| Part One: The diagnostic significance of MSCT and CAG compared with IVUS in CADObjective: To study value of MSCT, CAG, IVUS in the diagnosing of CAD. Methods: 10 patients with coronary artery disease (CAD) in our hospital from September 2007 to May 2008 were enrolled. Contrast-enhanced MSCT angiography, CAG and IVUS were performed in every patient. We study the diagnostic sensitivity, specificity, positive predict value and negative predict value among 64-slice computed tomography (MSCT) and coronary angiography (CAG) with the intravascular ultrasound (IVUS) as a gold reference, in identifying different types of coronary artery lesion. Results: A total of 77 segments in 25 vessels of 10 patients (LAD: 10, RCA: 8, LCX:7) were investigated by MSCT, CAG and IVUS. 64-slice all segments which the MSCT visualized compared with IVUS reach moderate to image quality. On the segment basis, the sensitivity, specificity, positive predict value and negative predict value of MSCT were 91.3% versus 84.8%, 93.5% versus 80.6%, 95.4% versus 86.7%, 87.9% versus 78%, respectively. On the plaque basis, the sensitivity, positive predict value of MSCT and CAG were 78.2% versus 67.3%, 93.5% versus 92.5%respectively. . Sensitivity for the detection of <50%, 50～75%, and >75% stenosis in MSCT and CAG were 73.3% versus 60%, 80% versus 70%, 100% versus 100% respectively.The mean plaque area, the vessel CSA, the eccentric index, the remodeling index (RI) determined by MSCT and IVUS were 8.2±3.2 mm2 versus7.5±4.99mm2, 18.86±8.7 mm2 versus 17.12±5.36 mm2, 0.86±0.16 versus 0.91±0.16, 1.03±0.2 versus 1.07±0.19, respectively. The minimal lumen area (MLA),determined by MSCT, CAG and IVUS were 9.54±3.88 mm2,7.63±4.45 mm2,8.56±4.18 mm2 respectively. The mean lumen stenosis determined by MSCT, CAG, IVUS was 51.5±17.2%,40.9±19.9%,61.9±16.9% respectively. There was good correlation between MSCT and IVUS in mean plaque area. But that the MSCT overestimated the plaque area was also observed. The sensitivity in detecting calcified, fibrous and soft plaques, was 84%, 57%, 46.7% respectively. The specifity was 96%, 85.2%, 91.2%. The sensitivity of calcified plaques was high, but the sensitivity of the fibrous and soft plaque was low relatively. The CT value of the fibrous soft and calcified plaque that has been versified by IVUS was 117±35Hu,54±49Hu,360±165Hu, respectively. A significant difference of the mean CT attenuation within atherosclerotic lesions of hypo-echogenic and hyper-echogenic appearance in IVUS could be observed. However, we observed substantial overlap of attenuation values between the two plaque types.Conclusion: 1. MSCT has these characterizations, such as :①MSCT has high resolution in the image quality.②MSCT has high specifity and negative predict value.③MSCT was similar in detecting plaques of different stenosis extent and different location compared with coronary angiography (CAG).④. MSCT has better performance in inspecting the mean lumen area and the mean percent of area stenosis than CAG.⑤. MSCT can detect the positive remodeling of vessel, the plaques'morphology and configuration, accurately. CT values can accurately reflect the nature of plaque.⑥. MSCT was a noninvasive method. It can substitute the traditional CAG to some extent. 2. There were advantage and dis advantage in three types of methos. We should comprehensively utilize these methods according the patients condition.Part Two: The significance of IVUS in CAD patients with negative findings in coronary angiographyObjective: To discuss the value of IVUS in CAD patients who appear"normal"in CAG.Methods: 14 patients of CAD who appear"normal"in CAG were enrolled. Every patient inspected by intravascular ultrasound to analyze the morphology characterization of plaque, the percent of vessel obstruction and the vessel remodeling.Results: 24 plaques in 14 vessels (LAD11, RCA2,LCX1) were detected by IVUS in 14 patients who had the negative findings in CAG.. 24 plaques were detected by IVUS(LAD15, RCA4, LCX1, LM4). 5 fibrous plaque, 14 soft plaques,3 fibrous-soft plaque, 2 calcified plaques were found by IVUS. 18 Eccentric plaques, 9 positive remodeling vessels in 9 lesions, 10 plaques locate within the ostium of the bifurcate vessel were confirmed. The maximum and minimal plaque thickness, the plaque eccentric index, the minimal lumen diameter, the mean plaque area, the mean EEM CSA, MLA, the mean obstruction percent of diameter and area and RI were 1.475±0.298mm, 0.225±0.3mm, 0.83±0.23,2.72±0.46mm,8.5±2.3mm2, 16±3.6mm2, 7.2±1.6mm2, 27±11.4%, 45.1±18.36%,1.16±0.16, respectively. Lipid cores were detected in 8 lesions. The ratio of lipid core/plaque area was 36.2±3.3%, the mean lipid core area was 2.47±1.53mm2, the mean fibrous cap thickness was 0.5±0.36mm.The patients implanted stent were all with unstable pectoris angina. 4 soft plaques and 2 fibrous plaques were detected. All the lesions located in the LAD. The maximum and minimal lumen diameter, the lumen diameter, MLA, EEM CSA, stenosis degree of diameter, stenosis degree of area, RI and the eccentric index were 1.78±0.86mm,1.54±0.97mm,4.43±1.68mm2,11.66±9.43 mm2,36.26±6.02%,61.66±8.08%,5.16±2.78 mm2,1.26±0.19,0.94±0.23 respectively. After 2.12±3.04 years follow-up, alleviation of angina pectoris in 6 patients received stent implantation was observed.Conclusions: 1. IVUS can detect the types and nature of the lesions accurately in the patients who had the negative findings in the CAG. 2. The reasons of the negative results may be: the positive remodeling of vessels, the eccentric characterization of plaques, the plaque location in the ostium of the bifurcate vessels, the"normal"reference vessels have lesions in some extent. 3. The characterizations of unstable plaque was the big lipid pool, thin fibrous cap, great degree of lipid pool/plaque area, positive vessel remodeling and eccentric characterization. The PCI should be considered when the unstable plaque characterization, the clinical evidence of myocardium ischemia, the severe symptom of UA, the important location of coronary artery.
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