| Objective: Compare with standard prospective ECG gated and FBP reconstruction mode, analysis the coronary artery image quality and radiation dosage level of DSCT under dual energy with FBP and SAFIRE reconstruction. To evaluate the feasible of DSCT coronary artery imaging applying dual energy and low dose mode, to determine an appropriate ke V level and optimize the scanning protocol. Methods: Continuous collection 80 cases, all the patients underwent DSCT coronary artery angiography examination. The patients were divided into control group(group A) and experimental group(group B) by using the table of random number. Group A(40 cases) performed DSCT coronary artery angiography exam by using prospective ECG gated scan mode. Group B(40 cases) used dual energy as the scanning method. According to the different reconstruction arithmetic model, group B was divided into two groups. Group B1 used FBP reconstruction model while group B2 applied SAFIRE reconstruction model. All the scanning data acquired were sent to the reprocessing workstation for further evaluation. All the data were measured by one doctor who was engaged in the diagnosis of coronary artery image for more than 5 years, and the image quality analysis and evaluation were performed by two senior radiologists. Image evaluation includes the axial image and curved reconstruction. Statistical analyses were performed after the data collected. Result: Group A: the heart rate 54~62 times/min, BMI was located between 24~28kg/m2. Objective evaluation for image quality: Aortic CT value=(398.76±46.67)HU, SD value=(22.6±5.18)HU, SNR value=(17.6±3.2), CNR value=(22.1±3.6). The subjective image quality score:(476±0.09), radiation dose indexes CTDIvol(33.62±9.28) m Gy, DLP(473.2±52.06) m Gy *cm, effective radiation dose(6.6±0.7)m Sv; group B: heart rate=52~62 times/min, BMI was located between 24.2~28kg/m2; the subjective image quality evaluation: group B1: aortic CT value=( 438.2±38.3) HU, SD value=(18.6±3.86)HU, SNR values=(23.5±3.2), CNR values=(28±2.5), the subjective image quality score:(4.78±0.06); group B2: aortic CT value=(437.3±38.1)HU, SD value=(13.4±3.68)HU, SNR values=(32.6±2.1), CNR values=(39.2±2.3), the subjective image quality score:(4.84±0.05). There were significant differences in ke V, SNR, SD, CNR and CT value in B group(P<0.05), and in 75 ke V level had a high CT value and the CNR, SNR were the highest, while the noise(SD) was decreased. So 75 ke V was selected as the best purified ke V level. In group B, CTDIvol=(16.83±2.13)m Gy, DLP=(238.7±30.82) m Gy *cm, the effective radiation dose=(3.3±0.43)m Sv; the image quality objective evaluation: the CT value, SNR value and CNR value were significantly higher than those in group, the SD value was lower than group A, There were significant differences in these index(P<0.05); The SNR value and CNR value of group B2 were significantly higher than those in group B1, the SD value was significantly lower than that in group B1(P<0.05). Subjective evaluation of image quality: group B2 and B1 group, A group, there were statistically significant among group B2, group B1 and Group A(P<0.05), the segment score of B2 group was superior to other groups. Radiation dose comparison: the CTDIvol value and DLP value of group B were significantly lower than that in group A(P<0.05), The ED value of B group was significantly lower than that of A group(P<0.05). Conclusion: Using SAFIRE combine with purified single spectrum technique can significantly improve the image quality and reduce radiation dose in the coronary artery imaging. The best single energy level is 75 ke V. |
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