| 1. |
- Opheim, G., et al.
(författare)
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7T Epilepsy Task Force Consensus Recommendations on the Use of 7T MRI in Clinical Practice
- 2021
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 0028-3878 .- 1526-632X. ; 96:7, s. 327-341
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Tidskriftsartikel (refereegranskat)abstract
- Identifying a structural brain lesion on MRI has important implications in epilepsy and is the most important factor that correlates with seizure freedom after surgery in patients with drug-resistant focal onset epilepsy. However, at conventional magnetic field strengths (1.5 and 3T), only approximately 60%-85% of MRI examinations reveal such lesions. Over the last decade, studies have demonstrated the added value of 7T MRI in patients with and without known epileptogenic lesions from 1.5 and/or 3T. However, translation of 7T MRI to clinical practice is still challenging, particularly in centers new to 7T, and there is a need for practical recommendations on targeted use of 7T MRI in the clinical management of patients with epilepsy. The 7T Epilepsy Task Force-an international group representing 21 7T MRI centers with experience from scanning over 2,000 patients with epilepsy-would hereby like to share its experience with the neurology community regarding the appropriate clinical indications, patient selection and preparation, acquisition protocols and setup, technical challenges, and radiologic guidelines for 7T MRI in patients with epilepsy. This article mainly addresses structural imaging; in addition, it presents multiple nonstructural MRI techniques that benefit from 7T and hold promise as future directions in epilepsy. Answering to the increased availability of 7T MRI as an approved tool for diagnostic purposes, this article aims to provide guidance on clinical 7T MRI epilepsy management by giving recommendations on referral, suitable 7T MRI protocols, and image interpretation.
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| 2. |
- Jungmann, P. M., et al.
(författare)
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Magnetic Resonance Imaging Score and Classification System (AMADEUS) for Assessment of Preoperative Cartilage Defect Severity
- 2017
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Ingår i: Cartilage. - : SAGE Publications. - 1947-6035 .- 1947-6043. ; 8:3, s. 272-282
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To design a simple magnetic resonance (MR)–based assessment system for quantification of osteochondral defect severity prior to cartilage repair surgery at the knee. Design: The new scoring tool was supposed to include 3 different parameters: (1) cartilage defect size, (2) depth/morphology of the cartilage defect, and (3) subchondral bone quality, resulting in a specific 3-digit code. A clearly defined numeric score was developed, resulting in a final score of 0 to 100. Defect severity grades I through IV were defined. For intra- and interobserver agreement, defects were assessed by 2 independent readers on preoperative knee MR images of n = 44 subjects who subsequently received cartilage repair surgery. For statistical analyses, mean values ± standard deviation (SD), interclass correlation coefficients (ICC), and linear weighted kappa values were calculated. Results: The mean total Area Measurement And DEpth & Underlying Structures (AMADEUS) score was 48 ± 24, (range, 0-85). The mean defect size was 2.8 ± 2.6 cm2. There were 36 of 44 full-thickness defects. The subchondral bone showed defects in 21 of 44 cases. Kappa values for intraobserver reliability ranged between 0.82 and 0.94. Kappa values for interobserver reliability ranged between 0.38 and 0.85. Kappa values for AMADEUS grade were 0.75 and 0.67 for intra- and interobserver agreement, respectively. ICC scores for the AMADEUS total score were 0.97 and 0.96 for intra- and interobserver agreement, respectively. Conclusions: The AMADEUS score and classification system allows reliable severity encoding, scoring and grading of osteochondral defects on knee MR images, which is easily clinically applicable in daily practice. © 2016, © The Author(s) 2016.
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| 3. |
- de Windt, Tommy S, et al.
(författare)
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Is Magnetic Resonance Imaging Reliable in Predicting Clinical Outcome After Articular Cartilage Repair of the Knee?: A Systematic Review and Meta-analysis.
