| 1. |
- Lindberg, Frida, 1982-, et al.
(författare)
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Aesthetic ultrasound devices : Current state of knowledge and suggested measurement set-up for characterization of exposure
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report concerns the ultrasound devices used for the aesthetic purposes of body contouring and fat reduction (ablation of adipose tissue). Such devices have recently become more frequent on the Swedish market. These ultrasound devices are currently not medically regulated in Sweden and little is known about their safety and potentially harmful exposure when using them.This report aims to provide relevant information about present guidelines and scientific results in the area, a survey of the Swedish market and also recommendations on how to characterize the ultrasound emitted by these devices. This information provides an important basis for possible future regulatory actions.All aesthetic ultrasound devices found on the Swedish market use low-frequency non-thermal ultrasound. These types of devices (with one exception) have not yet been studied in peer-reviewed publications and the technical specifications from the suppliers are often incomplete. Consequently, there is a need to evaluate the devices in order to gain adequate knowledge about possible risks associated with their use.Ultrasound exposure should be characterized by its frequency and acoustic pressure. It has not been fully investigated whether the mathematical equation for the mechanical index is valid for the low frequencies used by aesthetic ultrasound equipment on the Swedish market. In this report, two different hydrophone measurement set-ups for characterization of ultrasound exposure are proposed. The most common reason behind adverse events or exposure of non-target tissue regions is most likely handling errors by the operator. Hence, only characterization of the ultrasound field does not necessarily imply the safe use of aesthetic ultrasound devices.It is recommended that the Swedish Radiation Safety Authority and the Swedish Medical Products Agency discuss their respective future responsibility and how aesthetic ultrasound devices should be regulated.
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| 2. |
- Lindberg, Frida, 1982-, et al.
(författare)
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Assessment of intramuscular activation patterns using ultrasound M-mode strain
- 2013
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Ingår i: Journal of Electromyography & Kinesiology. - : Elsevier BV. - 1050-6411 .- 1873-5711. ; 23:4, s. 879-885
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Tidskriftsartikel (refereegranskat)abstract
- The intramuscular activation pattern can be connected to the motor unit recruitment strategy of force generation and fatigue resistance. Electromyography has earlier been used in several studies to quantify the spatial inhomogeneity of the muscle activation. We applied ultrasound M-mode strain to study the activation pattern through the tissue deformation. Correlation values of the strain at different force levels were used to quantify the spatial changes in the activation. The assessment was done including the biceps brachii muscle of 8 healthy subjects performing isometric elbow flexion contractions ranging from 0% to 80% of maximum voluntary contraction. The obtained results were repeatable and demonstrated consistent changes of the correlation values during force regulation, in agreement with previously presented EMG-results. Both intra-subject and inter-subject activation patterns of strain were considered along and transverse the fiber direction. The results suggest that ultrasound M-mode strain can be used as a complementary method to study intramuscular activation patterns with high spatial resolution.(C) 2013 Elsevier Ltd. All rights reserved.
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| 3. |
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| 4. |
- Lindberg, Frida, 1982-, et al.
(författare)
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Evaluation of ultrasound Tissue Velocity Imaging : a phantom study of velocity estimation in skeletal muscle low-level contractions
- 2013
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Ingår i: BMC Medical Imaging. - : BioMed Central. - 1471-2342. ; 13:1, s. 16-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Tissue Velocity Imaging (TVI) is an ultrasound based technique used for quantitative analysis of the cardiac function and has earlier been evaluated according to myocardial velocities. Recent years several studies have reported applying TVI in the analysis of skeletal muscles. Skeletal tissue velocities can be very low. In particular, when performing isometric contractions or contractions of low force level the velocities may be much lower compared to the myocardial tissue velocities. Methods: In this study TVI was evaluated for estimation of tissue velocities below the typical myocardial velocities. An in-house phantom was used to see how different PRF-settings affected the accuracy of the velocity estimations. Results: With phantom peak velocity at 0.03 cm/s the error ranged from 31% up to 313% with the different PRF-settings in this study. For the peak velocities at 0.17 cm/s and 0.26 cm/s there was no difference in error with tested PFR settings, it is kept approximately around 20%. Conclusions: The results from the present study showed that the PRF setting did not seem to affect the accuracy of the velocity estimation at tissue velocities above 0.17 cm/s. However at lower velocities (0.03 cm/s) the setting was crucial for the accuracy. The PRF should therefore preferable be reduced when the method is applied in low-level muscle contraction.
