Quantification of breast density using dual energy mammography

描述（由申请人提供）：在美国女性中，乳腺癌是最常见的癌症，也是癌症死亡的第二大原因。乳腺密度是指纤维腺组织与总纤维腺组织和脂肪组织的比值，是乳腺癌发生的重要危险因素。乳房x线照相术上致密的乳房是指由于纤维腺组织相对于脂肪组织的显著体积分数而使x射线光子衰减的比例更大的乳房。目前还没有公认的标准来可靠地测量乳腺密度。单独的主观视觉评估不足以量化乳腺密度。其他更多的定量尝试受到一些限制，例如只提供一个面积，而不是乳房密度的体积测量，或者假设乳房厚度恒定。先前的研究表明，乳房x线摄影密度每增加1%，患乳腺癌的相对风险就会增加2%，这表明需要一种准确的方法来测量乳房密度。本提案的目的是开发一种方法，客观和定量测量密度的妇女乳房双能量乳房x光检查。双能成像利用纤维腺体和脂肪组织之间x射线光子衰减的差异能量依赖。图像像素被分解成两个主要乳腺组织的单独厚度测量值。具体目的是：(1)建立分析模拟模型，探讨双能量乳房x线摄影准确测量乳腺密度的可行性。(2)探讨双能量乳房x线摄影可以准确测量乳腺幻像的假设。(3)磁共振成像（MRI）和锥束计算机断层扫描双能量技术在死后乳腺组织中乳腺密度量化的验证。(4)验证双能乳腺x线摄影与MRI测量的乳腺密度相关系数大于0.95的假设。提出的方法提供了乳腺密度的一个像素逐像素的基础上的体积测量，它有可能被纳入常规筛查乳房x线摄影。这些优势应该转化为对乳腺癌风险更准确的评估。该项目的长期计划是开发一种临床可行的方法，用双能x线乳房x线摄影测量女性乳房的密度。

DESCRIPTION (provided by applicant): Among American women breast cancer is the most common cancer and the 2nd leading cause of death from cancer. Breast density, which is defined as the ratio of fibroglandular tissue to the total fibroglandular and adipose tissue, is an important risk factor in the development of breast cancer. A mammographically dense breast refers to a breast which attenuates a greater proportion of x-ray photons due to its significant volume fraction of fibroglandular tissue relative to adipose tissue. There are currently no accepted standards to reliably measure breast density. Subjective visual assessment alone is inadequate to quantify breast density. Other more quantitative attempts have suffered from a number of limitations such as providing only an area as opposed to volumetric measure of breast density or assuming a constant breast thickness. Previous studies have shown that the relative risk for developing breast cancer increases by 2% for every 1% increase in mammographic density, indicating the need for an accurate method to measure breast density. The goal of this proposal is to develop a method to objectively and quantitatively measure the density of a woman's breast using dual energy mammography. Dual energy imaging exploits the differential energy dependence in x-ray photon attenuation between fibroglandular and adipose tissue. Image pixels are decomposed into separate thickness measurements for each of the two primary breast tissues. The specific aims are: (1) Development of an analytical simulation model to investigate the feasibility of accurate breast density measurements using dual energy mammography. (2) Investigation of the hypothesis that breast density can be accurately measured in breast phantoms using dual energy mammography. (3) Validation of the dual energy technique for breast density quantification with magnetic resonance imaging (MRI) and cone-beam computed tomography in postmortem breast tissue. (4) To test the hypothesis that breast density measured in human volunteers with dual energy mammography and breast density measured with MRI have a correlation coefficient higher than 0.95. The proposed method provides a volumetric measure of breast density on a pixel by pixel basis and it has the potential to be incorporated into routine screening mammography. These advantages should translate into a more accurate assessment of breast cancer risk. The long-range plan for this project is to develop a clinically feasible method to measure the density of a woman's breast with dual energy x-ray mammography.