超音波画像の高分解能化のための位相コヒーレンス因子の効果の増強  [in Japanese] Enhancing effect of phase coherence factor for improvement of spatial resolution in ultrasonic imaging  [in Japanese]

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Abstract

<B>目的</B>:空間分解能は超音波画質を決定づける重要な要素の1つである.本研究では,個々のトランスデューサ素子から受信した超音波エコーの位相分散を用いた撮像法について,さらに分解能を向上させるための検討を行った.<B>方法</B>:受信した超音波エコー信号の位相分散から取得した位相コヒーレンス因子(phase coherence factor: PCF)を用いる位相コヒーレンス撮像法は,近年提案されたものである.この手法では,遅延和(delay-and-sum: DAS)ビーム形成により取得したPCFを用いて超音波RF信号を重み付けすることによって空間分解能が向上する.本研究では,空間分解能をさらに向上させるための指数PCF,高調波PCFおよびガウスPCFを提案する.<B>結果</B>:ファントムを用いた実験により,本研究において新たに提案したPCF撮像法の空間分解能を評価した.ストリングファントムから得られたエコーの横方向振幅分布の半値全幅は,2.61 mm(DASのみ),1.46 mm(従来のPCF),0.48‐0.62 mm(提案したPCF)であった.<B>結論</B>:本研究で新たに提案したPCFは,従来のPCFに比べて良好な空間分解能を示した.また,提案したPCFは従来のPCFに比べ,一様散乱媒質からのエコーの描出能が高かった.

<B>Purpose</B>: Spatial resolution is one of the important factors that determines ultrasound image quality. In the present study, methods using the phase variance of ultrasonic echoes received by individual transducer elements have been examined for improvement of spatial resolution. <B>Method</B>: An imaging method, i.e., phase coherence imaging, which uses the phase coherence factor (PCF) obtained from the phase variance of received ultrasonic echoes, was recently proposed. Spatial resolution is improved by weighting ultrasonic RF signals obtained by delay-and-sum (DAS) beam forming using PCF. In the present study, alternative PCFs, i.e., exponential PCF, harmonic PCF, and Gaussian PCF, have been proposed and examined for further improvement of spatial resolution. <B>Result</B>: Spatial resolutions realized by the proposed PCFs were evaluated by an experiment using a phantom. The full widths at half maxima of the lateral profiles of an echo from a string phantom were 2.61 mm (DAS only), 1.46 mm (conventional PCF), and 0.48-0.62 mm (proposed PCFs). <B>Conclusion</B>: The PCFs newly proposed in the present study showed better spatial resolutions than the conventional PCF. The proposed PCFs also realized better visualization of echoes from a diffuse scattering medium than the conventional PCF.

Journal

  • Choonpa Igaku

    Choonpa Igaku 45(1), 47-55, 2018

    The Japan Society of Ultrasonics in Medicine

Codes

  • NII Article ID (NAID)
    130006315391
  • Text Lang
    JPN
  • ISSN
    1346-1176
  • Data Source
    J-STAGE 
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