1,720,988 research outputs found
NEURAL SLE: THE ROLE OF IMAGING IN EARLY DIAGNOSIS
No full textNeuropsychiatric systemic lupus erythematoaus (NPSLE) affects 14-75% of SLE patients depending on both the population studied and the methodology of assessment. Owing to the poor correlation between instrumental data and clinical manifestations, NPSLE remains a major diagnostic challenge. Although a wide range of neuroimaging tools have been used to evaluate CNS complaints, no single technique has proven to be definitive. Since neurometabolic impairment, neurochemistry and perfusional abnormalities may precede anatomic lesions, new functional techniques have been applied in order to identify early pathologic changes not detectable by conventional imaging.
Conventional Magnetic Resonance Imaging (cMRI), given the excellent anatomic details yielded, is actually considered the referral morphological technique. Major limitations of cMRI are the inability to differentiate lesions indicating active acute NPSLE from chronic lesions that represents past NPSLE or changes unrelated to NPSLE. Therefore, cMRI is not very specific and even if small punctate lesions are common, their relationship with clinical picture should not always be interpreted as indicating active disease. Computed tomography (CT), due to its low sensitivity to the nonfocal presentations of NPSLE, is actually reserved in emergency clinical setting when dealing with acute neurological events. More recently, new MRI techniques have been applied for the evaluation of NPSLE. Among these, Magnetic Resonance Spectroscopy (MRS) uses the same technology as conventional MRI (cMRI),and allows to determine the biochemical composition of CNS tissue. MRS may be useful to explore cognitive dysfunction and to characterize lesions identified on cMRI contributing to define the type of injury being atrophic, ischemic or inflammatory. Magnetization Transfer Imaging (MTI) is able to show a diminished homogeneity of brain tissue. It has a high sensitivity in diagnosing and quantifying the structural brain damage and in monitoring the progression of the disease. Diffusion Weighted Imaging (DWI) allows the early detection of ischemic lesions. This method seems to be useful in the distinction between recent or past T2 hyperintense punctate lesions identified by cMRI. Perfusion Weighted Imaging (PWI) is a technique complementary to classical DWI which can be useful for studying cerebrovascular diseases. It is used to assess blood flow and residual tissue perfusion in ischemic areas. At present, reports on the use of PWI in NPSLE are still very few, and usually concern patients with acute focal symptoms only.Functional radionuclide brain scanning include Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT). PET is able to evaluate glucose uptake and utilization, brain oxygen consumption and cerebral blood flow (CBF). PET has a high sensitivity and a good correlation with disease outcome but, unfortunately, has a limited utility due to its high cost, elevated radiation dose and low specificity. PET remains an important research technique for metabolic and functional studies with limited indications in daily clinical practice. Brain SPECT performance is similar to PET concerning brain perfusion, but it is a much less expensive technique and a much more widely available technology. Its major drawback is that, together with PET, SPECT is characterized by low specificity. SPECT may be useful for patients' follow-up and to study perfusion abnormalities in patients with uncertain neurologic involvement or cMRI negative imaging. PET and SPECT must be used coupled with cMRI.
In conclusion, due to the availability of new functional modalities useful to explore CNS involvement, neuroimaging has greatly advanced the understanding of NPSLE. Without a "gold standard" technique it is very difficult to identify an ideal and specific diagnostic approach. Dealing with NPSLE, it seems reasonable to combine different diagnostic tools (both anatomic and functional) considering that each modality may have special uses in the proper clinical and research situation. Further research and more follow up data may help to determine the best combination of methods to diagnose NPSLE and to understand underlying pathogenetic mechanisms. Finally it must be remembered that, to date, since the diagnose of NPSLE still lies on the clinical assessment, neuroimaging has a confirmatory role and is fundamental for the exclusion of other pathologies
Recent advances and future perspective in neuroimaging in neuropsychiatric systemic lupus erythematosus
No full textInvolvement of the central nervous system (CNS) is one of the most important complications of systemic lupus erythematosus (SLE), occurring in 14-75% of SLE patients. Neurological and psychiatric involvement is mainly manifested as cerebrovascular disease, seizures, cognitive impairment, headaches and psychosis. However, diagnosis of brain involvement in SLE (i.e., neuropsychiatric lupus: NPSLE) as well as understanding of pathogenetic mechanisms still remains a difficult challenge. Although a wide range of neurodiagnostic tools have been used in the last decade to assess CNS involvement, no single technique has proven to be definitive or reliable. Since neurometabolic impairment, neurochemistry and perfusion abnormalities in NPSLE may precede anatomic lesions, new functional techniques such as magnetic resonance spectroscopy, diffusion and perfusion weighted imaging, and magnetization transfer imaging may be useful in order to indentify pathologic changes unrevealed by conventional imaging. So these new diagnostic tools could modify diagnostic and therapeutic approaches to this major unsolved problem, also shedding some light on the physiopathology of CNS disease in SLE
Central nervous system involvement in Sjögren's syndrome: Unusual, but not unremarkable-clinical, serological characteristics and outcomes in a large cohort of Italian patients
No full textObjectives: To perform an observational retrospective cross-sectional case-control study to evaluate prevalence, clinical patterns and outcomes of CNS involvement in a large cohort of primary SS (pSS) patients. Methods: A total of 424 pSS patients, diagnosed according to the 2002 criteria proposed by the American-European Consensus Group, were checked for CNS involvement after exclusion of secondary causes. Demographic, clinical, seroimmunological data were compared between patients with and without CNS involvement. Neuroimaging data were also analysed. Results: CNS involvement was detected in 25 (5.8%) patients (24 females and 1 male) both at disease onset (52%) and later (48%) with a mean latency after diagnosis of 7 years. Diffuse (40%), focal/multifocal (36%), multiple sclerosis (MS)-like disease (20%) and isolated optic neuritis (4%) were the most common CNS clinical pictures. Disease duration, lung involvement and decreased C4 were associated with CNS involvement, while articular manifestations were more frequently observed in patients without neurological complications. Most cases had an acute, often recurrent course with spontaneous remission or only mild neurological impairment. Conclusions: CNS involvement represents a rare but not negligible complication of pSS, which may occur with a bimodal temporal pattern, both at onset and later, prompting attention in the differential diagnosis of apparently isolated neurological syndromes. Lung involvement emerged as the strongest risk factor for CNS involvement with a relative risk of 7.9, along with disease duration and decreased C4. © The Author 2010
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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