Screening Lung Cancer by Ultra Low-Dose Computed Tomography

首席调查人员/项目主任(最后、第一、中间)：梁，Jerome Z。 项目摘要/摘要 根据美国癌症协会的统计，肺癌是#年癌症相关死亡的主要原因 在美国，2007年确诊的新病例有212,380例，死亡160,390例。肺的早期检测 癌症(小于3厘米)可以达到90%的十年存活率。癌症的早期征兆是小肺 结节。目前通过高分辨率计算机断层扫描(CT)进行肺结节的筛查， 这会带来很大的辐射，可能会使患癌症的风险增加高达2% 最近发表在《新英格兰医学杂志》上的一篇报道。除了筛查，更多的CT扫描是 为后续和/或活组织检查程序进行检查。CT已经尝试过降低辐射风险 厂商由硬件优化和软件增强两个方面组成。我们一直在探索适应性 在极低mAs水平下重建超低剂量下类似图像质量的噪声处理策略 当前可用的硬件配置上的CT应用程序。一种迭代的图像重建算法 统计代价函数是需要强大的计算引擎(一半以上的代价)的策略之一 百万美元)。另一种是通过统计成本函数进行数据恢复后的分析图像重建 策略，生成与迭代方法类似的结果，大大减少了计算负担。 我们的体模实验和志愿者实验都证明了后者的巨大潜力。 一种在保持图像质量和重建速度的同时减少辐射的恢复策略 目前可用的CT扫描仪。建议的具体目的是进一步探索筛查肺部的潜力。 结节有： (Sa-1)。进一步研究尽可能低mAs的自适应噪声处理策略 对于肺部筛查： 因为低mAs CT数据的一阶矩和二阶矩包含了基本的统计信息 对于噪声(高阶矩对降噪影响较小)，我们将研究其性质 随着mas水平的降低，数据的样本均值和方差降至最低。此外，数据 将研究与断层成像相关的三维空间域中的相关性。 噪声属性和数据相关性都将被合并到统计成本函数中，即， 哈胡宁-洛夫域惩罚加权最小二乘法可有效地最小化数据 以分析的方式以最快的速度进行修复。从恢复的数据重建图像还将 以最快的速度进行分析。为了比较的目的，在相似的情况下迭代图像重建 统计成本函数将得到完善。 (SA-2)。通过检测小的肺结节来评估所调查的适应性策略： 提出的策略将首先通过对拟人化幻影的重复实验进行评估 使用噪声分辨率折衷测量和接收机操作特性的可变低mAs协议 (ROC)和信道化霍特林踪迹(CHT)观察者研究。然后对患者的肺进行评估 与同一CT扫描仪当前使用的mAs水平进行比较的结节检测，其中定量 将使用性能等价性测试和ROC研究来制定措施。成功的评估者 策略可能导致对肺结节进行超低剂量CT筛查的大型临床试验，并可能是 扩展到其他重要器官的筛查，如结肠、心脏和乳房。 小灵通398(04/06版)第__1页_续格式页

Principal Investigators/Program Directors (Last, First, Middle): Liang, Jerome Z. Project Summary/Abstract According to American Cancer Society statistics, lung cancer is the leading cause of cancer-related death in the United States, 212,380 of new cases diagnosed and 160,390 deaths in 2007. Early detection of lung cancers (less than 3 cm) can achieve a 90% ten-year survival rate. Early sign of the cancer is small lung nodules. Current screening of the lung nodules is performed by high-resolution computed tomography (CT), which carries a significant radiation and could increase the risk of getting cancer by as high as 2% according to a recent report in The New England Journal of Medicine. In addition to the screening, more CT scans are performed for follow-up and/or biopsy procedures. Reducing the radiation risk has been attempted by CT manufacturers by both hardware optimization and software enhancement. We have been exploring adaptive noise-treatment strategies to reconstruct similar image quality at significantly low mAs level for ultra low-dose CT applications on currently available hardware configuration. Iterative image reconstruction under a statistical cost function is one of the strategies which needs powerful computing engine (costs more than a half million dollars). Analytical image reconstruction after data restoration by a statistical cost function is another strategy which generates similar results as the iterative means with a dramatic reduction of computing burden. Our pilot studies by both phantom and volunteer experiments have demonstrated great potential of the latter restoration strategy for radiation reduction while retaining the image quality and reconstruction speed on currently available CT scanners. The proposed specific aims to further explore the potential for screening lung nodules are: (SA-1). To further investigate the adaptive noise-treatment strategies toward as low mAs as achievable for lung screening: Because the first and second moments of low-mAs CT data contain the essential statistical information about the noise (higher order moments have less impact on noise reduction), we will study the properties of sample mean and variance of the data as mAs level goes down as low as achievable. In addition, data correlations in the three-dimensional spatial domain associated with tomographic imaging will be investigated. Both the noise properties and data correlation will be incorporated into a statistical cost function, i.e., Kharhunen-Lo¿ve domain penalized weighted least-squares, which can be efficiently minimized for data restoration by an analytical fashion at the highest speed. Image reconstruction from the restored data will also be analytical at the highest speed. For comparison purpose, iterative image reconstruction under a similar statistical cost function will be refined. (SA-2). To evaluate the investigated adaptive strategies by the detection of small lung nodules: The presented strategies will be first evaluated by repeated experiments on anthropomorphic phantoms with variable low mAs protocols using noise-resolution tradeoff measure and receiver operating characteristics (ROC) and channelized Hotelling trace (CHT) observer studies. Then the evaluation will be on patient lung nodule detection with comparison to currently-used mAs level by a same CT scanner, where quantitative measures will be made using performance equivalence tests and ROC studies. The successfully evaluated strategies may lead to a large clinical trial for ultra low-dose CT screening of the lung nodules, and could be extended to screening of other vital organs, such as the colon, heart, and breasts. PHS 398 (Rev. 04/06) Page __1___ Continuation Format Page