2D乳房X光與自動乳房超音波的腫瘤對位

Abstract

在乳癌診斷上，乳房X光攝影及超音波扮演一個很重要的角色。在現今的超音波中，為了克服傳統手持式超音波的限制，像是因不同檢查者而影響檢查結果、過程過於耗時等，而發展出自動乳房超音波。而現今的臨床工作流程，放射科醫生需要同時檢查乳房X光攝影影像及自動乳房超音波影像來決定是否有可疑的腫瘤存在，且這檢查過程是耗時的。因此，在本篇研究中，我們提出一個腫瘤在乳房X光攝影影像及自動乳房超音波影像之間對位的方法來加速檢查過程。首先，在乳房X光攝影影像，利用偵測乳房表面來找到腫瘤投影在乳房表面的位置。接著，在乳房X光攝影影像及自動乳房超音波影像設定參考點：乳頭、胸腔、腫瘤，用來定位腫瘤相對於乳頭的位置。最後，根據腫瘤在乳房X光攝影影像的位置來推估腫瘤在自動乳房超音波影像的相對位置，反之亦然。我們使用了44個病人案例，每個案例都包含MLO、CC兩個相位的乳房X光攝影影像及自動乳房超音波影像。根據實驗的結果，不論是在乳房X光攝影影像或是自動乳房超音波影像上，實際與推估的腫瘤位置誤差約在2公分之內。

Mammogram and ultrasound (US) play an important role in breast cancer diagnosis. Nowadays, Automated Breast Ultrasound (ABUS) has been developed to overcome the limitation of conventional handheld US such as operator dependence and time-consuming in ultrasound screening. In the present clinical workflow, the radiologist needs to review both mammography and ABUS image for checking a suspicious tumor. However, this is a time-consuming process. To increase the efficiency of the screening process, we develop a tumor mapping method between mammogram and ABUS image to identify the same tumor location in mammogram and ABUS image in a more systematic way. Our method involves the following steps to determine the location of the tumors. We first measure the border of a breast in the mammogram image for getting the projection of the tumor on the breast surface. Once we get the projection of the tumor on the breast surface, we use it with nipple and chest wall as reference points to determine the tumor location relative to the nipple in mammogram and ABUS image. Given the relative location of the tumor to the nipple in mammogram, we can use it to extract the actual tumor location from the ABUS image. In this thesis, we use 44 samples to evaluate our proposed method. Each case consists of MLO and CC view mammograms and ABUS image. Our estimation provides the accuracy of the tumor locations within 2cm to the actual location in both mammogram and ABUS image.