary somatosensory cortices extending to the primary auditory cortices and lower in the lateral occipital area. Interestingly, mean CBF and BOLD-ALFF results overlapped at the visual cortex to a very small degree. Importantly...

Accuracy of pulsed arterial spin labeling magnetic resonance imaging in the human brain : tag width and timing effects; Accuracy of pulsed ASL MRI in the human brain : tag width and timing effects

Bolar, Divya Sanam
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 39 p.
ENG
Relevância na Pesquisa
27.52%
Arterial spin labeling (ASL) is the only non-invasive magnetic resonance imaging (MRI) technique that allows absolute quantification of cerebral blood flow (CBF). It involves using radiofrequency pulses designed to invert the spins of water in arterial blood, effectively creating a magnetic bolus. This inverted blood can be considered an endogenous contrast agent; imaging as it traverses the vascular tree allows CBF measurements. Such types of experiments are especially useful for functional neuro-activation studies and in settings of neuropathology. Two flavors of ASL exist: continuous ASL and pulsed ASL. Pulsed ASL has the advantage of not requiring specialized imaging hardware, and can be performed using standard clinical scanners found in most hospitals. Pulsed ASL techniques, however, may yield inaccurate perfusion values and diminished perfusion sensitivity if appropriate labeling parameters are not chosen, particularly during global challenges such as hypercapnia. In this study, the accuracy of QUIPSS II (Quantitative Imaging of Perfusion using a Single Subtraction - second version) ASL for measuring flow changes during a global flow perturbation (hypercapnia) was assessed.; (Cont.) Multiple inversion time ASL experiments were performed to examine bolus delivery dynamics under conditions of normocapnia and hypercapnia and at variable inversion band thicknesses. Tag delivery (inflow) curves revealed that typical published parameter values can cause substantial perfusion error during global challenges and render perfusion increases nearly undetectable. Theoretical criteria for choosing optimal QUIPSS II ASL parameter values are explored...

Development of MRI radiofrequency coils to study neurophysiological changes in a neonatal animal model at 9.4T

Silva, Andreia Capaz
Fonte: Universidade de Lisboa Publicador: Universidade de Lisboa
Tipo: Dissertação de Mestrado
Publicado em //2013 ENG
Relevância na Pesquisa
27.35%
Tese de mestrado em Engenharia Biomédica e Biofísica, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2013; A lesão cerebral hipóxico-isquémica é uma causa comum de lesão cerebral em recém-nascidos, resultando num alto risco de morte prematura ou deficiência. Estas lesões cerebrais devem-se a um fluxo insuficiente de sangue (isquémia) e a um fornecimento reduzido de oxigénio (hipóxia) ao cérebro, eventos que provocam lesões cerebrais agudas resultando numa série de acontecimentos que induzem lesão permanente e morte celular. O diagnóstico da lesão hipóxico-isquémica é difícil e uma detecção tardia da condição pode resultar num tratamento menos eficiente e posteriores sequelas neurológicas. A introdução da ressonância magnética como ferramenta clínica para avaliação da lesão cerebral hipóxico-isquémica neonatal permitiu a determinação da localização, extensão e evolução das lesões cerebrais hipóxico-isquémicas, sendo a mais sensível e específica das técnicas de imagem. Diversas modalidades de ressonância magnética têm vindo a ser exploradas para avaliar lesões cerebrais hipóxico-isquémicas neonatais para avaliação de mudanças neurofisiológicas entre estas modalidades encontra-se a arterial spin labelling. Arterial spin labelling (ASL) é uma técnica de ressonância magnética que mede a perfusão cerebral (fornecimento de sangue a um tecido capilar) de forma não invasiva. Nesta técnica o sangue arterial...

Physiologically Informed Bayesian Analysis of ASL fMRI Data

Frau-Pascual, Aina; Vincent, Thomas; Sloboda, Jennifer; CIUCIU, Philippe; Forbes, Florence
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/01/2015
Relevância na Pesquisa
27.35%
Arterial Spin Labelling (ASL) functional Magnetic Resonance Imaging (fMRI) data provides a quantitative measure of blood perfusion, that can be correlated to neuronal activation. In contrast to BOLD measure, it is a direct measure of cerebral blood flow. However, ASL data has a lower SNR and resolution so that the recovery of the perfusion response of interest suffers from the contamination by a stronger hemodynamic component in the ASL signal. In this work we consider a model of both hemodynamic and perfusion components within the ASL signal. A physiological link between these two components is analyzed and used for a more accurate estimation of the perfusion response function in particular in the usual ASL low SNR conditions.

