Association between Statin Use and Balance in Older Adults

ABSTRACT: Background: Several medications have been associated with an increased risk of balance deficits and greater likelihood to sustain a fall, representing a large health and economic issue. Statins are regularly prescribed to prevent strokes and heart attacks, but their impact on balance is unknown. The aim of this paper was to determine whether statin use is associated with poorer balance performances in older adults. Methods: All participants, one group taking statins (n = 34), and the other group not taking statins (n = 31), completed a balance assessment with their eyes closed and their eyes opened on a MatScan Pressure Sensing Mat. Center of Pressure (CoP) velocity, peak-to-peak distance, and standard deviation were collected in both anteroposterior (AP) and mediolateral (ML) directions. Multiple linear regression analyses were performed for each balance outcome, testing the statin use status as a predictor and controlling for appropriate factors including participants characteristics, lipid profile, and cardiovascular disease. Results: After controlling for confounding factors, statin use significantly predicted both CoP ML-Amplitude (beta = 0.638, p = 0.004) and ML-Velocity (beta = 0.653, p = 0.002) in the eyes-opened condition. Conclusions: The present study detected a negative association between statin use and balance control in the ML direction, suggesting that caution should be taken when prescribing statins in older adults, as this could decrease ML stability and ultimately increase fall and fracture risks

Assessing Reliability of Myocardial Blood Flow After Motion Correction With Dynamic PET Using a Bayesian Framework

The estimation of myocardial blood flow (MBF) in dynamic PET can be biased by many different processes. A major source of error, particularly in clinical applications, is patient motion. Patient motion, or gross motion, creates displacements between different PET frames as well as between the PET frames and the CT-derived attenuation map, leading to errors in MBF calculation from voxel time series. Motion correction techniques are challenging to evaluate quantitatively and the impact on MBF reliability is not fully understood. Most metrics, such as signal-to-noise ratio (SNR), are characteristic of static images, and are not specific to motion correction in dynamic data. This study presents a new approach of estimating motion correction quality in dynamic cardiac PET imaging. It relies on calculating a MBF surrogate, K 1 , along with the uncertainty on the parameter. This technique exploits a Bayesian framework, representing the kinetic parameters as a probability distribution, from which the uncertainty measures can be extracted. If the uncertainty extracted is high, the parameter studied is considered to have high variability - or low confidence - and vice versa. The robustness of the framework is evaluated on simulated time activity curves to ensure that the uncertainties are consistently estimated at the multiple levels of noise. Our framework is applied on 40 patient datasets, divided in 4 motion magnitude categories. Experienced observers manually realigned clinical datasets with 3D translations to correct for motion. K 1 uncertainties were compared before and after correction. A reduction of uncertainty after motion correction of up to 60% demonstrates the benefit of motion correction in dynamic PET and as well as provides evidence of the usefulness of the new method presented

Search for 22^{22}Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes

Classical novae are thermonuclear explosions in stellar binary systems, and important sources of $^{26}$Al and $^{22}$Na. While gamma rays from the decay of the former radioisotope have been observed throughout the Galaxy, $^{22}$Na remains untraceable. The half-life of $^{22}$Na (2.6 yr) would allow the observation of its 1.275 MeV gamma-ray line from a cosmic source. However, the prediction of such an observation requires good knowledge of the nuclear reactions involved in the production and destruction of this nucleus. The $^{22}$Na($p,\gamma$)$^{23}$Mg reaction remains the only source of large uncertainty about the amount of $^{22}$Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in $^{23}$Mg. In the present work, a combined analysis of particle-particle correlations and velocity-difference profiles is proposed to measure femtosecond nuclear lifetimes. The application of this novel method to the study of the $^{23}$Mg states, combining magnetic and highly-segmented tracking gamma-ray spectrometers, places strong limits on the amount of $^{22}$Na produced in novae, explains its non-observation to date in gamma rays (flux < 2.5x$10^{-4}$ ph/(cm$^2$s)), and constrains its detectability with future space-borne observatories.Comment: 18 pages, 3 figures, 1 tabl

