| Part I Feasibility of prospectively ECG-gated DSCT coronary angiography.Objective:Explore the feasibility of prospectively ECG-gated DSCT coronary angiography.Methods Five hundred patients[Body mass index(BMI):22-26 kg/m2, with stable HR, range from 47 bpm to 126 bpm,HR≤75 bpm 300 patients, HR>75 bpm 200 patients] with suspected or known coronary artery disease underwent retrospectively ECG-gated helical DSCT coronary angiography. Grouping them into 6 groups separately according to the average HR of scanning.HR≤75 bpm (group A—F):Group A 34 patients:HR≤50 bpm, Group B 47 patients:51-55 bpm, Group C 51 patients:56-60 bpm, Group D 62 patients:61-65 bpm, Group E 60 patients:66-70 bpm, Group F 46 patients:71-75 bpm;HR>75 bpm (group a—f):Group a 47 patients:76-80 bpm, Group b 41 patients:81～85 bpm, Group c 33 patients:86-90bpm, Group d 30 patients:91-95bpm, Group e 27 patients:96～100 bpm, Group f 22 patients:HR≥101 bpm;Images were reconstructed from 24% to 77% of the R-R interval in 3% increments. Two independent readers assessed the overall image quality on a four-grade scale and determined the optimal reconstruction windows of each coronary segment and the ranges. Coronary arteries were segmented according to the guideline of the American Heart Association (AHA). The degree of inter-observer agreement was determined by Kappa statistics. Then analyze the agreement of the optimal reconstruction windows in the same group.Results The optimal construction windows in 4112 segments out of 4176 segments in group (A-F)were concentrated in 71%, ranged from 65%—77%. In group A, the optimal reconstruction windows of 2.31%,4.83%,91.81%,1.05% of segments were 77%,74%,71%,68%, respectively;In group B, the optimal reconstruction windows of 3.32%,5.59%,84.89%,6.19% were 77%,74%,71%, 68%, respectively;In group C, the optimal reconstruction windows of 3.24%, 4.79%,86.60%,5.36% were 77%,74%,71%,68%,respectively;In group D, the optimal reconstruction windows of 3.15%,8.18%,81.89%,5.37%,1.40% were 77%,74%,71%,68%,65%,respectively;In group E,the optimal reconstruction windows of 2.63%,7.89%,81.00%,6.33%,1.08%,0.84%,0.24% were 77%,74%,71%,68%,65%,44%,41%,respectively;In group F,the optimal reconstruction windows of 2.52%,6.60%,74.06%,4.87%,3.30%,1.89%,5.50%,1.26% were 77%,74%,71%,68%,65%,44%,41%,38%, respectively.The optimal construction windows in 2605 segments out of 2742 segments in group(a-f)were concentrated in 41%,ranged from 35%—47%.In group a,the optimal reconstruction windows of 1.27%,0.95%,9.65%,58.23%,16.61%,2.22%,7.12%,3.96% of segments were 50%,47%,44%,41%,38%, 74%,71%,68%,respectively;In group b,the optimal reconstruction windows of 8.35%,71.05%,12.97%,1.24%,4.44%,1.95% were 44%, 41%,38%,74%,71%,68%,respectively;In group c,the optimal reconstruction windows of 7.19%,79.30%,10.24%,1.96%,1.31%were 44%,41%,38%,71%, 68%,respectively;In group d,the optimal reconstruction windows of 6.60%,81.66%,10.76%,0.98% were 44%,41%,38%,71%,respectively;In group e,the optimal reconstruction windows of 3.97%,91.27%,4.76% were 44%,41%,38%,respectively;In group f,the optimal reconstruction windows of 3.65%,91.69%,4.65% were 44%,41%,38%,respectively.The image quality assessment has a high inter-observe agreement(Kappa=0.823). Conelusion The optimal reconstruction windows of patients with stable HR(≤75 bpm)can get diagno stic images which were concentrated in 71%, ranged from 65%-77%,and patients with stable HR(>75 bpm)can get diagnostic images which were concentrated in 41%,ranged from 35%-47% respectively.The prospectively ECG-gated DSCT coronary angiography can be used in patients with stable HR. Part II The clinical application