彈性影像被廣泛應用於各種疾病的診斷，例如肝硬化、乳癌等。而皮膚與疤痕的彈性亦可作為臨床上重要的診斷指標。現有的臨床超音波量測儀器多使用低頻 (<15 MHz)超音波探頭追蹤剪切波波速並將其轉化為彈性值。低頻超音波探頭較難以得到高解析度的薄層組織影像。此外，多數過往的臨床研究未考慮薄層組織中的邊界效應，將使得剪切波波速的估算出現誤差，因此計算得到的彈性值亦有誤差存在。
在本研究中，我們使用外部震盪器產生橫向傳播的剪切波，並使用40 MHz高頻超音波影像系統追蹤剪切波的傳遞情況。考慮剪切波在薄層組中的頻散現象，我們分析剪切波的相速度並且結合萊姆波模型以估計疤痕之彈性。我們透過薄層仿體的實驗來驗證實驗架構和演算法的可行性，而其結果也表明此方法具有可靠性，且透過萊姆波模型估算出來的彈性比起傳統使用剪切波模型來的準確。此技術也被實際應用於臨床人體實驗，結果顯示此技術能呈現高解析度的灰階影像，並有效地分辨疤痕與正常皮膚的軟硬程度。此外，透過萊姆波模型估算彈性值可得到更為準確的結果。

Elastography has been widely applied on the diagnosis of many diseases, such as liver cirrhosis and breast cancer. Existing commercial ultrasound elastography systems utilize low-frequency (< 15 MHz) transducer to detect shear wave velocity and convert it to elasticity. The low-frequency transducer could not provide high resolution image for thin-layer tissues. Besides, most of the previous clinical studies did not consider the dispersion effect in the thin-layer tissue, which would lead the bias or errors for the estimation of shear wave. The calculated elasticity would be biased, too.
In this study, we used an external vibrator to generate shear wave within tissues and utilized a 40 MHz high-frequency transducer to detect the shear wave propagation. For thin layer tissue like skin, the dispersion effect should be considered. We analyzed the phase velocity of shear wave and applied Lamb wave fitting to estimate the elasticity of scar. Phantom experiments were conducted to validate the system setup and algorithm of this technique. Results showed that this technique is reliable and the estimated results were more accurate than the results estimated by shear wave model. This technique was also applied on several clinical cases. High resolution B-mode images could be obtained. The results showed that this technique could distinguish the stiffness of scar and normal skin. Besides, the elasticity estimated by Lamb wave model could be more accurate.

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