Application Of Adaptive Statistical Iterative Reconstruction V(AsiR-V) Combining With Low Tube Voltage And Low Contrast Dosage In Coronary CTA

Part 1 Effects of different pre-ASiR-V and post-ASiR-V weights on radiation dose and image quality of coronary CTAObjectiveTo investigate the comparative study of different pre and post multi-model-based iterative reconstruction（ASiR-V）algorithms on image quality and radiation dose in coronary CT angiography（CCTA）,and to determine the optimal pre-ASiR-V and post-ASiR-V weights.MethodsThe first part of the experiment was completed in two sections.Section I:180patients undergoing CCTA were prospectively enrolled in the study and randomized to 6 groups（A,B,C,D,E and F）,scanned using 0%,20%,40%,60%,80%and100%pre-ASiR-V weights,and reconstructed using 60%post-ASiR-V weights in each group;The dose length product（DLP）,CT dose index volume（CTDIvol）were recorded for all patients.The CT values,standard deviation（SD）,contrast-to-noise ratio（CNR）and signal-to-noise ratio（SNR）of the aortic root（Ao）,left main artery（LMA）,right coronary artery（RCA）opening,proximal segment of the left circumflex artery（LCX）,proximal segment of the left anterior descending artery（LAD）and left anterior pectoralis muscle were recorded and calculated according to the formula.Subjective image quality was assessed using a 4-point scale.After statistical analysis,the optimal pre-ASiR-V weight group was optimized.Section II:The images of the best pre-ASiR-V weight group（group D）obtained in section I were post-reconstructed from 0%to 100%post-ASiR-V with 20%interval to obtain 6different subgroup images（D₁,D₂,D₃,D₄,D₅,D₆）,and the CT value,SNR,CNR and SD of the vessels in each group were recorded and evaluated objectively and subjectively to optimize the post-ASiR-V weights with optimal image quality.Results1.with the increase of pre-ASiR-V weights the effective dose（ED）values gradually decreased.Compared with group A,the ED values of groups B～F decreased by 4.14%,6.55%,11.7%,15.52%,16.55%,respectively.The ED values of group A were not statistically different from those of groups B（P=0.855）and C（P=0.441）,and from those of groups D（P=0.013）,E（P=0.000）,and group F（P=0.000）were statistically different,and there was no statistical difference between groups D,E and F（P=0.132）.2.SD,SNR and CNR were statistically different among groups A～F,with the lowest SD in LMA,LAD proximal segment,LCX proximal segment and RCA proximal segment in group D;vascular SNR and CNR were at high and higher values in groups C and D.With the change of post-ASiR-V weights,the SD in groups D₁to D₆generally decreased with the increase of posterior grading weights,and SNR and CNR increased with the increase of weights.3.There was no significant difference in the subjective evaluation of images in groups A～F with different pre-ASiR-V weights（F=0.577,P=0.717）,and the highest score was（3.37±0.72）when the pre-ASiR-V was 60%（group D）;there was also no statistical difference in the subjective evaluation of images in groups D₁～D₆with different post-ASiR-V weights（F=1.257,P=0.285）,and the highest image quality score was（3.47±0.68）when the post-ASiR-V was 80%（group D₅）.ConclusionRevolution CT at 100 k Vp with a noise index of 11,combined with 60%pre-ASiR-V and 80%post-ASiR-V can significantly reduce the radiation dose received by the patients and significantly reduce the image noise level while obtaining high quality images.Part 2 Clinical application of adaptive statistical iterative reconstruction V（ASiR-V）combining with low tube voltage and low contrast media dosage in CCTAObjective To discuss the application of ASiR-V combined with low tube voltage and low contrast media dosage in CCTA.Methods Prospectively,90 patients with suspected coronary artery disease in our hospital were collected and randomly divided into three groups: control（group A）,experimental（group B）and experimental（group C）.Group A was reconstructed using tube voltage 120 k Vp,0% pre-ASiR-V scan and filtered back projection（FBP）with a contrast injection protocol of 1.0 ml/kg.Group B used 120 k Vp,60% pre-ASiR-V scan and 80% post-ASiR-V reconstruction with a contrast injection regimen of 1.0 ml/kg.Group C used 100 k Vp,60% pre-ASiR-V scan and 80% post-ASiR-V reconstruction with a contrast injection regimen of 0.8 ml/kg.The remaining parameters were unchanged.The CT values and standard deviation（SD）of each vessel and left anterior pectoral muscle were recorded for the three groups of patients,and the standard deviation was the noise,In addition,each patient’s CTDIvol,DLP was recorded.Contrast dosage,SNR,CNR and ED were calculated according to the formula.Two experienced physicians used a double-blind method to assess image quality.Kappa test was used for inter-physician agreement evaluation.Results1.There was no significant difference in the gender comparison between the three groups of Group A,Group B and Group C（（?）2=4.916,P=0.086）;there was also no significant difference in the distribution