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- Van Holsbeke, C., et al.
(författare)
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Ultrasound methods to distinguish between malignant and benign adnexal masses in the hands of examiners with different levels of experience
- 2009
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Ingår i: Ultrasound in Obstetrics & Gynecology. - : Wiley. - 1469-0705 .- 0960-7692. ; 34:4, s. 454-461
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To determine the effect of an ultrasound training course on the performance of pattern recognition when used by less experienced examiners and to compare the performance of pattern recognition, a logistic regression model and a scoring system to estimate the risk of malignancy between examiners with different levels of experience. Methods Using ultrasound images of selected adnexal masses, two trainees classified the masses as benign or malignant by using pattern recognition both before and after they bad attended a theoretical gynecological ultrasound course. They also classified the masses by using a logistic regression model and a scoring system, but only after they bad attended the course. The performance of these three methods when they were used by the trainees was then compared with that when they were used by experts. Results One hundred and sixty-five adnexal masses were included, of which 42% were malignant (21% invasive tumors and 21% borderline tumors). The area under the receiver- operating characteristics curve of pattern recognition when used by the trainees was similar before and after they had attended the course. Training decreased sensitivity (84% vs. 70% for Trainee 1, P = 0.004; 70% vs. 61% for Trainee2, P = 0.08) and increased specificity (77% vs. 92% for Trainee 1, P = 0.001; 89% vs. 95% for Trainee 2, P = 0.058). The performance of pattern recognition was poorer in the hands of the trainees than in the bands of the experts. The sensitivities of the logistic regression model were 70% and 54% for the trainees vs. 83% for an expert (P = 0.020 and < 0.001, respectively) and the specificities were 84% and 94% vs. 89% (P = 0.25 and 0.59, respectively). The sensitivities of the scoring system were 59% and 54% for the trainees vs. 75% for the expert (P = 0.002 and < 0.001, respectively), and the specificities were 90% and 93% vs. 85% (P = 0.103 and 0.008, respectively). Conclusion Theoretical ultrasound teaching did not seem to improve the performance of pattern recognition in the bands of trainees. A logistic regression model and a scoring system to classify adnexal masses as benign or malignant perform less well when they were used by inexperienced examiners than when used by an expert. Before using a model or a scoring system, experience and/or proper training are likely to be of paramount importance if diagnostic performance is to be optimized. Copyright (C) 2009 ISUOG. Published by John Wiley & Sons, Ltd.
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- Cladek, Bernadette R., et al.
(författare)
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In situ inelastic neutron scattering of mixed CH4–CO2 hydrates
- 2022
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 327
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Tidskriftsartikel (refereegranskat)abstract
- An abundant source of CH4 can be found in natural hydrate deposits. Recent demonstration of CH4 recovery from hydrates via CO2 exchange has revealed the potential as a fuel source that also provides a medium for carbon sequestration. It is vital to understand the structural and dynamic impacts of guest variation in CH4, CO2, and mixed hydrates and link the results to the stability of various deposits in nature, harvesting methane, and sequestering CO2. Molecular vibrations are examined in CH4, CO2, and mixed CH4-CO2 hydrates at 5 and 190 K and Xe hydrates for comparison. Inelastic neutron scattering (INS) is an ideal spectroscopy technique to observe the dynamic modes in the hydrate structure and enclathrated CH4, as it is extremely sensitive to 1H. The presence of CO2 in hydrates tightens the lattice. It introduces more active librational modes to the host lattice, while hindering the motion of CH4 in mixed CH4-CO2 hydrate at 5 K. At 190 K, a large broadening of the CH4 librational modes indicates disorder in the structure leading to dissociation.
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| 5. |
- Daemen, A., et al.
(författare)
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Improving the preoperative classification of adnexal masses as benign or malignant by second-stage tests
- 2011
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Ingår i: Ultrasound in Obstetrics & Gynecology. - : Wiley. - 1469-0705 .- 0960-7692. ; 37:1, s. 100-106
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Tidskriftsartikel (refereegranskat)abstract
- Objective The aim of this study was to establish when a second-stage diagnostic test may be of value in cases where a primary diagnostic test has given an uncertain diagnosis of the benign or malignant nature of an adnexal mass. Methods The diagnostic performance with regard to discrimination between benign and malignant adnexal masses for mathematical models including ultrasound variables and for subjective evaluation of ultrasound findings by an experienced ultrasound examiner was expressed as area under the receiver-operating characteristics curve (AUC), sensitivity and specificity. These were calculated for the total study population of 1938 patients with an adnexal mass as well as for sub-populations defined by the certainty with which the diagnosis of benignity or malignancy was made. The effect of applying a second-stage test to the tumors where risk estimation was uncertain was determined. Results The best mathematical model (LR1) had an AUC of 0.95, sensitivity of 92% and specificity of 84% when applied to all tumors. When model LR1 was applied to the 10% of tumors in which the calculated risk fell closest to the risk cut-off of the model, the AUC was 0.59, sensitivity 90% and specificity 21%. A strategy where subjective evaluation was used to classify these 10% of tumors for which LR1 performed poorly and where LR1 was used in the other 90% of tumors resulted in a sensitivity of 91% and specificity of 90%. Applying subjective evaluation to all tumors yielded an AUC of 0.95, sensitivity of 90% and specificity of 93%. Sensitivity was 81% and specificity 47% for those patients where the ultrasound examiner was uncertain about the diagnosis (n = 115; 5.9%). No mathematical model performed better than did subjective evaluation among the 115 tumors where the ultrasound examiner was uncertain. Conclusion When model LR1 is used as a primary test for discriminating between benign and malignant adnexal masses, the use of subjective evaluation of ultrasound findings by an experienced examiner as a second-stage test in the 10% of cases for which the model yields a risk of malignancy closest to its risk cut-off will improve specificity without substantially decreasing sensitivity. However, none of the models tested proved suitable as a second-stage test in tumors where subjective evaluation yielded an uncertain result. Copyright (C) 2010 ISUOG. Published by John Wiley & Sons, Ltd.
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