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首页> 外文期刊>Ultrasonics, Ferroelectrics and Frequency Control, IEEE Transactions on >Effects of frequency and bandwidth on diagnostic information transfer in ultrasonic B-Mode imaging
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Effects of frequency and bandwidth on diagnostic information transfer in ultrasonic B-Mode imaging

机译：频率和带宽对超声B型成像诊断信息传输的影响

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摘要

Transmitted pressure pulses in ultrasonic Bmode imaging systems are commonly characterized by their center frequency and bandwidth. Both parameters are associated with tradeoffs in spatial resolution and signal-to-noise in ultrasonic system design, with no general understanding of where they are optimal when applied to specific clinical exams. We use the ideal observer and simple psychophysical studies with human observers to evaluate the efficiency of information transfer in B-mode imaging as a function of the transmitted pulse center frequency and fractional bandwidth. Our approach uses a statistical model of backscatter relevant to breast imaging, and a 2-D model of pulse propagation based on Rayleigh-Sommerfeld diffraction theory. The statistics of the backscattered signal are combined in an ideal observer calculation that quantifies the task-relevant information contained in the radio-frequency (RF) signal after delay-andsum beamforming. This is followed by a psychophysical evaluation of observer performance on B-mode envelope-detected images in three simple tasks. This experimental design allows us to track the flow of diagnostic information through RF acquisition and subsequent reading of the envelope image. In a low-contrast detection task and a high-contrast boundary discrimination task, optimal efficiency for human observers is observed at the highest center frequencies tested (15 MHz) and at moderate bandwidth (40%). For detection of scattering material in a high-contrast hypoechoic lesion, optimal efficiency was observed at lower center frequencies (5 MHz) and higher bandwidth (80%). The ideal observer analysis shows that this task dependence does not arise in the acquisition stage, where efficiency is maximized at 15 MHz with bandwidths of 60% or greater, but rather in the subsequent processing and reading of the envelope image. In addition, at higher frequencies more information is lost in the processing and reading than in the acquisition of reflecte- signals.
机译：超声Bmode成像系统中传输的压力脉冲通常以其中心频率和带宽为特征。这两个参数都与超声系统设计中的空间分辨率和信噪比之间的权衡有关，而对于将其应用于特定的临床检查时，尚无最佳的选择。我们使用理想的观察者和与人类观察者一起进行的简单心理生理研究来评估B模式成像中信息传输的效率，该效率取决于所传输的脉冲中心频率和分数带宽。我们的方法使用与乳房成像相关的反向散射统计模型，以及基于瑞利-索默菲尔德衍射理论的脉冲传播二维模型。反向散射信号的统计信息在理想的观察者计算中进行了合并，该计算可量化延迟和求和波束成形后射频（RF）信号中包含的与任务相关的信息。接下来是在三个简单任务中对B模式包络检测图像上的观察者性能进行心理生理评估。这种实验设计使我们能够通过RF采集和随后读取的信封图像来跟踪诊断信息的流向。在低对比度检测任务和高对比度边界判别任务中，在最高测试中心频率（15 MHz）和中等带宽（40％）下，观察者的观察者可获得最佳效率。为了检测高对比度低回声病变中的散射物质，在较低的中心频率（5 MHz）和较高的带宽（80％）下观察到最佳效率。理想的观察者分析表明，这种任务依赖性在采集阶段不会出现，在采集阶段，带宽在60％或更高时，效率在15 MHz时最大，而在随后的信封图像处理和读取中。另外，在较高的频率下，与获取反射信号相比，在处理和读取中丢失的信息更多。

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