| Summary: | 碩士 === 國立臺灣大學 === 資訊工程學研究所 === 96 === Several imaging modalities such as mammography, ultrasound (US), and magnetic resonance imaging (MRI) have been applied to evaluating the therapeutic response of neoadjuvant therapy for breast cancer. In this paper, the three-dimensional (3-D) Doppler US is adopted for evaluating the vascularity. The conventional vascularity index (VI) method is usually used to evaluate the vascularity. From our experiments, this method could not have enough reproducibility for monitoring the chemotherapy response due to the artificial vessel noise by breath and heartbeat. Hence, a new vascularity evaluation method based on the vessel length is proposed to reduce the vessel noise in this paper. At first, the 3-D thinning algorithm for the vessel image is performed to extract the vessel skeleton and then the vessel lengths could be found from the skeleton as the vascularity. Nevertheless, this proposed vessel length information still does not have enough reproducibility due to the vessel noise. In order to improve the vessel reproducibility, a vessel noise reduction method is developed to analyze the vessel lengths. In the proposed noise reduction method, only the lengths of vessels larger than a threshold are counted. The threshold could be a fixed value or proportion to the maximum vessel radius. In the relative noise reduction method, the average reproducibilities of 20% and 10% reductions are 0.075 and 0.078 in our cases. The reproducibility of fixed threshold reduction by 5-pixel and 3-pixel are 0.119 and 0.097 respectively. The relative threshold reductions have better performance than the fixed threshold reductions. Furthermore, the response during the chemotherapy for a patient could also be evaluated by the changes of vessel lengths. The therapy evaluation result of 20% reduction is worse than that of 10% reduction. Therefore, we conclude that the 10% noise reduction method is a better evaluation method for the response of chemotherapy.
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