|M.Sc Student||Ilana Katz-Hanani|
|Subject||Feasibility Study of Breast Imaging by Ultrasound Using|
Through Transmission Coded Signals
|Department||Department of Biomedical Engineering||Supervisors||Professor Azhari Haim|
|? 42? Gaitini Diana|
|Full Thesis text|
Breast cancer is a leading cause of death among females at ages 20 to 59 years. The most beneficial factor in fighting breast cancer is early detection. The aim of the current study was to examine the feasibility of implementing a new breast imaging approach utilizing through transmission ultrasonic imaging and coded signals.
The research explored three approaches: (i) Establishing a baseline of ultrasonic properties of the breast in-vivo with and without coded excitations. (ii) Assessment of the tissue nonlinearity property using coded excitations. (ii) Optimization of the nonlinearity property stemming from the combination of coded excitations and contrast enhancing material.
For those purposes women with and without suspicious lesions as well as ex-vivo tissue specimens and a tube phantom were scanned using a computerized ultrasonic scanner developed in our laboratory. Coded excitations comprising of two consecutive pulses inverted relative to each other were transmitted.
For the in-vivo baseline experiments it was found that both breast attenuation coefficient and speed of sound are strongly related to age, whereas the nonlinear parameter has no correlation to age. For the ex-vivo experiments it was found that nonlinearity is lower by 20.9%±5 in cooked and hence stiffer tissues (lesion equivalent) than in the normal tissue. In the tube phantom study, it was found that for the optimal pulse sequence, the contrast enhancing material has increased the nonlinearity parameter by 139%±83 relative to baseline.
In conclusion, our main findings are: (i) There is a strong correlation between speed of sound, attenuation coefficient and women’s age, (ii) The coded signals can potentially differentiate between tissues with different stiffness. (iii) The coded signals appear to augment substantially the effect of the contrast agent and potentially have high clinical merit.