Quantitative study of signal decay due to magnetic susceptibility interfaces: MRI simulations and experiments

Guio, François De; Benoit-Cattin, Hugues; Davenel, A.

doi:10.1109/iembs.2007.4352613

Cited by 3 publications

(1 citation statement)

References 26 publications

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“…In this way, the ball is thrown forward with as much force as possible, so that it falls within the throwing sector. The reliability obtained [85] through a test-retest is r = 0.98, and the validity of the drop jump test was evaluated using the intraclass correlation coefficient (ICC), which yielded a score of 0.98, indicating consistency between the means of each throwing mode (standing, kneeling, sitting, one-handed). The correlation coefficient was also calculated, resulting in a score of r = 0.49, with a significant p-value of <0.01 [67].…”

Section: Bmentioning

confidence: 99%

Stress Levels and Hormonal Coupling and Their Relationship with Sports Performance in an Elite Women’s Volleyball Team

Miguel-Ortega,

Fernández-Landa,

Calleja-González

et al. 2023

Applied Sciences

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The testosterone–cortisol ratio is a concept in human biology that refers to the balance between testosterone, the main anabolic steroid, and cortisol, another steroid hormone. The two hormones are said to be habitually positively “coupled”. Increases or decreases in testosterone tend to be associated with corresponding increases or decreases in cortisol, and vice versa. The present study explored hormone coupling and its relationship to stress levels in the sport performances of an elite women’s volleyball team. (1) Aim: to assess the testosterone–cortisol concentration dynamic over 16 weeks and its link to sport performance in elite female volleyball players (height: 1.8 ± 0.1 m; 24.2 ± 2.7 years; playing experience 15 ± 2.8 years; years played at elite level 4.2 ± 2.2; testosterone–cortisol index time 1: 3.9 vs. time 2: 4.3) (n = 11). (2) Methods: blood samples (hormones among other biochemical parameters) and sports performance measurements (aerobic and anaerobic power among other tests) were taken from members of an elite women’s volleyball team over 16 weeks of competition. (3) Results: female volleyball players showed patterns of hormonal change and adaptation to stress. (4) Conclusions: the current investigation demonstrated that elite female volleyball players have higher basal levels of testosterone and cortisol than normal healthy women. The impact of training and competition is clearly reflected in the levels of T. Cortisol levels increase at the beginning of training and remain elevated throughout the season, but without significant changes.

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Section: Bmentioning

confidence: 99%

Stress Levels and Hormonal Coupling and Their Relationship with Sports Performance in an Elite Women’s Volleyball Team

Miguel-Ortega,

Fernández-Landa,

Calleja-González

et al. 2023

Applied Sciences

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Study of MRI Susceptibility Artifacts for Nanomedical Applications

Wortmann

Dahmen

Fatikow

2010

Journal of Nanotechnology in Engineering and Medicine

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This article deals with the exploitation of magnetic susceptibility artifacts in magnetic resonance imaging (MRI) for the recognition of metallic delivery capsules. The targeted application is a closed-loop position control of magnetic objects implemented using the components of a clinical MRI scanner. Actuation can be performed by switching the magnetic gradient fields, whereas object locations are detected by an analysis of the MRI scans. A comprehensive investigation of susceptibility artifacts with a total number of 108 experimental setups has been performed in order to study scaling laws and the impact of object properties and imaging parameters. In addition to solid metal objects, a suspension of superparamagnetic nanoparticles has been examined. All 3D scans have been segmented automatically for artifact quantification and location determination. Analysis showed a characteristic shape for all three base types of sequences, which is invariant to the magnetic object shape and material. Imaging parameters such as echo time and flip angle have a moderate impact on the artifact volume but do not modify the characteristic artifact shape. The nanoparticle agglomerates produce imaging artifacts similar to the solid samples. Based on the results, a two-stage recognition/tracking procedure is proposed.

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Interactions between Stress Levels and Hormonal Responses Related to Sports Performance in Pro Women’s Basketball Team

Miguel-Ortega,

Calleja-González,

Mielgo-Ayuso

2024

JFMK

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The testosterone to cortisol ratio (T:C ratio) is a measure of whether elite athletes are recovering from their training. This study described this hormone balance stress in elite women’s basketball. (1) Objectives: to analyse the fluctuation of T:C ratio over a 16-week period and explore itis relation to their athletic performance. The participants characteristics were: (height: 177.6 ± 6.4 cm; body mass: 77.808 ± 12.396 kg age: 26.0 ± 5.9 years; and a playing experience of 14.7 ± 2.9 years with 5.0 ± 1.2 years at the elite level. The T:C ratio at Time 1 is: 4.0 ± 2.4 (n = 12); and at Time 2 is: 5.1 ± 4.3 (n = 12). (2) Methods: during 16 weeks of competition, participants underwent analysis of blood samples to assess various biochemical parameters including hormone levels. In addition, their athletic performance was assessed with the following tests: jumping (SJ, CMJ, ABK, DJ); throwing test with a medicine ball (3 kg); Illinois COD agility test; sprint repeatability with change of direction; 20-m speed test without change of direction; and Yo-yo intermittent endurance test IET (II). (3) Results: The main alterations observed were an increase in T levels (1.687%) and a decrease in C levels (−7.634%) between moments, with an improvement (26.366%) in the T:C ratio. Improvements were also observed in some of the tests developed, such as jumping (SJ: 11.5%, p = 0.029; CMJ: 10.5%, p = 0.03; DJ: 13.0%, p = 0.01), upper body strength (MBT: 5.4%, p = 0.03), translation ability (20 m: −1.7%), repeated sprint ability (RSA: −2.2%), as well as intermittent endurance test (Yy (IET): 63.5%, p = 0.01), with significant changes in some of the performance tests. (4) Conclusions: T:C ratio may differ in a manner unrelated to training volume, showing some variation. These results may be attributed to the accumulation of psychophysiological stress during the season.

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Quantitative study of signal decay due to magnetic susceptibility interfaces: MRI simulations and experiments

Cited by 3 publications

References 26 publications

Stress Levels and Hormonal Coupling and Their Relationship with Sports Performance in an Elite Women’s Volleyball Team

Stress Levels and Hormonal Coupling and Their Relationship with Sports Performance in an Elite Women’s Volleyball Team

Study of MRI Susceptibility Artifacts for Nanomedical Applications

Interactions between Stress Levels and Hormonal Responses Related to Sports Performance in Pro Women’s Basketball Team

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