FIG. 1.

Comparison of temporal signal-to-noise ratio (SNR) and frame-by-frame perfusion image series by three-dimensional (3D) background suppression (BS) GRASE and two-dimensional (2D) echo-planar imaging (EPI) pseudocontinuous arterial spin labeling (pCASL). Although mean cerebral blood flow (CBF) maps are comparable, the temporal SNR (tSNR) of 3D GRASE pCASL is approximately three times that of 2D EPI pCASL, resulting in reliable frame-by-frame perfusion image series, while large variations exist in 2D EPI pCASL image series.