305,190 research outputs found
Intestinal interposition : the prevalence and clinical relevance of non-hepatodiaphragmatic conditions (nonChilaiditi forms) documented by CT and review of the literature [Interposizione intestinale : prevalenza e impatto clinico delle condizioni non epatodiaframmatiche (non-Chilaiditi) documentate con TC e revisione della letteratura]
No full textRiassunto
Obiettivo. Scopo del nostro lavoro è stato valutare la
prevalenza e l’impatto clinico delle forme di interposizione
intestinale non epatodiaframmatiche in una popolazione
adulta studiata con tomografi a computerizzata (TC) per
differenti indicazioni medico-chirurgiche.
Materiali e metodi. Da novembre 2008 ad aprile 2009,
due autori hanno valutato insieme i casi di interposizione
intestinale su 4338 pazienti adulti sottoposti a indagini TC.
In tale studio, sono state evidenziate sia interposizioni di
tipo epatodiaframmatico, che sono state defi nite Chilaiditi
come da letteratura, sia altri tipi di interposizione defi nite
secondo i diversi rapporti anatomici: splenorenale,
retrogastrica, epatocavale, retrosplenica e retrorenale, che
sono state raggruppate sotto il termine non-Chilaiditi. È
stato successivamente sottoposto ai pazienti dei due gruppi
e ad un gruppo controllo un questionario relativo ai
disturbi clinici associati più frequentemente alla sindrome
di Chilaiditi. Sono stati quindi comparati i dati clinici
relativi ai tre gruppi.
Risultati. Su 4338 pazienti sono stati osservati 130 (3%)
pazienti con interposizione colica per un totale di 143
manifestazioni, 90 Chilaiditi e 53 non-Chilaiditi: 30
interposizioni di tipo splenorenale, 12 di tipo retrogastrico,
5 epatocavale, 4 retrosplenico e 2 retrorenale. L’analisi
statistica ha evidenziato che le forme di Chilaiditi
producono una maggiore sintomatologia (24,4%), seguite
dalle forme non-Chilaiditi (18,9%) e infi ne dai casi controllo (10,8%). Tale analisi è stata validata dal test di
signifi catività χ2.
Conclusioni. Le forme non-Chilaiditi hanno rappresentato
più della metà delle forme Chilaiditi, con la manifestazione
splenorenale di gran lunga la più frequente. Abbiamo
inoltre evidenziato che anche le forme non-Chilaiditi sono
statisticamente più sintomatiche dei casi controllo.PURPOSE:
This study was done to assess the prevalence and clinical impact of non-hepatodiaphragmatic interpositions in a sample of adult patients undergoing computed tomography (CT) for a variety of medical reasons.
MATERIALS AND METHODS:
From November 2008 to April 2009, two observers jointly examined the cases of intestinal interposition in 4,338 adults undergoing CT investigations. This study sought to identify not only hepatodiaphragmatic intestinal interpositions, defined as Chilaiditi, but also other forms of intestinal interposition, which we termed non-Chilaiditi. The latter were divided into five different classes on the basis of their anatomical relationships: splenorenal, retrogastric, hepatocaval, retrosplenic, and retrorenal. Moreover, a questionnaire investigating the clinical symptoms reported to be associated with Chilaiditi syndrome was given to patients exhibiting any form of intestinal interposition and to a control sample. Finally, clinical data related to the three groups were compared.
RESULTS:
Of the 4,338 patients examined, 130 (3%) were found to have intestinal interposition, for a total of 143 forms: 90 Chilaiditi and 53 non-Chilaiditi. Of the latter, 30 were splenorenal, 12 retrogastric, five hepatocaval, four retrosplenic and two retrorenal. Statistical analysis showed that the Chilaiditi group suffered most symptoms (24.4%), followed by the non-Chilaiditi group (18.9%) and control cases (10.8%). Our results were validated using the χ(2) test of significance.
