使用光學解析度光聲顯微術之脈波速度量測: 可行性研究

Pulse-Wave-Velocity Measurement Using Optical Resolution Photoacoustic Microscopy: Feasibility Study

江長霖(Jiang, Chang Lin)

指導教授 ： 李夢麟

國立清華大學/電機資訊學院/電機工程學系所/碩士(2016年)

摘要

因為動脈硬化會造成脈波速度提升，所以脈波速度可以用來評估動脈硬化的程度。因此對於心血管疾病來說，脈波速度是一項很重要的指標性參數。除此之外，如果我們還知道血管壁厚度、血液密度等資訊，再搭配上脈波速度，便能估出血壓。
本研究利用光學解析度光聲顯微鏡的高對比、高解析度、非侵入式、能提供單一血管資訊等特性，來做為微細血管脈波速度量測的工具，並驗證其可行性。實驗方面，採用Foot-to-Foot的方法，來估計脈波速度。在小鼠耳朵上，分別在每條被選取不同直徑的動脈上選三個點。針對被選定的點，做定點式監控25秒。同時監控小鼠的心電圖，做為脈波從心臟到該點的時間依據，藉由兩點的血流速度(文獻上的方法)與總血紅蛋白變化(我們提出的參數)，估出的脈波在兩點傳遞的時間差，最後將已知的兩點距離除以傳遞時間差，便可得到脈波速度。在實驗中，改良數位類比轉換卡的接收處發來源，讓接收處發更準確，並降低血液流速估計的誤差。在訊號處理方面，補償心電圖的QRS複合波，使R波峰能取地更準確。在重複地幾次實驗後，我們發現藉由總血紅蛋白變化測量出的脈波速度，與藉由血流速度變化測量出來的脈波速度接近，證明了我們提出總血紅蛋白變化測量脈波方式的可行性。然而，我們測量出的脈波速度比文獻上測量出的結果還要小，我們檢查每一個實驗步驟與處理流程，發現了我們算出的血流速度與總血紅蛋白變化趨勢，相較文獻上算出的血流速度變化的趨勢是比較不整齊，且有較多雜訊。我們認為原因可能出在麻醉方式的不同，關於這部分需要再進一步的研究。

關鍵字

脈波速度 ； 光學解析度光聲顯微術

並列摘要

Because arterial stiffness cause pulse wave velocity (PWV) increase, pulse wave velocity (PWV) can assess the level of arterial stiffness. Therefore, pulse wave velocity is an important physiological parameter for cardiovascular diseases. In addition, if we also know the information of vascular wall thickness, blood density and so on, along with PWV, blood pressure can be estimated.
Optical resolution photoacoustic microscopy (OR-PAM) has the characteristic of high resolution, high sensitive, and can produce the noninvasive single micro-vessel image in vivo. It can provide single-vessel information and measure any position which we need in the small animal peripheral vasculature. Hence, we select OP-PAM to measure to PWV in single micro-vessel in small animals. We adopt Foot-to-Foot method to estimate pulse wave velocity (PWV). We scan respectively three points on a single micro-vessel on the mouse ear and record ECG simultaneously. With the variation of blood flow (proposed in the literature) and total hemoglobin concentration (HbT, proposed in this study), both of which can be accessed via OR-PAM, we can get estimate different time between the two measuring points. Finally, we can get PWV by the ratio of traveling distance to time difference between the two imaging points. In order to decrease trigger jitter which decreases the estimation accuracy of blood flow, photodiode triggering is performed. We also compensated the jitter with QRS complex wave of ECG profile. The order of PWV which was estimated by the variation of HbT was very close to the order of PWV which was estimated by the variation of flow speed. Therefore, the method which we proposed should be feasible. However, the order of PWV we estimated was wrong. We found the problem at our profile. Unlike the profile in the literature, our profiles were relatively noisy. We think that the reason may be different in the way of anaesthesia, which requires further study.

並列關鍵字

Pulse Wave Velocity ； Optical Resolution Photoacoustic Microscopy

參考文獻

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