Magnus Cinthio
Senior lecturer
Ultrasonic Methods for 2D Arterial Wall Movement Measurements
Author
Summary, in English
Cardiovascular diseases constitute the major cause of morbidity and mortality in the Western World. To increase our knowledge of cardiovascular diseases, it is important to find methods, preferably non-invasive ones, to study very early manifestations of vascular disease. Changes in the mechanical properties of the arteries can be an early manifestation of vascular disease. Further, changes in the mechanical properties of arteries can have important haemodynamic consequences, and are being increasingly recognised as important factors in cardiovascular morbidity and mortality. To obtain a measure of the mechanical properties in the arteries, arterial characterisation is performed. This thesis consists of seven papers concerning arterial characterisation and new ultrasonic methods for arterial characterisation.
The first paper is an introduction and an overview of the area around vessel characterisation.
Papers II and III describe and evaluate a new method for local non-invasive pulse-wave velocity (PWV) estimation. The PWV estimation was based on arterial-wall movement, which was detected by Tissue Doppler Imaging (TDI). The method was evaluated and optimised on an <i>in vitro</i> set-up and validated <i>in vivo</i> with respect to repeatability and reproducibility in a clinical study. In the evaluation, it was shown that system parameters have a significant effect on the PWV variance, whereas the PWV mean remains unchanged. Furthermore, it was established that high temporal resolution is the most vital parameter for minimising the PWV variance.
The <i>longitudinal</i> movement of blood-vessel walls has so far gained little or no attention, as it has been presumed that these movements are of a negligible magnitude. The fourth paper presents results from the first <i>in vivo</i> study with a new unique ultrasonic method for measurement of both the radial and the longitudinal movement of the arterial wall, and it is shown that the magnitude of the longitudinal movement is not negligible, that movement due to breathing affects the recording of arterial longitudinal movement in common carotid artery, and that there was a shear stress present within the arterial wall in one volunteer. The new unique ultrasonic method is evaluated <i>in vitro</i> in paper V, and accuracy, reproducibility, and resolution were all considerably better than the resolution of the applied ultrasound scanner.
The sixth paper describes a new method for arterial luminal diameter measurement with ultrasound. Features of the new method are its robustness, fastness, and resolution. The method was calibrated on a vessel phantom and was evaluated <i>in vivo</i> with respect to accuracy and reproducibility, which both were considerably better than the resolution of the applied ultrasound scanner.
The seventh paper presents results from an <i>in vivo</i> study where a new digitised ultrasonic method called Elastart, which measures arterial lumen diameter at diastole and arterial distension with tissue Doppler, is compared with a golden standard method. The evaluation of the method <i>in vivo</i> against a golden standard showed that no difference in reproducibility between the two systems could be found. However, measurements of the arterial lumen diameter showed a slight underestimation of the Elastart system compared with the golden standard.
The first paper is an introduction and an overview of the area around vessel characterisation.
Papers II and III describe and evaluate a new method for local non-invasive pulse-wave velocity (PWV) estimation. The PWV estimation was based on arterial-wall movement, which was detected by Tissue Doppler Imaging (TDI). The method was evaluated and optimised on an <i>in vitro</i> set-up and validated <i>in vivo</i> with respect to repeatability and reproducibility in a clinical study. In the evaluation, it was shown that system parameters have a significant effect on the PWV variance, whereas the PWV mean remains unchanged. Furthermore, it was established that high temporal resolution is the most vital parameter for minimising the PWV variance.
The <i>longitudinal</i> movement of blood-vessel walls has so far gained little or no attention, as it has been presumed that these movements are of a negligible magnitude. The fourth paper presents results from the first <i>in vivo</i> study with a new unique ultrasonic method for measurement of both the radial and the longitudinal movement of the arterial wall, and it is shown that the magnitude of the longitudinal movement is not negligible, that movement due to breathing affects the recording of arterial longitudinal movement in common carotid artery, and that there was a shear stress present within the arterial wall in one volunteer. The new unique ultrasonic method is evaluated <i>in vitro</i> in paper V, and accuracy, reproducibility, and resolution were all considerably better than the resolution of the applied ultrasound scanner.
The sixth paper describes a new method for arterial luminal diameter measurement with ultrasound. Features of the new method are its robustness, fastness, and resolution. The method was calibrated on a vessel phantom and was evaluated <i>in vivo</i> with respect to accuracy and reproducibility, which both were considerably better than the resolution of the applied ultrasound scanner.
The seventh paper presents results from an <i>in vivo</i> study where a new digitised ultrasonic method called Elastart, which measures arterial lumen diameter at diastole and arterial distension with tissue Doppler, is compared with a golden standard method. The evaluation of the method <i>in vivo</i> against a golden standard showed that no difference in reproducibility between the two systems could be found. However, measurements of the arterial lumen diameter showed a slight underestimation of the Elastart system compared with the golden standard.
Department/s
- Division for Biomedical Engineering
Publishing year
2004
Language
English
Document type
Dissertation
Publisher
Magnus Cinthio, Department of Electrical Measurements, LTH, Box 118, 221 00 Lund, Sweden,
Topic
- Medical Engineering
Keywords
- tissue Doppler imaging
- Cardiovascular system
- Diagnostik
- Diagnostics
- Kardiovaskulära systemet
- arteries
- ultrasound
- shear stress
- axial movement
- radial movement
- Arterial distension
- Arterial lumen diameter
- PWV
- Arterial longitudinal movement
- pulse-wave velocity
Status
Published
Supervisor
- [unknown] [unknown]
ISBN/ISSN/Other
- ISRN: LUTEDX/TEEM - - 1080 - - SE
Defence date
10 December 2004
Defence time
10:15
Defence place
Room E:1406, E-building, at Lund Institute of Technology, Lund University
Opponent
- Lars-Åke Brodin (Professor)