CTPA Image Quality Optimization Research In Patients With Different Body Mass Index

Objective To analyze the quality and radiation dose of CTPA in patients with different body mass index(BMI)in 80 k V,and evaluate the relevance rate of CT value,noise and effective dose with body weight,body mass index(BMI),lean body mass(LBM),body fat weight and body fat rate.Methods The patients who were suspected of pulmonary embolism and required CTPA examination were divided into mild(BMI ?18.5 kg / ?),normal(18.5 kg / ? <BMI <25 kg / ?),overweight(25 kg / ?)and obesity(BMI?28 kg / ?)groups,the value of CT pulmonary artery trunk and aorta,the right upper lobe artery and the right pulmonary vein,and the right upper lobe basilar artery and right lower lobe vein were measured,the mean pulmonary arteries CT values and the CT values rate of the pulmonary arteries and vine were calculated,and the differences of the pulmonary arteries CT values?noise?single to nosie(SNR)and contrast-to-noise ratio(CNR)between the four groups were compared,and the relationship between the pulmonary arteries CT values?noise?radiation dose with body weight?BMI? LBM?body fat and body fat rate.Results The pulmonary arteries CT values?noise?SNR?CNR and radiation dose in different BMI groups were statistically significant(P <0.05).There were generally negative correlation in body weight?BMI?LBM?body fat and body fat rate with pulmonary artery CT value,among them,the weight correlate greatly with pulmonary artery CT value(R =-0.500),but the correlation coefficient was statistically significant(P <0.05).There were a positive correlation in body weight?BMI?LBM?body fat and body fat rate with the noise and effective dose,the correlation coefficient was general in noise,was strong in effective dose(r=0.481,r=0.746),and the correlation coefficient was statistically significant(P <0.05).Conclusion With the increase of BMI in patients in CTPA,the quality of images is reduced in different degrees,the radiation dose of patients recived is increased in different degrees,especially in obese patients,and 80 k V is suitable for such patients.Therefore,in obese patients with CTPA examination,it is important to pay attention to the choice of the low voltage and appropriate image after reconstruction to ensure the image quality under the premise of minimizing the radiation dose of patients received.In addition,among the many factorsrelat to body,the weight greatestlly impact on the pulmonary artery CT value and the effective dose,BMI maximumly impact on the image noise.Objective To compare the CTPA image quality and radiation dose of obese patients with different reconstruction methods(FBP,i Dose1,i Dose3,i Dose5)under 80 k V and 120 k V conditions,so as to explore the greatest way to optimize CTPA image quality and radiation dose of obese patients.Methods Obese patients(BMI?28 k)with clinical suspected pulmonary embolism and required CTPA examination were enrolled,the CT value of pulmonary artery trunk and aorta,the right upper lobe artery and the right pulmonary vein,and the right upper lobe basilar artery and right lower lobe vein were measured,the mean pulmonary arteries CT values and the CT values rate of the pulmonary arteries and vine were calculated,and the differences of the pulmonary arteries CT values?noise?single to nosie(SNR)?contrast-to-noise ratio(CNR)and radiation dose between 80 k V and 120 k V with same reconstruction method are compared by using the t-test,and comparing the the CT value of pulmonary artery ?noise ?SNR and CNR of different reconstruction algorithms in same k V are compared by using the variance analysis.Results There were significant differences in CT value?noise ?CNRand radiation dose between 120 k V and 80 k V in the same reconstruction method(P <0.05),but there were no significantly differences in the CT value ratio of pulmonary arteriovenous and SNR(P> 0.05).There were significant differences in noise ?SNR and CNR of different reconstruction algorithms in same k V(P <0.05),but there were no significant differences in the CT value of pulmonary artery and the CT value ratio of pulmonary artery arteriovenous(P >0.05).Conclusion The 80 k V combine iterative reconstruction algorithm(i Dose3 or 5)can be used in obese patients with CTPA imaging,which not only improves the image quality compared with 120 k V,but also reduces the radiation dose of patients,but also makes up the disadvantages of increased image noise.