| 1. |
- Lindberg, Frida, 1982-
(författare)
-
Ultrasonic Quantification of Skeletal Muscle Dynamics : Feasibility and Limitations
- 2013
-
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.
|
|
| 2. |
- Nyman, Emma, 1990-
(författare)
-
Ultrasound measurements of subclinical carotid atherosclerosis : methodological and clinical studies
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ultrasound measurements of subclinical carotid atherosclerosis have been evaluated as an additional parameter in risk evaluation of cardiovascular diseases (CVD). The overall aim of this thesis was to increase knowledge regarding ultrasound measurements of subclinical carotid atherosclerosis. This included methodological studies of the reproducibility in commonly applied measurements and evaluation of subclinical carotid atherosclerotic progression. All studies within this thesis are based on material from the population based, randomized control trial VIPVIZA. Enrolled from a routine CVD prevention programme, all participants had an additional carotid ultrasound examination including measurements of carotid intima media thickness (cIMT) and carotid plaque detection. The group randomised to the intervention received a pictorial presentation which illustrating their individually measured subclinical atherosclerotic burden. At the 3-year follow-up the same measurements were repeated.Variability, defined by variation of coefficient (CV) of measurements, of plaque risk markers including echogenicity and plaque area were evaluated throughout the cardiac cycle. Additionally, the inter-observer reproducibility of plaque detection was evaluated, and the intervention effect on the 3-year cIMT and plaque progression was compared between intervention (n: 1575) and control group (n: 1579). Lastly, association of baseline carotid wall echogenicity and the 3-year progression of cIMT was evaluated. Small and echolucent plaques had higher CV in measurements of area and echogenicity, respectively. Cardiac cycle variations caused reclassification of up to one in four of the analysed plaques. Small carotid plaques contributed to decreased inter-sonographer reproducibility as compared to large plaques. In the 3-year follow-up the intervention group showed decreased progression of cIMT in the left carotid compared to the control group. No difference was found for in plaque related variables. The echogenicity of the carotid wall associated with the progression of cIMT over the 3-year follow-up period, where echolucent carotid wall had a higher rate of progression bilaterally.Variability of plaque risk markers and the reproducibility of plaque detection should be considered in analysis of subclinical carotid atherosclerosis by ultrasound. Progression of left cIMT was decreased by the intervention, which indicates that increased preventive actions were taken by the intervention group. The echogenicity of the carotid wall may contribute new insights regarding identification of progressive atherosclerotic diseases.
|
|
