| Objective: To approach the most optimizing imaging parameters of coronary artery(CA) with 16 slice spiral CT and evaluate the applicative value of MSCT on the diagnosis of coronary artery diseases.Materials and methods: 37 cases of patients , collected from 2OO3.Dec to2OO5.Apr in our hospital, all suspected to have coronary artery disease(CAD) byclinical doctors. 24 male , 13 female, age range from 23 to 90 years, average 61.5 years.37 cases were underwent examination with Siemens SOMATOMSensation-16 multi-slice spiral computer tomography(MSCT).Preliminary experiment tested the best delay time, then examination wereperformed with electrtcardio-gating control,, and patients were required to hold theirbreath while scaning. scan range started from trachea bifurcation, end to cardiacapex, the volume data of CA were collected. Voltage was 120KV, current flow was500mAs, collimating apparatus width was lmm, field of view wasl3~15cmX13~15cm, speed of bed movement was 5.7mm while sucker spinal one wrap. Spintime was 0.42 second per wrap. Pitch was 0.24, convolution function was B30f, scantime about 15~25 second. When scan finished, the volume data of CA would transmitedto workstation to rebuild the image . the computer will reassociate differentphases(25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%,) in a cardiac cycle then aquired CA image in different phases. The best image would be chosen to evaluate the CA diseases. Grouped by heart rate, evaluate the quality of image. Use statistical analysis sofeware package(SPSS 10.0) to deal with the data. Rank-sum test were used to compare different sections.when p<0.05,means the difference is significant statistically.Results: there was statistical significant difference in the coronary imagequality in different heart rate groups(H= 10.4442, P=0.0018). the imagequality was excellent when the heart rate no more than 65 times per minute.There was not statistical significant difference in the image quality of the LMin different R-R interval(H=0.5440, P=0.1341). however, the image qualitywas first class at 40%~75% R-R interval. There was not statistical significantdifference in the image quality of left anterior descending coronary(LAD)(H=5.1236, P=0.4153). however, the image quality was first class at55%~65% R-R interval. But the statistical difference in the image quality ofLeft circumflex coronary(LCX) was significant(H=43.1911 , P=0.0000).The image quality was much better at 50%~70% R-R interval(l~2class). And the statistical difference in the image quality of rightcoronary artery (RCA) was significant(H=l80.5381, P=0.0000). The imagequality was much better at 50%~65% R-R interval. However , there were 15cases of image quality unsatisfied(3 class). The image quality was much worse at25%~35% R-R interval.In 37 cases of patients, 120 branches were normal, 25 branches in 18cases was significant stenosis (stenosis extent more than 50% ). 1 brance wasunderwent coronary stenting. 2 branches in 2 cases were inborn variation. 1 casehad CAD with ventricular aneurysm. The study indicated that the stenosis of coronary could showed clearly in MSCT. The stenosis extent was higher in MSCT than that in SCT in 4 cases. The stenosis nature could identified by detected the CT value in MSCT. MSCT could evaluated coronary recanalization after stenting and found complication accurately. MSCT could revealed the feature of complicated congenital malformation accurately.Conclusion : MSCT has high temporal resolution and spatial resolution, it is a fast,economic, uninvaded method in checking CAD. But the heart rate has great effect onthe image quality. When HR< 65 /min, the image are good. W hen HR >66/min, the image of LM and LAD are still quatified. But the image quality of RCAand LCX decrease with the increase of heart rate. The quality image is different indifferent phases of R-R interval. The image quality of LM and LAD are evaluated tobe 1 class at the 40%~75% and 55%~65% R-R interval respectively. Theimage quality of LCX are evaluated to be 1-2 class at the 50%~70% R-Rinterval. The imag... |