- 2013
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Ingår i: The American journal of sports medicine. - : SAGE Publications. - 1552-3365 .- 0363-5465. ; 41:7, s. 1695-1702
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:While MRI can provide a detailed morphological evaluation after articular cartilage repair, its additional value in determining clinical outcome has yet to be determined. PURPOSE:To evaluate the correlation between MRI and clinical outcome after cartilage repair and to identify parameters that are most important in determining clinical outcome. STUDY DESIGN:Systematic review and meta-analysis. METHODS:A systematic search was performed in Embase, MEDLINE, and the Cochrane Collaboration. Articles were screened for relevance and appraised for quality. Guidelines in the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) Statement were used. Chi-square tests were performed to find variables that could determine correlation between clinical and radiological parameters. RESULTS:A total of 32 articles (total number of patients, 1019) were included. A majority (81%) were case series or cohort studies that used similar standardized MRI techniques. The mean Coleman score was 63 (range, 42-96). For the majority of MRI parameters, limited or no correlation was found. Nine studies (28%) found a correlation between clinical outcome and the composite magnetic resonance observation of cartilage repair tissue (MOCART) or Henderson score and 7 (22%) with defect fill. In 5 studies, a weak to moderate correlation was found between clinical outcome and the T2 index (mean Pearson coefficient r = .53). CONCLUSION:Strong evidence to determine whether morphological MRI is reliable in predicting clinical outcome after cartilage repair is lacking. Future research aiming specifically at clinical sensitivity of advanced morphological and biochemical MRI techniques after articular cartilage repair could be of great importance to the field.
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| 4. |
- Eder, Gabriele, et al.
(författare)
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Coloured BIPV : Market, Research and Development
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In the building sector, net-zero energy performance targets and reduction of CO2 emissions are the main drivers for building integrated photovoltaics. Recent market studies [10,18,19] show the history and perspective of the global market in the BIPV sector and calculate a global compound annual growth rate of ~ 40 % from 2009 up to 2020.In Europe, the BIPV market is in a transition. The past decades of a slowly emerging BIPV market have been characterized by the original dominant value of BIPV: a building that communicates an image of sustainability and innovation. Payback time or "return on investment" have not been the major parameters in the decision process for applying BIPV. This is changing now. In most European countries, the new regulations on energy performance in buildings (derived from the European Energy Performance of Buildings Directive and the Directive on energy efficiency) have been translated in national regulations/laws, stating that all new (and freshly refurbished) buildings of the EU member states should be nearly zero energy buildings (nZEBs) by 2020. Thus, the time for the regulations to become mandatory is very near. It is expected that the energy performance regulations are now taking over as the main driving factor for the BIPV market and that should have huge consequences in removing the difference between a conventional building component and a BIPV component both in aesthetical and construction terms. This has led to intensified research and development aiming to create BIPV products that come in a variety of colours and sizes, while at the same time being as close as possible to existing building components, to its requirements and how it is considered by the construction industry.The given market overview of state-of-the-art coloured BIPV products clearly reveals that for all parts of a BIPV module (glass, polymers, PV-active layers), there are technical solutions available for colouring. Pilot projects utilizing coloured BIPV products have been built in numerous (mainly European) cities clearly demonstrating the maturity of these solutions.The key aspect that has been slowing down the progress of implementation of these aesthetically appealing and technically sophisticated new products into a wider market are the costs. In this respect, a lot of effort has been made to improve and optimize the relationship between colour and efficiency/power generation of BIPV elements. The results of the past and on-going innovative research and intensified fundamental considerations are also summarized in this report.Besides the colour perception of the coloured BIPV elements under solar irradiation which is essential for the acceptance of the exterior appearance of a building, also transparency and inside visual comfort of BIPV – windows and façade elements are essential for the users and inhabitants.
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| 5. |
- Janssen, M. P. F., et al.
(författare)
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7-Tesla MRI Evaluation of the Knee, 25 Years after Cartilage Repair Surgery: The Influence of Intralesional Osteophytes on Biochemical Quality of Cartilage
- 2021
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Ingår i: Cartilage. - : SAGE Publications. - 1947-6035 .- 1947-6043. ; 13:1 suppl.