of prospectively ECG-gated transverse DSCT coronary angiography.Objective:To compare patients with suspicion or known of coronary artery disease (CAD) image quality, diagnostic performance of prospectively and retrospectively electrocardiography (ECG)-gated dual-source computed tomography coronary angiography (CTCA) for the diagnosis of significant coronary stenoses and compare effective radiation dose between prospectively and retrospectively ECG-triggering and invasive coronary angiography (CAG).Materials and methods:Five-hundred patients [322male,178 female;mean age 62 10 years, range from 36 years to 85 years,body mass index(BMI):22-26 kg/m2] with stable heart rates were retrospectively enrolled between July 2008 and March 2011;Two-hundred patients with heart rate≤75bmp(group 1) and fifty patients with heart rate>75bmp (group 2)were examined with prospectively ECG-gated dual-source CTCA.In group 1,50 patients scanned with a single-phase sequential scan (group lA)and 150 patients with the a multi-phase mode(the adaptive sequential scan) (group 1B), group2 (HR>75bmp) with the adaptive sequential scan; Two-hundred patients (132male,68 female;mean age 60.2±8.5 years, range from 44 to82 years)with heart rate≤75bmp(group 3) and fifty patients (29male,21 female;mean age 58.4±8.5 years, range from 40 to79 years)with heart rate>75bmp (group 4) were examined with retrospectively ECG-gated dual-source CTCA.In group3(mean heart rates≤75bmp),full tube current was applied from 60% to 80%, In group4(mean heart rates>75bmp), from 27% to77% of the R-R interval. Coronary artery segments were assessed for image quality and significant luminal diameter narrowing. Sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), and accuracy of both CTCA groups were determined with conventional catheter angiography (CAG) as a reference standard. Radiation dose values were calculated. Results:The group 1 and groups 3,group 2 and group 4 were well matched and comparable for the presence of known CAD,gender,heart rate,heart rate variability,the Agatston scores and body mass index(BMI)(p>0.05).There was no significant difference in the rate of non-diagnostic coronary segments between group 1A(2.2%,16/721) and group 1B(1.5%,32/2192)(p=0.16), between group 1(1.6%,24/1404) and group 3(1.3%,39/2892)(p=0.36), between group 2(3.0%,21/709) and group 4(1.9%,17/718)(p= 0.49);Segment-based sensitivity,specificity,PPV,NPV,and accuracy were 98％, 99%,94%,99%,and 94.5% among group 1;96%,98%,93%,98% and 93.5% among group 2,98%,99%,95%,99%,and 94.6% among group 3,96%, 97%,94%,98% and 93.9% among group 4,respectively.Patient-based sensitivity, specificity,PPV,NPV,and accuracy were 97%,94%,95%,97%,and 92% among group 1;96%,91%,93%,96% and 89% among group 2,98%,93%,96%,97%, and 95% among group 3,96%,96%,87%,90%,96% and 85% among group 4, respectively.There was no significant differenceMean effective radiation dose of prospectively ECG-gated CTCA(heart rate≤75bmp 2.87±0.5 mSv;heart rate>75bmp group2 3.2±0.6 mSv)was significantly(p<0.0001)smaller than that of retrospectively ECG-gated CTCA (heart rate≤75bmp 10.6±0.9 mSv；heart rate>75bmp 10.4±0.7 mSv) and significantly(p<0.0001)smaller than that of invasive coronary angiography (CA)(9.1±1.0mSv).The effective radiation dose of patients scanned with a single-plti-phase mode(the adaptive sequential scan)(3.0±0.4 mSv).Conclusion:Prospective ECG-gated CTCA yields similar image quality and performs as accurately as retrospectively ECG-gated CTCA in patients having stable heart rate while being associated with a lower effective radiation dose.
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