一般而言，評估內皮細胞需應用Flow- mediated dilatation (FMD)的方法，藉由在手臂或上臂給予約200mmHg的壓力，觀察血管阻斷後恢復之管徑擴張變化。傳統使用高解析度的超音波儀器並搭配2D彩色影像顯示軟體來觀察因FMD所引起的血管直徑改變，雖然許多學者認會此方法具有較好準確性跟重現性，是目前醫院最常使用的量測方法，但高價格與需要專業人士操作則是FMD的兩大缺陷。因此本研究採用光體積變化描記圖(Photoplethysmography，PPG)綠光來評估內皮情況，讓大家可以方便地隨時偵測自己的內皮情況是此研究的目標。 ;In past years the mortality caused by cardiovascular diseases (CVD) ranked high in top one causes mortality in Taiwan, clinical signs including atherosclerosis, high blood pressure, endothelial dysfunction etc. With medical progress and discovery of NO, we have further understanding of the cause of CVD and atherosclerosis. And vascular endothelial injury leading to vascular inflammation induces atherosclerosis. Therefore how to assess the endothelial function to prevent CVD is an important part of home care. Because of endothelial function is a reversible reaction . Then we could recover endothelial function by changing habits, like quit smoking, exercise, and diet. Hormone replacement therapy and medicine are also the solutions . Generally, the common approach to endothelial function assessment is Flow- mediated dilatation (FMD). FMD is the method by boosting to 200mmHg on arm and observing vascular diameter after blocking blood vessels. FMD ratio was defined by BAUS as the ratio of the brachial artery diameter during reactive hyperemia relative to the baseline. Although it is generally considered that FMD has better accuracy and reproducibility, also FMD is commonly used by hospital. However there are two flaws: expensive and technical threshold. In this study, we use greenlight Photoplethysmography (PPG) to assess endothelial function. Creating a convenient way to assess endothelial function is the goal of this study.