Coronary Artery Imaging With 64-row MDCT In Heart Rate Fluctuation: Pulsating Cardiac Phantom And Clinic Study

Background:Coronary artery CTA had become a important method of CHD examination through technique improving.Using more firmer material elevated the rotate rate of CT tube significantly,even 0.33s/r,it elevated the temporal resolution of MDCT.More broader detector enlarged the field of Z-axle,decurtating scan time significantly.Those and new software could reach a clear coronary artery image of in-moving heart.Although MDCT had elevated it's temporal resolution,most reasons influencing on coronary artery CTA have being there,such as heart rate fluctuation that was a challenge of coronary artery CTA.We must solve the influence of heart rate fluctuation on the image quality of coronary artery CTA.Our study explored the influence of heart rate fluctuation on the image quality of coronary artery CTA and to find some methods.The first part:Experiment study onePurpose Heart rate fluctuation is an important reason degrading cardiac image quality. The purpose of this study is to estimate the influence of heart rate fluctuation on coronary artery image quality using pulsating cardiac phantom.Materials and Methods:A novel pulsating cardiac phantom was made up of driver component, phantom component and control component.Phantom component included a chamber to simulate LV and eight simulated coronary arteries(3-5mm inner diameter, normal/with stent/in-stent restenosis/stenosis).There were two groups heart rate fluctuation:one group heart rates were 60bpm,60bpm±2.5bpm/±5bpm/±7.5bpm /±10bpm/±12.5bpm/±15bpm;the other group heart rates were 85bpm,85±2.5bpm /±5bpm/±10bpm/±15bpm.The cardiac phantom was scanned by 64-row MDCT(GE, LightSpeed VCT,0.35s/r) and reconstructed with multi-sector reconstruction algorithm at 70%R-R phase.The simulated coronary artery images were divided into four equidistance segments and estimated using four-point scale(4=clear coronary artery,3= slight blurring but without interruption,2=moderate blurring or interruption,1=severe blurring or interruption and can't be identified).Pearson correlation test and two-independent t-test were performed with SPSS statistical package.Results:The mean score of basic heart rate 60bpm group was 3.68±0.48,that of basic heart rate 85bpm group was 2.84±0.60,t-test showed a significant difference(p＜0.01) between two groups.Pearson correlation test showed that there was a significant negative correlation(p＜0.01) between the score of the coronary artery image quality and heart rate fluctuation,correlation coefficient was -0.25 at basic heart rate 60bpm (p＜0.01)and -0.56 at basic heart rate 85bpm(p＜0.01).Conclusion:There is a significant negative correlation between coronary artery image quality and heart rate fluctuation.Lower basic heart rate allows a higher heart rate fluctuation.Reducing basic heart rate has a potential to improve coronary artery image quality when heart rate fluctuation existing.Experiment study twoPurpose:To estimate the effect of different cardiac reconstruction algorithms on coronary artery image quality when existing heart rate fluctuation using a pulsating cardiac phantom.Materials and Methods:A pulsating cardiac phantom was made up of a chamber to simulate LV and eight simulated coronary arteries.The heart rate fluctuation was divided into two groups:one group were 60bpm,60±2.5/±5/±7.5 /±10/±12.5/±15bpm;the other group were 85bpm,85±2.5/±5/±10/±15bpm.The cardiac phantom was scanned by 64-row MDCT(GE,LightSpeed VCT,0.35s/r) and reconstructed with single-sector,multi-sector and de-banding reconstruction algorithm at 70%R-R phase.The simulated coronary artery images were divided into four equidistance segments and estimated using four-point scale(4=clear coronary artery,3= slight blurring but without interruption,2=moderate blurring or interruption,1=severe blurring or interruption and can't be identified).Paired-simples t-test was performed with SPSS statistical package.Results:The mean score with different reconstruction algorithms were:basic heart rate 60bpm group:3.75±0.43 for single-sector,3.68±0.48 for multi-sector and 3.97±0.16 for de-banding;basic heart rate 85bpm group:2.76±0.60 for single-sector,2.84±0.60 for multi-sector and 3.24±0.61 for de-banding.T-test showed there were significant difference between de-banding and multi-sector, de-banding and single-sector at 60bpm group(P＜0.05),de-banding and single-sector, de-banding and multi-sector at 85bpm group(P＜0.05).In addition,there was a significant difference between two basic heart rates with the same reconstruction algorithm(P＜0.05).Conclusion:For different cardiac reconstruction algorithms,the lower basic heart rate could achieve the better coronary artery image quality when heart rate fluctuation existing.At low basic heart rate,de-banding reconstruction could improve image quality significantly,While at high basic heart rate,de-banding got a best Banding Artifact score too.The second part:Clinical studyPurpose:To estimate the effect of De-banding algorithm reconstruction on image quality of 64-row MSCT coronary artery angiography.Materials and Methods:100 patients with good holding breath underwent 64-row MDCT coronary artery angiography,De-banding algorithm reconstruction and Multi-sector algorithm reconstruction were performed,data reconstruction used VR(volume rendering) and CPR(curved planar reformation).Using VR and CPR estimated Banding artifact,using axial images estimated Motion artifact.Estimating standard of Banding artifact:RCA stem,LMA,LAD,LCX were divided into nine segments according AHA(American Heart Association) and related reference and estimated using five-piont scale(5=clear coronary artery,no banding artifact,4=between 5 and 3,3=slight blurring coronary artery banding artifact and can be identified,2=between 3 and 1,1=severe blurring coronary artery banding artifact and can't be identified).Estimating standard of Motion artifact:RCA stem,LMA,LAD,LCX were divided into nine segments according AHA(American Heart Association) and related reference and estimated using five-piont scale(5=clear coronary artery,no motion artifact,4=between 5 and 3,3=slight blurring coronary artery motion artifact and can be identified,2=between 3 and 1,1=severe blurring coronary artery motion artifact and can't be identified).t-test was performed with SPSS10.0 statistical package.Results:The mean score of banding artifact with De-banding algorithm reconstruction was4.21±0.16,the mean score of banding artifact with Multi-sector algorithm reconstruction was3.61±0.21.T-test showed a significant difference(p＜0.05).The mean score of motion artifact with Multi-sector algorithm reconstruction was3.58±0.19,the mean score of motion artifact with De-banding algorithm reconstruction was3.18±0.24.T-test showed a significant difference(p＜0.05). Conclusion:De-banding algorithm reconstruction could improve banding artifact of 64-row MDCT coronary artery angiography significantly,but could not improve motion artifact of 64-row MDCT coronary artery angiography.