Stephanie M. Wilbrand

The relationship between carotid artery plaque stability and white matter ischemic injury

Higher local carotid artery strain has previously been shown to be a characteristic of unstable carotid plaques. These plaques may be characterized by microvascular changes that predispose to intraplaque hemorrhage, increasing the likelihood of embolization. Little is known however, about how these strain indices correspond with imaging markers of brain health and metrics of brain structure. White matter hyperintensities (WMHs), which are bright regions seen on T2-weighted brain MRI imaging, are postulated to result from cumulative ischemic vascular injury. Consequently, we hypothesized that plaques that are more prone to microvascular changes and embolization, represented by higher strain indices on ultrasound, would be associated with an increased amount of WMH lesion volume. This relationship would suggest not only emboli as a cause for the brain degenerative changes, but more importantly, a common microvascular etiology for large and small vessel contributions to this process. Subjects scheduled to undergo a carotid endarterectomy were recruited from a neurosurgery clinic. Prior to surgery, participating subjects underwent both ultrasound strain imaging and brain MRI scans as part of a larger clinical study on vascular health and cognition. A linear regression found that maximum absolute strain and peak to peak strain in the surgical side carotid artery were predictive of WMH burden. Furthermore, the occurrence of microembolic signals monitored using transcranial Doppler (TCD) ultrasound examinations also correlated with increasing lesion burden. It is becoming increasingly recognized that cognitive decline is often multifactorial in nature. One contributing extra-brain factor may be changes in the microvasculature that produce unstable carotid artery plaques. In this study, we have shown that higher strain indices in carotid artery plaques are significantly associated with an increased WMH burden, a marker of vascular mediated brain damage.

Carotid atherosclerotic plaque instability and cognition determined by ultrasound-measured plaque strain in asymptomatic patients with significant stenosis

OBJECTIVE This article describes the use of ultrasound measurements of physical strain within carotid atherosclerotic plaques as a measure of instability and the potential for vascular cognitive decline, microemboli, and white matter changes. METHODS Asymptomatic patients with significant (> 60%) carotid artery stenosis were studied for dynamic measures of plaque instability, presence of microemboli, white matter changes, and vascular cognitive decline in comparison with normative controls and premorbid state. RESULTS Although classically asymptomatic, these patients showed vascular cognitive decline. The degree of strain instability measured within the atherosclerotic plaque directly predicted vascular cognitive decline in these patients thought previously to be asymptomatic according to classic criteria. Furthermore, 26% of patients showed microemboli, and patients had twice as much white matter hyperintensity as controls. CONCLUSIONS These data show that physical measures of plaque instability are possible through interpretation of ultrasound strain data during pulsation, which may be more clinically relevant than solely measuring degree of stenosis. The data also highlight the importance of understanding that the definition of symptoms should not be limited to motor, speech, and vision function but underscore the role of vascular cognitive decline in the pathophysiology of carotid atherosclerotic disease. Clinical trial registration no.: NCT02476396 (clinicaltrials.gov).

Landscape, Territory, and Civil Society in Catalonia

In recent decades intense territorial transformations in European Mediterranean countries have caused radical changes in their landscapes, with a resulting impact on the territorial identity of local societies. Faced with the risk of irreversible loss of sense of place and of local identity, as a result of nonconsensual processes almost always poorly explained by the administration, civil society has recently reacted in an increasingly indignant and organized manner, demanding a new culture of territory. This article analyzes, in the case of Catalonia, the interaction between landscape, territory, and civil society and demonstrates that this interaction, organized in a large number of associations in defence of territorial identity, has shown itself to be extraordinarily vital and dynamic. In this context, landscape has been revealed as the catalyst and unifying element of growing conflicts of a territorial and environmental nature palpable in Catalan society.

The Preservation of Cognition 1 Year After Carotid Endarterectomy in Patients With Prior Cognitive Decline

BACKGROUND Vascular cognitive decline is critically important in the course of atherosclerosis and stroke. OBJECTIVE To explore the hypothesis that carotid endarterectomy (CEA) by removing an unstable plaque may slow the course of vascular cognitive decline in both symptomatic and asymptomatic patients. METHODS Patients with clinically significant (>60%) carotid stenosis were studied preop and 1 yr post-CEA for clinical symptoms, vascular cognitive decline, instability of carotid plaque-presence of microemboli, brain white matter changes, and medical risk factors. RESULTS Forty-six percent were classically symptomatic. All patients showed vascular cognitive decline at presentation which correlated with degree of plaque instability. Significant white matter hyperintensity changes (48.7%) and cerebral emboli (25%) were also seen at baseline in both classically symptomatic and asymptomatic. One year after CEA, both groups showed no decline in cognitive function and significant improvement in 2 tests (P = .028 and P = .013). Brain white matter hyperintensities were unchanged. Microemboli were reduced but remained present (17.86%). Improvement was predicted by the presence of hypertension (P = .001), or less advanced cognitive decline preoperatively (P = .009). CONCLUSION This study demonstrates the importance of vascular cognitive decline in atherosclerotic disease. This is a function of the degree of instability of the atherosclerotic plaque more than the presence of stroke symptoms. It further suggests that atherosclerotic vascular cognitive decline need not be inevitable, and may be modified by treating hypertension and removal of the unstable plaque. This highlights the need for continued research on the cognitive effects of cerebrovascular disease and the synergistic benefits of intensive medical and surgical therapy.

