10 research outputs found

    Quantification and visualization of cardiovascular 4D velocity mapping accelerated with parallel imaging or k-t BLAST: head to head comparison and validation at 1.5 T and 3 T

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    <p>Abstract</p> <p>Background</p> <p>Three-dimensional time-resolved (4D) phase-contrast (PC) CMR can visualize and quantify cardiovascular flow but is hampered by long acquisition times. Acceleration with SENSE or k-t BLAST are two possibilities but results on validation are lacking, especially at 3 T. The aim of this study was therefore to validate quantitative in vivo cardiac 4D-acquisitions accelerated with parallel imaging and k-t BLAST at 1.5 T and 3 T with 2D-flow as the reference and to investigate if field strengths and type of acceleration have major effects on intracardiac flow visualization.</p> <p>Methods</p> <p>The local ethical committee approved the study. 13 healthy volunteers were scanned at both 1.5 T and 3 T in random order with 2D-flow of the aorta and main pulmonary artery and two 4D-flow sequences of the heart accelerated with SENSE and k-t BLAST respectively. 2D-image planes were reconstructed at the aortic and pulmonary outflow. Flow curves were calculated and peak flows and stroke volumes (SV) compared to the results from 2D-flow acquisitions. Intra-cardiac flow was visualized using particle tracing and image quality based on the flow patterns of the particles was graded using a four-point scale.</p> <p>Results</p> <p>Good accuracy of SV quantification was found using 3 T 4D-SENSE (r<sup>2 </sup>= 0.86, -0.7 Âą 7.6%) and although a larger bias was found on 1.5 T (r<sup>2 </sup>= 0.71, -3.6 Âą 14.8%), the difference was not significant (p = 0.46). Accuracy of 4D k-t BLAST for SV was lower (p < 0.01) on 1.5 T (r<sup>2 </sup>= 0.65, -15.6 Âą 13.7%) compared to 3 T (r<sup>2 </sup>= 0.64, -4.6 Âą 10.0%). Peak flow was lower with 4D-SENSE at both 3 T and 1.5 T compared to 2D-flow (p < 0.01) and even lower with 4D k-t BLAST at both scanners (p < 0.01). Intracardiac flow visualization did not differ between 1.5 T and 3 T (p = 0.09) or between 4D-SENSE or 4D k-t BLAST (p = 0.85).</p> <p>Conclusions</p> <p>The present study showed that quantitative 4D flow accelerated with SENSE has good accuracy at 3 T and compares favourably to 1.5 T. 4D flow accelerated with k-t BLAST underestimate flow velocities and thereby yield too high bias for intra-cardiac quantitative in vivo use at the present time. For intra-cardiac 4D-flow visualization, however, 1.5 T and 3 T as well as SENSE or k-t BLAST can be used with similar quality.</p

    Does our current environmental monitoring support adaptive management?

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    European environmental and rural development policies require programmes of statutory monitoring using prescribed parameters - for example water quality parameters are monitored by all countries that implement the Water Framework Directive. These data are a significant resource that could potentially be used for adaptive (co-)management and governance. These approaches not only require the use of multiple forms of information to learn and update resource management, but can also imply a more holistic and participatory approach. We have studied the monitoring regimes entailed for Water Framework Directive, Natura 2000 Directives and Agri-Environmental Schemes of the CAP Rural Development Programme across nine European cases in 6 member states and 3 regions. Building on established principles for monitoring socio-ecological systems (see Waylen et al. 2016), expert colleagues from across Europe have analysed published documents to see if the current monitoring schemes supported a move to the new paradigm of holistic, participatory and systemic management approaches.  Overall, data are focused on a narrow set of indicators that in turn enable only a partial perspective on ecosystem management. This matters because policy-driven monitoring may be the main source of information that can be used for formal statutory management. For example, social aspects or drivers of the socio-ecological system are nearly never monitored and incorporated into evaluation, particularly for older policies. The monitoring continues to describe the state of the environment -with great for some aspects - rather than assessing how an intervention has contributed to conservation or allowed sustainable use. This means we will struggle to understand socio-ecological systems, and learning from the effects of management actions. Furthermore, whilst the implementation of WFD, N2K and AES has evolved, there is no documented link to the use of the data in this process of change i.e. it is unknown if and how the monitoring programmes have influenced changed management. There were also positive findings - some member states offer open access to data; are working on integrated monitoring and reporting; and use citizen science to both monitor trends and engage people in learning about their environment. Reappraising what is monitored could lead to a rebalancing of monitoring that could greatly assist future adaptive management. Many European policy-driven monitoring processes could be tweaked to make them more fit to improve ecosystem management. Our framing positions the work differently to the more conventional  'fitness' checks conducted recently: we can reflect on how our work contributes to these institutional evaluations in the discussion. References: Waylen, K.A. &amp; Blackstock, K.L. In press. Monitoring for adaptive management or modernity? Lessons from recent initiatives for holistic environmental management Environmental Policy and Governance, DOI: 10.1002/eet.1758peerReviewe

    Policy-driven monitoring and evaluation : Does it support adaptive management of socio-ecological systems?

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    Inadequate Monitoring and Evaluation (M&E) is often thought to hinder adaptive management of socio-ecological systems. A key influence on environmental management practices are environmental policies: however, their consequences for M&E practices have not been well-examined. We examine three policy areas - the Water Framework Directive, the Natura 2000 Directives, and the Agri-Environment Schemes of the Common Agricultural Policy - whose statutory requirements influence how the environment is managed and monitored across Europe. We use a comparative approach to examine what is monitored, how monitoring is carried out, and how results are used to update management, based on publicly available documentation across nine regional and national cases. The requirements and guidelines of these policies have provided significant impetus for monitoring: however, we find this policy-driven M&E usually does not match the ideals of what is needed to inform adaptive management. There is a tendency to focus on understanding state and trends rather than tracking the effect of interventions; a focus on specific biotic and abiotic indicators at the expense of understanding system functions and processes, especially social components; and limited attention to how context affects systems, though this is sometimes considered via secondary data. The resulting data are sometimes publicly-accessible, but it is rarely clear if and how these influence decisions at any level, whether this be in the original policy itself or at the level of measures such as site management plans. Adjustments to policy-driven M&E could better enable learning for adaptive management, by reconsidering what supports a balanced understanding of socio-ecological systems and decision-making. Useful strategies include making more use of secondary data, and more transparency in data-sharing and decision-making. Several countries and policy areas already offer useful examples. Such changes are essential given the influence of policy, and the urgency of enabling adaptive management to safeguard socio-ecological systems
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