We have previously proposed the use of acoustic microbubble delivery in blood vessels to improve the efficacy of acoustic targeted drug therapy. The technical requirement is the detailed visualization of the blood vessel network (BVN) for navigation around a target such as a tumor. To obtain the accurate shape of BVN for this purpose, we have experienced a problem of expansion and deficiency in 3D Doppler-mode volumes. Therefore, we have proposed a new BVN reconstruction method by fusing B-mode and Doppler-mode volumes, which were acquired simultaneously in the same coordinate space, considering the weight coefficient in each volume. In this presentation, we introduce the accuracy improvement to extract the weight coefficients.