Search results for "Computer-assisted"
showing 10 items of 1186 documents
Granulometric analysis of corneal endothelium specular images by using a germ–grain model
2007
Specular microscopy is widely used to study the human corneal endothelium status in vivo. In this paper, the corneal endothelium is represented as a binary image composed of the cell inscribed circles. The granulometric distribution function of the complement of this image is used as a functional descriptor, which provides information about the shape, size and spatial arrangement of cells. Experimental evaluation using bootstrap techniques shows its ability to discriminate between controls and pathological cases. It represents a reliable and graphical alternative to the classical indices (cell density, hexagonality and coefficient of variation of cell areas), which behave poorly when detect…
Prevalence of anatomical variants and coronary anomalies in 543 consecutive patients studied with 64-slice CT coronary angiography
2008
The aim of our study was to assess the prevalence of variants and anomalies of the coronary artery tree in patients who underwent 64-slice computed tomography coronary angiography (CT-CA) for suspected or known coronary artery disease. A total of 543 patients (389 male, mean age 60.5 +/- 10.9) were reviewed for coronary artery variants and anomalies including post-processing tools. The majority of segments were identified according to the American Heart Association scheme. The coronary dominance pattern results were: right, 86.6%; left, 9.2%; balanced, 4.2%. The left main coronary artery had a mean length of 112 +/- 55 mm. The intermediate branch was present in the 21.9%. A variable number …
Rationale, design and methods of CTCA-PRORECAD (Computed Tomography Coronary Angiography Prognostic Registry for Coronary Artery Disease): a multicen…
2013
PURPOSE: This study was done to assess the prognostic value of computed tomography coronary angiography (CTCA) in a large multicentre population of patients with suspected coronary artery disease (CAD) and, in particular, its incremental value compared with traditional methods for risk stratification. MATERIALS AND METHODS: This is a retrospective observational study that began in January 2003 conducted on patients with suspected CAD assessed with CTCA on the basis of symptoms (chest pain, dyspnoea) and/or abnormal or equivocal stress test and/or a high cardiovascular risk profile. The participating centres will provide data obtained with CTCA performed with 16-slice or higher equipment. Ex…
Prognostic outcome of routine clinical noninvasive Multidetector row Computed Tomography Coronary Angiography in Patients with suspected coronary art…
2011
The aim of the study was to assess the prognostic value of multidetector-row CT coronary angiography (MDCT-CA) in patients with suspected coronary artery disease (CAD) in a routine clinical context.A total of 125 patients (82 men, age 57.4±10.3 years) with suspected CAD underwent MDCT-CA. All patients were assessed for cardiovascular risk factors, symptoms and coronary calcium score. A 2-year follow-up study for the occurrence of major adverse cardiac events was performed.According to the Morise pretest score, 76 patients (60.8%) were at intermediate risk. Patients with suspected CAD presented the following prognostic outcome (p0.0001): in 41 patients with normal coronary arteries at MDCT-C…
Acceptance of noninvasive computed tomography coronary angiography: for a patient-friendly medicine.
2014
PURPOSE: This study was done to evaluate the psychological state and anxiety of patients undergoing computed tomography coronary angiography (CTCA), and assess their acceptance and satisfaction compared to invasive conventional coronary angiography (CCA). MATERIALS AND METHODS: A total of 442 consecutive patients (282 male; mean age 57.7 ± 9.5 years) who underwent CTCA for suspected or known coronary artery disease were evaluated with the Endler Multimodality Anxiety Scales (EMAS) before and after the scan, and a questionnaire administered after the scan. Among the 442 patients, 181 had a history of CCA. Two radiologists assessed the image quality of CTCA. RESULTS: Anxiety was more intense …
A systematic comparison of kinetic modelling methods generating parametric maps for [11C]-(R)-PK11195
2006
[(11)C]-(R)-PK11195 is presently the most widely used radiotracer for the monitoring of microglia activity in the central nervous system (CNS). Microglia, the resident immune cells of the brain, play a critical role in acute and chronic diseases of the central nervous system and in host defence against neoplasia. The purpose of this investigation was to evaluate the reliability and sensitivity of five kinetic modelling methods for the formation of parametric maps from dynamic [(11)C]-(R)-PK11195 studies. The methods we tested were the simplified reference tissue model (SRTM), basis pursuit, a simple target-to-reference ratio, the Logan plot and a wavelet based Logan plot. For the reliabilit…
All-optical signal processing at ultra-low powers in bottle microresonators using the Kerr effect.
2010
We present experimental results on nonlinear, ultra-low power photonics applications based on a silica whispering-gallery-mode microresonator. Our bottle microresonator combines an ultrahigh quality factor of Q10(8) with a small mode volume V. The resulting Q(2)/V-ratio is among the highest realized for optical microresonators and allows us to observe bistable behavior at very low powers. We report single-wavelength all-optical switching via the Kerr effect at a record-low threshold of 50 microW. Moreover, an advantageous mode geometry enables the coupling of two tapered fiber waveguides to a bottle mode in an add-drop configuration. This allows us to route a CW optical signal between both …
Measuring Spatiotemporal Dependencies in Bivariate Temporal Random Sets with Applications to Cell Biology
2008
Analyzing spatiotemporal dependencies between different types of events is highly relevant to many biological phenomena (e.g., signaling and trafficking), especially as advances in probes and microscopy have facilitated the imaging of dynamic processes in living cells. For many types of events, the segmented areas can overlap spatially and temporally, forming random clumps. In this paper, we model the binary image sequences of two different event types as a realization of a bivariate temporal random set and propose a nonparametric approach to quantify spatial and spatiotemporal interrelations using the pair correlation, cross-covariance, and the Ripley K functions. Based on these summary st…
Exploring the mediator role of self-critical rumination between emotion regulation and psychopathology: A validation study of the Self-Critical Rumin…
2021
Abstract Self-critical rumination is a negative and repetitive self-thinking process related to different disorders and negative psychological outcomes such as emotion dysregulation. The objectives of this study are twofold: (a) to examine the factor structure of the Spanish version of the Self-Critical Rumination Scale (SCRS), providing further evidence on its construct validity, and (b), to explore the mediator role of self-critical rumination between emotion dysregulation and psychopathology. A sample of 431 Spanish participants were recruited and completed online questionnaires. Confirmatory factor analysis, mediation analysis, and Pearson's correlations were conducted. A single factor …
Three-dimensional structure of hepatitis B virus core particles determined by electron cryomicroscopy
1994
Human hepatitis B virus core protein expressed in E. coli assembles into two sizes of particle. We have determined their three-dimensional structures by electron cryomicroscopy and image processing. The large and small particles correspond to triangulation number T = 4 and T = 3 dimer clustered packings, containing 240 and 180 protein subunits, respectively. The local packing of subunits is very similar in the two sizes of particle and shows holes or channels through the shell. The native viral core particle packages RNA and is active in reverse transcription to DNA. The holes we observe may provide access for the necessary small molecules. Shells assembled from the intact core protein cont…