of general information age,weight,height and BMI between the three groups（P=0.964,P=0.328,P=0.090,P=0.198）.2.There was a significant difference in aortic and coronary CT values between group A and groups B and C（P values were 0.000,0.000,0.003,0.003,0.000,respectively）.After multiple comparisons,the differences between the CT values of each vessel in groups A and B were not significant（P values were 0.972,0.582,0.588,0.247 and 0.339,respectively）,and the differences between the CT values of vessels in groups A and C and in groups B and C were statistically significant（P values were0.000,0.000,0.008,0.024,0.000,0.000,0.000,0.002,0.001,0.000,respectively）.3.The SD in the aorta root was（39.20±8.64）,（22.77±4.81）and（25.77±4.6）,（F=57.981,P=0.000）in group A versus group B and group C,respectively;and in the right coronary artery was（37.92±14.32）,（26.73±12.38）and（30.80±12.86）,（F= 5.655,P=0.049）;（30.68±8.34）,（22.75±12.03）and（23.16±10.08）,（F=5.420,P=0.006）,respectively,for the left main trunk;（38.60±16.67）,（27.41±14.31）and（30.11±17.49）,respectively,for the anterior descending branch,（F= 3.911,P=0.024）;the circumflex branch was（44.10±14.95）,（32.93±13.46）and（35.91±14.45）,（F=4.909,P=0.010）,respectively.After multiple comparisons,it was revealed that there was a significant difference in the SD of blood vessels between group A and group B,and between group A and group C（P values were 0.000,0.001,0.004,0.009,0.003,0.000,0.037,0.007,0.045,0.029,respectively）,while the difference in SD between group B and group C was not significant（P values were 0.068,0.231,0.881,0.520 and 0.422,respectively）.4.The SNR in the aorta was（12.98±3.21）,（21.88±4.17）and（21.91±3.29）,（F=61.916,P=0.000）in group A versus group B and group C,respectively;and in the right coronary artery was（15.54±5.34）,（21.01±13.57）and（19.42±9.28）,（F= 4.669,P=0.012）;（16.17±5.24）,（25.07±12.12）and（26.28±11.41）,（F=9.006,P=0.000）,respectively,for the left main trunk;（14.21±4.88）,（18.53±8.97）and（19.41±10.42）,respectively,for the anterior descending branch,（F= 3.277,P=0.042）;the circumflex branch was（10.88±4.13）,（15.10±7.95）and（16.13±7.85）,（F=4.902,P=0.010）,respectively.After multiple comparisons,there was a significant difference in SNR values between group A and group B,and between group A and group C（P values were 0.000,0.004,0.001,0.049,0.020,0.000,0.014,0.000,0.019,0.004,respectively）,while the difference between group B and group C was not statistically significant（P values were 0.980,0.672,0.643,0.687 and 0.564,respectively）.5.The CNR in the aorta was（11.47±2.88）,（19.49±3.83）and（19.53±4.95）,（F=58.208,P=0.000）in group A versus group B and group C,respectively;and in the right coronary artery was（11.82±4.63）,（18.07±11.62）and（17.20±8.2）,（F= 4.595,P=0.013）;（14.20±4.71）,（21.61±10.17）and（23.23±10.30）,（F=9.005,P=0.000）for the left main trunk;（13.01±5.15）,（17.23±2.56）and（17.15±9.06）for the anterior descending branch,（F= 3.162,P=0.047）;the circumflex branch was（9.43±3.57）,（12.88±6.87）and（14.13±6.85）,（F=4.986,P=0.009）,respectively.After multiple comparisons,it was revealed that there was a significant difference in vascular CNR values between group A and group B,and between group A and group C（P values were 0.000,0.006,0.002,0.031,0.028,0.000,0.010,0.000,0.034,0.003,respectively）,while the difference in CNR values between group B and group C was not significant（P values were 0.690,0.847,0.475,0.966 and 0.422,respectively）.6.CTDIvol was（23.88±2.40）m Gy,（21.42±1.39）m Gy and（16.70±3.79）m Gy in groups A and B and C,respectively,（F=54.273,P=0.000）,with a reduction of approximately 10.30% and 30.07% in groups B and C,respectively,and a reduction of approximately 22.04% in group C compared to group B.DLP was（275.36±28.05）m Gy·cm,（235.15±18.97）m Gy·cm and（182.52±28.66）m Gy·cm,respectively,（F=98.864,P=0.000）,a decrease of about 14.60% and 33.72% in groups B and C,respectively,and a decrease of about 22.38% in group C compared to group B.ED was（3.85±0.39）m Sv,（3.29±0.27）m Sv and（2.56±0.40）m Sv,respectively,（F=98.912,P=0.000）,with about 14.55% and 33.51% reduction in groups B and C,respectively,and about 22.19% reduction in group C compared to group B.7.Contrast agent dosage in group A,group B and group C was（65.3±10.05）ml,（66.73±9.88）ml and（50.63±7.85）ml,respectively,and there was a statistical difference（P=0.000）between group A,group B and group C.Compared with group A and group B,the dosage was reduced by 20% in group C.8.The subjective scores of the three groups were（3.17±0.75）,（3.40±0.72）,and（3.37±0.73）in group A versus group B and group C,respectively,with no significant difference in subjective scores between the three groups（F=0.897,P=0.411）.There was good agreement between the two physicians on subjective scores of image quality with a Kappa value of 0.775.Conclusion Low tube voltage and low contrast agent dosage combined with pre and post ASiR-V can significantly reduce coronary CTA radiation dose and contrast agent dosage,while obtaining image quality that meets clinical diagnosis.