IMPROVED TUMOR DETECTION BY ULTRASONIC SPECKLE REDUCTION

超声散斑是临床降噪的最重要来源 超声波扫描图像。超声扫描对肿瘤的可探测性 图像，尤其是周围对比度相对较低的图像 正常组织，可能会因斑点而大大减少。总体目标 该项目提案的一部分是对肿瘤改善情况的评估 在诊断超声中可以通过 超声图像相干斑抑制技术的应用 以及定义将导致以下结果的波形处理形式 图像质量和肿瘤可探测性的最佳改进。 一种多功能的超声波形采集实验室系统 将构建来自幻影和体外人体组织的数据。一个 各种包含低对比度、高回声和高回声的超声体模 低回声靶点，类似于人体低对比度肿瘤，将 使用这个专用的实验室系统进行扫描。新鲜病理肝脏 转移性肿瘤标本和一些正常肝脏标本 也会用实验室系统进行扫描。各种各样的计划 对于超声散斑抑制将采用：基本原理 将使用使用空间或频率的技术 产生不同(可能不相关)图像的分集技术 然后可以对其进行平均以创建具有减少的超声图像 斑点。空间分集将通过两个线性平移来实现 垂直于扫描平面并通过换能器角度的换能器 技巧。频率分集将通过改变 超声激励的周期数和中心频率 超声换能器，并通过对获得的扫描数据进行数字滤波 采用宽带换能器。频率与频率之间的关系 参数(中心频率、带宽)和换能器 将确定平移/旋转和散斑去相关 实验上，并与先前的理论预测(格尔巴赫的)进行了比较。 斑点抑制技术的效果将通过以下方式进行评估 接收器工作特性(ROC)分析观察者的能力 在通过各种方法创建的图像中检测低对比度目标和肿瘤 加工方案。 在这些研究中创建的知识框架将表明 临床扫描仪的硬件和波形处理改进，这 将改进和更早地发现实质器官中的肿瘤 身体。

Ultrasonic speckle is themost important source of noise degrading clinical ultrasound scan images. The detectability of tumors in ultrasonic scan images, particularly those of relatively low contrast in the surrounding normal tissues, may be greatly decreased due to speckle. The overall aim of the project proposal is the evaluation of the improvement in tumor detectability which may be achieved in diagnostic ultrasound through the application of techniques for the reduction of speckle in untrasonic images and definition of those forms of waveform processing which will lead to optimum improvement in image quality and tumor detectability. A versatile laboratory system for the acquisition of ultrasonic waveform data from phantoms and human tissues in vitro will be constructed. A variety of ultrasonic phantoms containing low-contrast, hyperechoic and hypechoic targets, similar to low-contrast tumors in the human body, will be scanned using this dedicated laboratory system. Fresh pathologic liver specimens involved with metastatic tumor, and some normal liver specimens will be scanned with the laboratory system as well. A variety of schemes for ultrasonic speckle reduction will be employed: the basic principle will be to use techniques which employ either spatial or frequency diversity techniques to produce differing (possibly uncorrelated) images which may then be averaged to create ultrasonic images with reduced speckle. Spatial diversity will be achieved by both linear translation of transducers perpendicular to scan planes and through transducer angulation techniques. Frequency diversity will be attained by both altering the number of cycles and center frequencies of ultrasound exciting the ultrasound transducer, and via digital filtering of scan data obtained employing broad-band transducers. The relationship between frequency parameters (center frequency, bandwidth) and transducer translation/rotation and speckle decorrelation will be determined experimentally and compared to prior theoretical predictions (of Gehlbach). The effects of the speckle reduction techniques will be evaluated via receiver operating characteristic (ROC) analysis of observers' ability to detect low-contrast targets and tumors in images created via a variety of processing schemes. The framework of knowledge created in these studies will indicate possible hardware and waveform processing improvements in clinical scanners, which will give improved and earlier detection of tumors in parenchymal organs of the body.