IMPROVED TUMOR DETECTION BY ULTRASONIC SPECKLE REDUCTION

超声散斑噪声是影响临床质量的最重要的噪声源 超声扫描图像。 超声对肿瘤的检出率 图像，特别是那些在周围环境中对比度相对较低的图像 正常组织，可能会大大减少由于斑点。 总体目标 项目建议书的一部分是评估肿瘤的改善情况， 在超声诊断中， 超声图象中斑点减少技术的应用 和定义那些波形处理的形式，这将导致 图像质量和肿瘤可检测性的最佳改善。 一种多功能超声波波形采集系统 将构建来自体外体模和人体组织的数据。 一 各种超声幻影，包含低对比度，高回声和 类似于人体中的低对比度肿瘤的低回声目标将 使用这个专用的实验室系统进行扫描。 新鲜病理肝脏 转移瘤标本及部分正常肝脏标本 也会被实验室系统扫描 多种方案 对于超声散斑减少将采用：基本原理 将使用技术，采用空间或频率 多样性技术产生不同的（可能不相关的）图像 然后可以将其平均以产生具有减小的 斑点。 空间多样性将通过线性平移 探头垂直于扫描平面并通过探头成角 技术. 频率分集将通过改变 周期数和超声激励的中心频率 超声换能器，并通过对所获得的扫描数据进行数字滤波 采用宽带换能器。 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（Gehlbach）进行了比较。 散斑减少技术的效果将通过 受试者工作特征（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， 处理方案。 在这些研究中建立的知识框架将表明， 临床扫描仪的硬件和波形处理改进， 将改善和早期检测实质器官中的肿瘤， 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.