Clinical Value Of 320 Row CT Low Dose Coronary Angiography In Evaluating Left Ventricular Function

The first part To evaluate the clinical value of 320 row CT low-dose coronary artery imaging in evaluating left ventricular function.Objective: To explore the clinical value of low dose scan 320 slice CT coronary angiography(320-CTCA)in evaluating left ventricular function.Using two-dimensional echocardiography(2DE)as the gold standard,we discussed the accuracy of 320-CTCA in evaluating left ventricular function.Methods: 97 cases who had suspected coronary heart disease and underwent 320-CTCA left heart function and 2DE examination within a week were collected continuously.There were 49 cases in males and 48 in females.The average age was 61.14 + 12.7 years old.320-CTCA left ventricular function examination was divided into routine scan group(47 cases)and low dose scan group(50 cases).The tube voltage of the routine scan group was 120 Kv and the scanning scope FOV was 16 cm and the low dose scan group selected different tube voltages according to the body mass index(BMI)(BMI?30kg/m2 used 120 Kv,20kg/m2<BMI<30kg/m2 used 100 Kv,BMI?20kg/m2 used 80Kv),the scanning scope FOV was adaptively selected among 12 cm,14cm and 16 cm according to the heart size.Using double blind 1-5 score(5 score divided into good image quality and 1 score undiagnosed)as the image quality score of the routine scan group and the low dose scan group.The dose length product(DLP)and the average volume CT dose index(CTDIvol)produced by each patient were recorded,and the effective radiation dose(ED)was calculated.Vertical sample t test was used to compare the difference of radiation dose produced by two scanning methods.320-CTCA left ventricular function examination was used to construct full cardiac cycle images at the interval of 10%R-R,and the software was used to calculate left ventricular end diastolic volume(EDV),end systolic volume(ESV),ejection fraction(EF),stroke volume(SV)and per minute output(CO)which were also calculated with 2DE.The consistency and correlation between the two methods were compared by paired t test and Pearson correlation analysis.Results: BMI,image quality score and ED were 23.70±3.51kg/m2,21.77±3.09kg/m2,4.23 ± 0.84 score,4.02±0.74 score,13.90 ± 8.17 mSv and 6.40 ± 4.34 mSv,respectively.There was no statistical difference of image quality score(t=1.332,P>0.05)and statistical difference of BMI and ED(t=2.970,5.127,P<0.05)between the two groups.The average effective radiation dose in the low dose scanning group was 53.9% lower than that in the conventional scan group.There was no statistical difference between 320-CTCA and 2DE in calculating EDV,ESV,EF and SV(t=1.020~1.803,P>0.05),and CO had statistical significance(t=3.441,P<0.05).The two methods of EF and SV were high correlation(r=0.851,0.816),and the correlation of ESV,EDV,CO was not high relatively.(r=0.490~0.732).Conclusion: With 2DE as the gold standard,320-CTCA can accurately and effectively evaluate the left ventricular function;the low dose scanning scheme of 320-CTCA left heart function examination can effectively reduce the radiation dose of the patients,and is more beneficial to the clinical CTCA one-stop left heart function examination.The second part Preliminary study on the changes of radiation dose assessed by low dose 320-CTCA and CTCA combined with left ventricular function Objective: To investigate the changes of radiation dose in low dose 320-CTCA and CTCA combined with left ventricular function.Methods: A total of 215 patients with suspected coronary heart disease and heart rate <80bpm and body mass index ranged from 20kg/m2 to 30kg/m2 were enrolled.There were 98 males and 117 females.106 cases were examined by 320-CTCA(group A)and 109 cases were examined with 320-CTCA left heart function(group B)using low dose scanning scheme.According to the patient's heart rate,the A group was divided into group A1: 51 cases,heart rate less than 65bpm;A2 group: 55 cases,65bpm< heart rate <80bpm;and B group was divided into B1 group: 56 cases,heart rate less than 65bpm;B2 group: 53 cases,65bpm< heart rate <80bpm.The quality of the images were scored by double blind 1-5 score(5 score divided into good image quality and 1 score undiagnosed).The dose length product(DLP)and the average volume CT dose index(CTDIvol)produced by each patient were recorded,and the effective radiation dose(ED)was calculated.Two independent sample t tests were used to compare the difference of radiation dose between the A1 group and the B1 group,the A2 group and the B2 group.Results: BMI,image quality score and ED of group A1,group B1,group A2 and group B2 were 24.76±1.95kg/m2,24.49±2.28 kg/m2,24.80±2.58 kg/m2,24.19±2.33 kg/m2,4.02±0.74 score,4.23±0.84 score,4.04±0.94 score,4.15±0.74 score,1.86±1.16 m Sv,3.69±2.35 m Sv,6.06±2.66 m Sv,7.47±2.52 m Sv.There was no statistical difference in BMI and image quality score between group A1 and group B1(t=0.653,-0.202,P > 0.05),ED had statistical difference(t=-4.919,P < 0.05),and B1 group was 98.4% higher than that of A1 group.There was no statistical difference in BMI and image quality score between group A2 and group B2(t=1.299,-0.700,P > 0.05),ED had statistical difference(t=-2.702,P < 0.05),and B2 group was 23.2% higher than that of A2 group.Conclusion: When the heart rate is less than 80 bpm,CTCA is required to increase the 1.41 m Sv ~ 1.83 m Sv radiation dose to complete the assessment of CTCA left heart function.The heart rate is less than 65 bpm,and CTCA needs to increase the radiation dose of about 98.4% to complete the assessment of CTCA left heart function;65bpm< heart rate <80bpm,CTCA needs to increase the radiation dose of about 98.4% to complete the assessment of CTCA left heart function.