Figure 2

Flowing spins within the off resonance field are positively tagged as delay times are increased from 0 s (a) to 0.4 s (b) to 0.8 s (c), visualizing flow along the femoral vein. To compensate for T1 recovery during the delay time, 3D images acquired with a saturation bandwidth of 2 kHz were subtracted from those acquired with a saturation bandwidth of 100 Hz (a2, b2, c2), enhancing the tagged spins. The off-resonant frequency band around 400 Hz is clearly affected by the fat saturation pulse (red arrow, a3-c3). The same T1 compensation was also applied to fat suppressed images (a4-c4). Note that the fat suppression is played out before the acquisition and would not affect the flowing tagged spins relocated away from this specific fat saturation frequency band.