Dual-venc 4D flow MRI can improve velocity-to-noise ratio (VNR) using a low-venc velocity map to provide a good VNR and a high-venc velocity map to correct the velocity aliasing. However, dual-venc 4D flow MRI significantly lengthens the scan duration to longer than the 10min delayed enhancement wait time and therefore it is difficult to take advantage of T1 shortening immediately after contrast injection. On the other hand, whole volume acquisition saturates blood signal and decreases SNR for 4D flow MRI, especially without contrast agent. Multi Thin Slab (MSLAB) 4D flow MRI acquisition technique provides bright blood imaging with improved SNR and motion robustness. Therefore, by combining dual-venc with MSLAB we propose a more accurate 4D flow method without requirement of contrast agent. In this study, we analyzed our proposed method in a pulsatile flow phantom in terms of VNR and performance in a volunteer.