ABSTRACT
Objective To explore the feasibility of reducing the tube voltage to 80 kV,while ensuring the CT image quality for the diagnosis when the patients with high BMI (26 kg/m2≤BMI≤30 kg/m2)undergo coronary CTA examination,using low concentration isotonic contrast medium (270 mg I/mL)and iterative reconstruction techniques (SAFIRE-3).Methods Sixty patients with high BMI who underwent coronary CTA were randomly divided into group A and group B.Group A was set as"double low"group (n=30,tube voltage=80 kV),using SAFIRE-3 technology and 270 mg I/mL contrast agent.Group B was set as conventional group (n=30,tube voltage=120 kV),using filtered back projection (FBP)technology and 350 mg I/mL contrast agent.Adaptive cardio-sequence prospective ECG-gated technology (CorAdSeq)was applied in both groups,and the collecting phase was 65%-75% R-R interval (heart rate <75 beats per minute)or 40%-50% R-R interval(heart rate ≥75 beats per minute).Subjective and objective assessment methods were applied to evaluate the quality of images.The image quality and radiation dose of"double low"group was analyzed with conventional group as the control group.SPSS 1 9.0 software was applied for statistical analysis.The independent samples t-test was used to evaluate the differences among different measurements data.P<0.05 was considered statistically significant.Results The EDssde of group A [(1.124±0.314)mGy·cm]was significantly lower than that of group B [(3.542±0.797)mGy·cm],and the difference was statistically significant(P<0.001).The difference in noise between group A and B was statistically significant(P<0.05). The SNR and CNR in the group A were not lower than those in the group B and even the CNR in the partial coronary segment of the group A was higher than that in the group B,exhibiting statistically significant difference(P<0.05).Image quality index in the group A was higher than that in group B,and the difference was statistically significant (P<0.05).Conclusion Compared with conventional coronary CTA examination,"double low"coronary CTA examination in patients with high BMI (26 kg/m2≤BMI≤30 kg/m2)can acquire nice CT images suitable for clinical diagnosis and can significantly reduce the radiation dose and the amount of contrast agent.
ABSTRACT
Objective To explore the image quality and radiation dose for coronary angiography using DSCT (dual-source computed tomography) under lower tube voltage and lower contrast agent concentration ('double low').Methods A total of 160 patients with suspected coronary artery disease underwent dual-source CCTA.80 patients (BMI ＜ 25 kg/m2) were randomly assigned to group A (270 mg I/ml-80 kV) and B (350 mg I/ml-120 kV).The other 80 patients (25 ≤ BMI ＜30 kg/m2) were randomly assigned to group C (270 mg I/ml-100 kV) and D (350 mg I/ml-120 kV),sonogram affirmed iterative reconstruction technology and 270 mg I/ml contrast agent were applied to group A and C ; FBP technology and 350 mg I/ml contrast agent were applied to group B and D.Adaptive cardio-sequence prospective ECG-gated technology was applied in all patients,while the acquisition phase was 65％-75％ RR interval (when heart rate ＜ 75 beats / min) or 40％-50％ RR interval at when heart rate ≥ 75 beats/min.Volume CT dose index (CTDIvol),dose length product (DLP),effective dose (E),size specific dose estimates (SSDE),image noise,CT value,signal-to-noise ratio (SNR),and contrast-to-noise ratio(CNR) were all evaluated for each patient.Results There was not statistical difference in scan length among groups A and B,C and D.There was statistical difference in tube current between group A and B (t =8.932,P ＜0.05).There was not statistical difference in tube current between group C and D (tCD =-1.212,P ＞ 0.05).There was statistical difference in CTDIvol,DLP,E and SSDE between group A and B,C and D (tCTDIvol =-16.141,-11.440 ; tDLP =-17.454,-10.521 ; t =-17.444,-10.523 ;tSSDE =-13.032,-9.119,P ＜0.05).Compared to group B,the SSDE in group A decreased by 64.4％.Compared to group D,the SSDE in group C decreased by 39.3％.There was no statistical difference in image noise between group A and B,C and D (P ＞ 0.05).There was statistical difference in CT value,SNR and CNR between group A and B (t =0.436,4.623,3.272,P ＜ 0.05).There was no statistical difference in CT value and CNR between group C and D,while there was statistical difference in SNR between group C and D (t =2.981,P ＜0.05).There was no statistical difference in image quality scores between group A and B,C and D (P ＞ 0.05).Conclusion Compared with conventional DSCT coronary angiography,'double low' DSCT coronary scanning solution can significantly reduce the radiation dose and contrast agent,and could provide the effective coronary images which meet the clinical diagnostic needs.
ABSTRACT
Objective To explore the feasibility of “double low ”(low tube voltage and low contrast agent concentration)imaging technology of dual-source computed tomography (DSCT)in coronary angiography for low-weight patients.Methods 60 patients (BMI≤25 kg/m2 )who underwent coronary CT angiography (CCTA)on DSCT scanner were divided randomly into 2 groups:group A was “double low”group (n = 30,tube voltage = 80 kVp,using sinogram affirmed iterative reconstruction technology and 270 mg I/mL concentration of contrast agent);Group B was conventional group (n=30,tube voltage=120 kVp,using filtered back projection technology and 350 mg I/mL concentration of contrast agent).Adaptive cardiosequence prospective ECG-gated technology (CorAdSeq)was applied in both the groups,The collecting phase was 65%-75% RR interval (when heart rate<70 beats per mi-nute)or 40%-50% RR interval (when heart rate≥70 beats per minute).Subjective and objective methods were applied to evaluate the image quality.The image quality and.radiation dose were compared between the “double low”group and the conventional group by using SPSS 1 9.0 software.The differences between measurement data were analyzed by using independent samples t-test.Results The effective dose with size specific dose estimates (EDssde)of group A(1.22±0.31)mGy/cm was significantly lower than that of group B (3.44±0.80)mGy/cm with P <0.001.Contrast-noise ratio,signal-noise ratio and CT value of group A were signifi-cantly higher than those of group B (all P <0.05 ).Conclusion Compared with conventional DSCT coronary angiography,“double low”DSCT coronary scanning proposal for low-weight patients can significantly reduce the radiation dose and the amount of contrast agent,and the image quality can meet the needs of clinical diagnosis.