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| 5. |
- Lindberg, Frida, 1982-
(författare)
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Ultrasonic Quantification of Skeletal Muscle Dynamics : Feasibility and Limitations
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pain and disorders of the human skeletal muscles are one of the most common reasons for medical consultations in the western countries today and there is a great need to improve both the understanding and treatment of several different muscular conditions.Techniques describing the muscle function in vivo are often limited by either their invasiveness or lack of spatial resolution. Electromyography (EMG) is the most common approach to assess the skeletal muscle function in vivo, providing information on the neurological input. However, the spatial resolution is in general limited and there are difficulties reaching deep musculature without using invasive needles. Moreover, it does not provide any information about muscle structure or mechanical aspects.Quantitative ultrasound techniques have gained interest in the area of skeletal muscles and enables non-invasive and in-vivo insight to the intramuscular activity, through the mechanical response of the activation. However, these techniques are developed and evaluated for cardiovascular applications and there are important considerations to be made when applying these methods in the musculoskeletal field. This thesis is based on the work from four papers with the main focus to investigate and describe some of these considerations in combination with the development of processing and analyzing methods that can be used to describe the physiological characteristics of active muscle tissue.In the first paper the accuracy of the Doppler based technique Tissue Velocity Imaging (TVI) was evaluated in a phantom study for very low tissue velocities and the effect of the pulse repetition frequency was considered. The second paper presents a biomechanical model to describe the TVI strain’s dependency on the muscle fiber pennation angle. In the third and fourth papers the intramuscular activity pattern was assessed through the regional tissue deformation by motion mode (M-mode) strain imaging. The activity patterns were analyzed during force regulation and for the effects of fatigue.The work of this thesis show promising results for the application of these methods on skeletal muscles and indicate high clinical potential where quantitative ultrasound may be a valuable tool to reach a more multifaceted and comprehensive insight in the musculoskeletal function. However, the methodological considerations are highly important for the optimized application and further evaluation and development of analyzing strategies are needed.
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| 6. |
- Wang, Ruoli, et al.
(författare)
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Passive Mechanical Properties of Human Medial Gastrocnemius and Soleus Musculotendinous Unit.
- 2021
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Ingår i: BioMed Research International. - : Hindawi Publishing Corporation. - 2314-6133 .- 2314-6141. ; 2021
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Tidskriftsartikel (refereegranskat)abstract
- The in vivo characterization of the passive mechanical properties of the human triceps surae musculotendinous unit is important for gaining a deeper understanding of the interactive responses of the tendon and muscle tissues to loading during passive stretching. This study sought to quantify a comprehensive set of passive muscle-tendon properties such as slack length, stiffness, and the stress-strain relationship using a combination of ultrasound imaging and a three-dimensional motion capture system in healthy adults. By measuring tendon length, the cross-section areas of the Achilles tendon subcompartments (i.e., medial gastrocnemius and soleus aspects), and the ankle torque simultaneously, the mechanical properties of each individual compartment can be specifically identified. We found that the medial gastrocnemius (GM) and soleus (SOL) aspects of the Achilles tendon have similar mechanical properties in terms of slack angle (GM: -10.96° ± 3.48°; SOL: -8.50° ± 4.03°), moment arm at 0° of ankle angle (GM: 30.35 ± 6.42 mm; SOL: 31.39 ± 6.42 mm), and stiffness (GM: 23.18 ± 13.46 Nmm-1; SOL: 31.57 ± 13.26 Nmm-1). However, maximal tendon stress in the GM was significantly less than that in SOL (GM: 2.96 ± 1.50 MPa; SOL: 4.90 ± 1.88 MPa, p = 0.024), largely due to the higher passive force observed in the soleus compartment (GM: 99.89 ± 39.50 N; SOL: 174.59 ± 79.54 N, p = 0.020). Moreover, the tendon contributed to more than half of the total muscle-tendon unit lengthening during the passive stretch. This unequal passive stress between the medial gastrocnemius and the soleus tendon might contribute to the asymmetrical loading and deformation of the Achilles tendon during motion reported in the literature. Such information is relevant to understanding the Achilles tendon function and loading profile in pathological populations in the future.
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