Implementation of image processing approach to translation of ASL finger-spelling to digital text

Mandloi, Divya
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado Formato: 615695 bytes; application/pdf
EN_US
Relevância na Pesquisa
37.17%
This thesis describes the ongoing development of an image processing technique for the translation of American Sign Language (ASL) finger-spelling to text. The present analysis is the phase one of a broader project, the Sign2 Project, which is focused on a complete technological approach to the translation of ASL to digital audio and/or text. The methodology adopted in this analysis employs a gray-scale image processing technique to convert the American Sign Language finger-spelling to text. It attempts to process static images of the subject considered, and then matches them to a statistical database of pre-processed images to ultimately recognize the specific set of signed letters. This phase of the Sign2 Project considers the hand of the subject alone and not the entire subject, as its scope is restricted to recognizing the finger spelling and not the American Sign Language as a whole. Since the approach taken in this analysis is vision-based, the amount of processing is minimized as compared to other approaches and hence projects itself as a viable technique to be implemented in real time systems. Devices like kiosks and PDAs can incorporate this technology to enable communication between the hearing and non-hearing individuals who are geographically placed apart with the least possible run times which is mandatory for real-time systems. In this investigation...

Implementation of image processing approach to translation of ASL finger-spelling to digital text

Mandloi, Divya; Sarella, Kanthi; Glenn, Chance
Fonte: Rochester Institute of Technology: The Laboratory for Advanced Communications Technology Publicador: Rochester Institute of Technology: The Laboratory for Advanced Communications Technology
Tipo: Artigo de Revista Científica Formato: 1001873 bytes; application/pdf
EN_US
Relevância na Pesquisa
37.01%
The present analysis is the phase one of a broader project, the Sign2 Project, which is focused on a complete technological approach to the translation of American Sign Language (ASL) finger-spelling to digital audio and/or text. The methodology adopted in this analysis employs a grayscale image processing technique. We will describe the latest results as well as future enhancements to the system. This paper will also discuss the application of the approach to the telecommunication Industry.

Mobile to cloud co-processing of ASL finger spelling to text conversion

Hays, Philip
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
37.35%
Computer recognition of American Sign Language (ASL) is a computationally intensive task. Although it has generally been performed using powerful lab workstations, this research investigates transcription of static ASL signs using an application on a consumer-level mobile device. The application provides real-time sign to text translation by processing a live video stream to detect the ASL alphabet as well as custom signs to perform tasks on the device. In this work several avenues for classification and processing were ex-plored to evaluate performance for mobile ASL transcription. The cho-sen classification algorithm uses locality preserving projections (LPP) with trained support vector machines (SVMs). Processing was investigated using either the mobile device only or with cloud assistance. In comparison to the native mobile application, the cloud-assisted application increased classification speed, reduced memory usage, and kept the network usage low while barely increasing the power required. A distributed solution has been created that will provide a new way of interacting with the mobile device in a native way to a hard-of-hearing person while also considering the network, power and processing constraints of the mobile device.

Code switching: American Sign Language and cued English

Hauser, Peter
Fonte: Gallaudet University Press Publicador: Gallaudet University Press
Tipo: Parte de Livro
EN_US
Relevância na Pesquisa
27.45%
Sociolinguistic studies on the codeswitching that occurs when American Sign Language (ASL) and English come into contact have claimed that the codeswitching is qualitatively different from spoken language codeswitching (e.g.,Davis 1989, 1990; Lucas and Valli 1989,1992). These studies have focused on the contact between users of ASL and users of spoken English. However, the codeswitching between English in a visual modality- cued American English (hereafter cued English)- and ASL has not been studied. This chapter focuses on the codeswitching of a ten-year-old bilingual deaf girl who is fluent in ASL and cued English. This chapter provides descriptive examples of ASL- cued English codeswitching as well as a discussion on social motivations for and functions of codeswitching. In the first section of this chapter, studies on spoken language codeswitching are introduced, followed by a second section discussing codeswitching in the Deaf community. The third section includes a description of cued English and a review of previous studies on cued languages. Following the review of literature, evidence of ASL-cued English codeswitching is demonstrated and compared with examples of codeswitching in spoken languages. The results of this chapter's study demonstrate that codeswitching between ASL and cued English follows a similar pattern found in spoken language codeswitching.; Reproduced with permission of Gallaudet University Press...

A professional development curriculum for educators of deaf students: comparative linguistics

Staehle, Sharon
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Master's Project Formato: 4296935 bytes; application/pdf
EN_US
Relevância na Pesquisa
27.35%
The teachers at Rochester School for the Deaf (RSD) find a challenge: their ability to translate fluently between two languages grammatically, American Sign Language (ASL) and English providing the instructions related to the literacy. Almost all of the teachers have been rated at the Advanced level of Sign Communication Proficiency Interview (SCPI), an assessment measurement. The indication is that they do not demonstrate complete bilingual competence. For the literacy skills, it is important for the teachers to be able to switch fluidly between the two langues of instruction - ASL and English - while teaching deaf and hard of hearing students in the classroom. This is where the attention shifts to the needs of teachers. To satisfy the teacher's particular needs, they need to attend professional development training to improve their language skills, enhance their metacognitive skills and be able to apply the bilingual strategy to their instruction. The one-year professional development training was designed to provide the resources for the teachers and teacher assistants to work in this area. After one year of training, they would have more knowledge in grammar translation between ASL and English and be able to apply bilingual strategies in the classroom. Consequently...

