CT examination
The CT scanners were the GE64 VCT and Siemens Dual Source CT in Institution 1; Siemens Sensation 64CT and Philips iCT256 in Institution 2; and Siemens Sensation 64CT and GE Discovery CT750 in Institution 3. After a plain CT scan, an enhanced scan was performed. A high-pressure syringe was used to inject 1.5 ml/kg of non-ionic contrast agent (300 mgI/ml) at a rate of 3 ml/s through the antecubital vein. The scanning process included the arterial phase (25–30 s), venous phase (55–60 s), and equilibrium period (120 s). The slice thickness was 2 mm, the tube voltage was 120 kV, the tube current was 280 mA, and the rotation speed was 0.5 s per rotation.