The Research Of 16-slice CT Coronary Artery Angiography: Quality Control And Clinical Application

PartⅠQuality Control of 16-slice CT Coronary Artery AngiographyChapterⅠComparative Study of Bolus Timing Technique at 16-slice CT Coronary AngiographyObjective To compare test bolus, bolus tracking of different threshold (100HU, 150HU) techniques for timing the scan of 16-slice CT coronary angiography. Materials and Methods 90 patients were randomized into three groups according to bolus timing technique: group1(bolus tracking, threshold 100HU, following 100ml contrast material+20ml saline chaser), group2(bolus tracking, threshold 150HU, following 100ml contrast material+20ml saline chaser), group3(20ml test bolus, following 100ml contrast material+20ml saline chaser). All patients performed ECG-gated 16-slice CT coronary angiography successfully. In group1and group2, the threshold in ascending aorta triggered acquisition, with an additional 4s delay. In group3, test bolus peak time adding 2s was used as a delay. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. All the delay time was recorded. Attenuation was measured in main vessels (ascending aorta, main pulmonary artery, superior vena cava and coronary sinus), right atria and the root of coronary artery (left main artery, left anterior descending artery, left circumflex artery and right coronary artery). One-Way ANONA was used to analyze all the data.Results The attenuation values of coronary arteries and aorta were the lowest in group 3, which had significant difference comparing group 1 and group 2, and there were no significant differences between group1 and group2. The attenuation values of pulmonary artery (PA), superior vena cava (SVC) and right atria (RA) were the highest in group 1. There were significant difference between group 1 and group 3 in the attenuation value of PA, which had no significant differences between group1 and group2. There were significant differences between group1 and group2, group3 in the attenuation of SVC and RA. There were no significant differences between any two groups in the attenuation of coronary sinus, but the attenuation values of coronary sinus in group 2 were the lowest. The delay time in group 3 was the shortest, which had significant differences comparing group2 and group3.Conclusion Bolus tracking was better than test bolus in gaining optimum coronary attenuation. Bolus tracking which threshold was defined 150HU was superior to bolus tracking which was defined 100HU.ChapterⅡInfluence of Reconstruction Phase and Heart Rate on MSCT Coronary AngiographyObjective To investigate the influence of reconstruction phase and heart rate on image quality of 16-slice CT coronary angiography, and confirm the optimal reconstruction time in patients of different heart rate.Material and methods 16-slice CT coronary angiography were performed in 93 patients. Test bolus technique was used in all patients. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. Images were reconstructed at 20%-80% of the cardiac cycle in increments of 10%. Patients were classified three groups according to heart rate (groupⅠ:≤60bpm,groupⅡ:60～70bpm,groupⅢ:≥70bpm). The image quality of reconstruction image quality was evaluated by VRT image, and the display of coronary artery was evaluated by axial image and MPR image.Results The best reconstruction time of Left anterior descending artery(LAD)was 50%-70%,60%-70%,60% respectively from groupⅠto groupⅢ; that of left circumflex artery(LCX) was 50%-60%,60%,40% respectively; that of right coronary artery(RCA) was 60%,50%-60%,40% respectively. The proximal segments of LM,LAD were not statistically significant in all groups, the mid and distant segments of LAD, all segments of LCX, proximal segments of RCA were not statistically significant between groupⅠand groupⅡ, but those were statistically significant compared to groupⅢ; the mid segments of RCA were statistically significant in any group.Conclusion With multi-reconstruction phase, 16-slice computed tomography coronary angiography can achieve good image quality in patients who heart rates are below 70beats per minute.PartⅡthe Clinical Application of 16-slice Computed Tomography Coronary Artery AngiographChapterⅠThe Measurement of Coronary Artery Size using 16-slice Computed TomographyObjective To investigate and measure the diameter of coronary artery using 16-slice computed tomography.Materials and methods 16-slice CT coronary angiography was performed in 104 cases whose coronary arteries were normal. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. 104 cases were divided into 3 groups according to age: the youth group (<45y), the middle group(45-64y) and the elder group(≥65y).104 cases were also divided 3 groups according to dominant pattern of coronary artery: balanced dominant pattern, right dominant pattern and left dominant pattern. The diameter of right artery (RCA) proximal, middle and distant segment were measured using CT, so as the diameter of left main artery (LM), left anterior descending artery (LAD) proximal, middle and distant segment, left circumflex artery proximal and distant segments.Results The diameter of RCA proximal segment, middle segment and distant segment was 4.05mm, 3.07mm and 3.29mm separately; the diameter of LM was 4.59mm; The diameter of LAD proximal segment, middle segment and distant segment was 3.98mm, 3.60mm and 2.85mm separately; the diameter of LCX proximal segment and distant segment was 3.39mm, 2.28mm separately.The diameters of coronary arteries were larger with the increasing of age. There was significant difference of LM diameter between the elder group and the youth, middle group, and there was no significant difference in the youth group and the elder group. There was no significant difference of other coronary artery segment's diameter in any two groups.The diameter of LM in left