The role of the region in the European Landscape Convention

ABSTRACT The role of the region in the European Landscape Convention. Regional Studies. In the year 2000, the Council of Europe approved the European Landscape Convention, the first international treaty exclusively dedicated to the protection, management and planning of landscape. This supranational agreement is signed at the national level, but encourages the principle of subsidiarity for the implementation at the regional or local level. However, the current structure of the treaty lacks strong incentives or sanctions for effective implementation at the regional level. Through a case study of Catalonia, this article demonstrates the value of regional actors in the multi-scalar treaty and argues for increased regional agency within the European Landscape Convention.

Quantification of carotid artery plaque stability with multiple region of interest based ultrasound strain indices and relationship with cognition

Vulnerability and instability in carotid artery plaque has been assessed based on strain variations using noninvasive ultrasound imaging. We previously demonstrated that carotid plaques with higher strain indices in a region of interest (ROI) correlated to patients with lower cognition, probably due to cerebrovascular emboli arising from these unstable plaques. This work attempts to characterize the strain distribution throughout the entire plaque region instead of being restricted to a single localized ROI. Multiple ROIs are selected within the entire plaque region, based on thresholds determined by the maximum and average strains in the entire plaque, enabling generation of additional relevant strain indices. Ultrasound strain imaging of carotid plaques, was performed on 60 human patients using an 18L6 transducer coupled to a Siemens Acuson S2000 system to acquire radiofrequency data over several cardiac cycles. Patients also underwent a battery of neuropsychological tests under a protocol based on National Institute of Neurological Disorders and Stroke and Canadian Stroke Network guidelines. Correlation of strain indices with composite cognitive index of executive function revealed a negative association relating high strain to poor cognition. Patients grouped into high and low cognition groups were then classified using these additional strain indices. One of our newer indices, namely the average L  -  1 norm with plaque (AL1NWP) presented with significantly improved correlation with executive function when compared to our previously reported maximum accumulated strain indices. An optimal combination of three of the new indices generated classifiers of patient cognition with an area under the curve (AUC) of 0.880, 0.921 and 0.905 for all (n  =  60), symptomatic (n  =  33) and asymptomatic patients (n  =  27) whereas classifiers using maximum accumulated strain indices alone provided AUC values of 0.817, 0.815 and 0.813 respectively.

Landscape identities in Catalonia

Abstract This article aims to analyse the subject of landscape modifications and the absorption of new elements within a context that enables broader reflection on the creation of territorial identities by consciously intervening in existing imaginaries. Although an extensive literature has been generated around imaginaries and landscape imaginaries, the benefits of creating new imaginaries or, if you will, new ‘landscapes of reference’ are not frequently touched upon as a constructive reaction to the homogenisation processes generated by the intense globalisation our lives are immersed in. The following pages deal with all these matters, taking into consideration the situation in Catalonia within the European context.

Influence of Ultrasound System and Gain on Grayscale Median Values: Influence of Ultrasound System and Gain on Grayscale Median Values

The purpose of this study was to determine the reliability of grayscale median (GSM) measurements across different ultrasound (US) systems and effects of gain on GSM values.

In-vivo quantitative ultrasound evaluation of carotid plaque

Carotid atherosclerotic plaque is a major contributor to cerebrovascular disease. Noninvasive quantitative ultrasound (QUS) evaluation of plaque morphology is requisite for comprehensive risk assessment. System and setting dependencies, however, limit current grayscale analyses. Here, integrated backscatter (IB) and attenuation coefficient (AC) were calculated in-vivo and compared with pathology scores of excised plaques. Radiofrequency data acquired prior to a carotid endarterectomy procedure were processed on 6 subjects. Average percent stenosis was 71.67±11.69. QUS parameters were calculated in-vivo with 70% axial overlap at end-diastole using the reference phantom method (AC, IB) and optimum power-spectral shift estimator (AC). Parametric maps were created to visualize QUS parameter variation in plaque. Histopathology examination was reported for a representative section of fixed plaque. Plaque was scored for hemorrhage, hemosiderin, and inflammation on an ordinal scale and was assessed for percent cholesterol/fibrinoid and calcium. Relationships between QUS parameters and histopathology were examined. Our results indicate that plaques with more calcium on histopathology (n=2, >20% calcium) have high IB (approaching 0 dB) and elevated AC (approaching 1.5 dB/cm-MHz). Plaques with high percent cholesterol/fibrinoid (n=4, >60% cholesterol/fibrinoid) have low IB (approaching −30 dB) and moderate AC (approaching 1 dB/cm-MHz). We are also able to distinguish calcified and soft plaque regions on parametric maps. These findings suggest that IB and AC can be used to noninvasively evaluate plaques based on tissue composition. Thus, these QUS parameters may provide important information for a risk-assessment model of carotid plaque. Future work will compare QUS parameters in-vivo with high frequency characterizations of plaque ex-vivo and 3D reconstructions of histopathology sections.