Quantification of breast density using dual energy mammography

描述（由申请人提供）：在美国妇女中，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体组织占总纤维腺体和脂肪组织的比例，是乳腺癌发生的重要危险因素。乳房摄影致密乳房是指由于纤维腺体组织相对于脂肪组织的显著体积分数而衰减更大比例的X射线光子的乳房。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。其他更定量的尝试受到许多限制，例如仅提供面积而不是乳房密度的体积测量或假设恒定的乳房厚度。以前的研究表明，乳腺摄影密度每增加1%，患乳腺癌的相对风险增加2%，这表明需要一种准确的方法来测量乳腺密度。本提案的目标是开发一种方法，使用双能量乳腺X射线摄影客观定量地测量女性乳房的密度。双能量成像利用纤维腺体和脂肪组织之间的x射线光子衰减的差异能量依赖性。图像像素被分解为两个主要乳腺组织中的每一个的单独厚度测量。具体目标是：（1）开发分析模拟模型，以研究使用双能量乳腺X射线摄影术精确测量乳腺密度的可行性。(2)对双能量乳腺X线摄影在乳房体模中可准确测量乳腺密度的假设的研究。(3)在死后乳腺组织中使用磁共振成像（MRI）和锥形束计算机断层扫描进行乳腺密度定量的双能量技术的验证。(4)旨在检验以下假设：在人类志愿者中使用双能量乳腺X射线摄影测量的乳腺密度与使用MRI测量的乳腺密度的相关系数高于0.95。所提出的方法提供了一个体积测量乳腺密度的像素像素的基础上，它有可能被纳入常规筛查乳腺X射线摄影。这些优势应该转化为更准确的乳腺癌风险评估。该项目的长期计划是开发一种临床上可行的方法，用双能X射线乳房摄影术测量妇女乳房的密度。公共卫生相关性：乳腺密度已被确定为乳腺癌发展中一个重要但未充分利用的风险因素。单独的主观视觉评估不足以量化乳腺密度。本提案的目标是开发一种方法，使用双能量乳腺X射线摄影客观定量地测量女性乳房的密度。所提出的方法提供了一个体积测量乳腺密度，它有可能被纳入常规筛查乳腺X线摄影。

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. PUBLIC HEALTH RELEVANCE: Breast density has been identified as an important yet underutilized risk factor in the development of breast cancer. Subjective visual assessment alone is inadequate to quantify 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. The proposed method provides a volumetric measure of breast density and it has the potential to be incorporated into routine screening mammography.