Fig. 1.

Injection protocol and timing characteristics for dual-contrast agent enhanced multi-phase SPCCT of the liver. The portal venous phase is reached within T₃ (~70 s) following CA injection in humans, whereas the exact time point of arterial distribution (T₁–T₀) depends on the individual patient blood flow. For dual-contrast SPCCT imaging, synchronised portal venous distribution of CA1 and arterial distribution of CA2 at one time point is necessary (= T₃). The sequence is started at T₀, where CA1 is injected. At T₃, CA1 shows a portal venous distribution. The time period T₁–T₀ defines the time necessary for enhancement in arterial phase. Then, CA2 is injected at T₂ to assure arterial phase of CA2 at T₃. At T₃, the SPCCT scan is performed, with an arterial distribution of CA2 and a portal venous contrast of CA1. Blue dotted line, arterial distribution of CA1; blue line, portal venous distribution of CA1; red line, arterial distribution of CA2