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在生物體內，血液流動的正常與否，足以影響各器官組織的運作，也提供我們研究心臟血管生理功能的參考。在目前所有的血流量測技術中，都卜勒超音波是最方便也最安全的一種，彩色都卜勒更是近十年來快速發展並廣泛應用的技術，成為目前心臟科臨床診斷上首要的檢查工具之一。
由於彩色都卜勒掃描的運算速度過慢，在得到一張血流區域的影像時，動脈血管內的血流流速輪廓(Velocity profile)已產生相當的變化。因影像左右兩側的血流流速並不是在同一時間取得，以致有彩色都卜勒超音波掃描的時間誤差(time distortion)問題。解決的方法，是利用心電圖得(ECG)訊號觸發超音波的探頭掃描，隨著每一次心跳週期，逐次延遲相對於ECG的探頭掃描起始時間，並利用多張掃描圖重組一張無時間誤差的掃描圖。重組的方法，可利用線性內插或弧線內插法來做修正。我們並針對二法之差異性加以比較。
根據研究結果顯示，時間誤差修正前後的流速輪廓可能有相當大的差異，在左心室出口道(LVOT)附近的血管截面，隨掃描方向自右而左可能有10%∼60%的流速誤差。一般而言，線性與弧線內插法修正的結果雖僅有些微差距，但在心室收縮期間，流速達到最高峰時，使用弧線內插法修正，應該有較佳的近似結果。
The blood flow is known to influence the action of organs in human bodies. It can also serve as an index for the study of cardiovascular functions. For measuring blood flow velocity, Doppler echocardiography is one of the most convenient and safe techniques. In the last decade, color Doppler flow mapping has been developed and applied extensively, and then become one of the major diagnostic tools in cardiology.
As the time consuming calculations for color Doppler scanning, the arterial blood flow velocity profiles have been altered because there is a significant time delay among different scanning lines in a color flow image. Time distortion in color Doppler echocardiogram exists because the velocities are not measured at the same time. To solve this problem, we used consecutively acquired color Doppler images to reconstruct a non delayed image. The color Doppler scanning for each frame was triggered by the QRS peak of ECG (electrocardiogram) signal of each heart beat, and an increasingly delayed time between the onset of sweep and the R-wave was made. Therefore, we could get a time-corrected profile from several consecutive flow maps by linear or spline interpolation. We also investigated the difference between these two methods.
In this research, we find a significant difference between the corrected and uncorrected blood flow velocity profiles. In the cross section of left ventricular outflow tract, there is 10%~60% difference in flow velocity viewing from right to left in the flow map following the sweep direction. There is no apparent difference found between the profiles corrected by linear and spline interpolation. Nevertheless, it should be a better estimation using spline interpolation when the flow velocity changes nonlinearly during the systolic cycle.
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