315 research outputs found
Track's Elevation Profile View on a Public GIS
Tato bakalářská práce se zabývá návrhem a implementací uživatelského skriptu pro GreaseMonkey (rozšíření pro Firefox), který umožňuje zobrazení výškového prifilu zadané trasy. Trasa je zadána za použití nástrojů veřejného GISu www.mapy.cz. Skript získá souřadnice z DOM struktury webové stránky, ty pak dále zpracovává a zobrazí výškový profil dané trasy. Vykreslení profilu je realizováno za pomocí služby serveru http://www.heywhatsthat.com/profiler.html [2] nebo podpůrného webu www.profile.hy.cz. Tento web byl vytvořen pro účely bakalářské práce. Umožňuje vykreslování výškového profilu v JavaScriptu za pomocí API www.vyskopis.cz [4].This bachelor's thesis describes the design and implementation of a user script for GreaseMonkey (plug-in for Firefox). This script adds a functionality to show height profile of a defined route. The route is defined using public GIS tools from www.mapy.cz. The script extracts coordinates from page DOM structure, processes it and draws a height graph. The graph is created using http://www.heywhatsthat.com/profiler.html [2] or www.profile.hy.cz, which provides height graph drawing using www.vyskopis.cz JavaScript API [4].
Advanced MRI in cerebral small vessel disease
Cerebral small vessel disease (cSVD) is a major cause of stroke and dementia. This review summarizes recent developments in advanced neuroimaging of cSVD with a focus on clinical and research applications. In the first section, we highlight how advanced structural imaging techniques, including diffusion magnetic resonance imaging (MRI), enable improved detection of tissue damage, including characterization of tissue appearing normal on conventional MRI. These techniques enable progression to be monitored and may be useful as surrogate endpoint in clinical trials. Quantitative MRI, including iron and myelin imaging, provides insights into tissue composition on the molecular level. In the second section, we cover how advanced MRI techniques can demonstrate functional or dynamic abnormalities of the blood vessels, which could be targeted in mechanistic research and early-stage intervention trials. Such techniques include the use of dynamic contrast enhanced MRI to measure blood–brain barrier permeability, and MRI methods to assess cerebrovascular reactivity. In the third section, we discuss how the increased spatial resolution provided by ultrahigh field MRI at 7 T allows imaging of perforating arteries, and flow velocity and pulsatility within them. The advanced MRI techniques we describe are providing novel pathophysiological insights in cSVD and allow improved quantification of disease burden and progression. They have application in clinical trials, both in assessing novel therapeutic mechanisms, and as a sensitive endpoint to assess efficacy of interventions on parenchymal tissue damage. We also discuss challenges of these advanced techniques and suggest future directions for research
Do retinal microvascular abnormalities shed light on the pathophysiology of lacunar stroke?
Background. Lacunar strokes account for 25% of all ischaemic stroke but the exact
nature of the causative cerebral small vessel abnormality remains unknown.
Pathological studies are technically difficult and brain imaging cannot adequately
characterise the cerebral small vessels. The retinal blood vessels are of similar size
and physiology to the cerebral small vessels and may act as a surrogate marker for
these cerebral small vessels. We therefore investigated retinal microvascular
abnormalities in lacunar stroke.
Methods. We performed a systematic review of retinal microvascular abnormalities
in lacunar stroke to clarify associations and identify where further research was
required. We then established a cohort of patients presenting with lacunar stroke
with cortical stroke controls to investigate differences in retinal microvascular
abnormalities between stroke subtypes. All patients had MRI brain at presentation
and digital retinal photography of both eyes. We investigated the prevalence of
retinopathy (hard and soft exudates or haemorrhages/microaneurysms), focal
arteriolar narrowing and arteriovenous nicking . We developed, validated and used
novel semi-automated techniques for measuring retinal arteriolar and venular widths,
retinal arteriolar geometry (branching co-efficients (change in arteriolar cross
sectional area across a bifurcation) and branching angles) and fractal dimensions
(reflecting branching complexity) of the vasculature. We also assessed MRI
parameters in lacunar stroke. We used multivariable analysis to correct for baseline
imbalances in vascular risk factors.
Results. From the systematic review we demonstrated that retinal microvascular
abnormalities are associated with incident and prevalent stroke but that in general,
strokes were inadequately characterised and there were no data regarding retinal
microvascular abnormalities in ischaemic stroke subtypes. We recruited 253
patients, 129 lacunar strokes and 124 cortical strokes, mean age 68 years. We found
no difference in the prevalence of retinopathy, arteriovenous nicking, focal arteriolar
narrowing or arteriolar widths between lacunar and cortical stroke subtypes. We
found that venules were wider in lacunar stroke. We found no differences in
arteriolar branching co-efficients or arteriolar branching angles between lacunar and
cortical strokes but found that deep white matter white matter hyperintensities on
MRI were associated with increased branching co-efficients and periventricular
white matter hyperintensities associated with decreased branching co-efficients. We
found that the fractal dimension of the vascular tree was decreased in lacunar stroke.
Furthermore we found that enlarged perivascular spaces on MRI are associated with
lacunar stroke and white matter disease.