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Tidskriftsartikel (refereegranskat)abstract
- Objective To evaluate the morphological and biochemical quality of cartilage transplants and surrounding articular cartilage of patients 25 years after perichondrium transplantation (PT) and autologous chondrocyte transplantation (ACT) as measured by ultra-high-field 7-Tesla (7T) magnetic resonance imaging (MRI) and to present these findings next to clinical outcome. Design Seven PT patients and 5 ACT patients who underwent surgery on the femoral condyle between 1986 and 1996 were included. Patient-reported outcome measures (PROMs) were assessed by the clinical questionnaires: Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), and Visual Analogue Scale (VAS) for knee pain. The morphological (MOCART score) and biochemical quality (glycosaminoglycans [GAGs] content and collagen integrity) of cartilage transplants and surrounding articular cartilage were analyzed by 7T MRI. The results of the PT and ACT patients were compared. Finally, a detailed morphological analysis of the grafts alone was performed. Results No statistically significant difference was found for the PROMs and MOCART scores of PT and ACT patients. Evaluation of the graft alone showed poor repair tissue quality and high prevalence of intralesional osteophyte formation in both the PT and ACT patients. Penetration of the graft surface by the intralesional osteophyte was related to biochemically damaged opposing tibial cartilage; GAG content was significantly lower in patients with an osteophyte penetrating the graft surface. Conclusions Both PT and ACT patients have a high incidence of intralesional osteophyte formation 25 years after surgery. The resulting biochemical damage to the opposing tibial cartilage might be dependent on osteophyte morphology.
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| 6. |
- Pierce, D. M., et al.
(författare)
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A Phenomenological Approach Toward Patient-Specific Computational Modeling of Articular Cartilage Including Collagen Fiber Tracking
- 2009
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Ingår i: Journal of Biomechanical Engineering. - : ASME International. - 0148-0731 .- 1528-8951. ; 131:9
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Tidskriftsartikel (refereegranskat)abstract
- To model the cartilage morphology and the material response, a phenomenological and patient-specific simulation approach incorporating the collagen fiber fabric is proposed. Cartilage tissue response is nearly isochoric and time-dependent under physiological pressure levels. Hence, a viscoelastic constitutive model capable of reproducing finite strains is employed, while the time-dependent deformation change is purely isochoric. The model incorporates seven material parameters, which all have a physical interpretation. To calibrate the model and facilitate further analysis, five human cartilage specmiens underwent a number of tests. A series of magnetic resonance imaging (MRI) sequences is taken, next the cartilage surface is imaged, then mechanical indentation tests arc completed at 2-7 different locations per sample, resulting in force/displacement data over time, and finally, the underlying bone surface is imaged. Imaging and mechanical testing are performed with a custom-built robotics-based testing device. Stereo reconstruction of the cartilage and subchondral bone surface is employed, which, together with the proposed constitutive model, led to specimen-specific finite element simulations of the mechanical indentation tests. The force-time response of 23 such indentation experiment simulations is optimized to estimate the mean material parameters and corresponding standard deviations. The model is capable of reproducing the deformation behavior of human articular cartilage in the physiological loading domain, as demonstrated by the good agreement between the experiment and numerical results (R-2 = 0.95 +/- 0.03, mean +/- standard deviation of force-time response for 23 indentation tests). To address validation, a sevenfold cross-validation experiment is performed on the 21 experiments representing health), cartilage. To quantify the predictive error, the mean of the absolute force differences and Pearson's correlation coefficient are both calculated. Deviations in the mean absolute difference, normalized by the peak force, range from 4% to 90%, with 40 +/- 25% (M +/- SD). The correlation coefficients across all predictions have a minimum of 0.939, and a maximum of 0.993 with 0.975 +/- 0.013 (M +/- SD), which demonstrates an excellent match of the decay characteristics. A novel feature of the proposed method is 3D sample-specific numerical tracking of the fiber fabric deformation under general loading. This feature is demonstrated by comparing the estimated fiber fabric deformation with recently published experimental data determined by diffusion tensor MRI. The proposed approach is efficient enough to enable large-scale 3D contact simulations of knee joint loading in simulations with accurate joint geometries. [DOI: 10.1115/1.3148471]
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