The application of low concentration of contrast agent combined with low tube voltage in CT pulmonary angiography

Abstract

Objective To evaluate the feasibility and value of using dilute iodine contrast agent combined with low tube voltage in CT pulmonary angiography (CTPA) . Methods A total of 60 patients with clinically suspected pulmonary embolism were enrolled in this prospective study. All of them were divided into three groups (n=20) using a table of random numbers method, and then underwent CTPA (group A: 120 kV, auto mA, 350 mgI/ml, FBP algorithm; group B: 100 kV, auto mA, 280 mgI/ml, AIDR3D standard algorithm; group C: 80 kV, auto mA, 245 mgI/ml, AIDR3D strong algorithm) .In these three groups, CT volume dose index (CTDIvol) , pulmonary artery enhanced CT values, background noise, signal to noise ratio (SNR) , and the contrast to noise ratio (CNR) in each group were calculated. All of the data and the subjective scores of image quality for each group were compared. Results The average CT value in group A was significantly lower than that in group C (F=2.65, P 0.05) . The noise in group A was much higher than that in groups B and C (F=16.38, P 0.05) . Compared with groups B and C, SNR and CNR were lower in group A with statistically significant differences (F=17.17, 19.13, P<0.001) . There was no statistical difference of the CTDIvol and image quality scores among three groups. Conclusions In CTPA, the application of dilute iodine contrast agent combined with low tube voltage and AIDR3D reconstruction algorithm for all except obese patients can decrease radiation dose while meeting the diagnostic requirements of image quality, which has a good clinical application value. Trial registration Peking Union Medical College Hospital, PUMCH-PULMONARY DISEASES 2011BA11B17. Key words: Pulmonary angiography; Tomography, X-ray computed; Contrast media; Tube voltage