High temporal signal-to-noise ratio (tSNR) is desired for arterial spin labeling (ASL) methods. The tSNR of velocity-selective arterial spin labeling (VSASL) was limited in practice due to its sensitivity to error sources such as motion, eddy currents and diffusion effects. A novel VSASL strategy was invented to enable dual-module (dm-) VS saturation (VSS) and VS inversion (VSI) labeling for further improved SNR efficiency with VSASL. This study focused on the tSNR performance analysis and found the tSNR was doubled in gray matter using the new dm-VSASL. The explanation of such significant improvement was explored and validated by in vivo experiments.