[Purpose] Evaluating blood flow (FV or RI) using ultrasonography is a useful method for quantifying the blood flow dynamics of vascular access points (VA); however, it can only be applied to one blood vessel at a time. Therefore, the accuracy of such blood flow evaluations is expected to decrease if a branching blood vessel is located in front of a stenotic lesion. In this study, we examined the dynamics of FV and RI in cases in which branched vessels were located in front of stenotic lesions. [Subjects] The subjects were divided into the following 3 groups: the normal group (normal), stenosis or obstruction group (stenosis), and the stenosis or obstruction and branching blood vessel in front of the lesion group (stenosis+branch). [Methods] The proportion of cases involving lesions that were assigned to the stenosis+branch group was calculated. The mean FV and RI values of the 3 groups were compared. The discriminatory abilities of FV and RI to detect stenotic lesions were analyzed in the stenosis group and stenosis+branch group via ROC curve analysis. [Results & Discussion] The results showed that FV and RI were extremely useful for detecting lesions in the stenosis group, as reported previously. In the stenosis+branch group, the reliability of FV was extremely low. This study indicated that detecting stenotic lesions based on FV is difficult in cases in which a branching blood vessel is located in front of the lesion. In addition, it demonstrated that it is important to simultaneously acquire physical findings when evaluating VA with ultrasonography. We conclude that the results of this study should be considered when evaluating VA, in order to improve the accuracy of VA lesion detection.
