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Objective:To evaluate the image quality of dual-source computed tomography pulmonary angiography (DE-CTPA) with low-dose contrast agent using the advanced modeled iterative reconstruction (ADMIRE) method with 70 kVp and non-linear blending in overweight patients.Methods:Seventy patients (normal BMI, 35; overweight, 35) with suspected pulmonary embolization who underwent DE-CTPA between October 2018 and March 2019 were included in this study. The imaging protocol included assessments at 70 kV/sn150 kV with 30 ml of contrast agent, and images were obtained at 70 kVp and 150 kVp with and without linear blending. The CT value, SD value, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of pulmonary arteries were compared and analyzed among groups 1 (70 kVp, normal BMI), 2 (non-linear blending, normal BMI), 3 (70 kVp, overweight), and group 4 (non-linear blending, overweight). The radiation dose parameters included CT volume dose index (CTDI vol), dose length product (DLP), and effective dose ( E). Results:The CT values for the pulmonary artery did not show significant differences among the four groups ( P>0.05). The SD value of the segmental artery in group 1 was higher than that in group 4 ( t=2.69, P<0.05). The SNR values of the pulmonary artery trunk and sub-segmental artery in group 2 were higher than those in group 3 ( t=1.44, 5.40, P<0.05), while the corresponding value of the left pulmonary artery trunk in group 2 was higher than those in groups 3 and 4 ( t=1.52, 1.52, P<0.05). The CNR values of the pulmonary artery trunk and sub-segmental artery in group 2 were higher than those in group 3 ( t=1.45, 5.01, P<0.05) and that of the left pulmonary artery trunk in group 2 was higher than those in groups 3 and 4 ( t=1.50, 1.50, P<0.05). The E values for normal BMI and overweight patients were(1.60±0.54)mSv and(1.88±0.45)mSv, respectively. Conclusions:For overweight patients, the CTPA protocol using ADMIRE with a 70 kV/sn150 kV scanning mode could yield diagnostic image quality with significantly lower radiation and contrast material doses.
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Purpose To quantitatively evaluate the ability of advanced virtual monoenergetic technique (monoplus) in improving the display of pulmonary arteries with dual-source CT dual-energy pulmonary angiography.Materials and Methods Thirty patients whose CT values in pulmonary artery and its branches were lower than 300 HU in mixed images while image quality was poor in distal branches were enrolled in this study.All these patients underwent dual-source dual-energy (100/Sn140 kVp) CT pulmonary angiography (CTPA) with small amount of contrast medium (30 ml) from September 2016 to December 2016.Non-linear blending images were assigned in group A,100 kVp images from one tube were assigned in group B,and optimized monoenergetic images with low keV monoplus (40+,50+,60+ keV) were assigned in group C,D and E,respectively.CT and SD values of segmental,subsegmental and distal branches were measured,and signal noise ratio (SNR) and contrast noise ratio (CNR) were calculated.Results Among all the 5 groups,CT values of pulmonary artery in group C,D and E were significantly higher than in group A and B (P＜0.05).SNR values of segmental artery in group C were significantly higher than those in group A (P＜0.05).SNR values of subsegmental artery in group C and D were significantly higher than those in group A (P＜0.05).SNR values of segmental and subsegmental pulmonary artery in group C,D and E were all significantly higher than those in group B (P＜0.05).The SNR values of distal branches in group C,D and E were not significantly different from those in group A (P＞0.05),but were significantly higher than those in group B (P＜0.05).CNR values in group C,D and E were not significantly different from those in group A (P＞0.05),but were significantly higher than those in group B (P＜0.05).Conclusion Combined with dual-source dual-energy CT pulmonary angiography,low keV monoplus images can effectively increase CT values of pulmonary artery and clearly display the distal branches.Meanwhile,the image quality is comparable with non-linear blending images,better than that of low tube voltage (100 kVp) images.