dominant pattern was the largest, and it had significant difference comparing other two groups, but there was no significant difference between the latter two groups. The diameters of LAD and LCX in left dominant pattern were the largest, and that of in right dominant pattern were the smallest. The diameter of LAD had no significant difference among three groups. The diameter of LCX proximal segment had no significant difference between balanced dominant pattern and right dominant pattern, but they had significant difference comparing the left dominant pattern. The diameters of LCX distant segment had significant difference between any two groups. The diameter of RCA in right dominant pattern was the largest. The diameters of RCA proximal segments had no significant difference between balanced dominant pattern and left dominant pattern, and there was significant difference in any other groups.Conclusion coronary artery size measured by MSCT can provide valuable information for coronary disease.ChapterⅡComparative Study Between 16-slice CT Coronary Angiography and Conventional Coronary AngiographyObjective To evaluate the clinical application of 16-slice CT coronary angiography (CTCA) and the impact of plaques differently characterized on assessing coronary artery stenosis.Material and methods 53 patients underwent both 16-slice MSCT and invasive coronary angiography (CAG). CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. CTCA was evaluated by consensus of two independent experienced radiologists unknowing CAG findings. Two methods were used to evaluate the stenosis of coronary artery: stenosis was analyzed on a patient basis, and stenosis was analyzed on coronary segment basis. For a determined plaque an attenuation value <60HU was considered as soft plaque; an attenuation value between 60 and129HU was considered medium plaque, and≥130Hu noncalcified. The plaques were then classified into calcified plaque, mixed plaque and non-calcified plaque. The diagnostic accuracy of 16-slice CTCA findings as well as detect≥50% stenoses caused by plaques was evaluated respectively regarding CAG as the standard of reference.Results The sensitivity, specificity, positive and negative predictive value to identity significant obstructed coronary artery was 93.5%,71.4%,82.9%,88.2% respectively on a patient basis, and that on coronary segment basis was 88.4%,94.3%,73.1%,97.9% respectively. The sensitivity, specificity, positive and negative predictive value to identity≥50% stenoses caused by calcification plaque, mixes plaque and non-calcified plaque was 80%, 64.4%, 43.5%, 90.4%; 96.7%, 82.4%, 90.6%, 93.3%; 95.5%, 80.0%, 91.3%, 88.9% respectively. MSCT had limitation in the evaluation of coronary artery stenoses caused by calcification.Conclusion 16-slice CT coronary angiography is a simple, reliable and noninvasive method. MSCT can identify the stenoses, especially to the significant stenoses (≥50%) and non-calcified and mixed plaque. it can be the choice for the ruling out coronary heart disease, evaluation of pre -operation of coronary artery. ChapterⅢEvaluation of Coronary Artery Plaque and Modeling by MSCT in Patients with Stable Angina and Unstable AnginaObjective Using 16-slice computed tomography to evaluate the attenuation of plaques and coronary artery remodeling in patients with stable angina (SA) and unstable angina (UA).Material and methods 16-slice CT coronary angiography were underwent in 11 patients of SA and 10 patients of UA. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. The presence of noncalcified plaques were inspected on the axial and MPR images. In patients with multiple plaques, CT attenuation was measured on the plaque at the lesion of maximum stenosis. The remodeling index (RI) was calculated by the cross-sectional vessel area at the region of maximum luminal narrowing by the mean of the 2 reference areas (the proximal and distant area of lesion).Result The attenuation of plaque was significantly higher in patients of SA ( 69.7±17.3HU) than in those of UA (36.0±9.6HU). There was significant difference between remodeling index of patients of SA and those of UA. Positive coronary artery remodeling (PCAR) was present in 7 of 10 (70%), and negative coronary artery remodeling (NCAR) was present in 2 of 10 (20%) in UA. PCAR was present in 2 of 11 (18.2%), and NCAR was present in 7 of 11 (63.6%) in SA. There were significant difference between PCAR and NCAR.Conclusion MSCT can differentiate plaque texture and measure modeling index in patients with SA and UA. It is helpful to diagnose and treat acute coronary event. ChapterⅣ16-slice Computed Tomography Diagnosing Congenital Coronary Artery AnomaliesObjective To investigate the clinical application value of 16-slice CT in diagnosing congenital coronary artery anomalies.Materials and methods 538 patients performed 16-slice CT coronary artery angiography were analyzed retrospectively to find the coronary artery anomalies. CT scanning parameters were as follows: collimation, 0.75mm; gantry rotation time, 420ms; table feed per rotation, 2.8mm; 120KV; 500mAs. For evaluation of coronary anomalies, axial and MPR images were used. The origins and course of coronary branches were assessed. If coronary anomaly was found, then the anomalous type was defined.Results 23 coronary artery anomalies were found, including high take-off position of left main coronary artery (11 cases), ectopic origin of right coronary artery from the left sinus of Valsalva (5 cases), separate origins of LAD and LCX from left sinus of Valsalva (3 cases), absence of left circumflex coronary artery (2 case), single coronary artery (1 case), ectopic origin of left circumflex artery from right sinus of Valsalva (1 case), and myocardial bridge (116 cases).Conclusion MSCT is a noninvasive, accurate, repeated method for diagnosis of congenital coronary artery anomalies.