- Prescribe a CT Perfusion study using the axial shuttle mode on the 8-cm section identified above. The perfusion study consists of two phases. The selected pelvic section is scanned every 2.8 s for 64.4 s (24 times) in the first phase and every 15 s for the next 120 s (8 times) in the second phase. The total duration of scanning is 184.4 s. The scanning parameters for both phases are: 120 kVp, 125 mA, 0.4 s rotation period, and 5 mm thick slices. All dynamic images will be reconstructed with adaptive statistical iterative reconstruction (ASIR) technique to reduce noise.