Computed tomography imaging acquisition and reconstruction
CTPA was performed on a 128-slice single-source CT scanner system (SOMATOM Definition AS + , Siemens Healthcare GmbH). Scanning was performed in the cranio-caudal direction. A total of 60 ml iodine-based contrast agent (75% Imeron 350, Bracco, 25% NaCl 0.9%) was applied with a flow rate at 4 mL/s followed by a NaCl chaser bolus of 30 mL) with bolus tracking with the region of interest (ROI) within the pulmonary trunk. CTPA data was reconstructed with a slice thickness of 1.5 mm and an increment of 1.2 with a medium-sharp convolution kernel recommended by the vendor for CTPA (Bf37).