Estimation and reliability of myocardial blood flow with dynamic PET

Dynamic Positron Emission Tomography (PET) enables the estimation of Myocardial Blood Flow (MBF), by modeling the temporal evolution of a radio-labeled pharmaceutical over multiple PET images acquired over time. Despite its advantages, the absolute quantification of MBF is not used routinely in the clinic due to a lack of clinical standardization. MBF estimates can be affected by patient motion, among other factors, which creates displacements between different PET frames and leads to errors in MBF calculation. Automated motion correction techniques are difficult to perform, due to the rapid change of the tracer spatial distribution throughout the PET images series, and the low resolution of PET image series. Furthermore, it is challenging to quantitatively evaluate the success of motion correction techniques, and their impact on MBF reliability is not fully understood. In this thesis, we developed a framework for estimating MBF along with the uncertainty on the estimate. The framework relies on Bayes theory, which represents the kinetic parameters as a probability distribution, from which uncertainty measures can be extracted. If the uncertainty extracted is high the parameter studied is considered to have high variability - or low confidence - and vice versa. A Bayesian model inference technique, called Variational Bayes, was chosen due to its relatively inexpensive computations compared to other Bayesian techniques. The reliability of parameter and uncertainty estimates were first evaluated through simulations and compared with another Bayesian model inference technique considered the "gold standard". It was found that the uncertainty metric was estimated robustly across multiple noise levels, which was necessary as motion can be seen as an additional source of noise. The uncertainty metric was then used to assess motion correction, performed manually by experienced observers. The uncertainty, calculated before and after motion correction, reduced significantly in moderate and high motion cases, demonstrating the usefulness of the method. The uncertainty was subsequently used to evaluate a motion correction algorithm, showing comparable performance to manual realignment provided by experienced users, with regards to the uncertainty metric. Finally, we investigated different situations where the use of the uncertainty metric may convey clinical information, besides assessing motion correction.</p

Estimation and reliability of myocardial blood flow with dynamic PET

Dynamic Positron Emission Tomography (PET) enables the estimation of Myocardial Blood Flow (MBF), by modeling the temporal evolution of a radio-labeled pharmaceutical over multiple PET images acquired over time. Despite its advantages, the absolute quantification of MBF is not used routinely in the clinic due to a lack of clinical standardization. MBF estimates can be affected by patient motion, among other factors, which creates displacements between different PET frames and leads to errors in MBF calculation. Automated motion correction techniques are difficult to perform, due to the rapid change of the tracer spatial distribution throughout the PET images series, and the low resolution of PET image series. Furthermore, it is challenging to quantitatively evaluate the success of motion correction techniques, and their impact on MBF reliability is not fully understood. In this thesis, we developed a framework for estimating MBF along with the uncertainty on the estimate. The framework relies on Bayes theory, which represents the kinetic parameters as a probability distribution, from which uncertainty measures can be extracted. If the uncertainty extracted is high the parameter studied is considered to have high variability - or low confidence - and vice versa. A Bayesian model inference technique, called Variational Bayes, was chosen due to its relatively inexpensive computations compared to other Bayesian techniques. The reliability of parameter and uncertainty estimates were first evaluated through simulations and compared with another Bayesian model inference technique considered the "gold standard". It was found that the uncertainty metric was estimated robustly across multiple noise levels, which was necessary as motion can be seen as an additional source of noise. The uncertainty metric was then used to assess motion correction, performed manually by experienced observers. The uncertainty, calculated before and after motion correction, reduced significantly in moderate and high motion cases, demonstrating the usefulness of the method. The uncertainty was subsequently used to evaluate a motion correction algorithm, showing comparable performance to manual realignment provided by experienced users, with regards to the uncertainty metric. Finally, we investigated different situations where the use of the uncertainty metric may convey clinical information, besides assessing motion correction.</p

De l'origine des loix, des arts, et des sciences et de leurs progrès chez les anciens peuples : Tome troisieme : depuis l'établissement de la Royauté chez les Hébreux.

Encabezamiento tomado del Graesse.Port. a dos tintas.Port. con esc. xil.Sign.: []\p4\s, A-Z\p4\s, 2A-2Z\p4\s, []\2p\s.Ilustracion xil. de escudo de armas real.Las h. de grab. calc.: "Patte direxit

De l'origine des loix, des arts, et des sciences et de leurs progrès chez les anciens peuples : Tome second depuis la mort de Jacob jusqu'à l'établissement de la Royanté chez les Hébreux.

Encabezamiento tomado del Graesse.Port. a dos tintas.Port. con esc. xil.Sign.: a\p3\s, A-Z\p4\s, 2A-2Z\p4\s, 3A-3H\p4\s, 3I\p3\s.Ilustracion xil. de escudo de armas real

De l'origine des loix, des arts, et des sciences et de leurs progrès chez les anciens peuples : Tome Premier depuis le Déluge jusqu'à la mort de Jacob.

Encabezamiento tomado del Graesse.Port. a dos tintas.Port. con esc. xil.Sign.: a-c\p4\s, d\p2\s, A-Z\p4\s, 2A-2Z\p4\s, 3A-3D\p4\s, 3E\p2\s.Ilustracion xil. de escudo de armas real.Las h. de grab. calc.: "Patte direxit