|M.Sc Student||Rothstein Tamara|
|Subject||Feasibility Study of Breast Tumor Detection and|
Characterization Using Computerized Ultrasonic
Mammography and Contrast Materials
|Department||Department of Biomedical Engineering||Supervisor||Professor Haim Azhari|
|Full Thesis text|
Introduction: Breast cancer is a major killer of women worldwide. Early detection is the key to breast cancer mortality decrease. This calls for a reliable screening method. Objective: to analyze the acoustic properties changes associated with the propagation of ultrasonic waves through media before and after ultrasound contrast agent (UCA) injection and to study the feasibility of a new breast imaging method combining projection imaging and UCA. Materials and Methods: Phantom study - Two transmission techniques were examined: Gaussian Pulses and Pulse Inversion. A computerized automatic ultrasonic scanning system was used for imaging. In order to simulate blood vessels, a phantom, consisting of a latex tube through which saline was circulated, was assembled. The phantom was placed within the scanner and sets of acoustic projection images were acquired before and after the addition of the UCA Definity™. The pre and postcontrast images were quantitatively compared in terms of amplitude and time of flight (TOF). In addition, non-linearity was evaluated by comparing the relative alteration of the positive and negative parts of the signal. In vivo - Twenty seven women were scanned using the same dedicated scanner as in the phantom experiments. Among them, fifteen were healthy volunteers and twelve were patients from Rambam Medical Center with suspicious mammography findings. Results: Phantom study - Statistically significant (p-value<0.001) changes in the projection images resulting from the UCA injection were observed in wave amplitude (22% ± 13%), TOF (7.9 nsec ± 6.3 nsec) and non-linear properties (35% ± 32% and 56% ± 17% for Gaussian Pulses and Pulse Inversion, respectively). In vivo - The number of breast lobes was found to be significantly higher in young premenopausal women (19 ± 7) than in older women (11 ± 5), with p-value < 0.05. The attenuation coefficient in the breast was found to significantly decrease with contrast injection (p-value < 0.05), while the SOS was found to significantly increase (p-value < 0.05). Eight out of twelve cases of patients with suspicious findings presented visual correlation between US mammogram images and clinical data (X-ray mammography, US or MRI). Conclusion: The results obtained for the phantom together with the ones from the in vivo experiments indicate the technical feasibility of the suggested method. Clinical relevance: This new ultrasonic technique may provide a novel cost effective non-invasive method for breast tumors detection and characterization which may be complementary or alternative to breast MRI.