Conclusions. We have clearly demonstrated that retinal microvascular abnormalities
differ between lacunar and cortical stroke suggesting that a distinct small vessel
vasculopathy may cause lacunar stroke. We have also identified MR markers of
lacunar stroke. These results suggest that venular disease (a hitherto underresearched
area) may play a role in the pathophysiology of lacunar stroke. Retinal
microvascular abnormalities can act as markers for cerebral small vessel disease. We
plan collaborative analyses with colleagues who have performed similar studies to
further assess retinal abnormalities in lacunar stroke
What matters to people and families affected by cerebral small vessel disease (SVD)?:A qualitative grounded theory investigation
BACKGROUND: Cerebral small vessel disease (SVD) is a common neurological disorder contributing to stroke, dementia, and disability. No treatment options exist although clinical trials are ongoing. We aimed to understand what matters to people and families affected by SVD to inform future research.METHODS: We thematically analysed unsolicited correspondences from members of the public addressed to members of the Edinburgh SVD Research Group on a variety of subjects related to SVD. We used inductive thematic codes, categorised under concerns, requests, emotions, and contributions, to form a grounded theory that categorised and ranked concerns raised.RESULTS: 101 correspondents expressed 346 concerns between August 2015 and February 2021, mostly via email. 60 correspondents (59.4 %) disclosed a SVD diagnosis, 39 (38.6 %) disclosed a previous stroke or TIA, and 40 (39.6 %) were family of people living with SVD. Primary concerns related to cognitive problems (number of correspondents (n)=43 (42.6 %)), lack of support or information from healthcare services ( n = 41 (40.6 %)), prognosis ( n = 37 (36.6 %)), sensory disturbances ( n = 27 (26.7 %)), functional problems ( n = 24, (23.8 %)), impact on daily life ( n = 24 (23.8 %)), and causes of SVD ( n = 19 (18.8 %)). 57 correspondents (56.4 %) expressed support for research, 43 (42.6 %) expressed an eagerness to understand SVD, 35 (34.7 %) expressed helplessness, and 19 (18.8 %) expressed frustration. CONCLUSIONS: Cognitive decline was the main concern for people and families living with SVD who corresponded with the Edinburgh SVD research group. These findings also indicate a need for more accessible services and better information about SVD for patients and families.</p
Shared decision making after severe stroke- how can we improve patient and family involvement in treatment decisions?
People who are well may regard survival with disability as being worse than death. However, this is often not the case when those surviving with disability (e.g. stroke survivors) are asked the same question. Many routine treatments provided after an acute stroke (e.g. feeding via a tube) increase survival, but with disability. Therefore, clinicians need to support patients and families in making informed decisions about the use of these treatments, in a process termed shared decision making. This is challenging after acute stroke: there is prognostic uncertainty, patients are often too unwell to participate in decision making, and proxies may not know the patients’ expressed wishes (i.e. values). Patients’ values also change over time and in different situations. There is limited evidence on successful methods to facilitate this process. Changes targeted at components of shared decision making (e.g. decision aids to provide information and discussing patient values) increase patient satisfaction. How this influences decision making is unclear. Presumably, a “shared decision-making tool” that introduces effective changes at various stages in this process might be helpful after acute stroke. For example, by complementing professional judgement with predictions from prognostic models, clinicians could provide information that is more accurate. Decision aids that are personalized may be helpful. Further qualitative research can provide clinicians with a better understanding of patient values and factors influencing this at different time points after a stroke. The evaluation of this tool in its success to achieve outcomes consistent with patients’ values may require more than one clinical trial. </jats:p
Little Association between Intracranial Arterial Stenosis and Lacunar Stroke
Atheromatous middle cerebral artery (MCA) stenosis could cause lacunar stroke by occluding lenticulostriate artery origins, but atheroma is common, and previous studies lacked suitable controls. We aimed to determine if intracranial atheroma was more common in lacunar than in cortical ischaemic stroke. We recruited patients with lacunar stroke and controls with mild cortical stroke, confirmed the stroke subtype with magnetic resonance imaging and used transcranial Doppler ultrasound imaging to record flow velocity and focal stenoses in the basal intracranial arteries 1 month after stroke. We compared ipsi- and contralateral MCA mean flow velocities between stroke subtypes and tested for associations using linear mixed models. Amongst 67 lacunar and 67 mild cortical strokes, mean age 64 and 67 years, respectively, we found no difference in MCA mean flow velocity between cortical and lacunar patients. Increasing age and white matter lesion scores were independently associated with lower MCA flow velocities (0.2 cms−1 fall in velocity per year increase in age, p = 0.045; 3.75 cms−1 fall in flow velocity per point increase in white matter lesion score, p = 0.004). We found no intracranial arterial stenoses. MCA atheromatous stenosis is unlikely to be a common cause of lacunar stroke in white populations. Falling velocities with increasing white matter lesion scores may reflect progressive brain tissue loss leaving less tissue to supply
Predicting specific abilities after disabling stroke:Development and validation of prognostic models
BACKGROUND: Predicting specific abilities (e.g. walk and talk) to provide a functional profile six months after disabling stroke could help patients/families prepare for the consequences of stroke and facilitate involvement in treatment decision-making. AIM: To develop new statistical models to predict specific abilities six months after stroke and test their performance in an independent cohort of patients with disabling stroke. METHODS: We developed models to predict six specific abilities (to be independent, walk, talk, eat normally, live without major anxiety/depression, and to live at home) using data from seven large multicenter stroke trials with multivariable logistic regression. We included 13,117 participants recruited within three days of hospital admission. We assessed model discrimination and derived optimal cut-off values using four statistical methods. We validated the models in an independent single-center cohort of patients (n = 403) with disabling stroke. We assessed model discrimination and calibration and reported the performance of our models at the statistically derived cut-off values. RESULTS: All six models had good discrimination in external validation (AUC 0.78–0.84). Four models (predicting to walk, eat normally, live without major anxiety/depression, live at home) calibrated well. Models had sensitivities between 45.0 and 97.9% and specificities between 21.6 and 96.5%. CONCLUSIONS: We have developed statistical models to predict specific abilities and demonstrated that these models perform reasonably well in an independent cohort of disabling stroke patients. To aid decision-making regarding treatments, further evaluation of our models is required
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