Teaching American Sign Language as a language other than English: Level II curriculum

Flannagan, Anita
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Masters Project Formato: 7993830 bytes; application/pdf
EN_US
Relevância na Pesquisa
27.52%
This curriculum is designed for teaching a full school year of ASL Level II as a foreign language course at the high school level. The unit plans in this curriculum have been derived from the New York State's checkpoints or guidelines for teaching ASL as a foreign language. Each unit plan contains objectives for both the students' receptive and expressive skills, knowledge of Deaf culture/history, various options or suggestions for assessment, evaluation, resources and materials. Also included are New York State's communication sub-topics and functions as outlined in New York State's checkpoints for teaching ASL. ASL teachers may use this curriculum as a guideline or checklist in order to ensure that they have covered New York State's checkpoints while creating lesson plans. Additionally, ASL teachers have the option of following this curriculum in its sequential order or modifying it to meet the needs of their students however, because ASL is a visual language, it is strongly recommended that ASL teachers using this curriculum teach students ASL without the use of voice. A list of teaching materials are suggested in this curriculum however, ASL teachers are expected to find additional teaching resources such as books, videotapes or websites that fit each unit and assign homework accordingly.

Teaching American Sign Language as a foreign language: a Level 1 curriculum

Brown, Joanna
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Masters Project Formato: 13159891 bytes; application/pdf
EN_US
Relevância na Pesquisa
27.49%
This curriculum contains unit plans for teaching one semester of ASL as a foreign language. The unit plans have been designed for teaching middle school aged students and are based on the New York State guidelines for teaching ASL as a foreign language. Each unit plan includes objectives/goals, procedures, activity options, extensions, assessment and evaluation suggestions, and references, resources, and materials. In addition, the unit plans include ways to integrate technology and Deaf community resources into the lessons and the learning. The following unit plans have been designed for use as a guideline for teachers of ASL. They can be altered and adapted, as needed, to fit the target age group or the class composition. By increasing or reducing the complexity of the lessons or activities, these unit plans can be used to teach elementary through college-age students. This curriculum has been designed to teach ASL from a Deaf culture perspective. Therefore, the units are designed to be taught using ASLwithout spoken English support. As one becomes familiar with the units, it will become clear that when teaching certain ideas/concepts the use of spoken Englishalone may be useful (this will depend on the ASL skillsof the students and the complexityof the topic). A resources...

Consistency of T2WI-FS/ASL fusion images in delineating the volume of nasopharyngeal carcinoma

Lin, Meng; Yu, Xiaoduo; Ouyang, Han; Luo, Dehong; Zhou, Chunwu
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Text
Publicado em 16/12/2015 EN
Relevância na Pesquisa
27.45%
Tumor extent assessment of nasopharyngeal carcinoma (NPC) is critical for delineating the radiotherapeutic target region. We aimed to investigate the use of the fusion images of fat suppressed T2WI (T2WI-FS) with arterial spin labeling (ASL) in measuring the volume of NPC. Two observers measured the volume of 21 untreated NPC using T2WI-FS, T2WI-FS/ASL (with PLD = 1.0, 1.5 and 2.0 s) fusion images and enhanced T1WI separately. Correlation and consistency were used to compare 1) measurements using T2WI-FS/ASL and T2WI-FS alone, taking enhanced T1WI images as a benchmark; 2) measurements between observers. Significant correlations existed between different series (r: 0.896~0.973). Measurements from the two observers using T2WI-FS/ASL had relatively higher intra-class correlation (ICC) (0.980~0.997) and lower within-subject coefficients of variation (wsCV) (14.76%~22.96%) when compared to using T2WI-FS alone (ICC: 0.978, 0.951, wsCV: 21.61%, 24.21%), while the T2WI-FS/ASL 1.0 s exhibited the best performance. Remarkably high ICC value (0.981~0.996) and relatively low wsCV (9.95%~17.91%) were obtained for the two observers using same series. Compared to those obtained using T2WI-FS alone, measurements made using T2WI-FS/ASL were more consistent with those made using enhanced T1WI. The T2WI-FS/ASL fusion images has the potential to be an alternative to enhanced T1WI...

Deaf-Blind Interpreting: Building on What You Already Know

Petronio, Karen; Eastern Kentucky University
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; Formato: application/pdf
Publicado em 18/10/2010 POR
Relevância na Pesquisa
27.35%
http://dx.doi.org/10.5007/2175-7968.2010v2n26p237This article focuses on visual considerations and describes the numerous similarities between video interpreting and deaf-blind interpreting. It also looks at linguistic considerations for deaf-blind interpreting and presents research findings showing similarities and differences between ASL and Tactile ASL. Because many interpreters are unfamiliar with tactile communication, there is a section that includes an overview of Tactile ASL. The issues, descriptions, and data presented in this article are based on situations in the United States and involve the use of ASL and Tactile ASL; however, it is highly likely that these discussions and findings also relate to deaf-blind interpreting done in other countries using other sign languages.