Research On The Application Of The Iterative Reconstruction(iDose~4) And Prospective Scanning In Low Radiation Dose Scanning And Patients With High Heart Rate Of Computed Tomography Coronary Angiography

Objective To investigate the application value of iDose4iteration reconstruction andprospective ECG-gated scanning in low radiation dose scanning and patients with high heartrate of computed tomography angiography(CTA) in coronary artery.Methods Using256-slice CT,240patients were collected and randomly divided intotwo groups,the first group using retrospective ECG-gated scanning and reconstructed byiDose4, the second group using prospective ECG-gated scanning and reconstructed by bothiDose4and FBP.There is no patient was taken drug before scan.The patients of theprospective ECG-gated group were divided into four groups according to the heart rateincluding<70b/m（group A）,70-80b/m（group B）,80-90b/m（group C）,≥90bpm（groupD）.Compare the difference between iDose4iterative reconstruction and the FBPreconstruction on image noise, CT values, CNR, SNR in prospectively ECG-gated group；Compare the difference between prospective ECG-gated and retrospective ECG-gated onimage quality and radiation. The image quality of coronary artery in different heart rategroups of prospective ECG-gated were evaluated and compared.Results There was significant difference between iDose4iterative reconstruction andFBP reconstruction on image noise(P<0.05),And the image noise reduced up to42.2%underiDose4iterative reconstruction；The CNR,SNR of right and left coronary artery bothimproved under iDose4iterative reconstruction of prospective ECG-gated group, there wassignificant difference between the two groups(P <0.05).There is no significant difference between prospectively ECG-gated group and retrospective ECG-gated group on imagequality(P>0.05), as well as the image noise, CT values, SNR, CNR of left and right coronaryartery；The effective radiation dose for the retrospective and prospective ECG-gated group is(5.5±1.8) mSv and (1.1±0.4)mSv,there was significant difference between the two groups (P<0.05),prospectively ECG gated group radiation decreased80.0%.In prospective ECG-gatedgroup, the image quality of coronary segments fulfilled the requirement of diagnosis in eachgroup was98.2%，96.6%，95.9%，81.1%；the image quality of coronary segments as excellentand good in each group was94.7%,89.9%,87.9%,73.9%.；Compared with group A, the imagequality of coronary segments as excellent and good in group B, group C,group D were bothdeclined, there was significant difference(P <0.05),the image quality of coronary segmentsfulfilled the requirement of diagnosis in group B, group C were declined compared withgroup A,but there was no significant difference(P>0.05)；the image quality of coronarysegments fulfilled the requirement of diagnosis in group D was declined compared withgroup A, there was significant difference(P <0.05).Conclusion1.iDose4iterative reconstruction can reduce image noise, improve imageSNR and CNR in CTCA of prospective ECG-gated.2. iDose4iterative reconstruction and prospective ECG-gated scanning can maintain optimalimage quality and substantially reduce radiation doses.3. The prospective ECG-gated scanning in CTCA with256-slice CT can used in patientswith high heart rate.