Abstract
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.