305 research outputs found

    Image perception and interpretation of abnormalities; can we believe our eyes? Can we do something about it?

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    The radiologist’s visual impression of images is transmitted, via non-visual means (the report), to the clinician. There are several complex steps from the perception of the images by the radiologist to the understanding of the impression by the clinician. With a process as complex as this, it is no wonder that errors in perception, cognition, interpretation, transmission and understanding are very common. This paper reviews the processes of perception and error generation and possible strategies for minimising them

    Translation invariant extensions of finite volume measures

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    We investigate the following questions: Given a measure μΛ on configurations on a subset Λ of a lattice L, where a configuration is an element of ΩΛ for some fixed set Ω, does there exist a measure μ on configurations on all of L, invariant under some specified symme- try group of L, such that μΛ is its marginal on configurations on Λ? When the answer is yes, what are the properties, e.g., the entropies, of such measures? Our primary focus is the case in which L = Zd and the symmetries are the translations. For the case in which Λ is an interval in Z we give a simple necessary and sufficient condition, local translation invariance (LTI), for extendibility. For LTI measures we construct extensions having maximal entropy, which we show are Gibbs measures; this construction extends to the case in which L is the Bethe lattice. On Z we also consider extensions supported on periodic configurations, which are analyzed using de Bruijn graphs and which include the extensions with minimal entropy. When Λ ⊂ Z is not an interval, or when Λ ⊂ Zd with d > 1, the LTI condition is necessary but not sufficient for extendibility. For Zd with d > 1, extendibility is in some sense undecidable

    Urinary Proteomics to Support Diagnosis of Stroke

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    Accurate diagnosis in suspected ischaemic stroke can be difficult. We explored the urinary proteome in patients with stroke (n = 69), compared to controls (n = 33), and developed a biomarker model for the diagnosis of stroke. We performed capillary electrophoresis online coupled to micro-time-of-flight mass spectrometry. Potentially disease-specific peptides were identified and a classifier based on these was generated using support vector machine-based software. Candidate biomarkers were sequenced by liquid chromatography-tandem mass spectrometry. We developed two biomarker-based classifiers, employing 14 biomarkers (nominal p-value <0.004) or 35 biomarkers (nominal p-value <0.01). When tested on a blinded test set of 47 independent samples, the classification factor was significantly different between groups; for the 35 biomarker model, median value of the classifier was 0.49 (−0.30 to 1.25) in cases compared to −1.04 (IQR −1.86 to −0.09) in controls, p<0.001. The 35 biomarker classifier gave sensitivity of 56%, specificity was 93% and the AUC on ROC analysis was 0.86. This study supports the potential for urinary proteomic biomarker models to assist with the diagnosis of acute stroke in those with mild symptoms. We now plan to refine further and explore the clinical utility of such a test in large prospective clinical trials

    Variability Measures of Positive Random Variables

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    During the stationary part of neuronal spiking response, the stimulus can be encoded in the firing rate, but also in the statistical structure of the interspike intervals. We propose and discuss two information-based measures of statistical dispersion of the interspike interval distribution, the entropy-based dispersion and Fisher information-based dispersion. The measures are compared with the frequently used concept of standard deviation. It is shown, that standard deviation is not well suited to quantify some aspects of dispersion that are often expected intuitively, such as the degree of randomness. The proposed dispersion measures are not entirely independent, although each describes the interspike intervals from a different point of view. The new methods are applied to common models of neuronal firing and to both simulated and experimental data

    Radiolabeled CCK/gastrin peptides for imaging and therapy of CCK2 receptor-expressing tumors

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    Cholecystokinin (CCK) receptors are overexpressed in numerous human cancers, like medullary thyroid carcinomas, small cell lung cancers and stromal ovarian cancers. The specific receptor-binding property of the endogenous ligands for these receptors can be exploited by labeling peptides with a radionuclide and using these as carriers to guide the radioactivity to the tissues that express the receptors. In this way, tumors can be visualized using positron emission tomography and single photon emission computed tomography imaging. A variety of radiolabeled CCK/gastrin-related peptides has been synthesized and characterized for imaging. All peptides have the C-terminal CCK receptor-binding tetrapeptide sequence Trp-Met-Asp-Phe-NH2 in common or derivatives thereof. This review focuses on the development and application of radiolabeled CCK/gastrin peptides for radionuclide imaging and radionuclide therapy of tumors expressing CCK receptors. We discuss both preclinical studies as well as clinical studies with CCK and gastrin peptides

    Central Nervous System Changes in Pediatric Heart Failure: A Volumetric Study

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    Autonomic dysfunction, mood disturbances, and memory deficits appear in pediatric and adult heart failure (HF). Brain areas controlling these functions show injury in adult HF patients, many of whom have comorbid cerebrovascular disease. We examined whether similar brain pathology develops in pediatric subjects without such comorbidities. In this study, high-resolution T1 brain magnetic resonance images were collected from seven severe HF subjects age (age 8–18 years [mean 13]; left ventricular shortening 9 to 19% [median 14%]) and seven age-matched healthy controls (age 8–18 years [mean 13]). After segmentation into gray matter (GM), white matter, and cerebrospinal fluid (CSF), regional volume loss between groups was determined by voxel-based morphometry. GM volume loss appeared on all HF scans, but ischemic changes and infarcts were absent. HF subjects showed greater CSF volume than controls (mean ± SD 0.30 ± 0.04 vs. 0.25 ± 0.04 l, P = 0.03), but total intracranial volume was identical (1.39 ± 0.11 vs. 1.39 ± 0.09 l, P = NS). Regional GM volume reduction appeared in the right and left posterior hippocampus, bilateral mid-insulae, and the superior medial frontal gyrus and mid-cingulate cortex of HF subjects (threshold P < 0.001). No volume-loss sites appeared in control brains. We conclude that pediatric HF patients show brain GM loss in areas similar to those of adult HF subjects. Substantial changes emerged in sites that regulate autonomic function as well as mood, personality and short-term memory. In the absence of thromboembolic disease and many comorbid conditions found in adult HF patients, pediatric HF patients show significant, focal GM volume loss, which may coincide with the multiple neurologic and psychological changes observed in patients with HF
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