Noninvasive Detection And Evaluation Of Coronary Atherosclerotic Plaque With MultiDetector Spiral Computed Tomography And Evaluation Of Its Coronary Imaging

Part1 Establishing atherosclerosis model with rabbit and detection atherosclerotic plaque by multidetector Computer TomographyObjective To probe and compare two methods of establishing atherosclerosis model with rabbit and detecting atherosclerotic plaque by multi-detector CT. Methods 9 adult NEW Zealand rabbits were randomized into three groups, 4 into treatment group A, 4 into treatment group B and 1 into control group. After fundamental anesthetized, the rabbits of treatment group A underwent hurt to endomembrane of aorta and then each rabbit fed on 3g cholesterol plus fundamental fodder each day. Each rabbit of treatment group B fed on 3g cholesterol plus fundamental fodder each day only without injury of aorta. The rabbit of control group fed on fundamental fodder only. After 16 weeks, the rabbits of treatment group A and the rabbit of control group underwent scan of 16—detector—row spiral CT, the rabbits of treatment group B underwent scan of 64-detector--row spiral CT, and subsequently all the rabbits were sacrificed for pathological examination. Results The rabbit of control group had smooth endomembrane. There were 135 pathological slices totally, 53 slices containing plaque were found in 60 slices of treatment group A, 37 slices containing plaque were found in 60 slices of treatment group B, and no slice containing was found in control rabbit .The difference among three groups was significant(P＜0.001). The mean thickness of each slice of endomembrane of treatment group A is 488±128μm (170μm～730μm), and treatment group B 532±230μm (50μm～950μm)。The difference between two groups was significant(P＜0.001). The sensitivity and speciality of 16—detector—row spiral CT is 45% and 86% respectively, 65% and 85% of 64—detector—row spiral CT accordingly. Conclusion Arteriosclerosis model can be successfully established with rabbit with two above methods. There were some limitation in more precise evaluation of plaque by MDCT. intravascular ultrasound(IVUS),based on segment. Methods The IVUS and MDCT scans (Lightspeed Ultra-16, GE, USA) were performed in 30 patients. A total of 94 coronary segments without significant coronary stenoses and stents were imaged and analyzed. MDCT data sets were evaluated for the presence and areas of plaques in the coronary segments. Plaque composition was analyzed according to IVUS (plaque echogenity: soft, intermediate, calcified) and MDCT criteria (plaque dencity expressed by Hounsfield units[HU]). Results were compared with IVUS in a blinded fashion. Results A total of 94 coronary artery segments were imaged and analyzed(left main, 19; left anterior descending, 49; left circumflex, 6; right coronary, 20). For the detection of segments with any plaque, MDCT had a sensitivity of 82% (46 of 56) and specificity of 89% (34 of 38). For calcified plaque, sensitivity was 92% (35 of 38 ) and specificity 96% (54of 56). Coronary segments containing noncalcified plaque were detected with a sensitivity of 73%(30 of 41) and specificity of 89%(47 of 53), but presence of exclusively noncalcified plaque was detected with 68% sensitivity (12 of 18). The density of 54 plaques were analyzes. With IVUS, the plaque was classified as calcified (n=19), intermediate(n=19) and soft (n=16). Using MDCT, calcified plaques had a density of 489±169(range 196 to 817 HU), intermediate plaques of 69±21(25 to 117 HU) and soft plaques 23±18 (-12 to 47). Nonparametric Kruskal-Wallis test revealed a significant difference of plaque density among the three groups (p＜0.001). The mean plaque areas measured by IVUS and MDCT were 5.3mm~2 versus 5.6 mm~2(p＜0.01, r=0.58) Conclusions The results indicate the potential of MDCT to detect coronary atherosclerotic plaque in patients without significant coronary stenoses. Coronary plaques configuration might be correctly differentiated by MDCT .Measurements of plaques areas derived by MDCT correlated well with IVUS. This noninvasive method might become an important tool for risk stratification. However, further improvements in image quality will necessary to achieve reliable assessment.Part3 Noninvasive Detection and Evaluation of Coronary Atherosclerotic Plaque with 64-Detector-Row Spiral Computed Tomography- Initial Result of Comparison With Intravascular UltrasoundObjectives The aim of the present study was to evaluate the ability and accuracy in detect atherosclerotic plaque in nonstenotic coronary arteries by 64-detector-row spiral computed tomography(MDCT). The results were compared with the findings of intravascular ultrasound(IVUS), based on plaque. Methods The IVUS and MDCT scans (Lightspeed VCT , GE) were performed in 18 patients . A total of 25 coronary segments without significant coronary stenoses and stents were imaged and analyzed. MDCT data sets were evaluated for the presence and areas of plaque one by one. Results were compared with IVUS in a blinded fashion. Results For the detection of any plaque, MDCT had a sensitivity of 96%(23 of 24) and specificity of 94%(35 of 37). The mean plaque areas measured by IVUS and MDCT were 7.8mm~2 versus 9.2 mm~2(p＜0.001 , r=0.87) Conclusions The results indicate the excellent ability of 64-detector row CT to detect coronary atherosclerotic plaque in patients without significant coronary stenoses. Measurements of plaques areas derived by MDCT correlated well with IVUS. The direct demonstration of plaque lipid pool of 64-detector row CT image will be very important for risk stratification and patients follow-up. Part 4 Analysis of main influence factors on coronary artery image quality with 64-detector-row spiral CTObjective TO explore the main influence factors heart rate(HR),heart rate changing, coronary calcium score(CCS),impact of intravascular enhancement, image noise, diameter of coronary artery et al)on the image quality of coronary artery with 64-slice helical CT. Methods 100 patients with suspected CAD were underwent MDCTA, the image quality score(IQS)was evaluated according to the same evaluation standard of reformatted image. The correlation between some factors for example HR and IQS were analyzed. Results The heart rate, heart rate changing, coronary calcium score, impact of intravascular enhancement and image noise had significant influence on IQS. The equation of multiple regression was IQS=4.21-0.030×(HR)-0.029×(HR changing)-0.001×(CCS)-0.003×(impact of intravascular enhancement)-0.027×(image noise). Conclusion Better HR control,proper select of scan and contrastPart5 64-Detector-Row Spiral CT of the coronary imaging:assessment of accuracy in detecting stenoses Objective To evaluate the accuracy in detecting coronary artery lesions of 64-multi detector computed tomography(MDCT).Methods Seventy two patients were studied by MDCT. The results were compared with invasive coronary angiography(ICA). Results In 1056 segments with diagnosis MDCT image quality(American Heart Association 15-segment model).Sensitivity for the detection of stenosis≥50%,≥75% on segments was 84.5% and 88.3% ,respectively, and specificity was 93.7% and 96.7%.Conclusion Our results indicate high quantitative and qualitative diagnostic accuracy of 64-multi detector CT in comparison to ICA with good image quality.