CONCLUSIONS:
The number of non-Chilaiditi cases amounted to just over half the number of Chilaiditi cases, with the splenorenal form being by far the most frequent. Statistical analysis showed that patients with non-Chilaiditi forms of intestinal interposition had more symptoms than did controls
Cerebral oxygen metabolism from MRI susceptibility
No full textThis article provides an overview of MRI methods exploiting magnetic susceptibility properties of blood to assess cerebral oxygen metabolism, including the tissue oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen (CMRO2). The first section is devoted to describing blood magnetic susceptibility and its effect on the MRI signal. Blood circulating in the vasculature can have diamagnetic (oxyhemoglobin) or paramagnetic properties (deoxyhemoglobin). The overall balance between oxygenated and deoxygenated hemoglobin determines the induced magnetic field which, in turn, modulates the transverse relaxation decay of the MRI signal via additional phase accumulation. The following sections of this review then illustrate the principles underpinning susceptibility-based techniques for quantifying OEF and CMRO2. Here, it is detailed whether these techniques provide global (OxFlow) or local (Quantitative Susceptibility Mapping - QSM, calibrated BOLD - cBOLD, quantitative BOLD - qBOLD, QSM+qBOLD) measurements of OEF or CMRO2, and what signal components (magnitude or phase) and tissue pools they consider (intravascular or extravascular). Validations studies and potential limitations of each method are also described. The latter include (but are not limited to) challenges in the experimental setup, the accuracy of signal modeling, and assumptions on the measured signal. The last section outlines the clinical uses of these techniques in healthy aging and neurodegenerative diseases and contextualizes these reports relative to results from gold-standard PET
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
CT ventilation imaging: technical backgroud and impact in acute lung injury and ARDS management
No full textTowards high-resolution quantitative assessment of vascular dysfunction
No full textNeurovascular alterations are increasingly recognized as a key feature of many
brain diseases. They can manifest as a reduction in resting cerebral blood flow or
cerebrovascular reactivity (CVR) in the whole brain or in specific regions,
depending on the underlying condition. Neurovascular impairment is observed
in hypertension, Alzheimer’s disease, stroke, multiple sclerosis and cerebral small
vessel disease. Magnetic resonance imaging (MRI)-derived CVR mapping is a
reliable marker of vascular dysfunction and has been performed mainly at
standard functional MRI (fMRI) resolutions of 2–3 mm using the blood oxygen
level dependent (BOLD) contrast. However, vascular alterations may occur at a
finer scale (i.e., in the capillary bed) which would be better characterized with
smaller voxel sizes. Capillaries in gray matter deliver oxygen and glucose to neural
tissue and are arranged in a mesh structure, with variable density across the
cortical depth. Given that the human cortex is, on average, 2.5 mm thick,
submillimetric voxel sizes are effective in increasing the spatial specificity of
measurements of hemodynamic and metabolic changes. Novel MRI sequences
offer the possibility to map physiological parameters at high resolution with
relatively simple experimental setups. In particular, pairing the BOLD
acquisition with a contrast sensitive to blood volume changes, while
administering a mild hypercapnic challenge, allows for simultaneous mapping
of CVR, cerebral metabolic rate of oxygen consumption and other relevant
parameters at a high resolution and can be performed at the clinical field
strength of 3 T
Epidemiological profile of non-traumatic emergencies of the neck in CT imaging: our experience
No full textPurpose This study was undertaken to collect information on the incidence and distribution of acute, non-traumatic conditions of the neck at our emergency radiology department and to review the literature about this topic.
Materials and methods We retrospectively reviewed 143 consecutive patients who underwent neck computed tomography (CT) for non-traumatic emergencies between 1 December 2008 and 31 December 2012. For each of the conditions identified, we defined the overall incidence, the incidence based on the site, gender, average age and age range.
Results Computed tomography examination was positive in 125 out of 143 patients (87.4 %), 74 men and 51 women, with an average age of 51.1 years, aged between 10 and 90 years. We found 79 inflammatory/infectious conditions (63.2 % of positive cases, 55.2 % of total cases), 46 men and 33 women, with an average age of 47 years. Computed tomography revealed 26 newly found tumours (20.8/18.2 %), 19 men and 7 women, with an average age of 68.5 years, aged between 49 and 97 years. In 20 cases, 9 men and 11 women, with an average age of 57.3 years, aged between 21 and 90 years, we diagnosed other acute conditions: six cases of foreign body ingestion (4.8/4.2 %), five benign swellings (4/3.5 %), five cases of vascular disorders (4/3.5 %), and four cases of oedema of the larynx (3.2/2.8 %)
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
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