Abstract：Objective: To evaluate the effect of injection rate, volume, and scanning direction on image quality of dual energy lung perfusion imaging using dual source CT (DSCT). Materials and Methods: Seventy-nine patients underwent DSCT examination from May to Aug. 2008. All patients were divided into six groups: group 1 to 3, contrast medium 300mgI/ml, dosage 1.5ml/kg, cranial to caudal direction, injection rate of 3, 4, 5ml/s: group 4, 5, contrast medium 300mgI/ml, dosage 1.5ml/kg, caudal to cranial direction, injection rate of 4ml/s, dosage 1.0 and 1.5ml/kg; group 6, contrast 350mgI/ml, scanning from caudal to cranial, dosage 1.2ml/kg, injection rate of 5ml/s. CT number on ascending aorta, pulmonary trunk, and superior vena cava were measured. Visualization scale of pulmonary artery and image quality dual energy lung perfusion imaging were recorded. Statistical analysis was performed using the software of SPSS 11.5 version. Results: Maximal pulmonary trunk enhancement and lowest superior vena cava enhancement were found in group 4 and group 6 with good image quality of dual energy lung perfusion imaging and pulmonary artery. Good interobserver agreement was found for dual energy lung perfusion imaging(Kappa value＝0.619, P＝0.000). Image quality of dual energy lung perfusion imaging correlated positively with pulmonary trunk enhancement. Radiation dose was decreased by 5.0% and 12.4% for dual energy mode, compared with conventional CT scan mode. Conclusions: Scanning protocols of group 4 and group 6 can provide better image quality of lung dual energy perfusion imaging; however, the parameters of group 4 are recommended for clinical routine use. Dual energy lung perfusion imaging has lower radiation dose than routine single source lung scan.
2009, Vol. 20 
