| Objective: Mu1ti-slice computed tomography (MSCT) is a non-invasive, less expensive imaging method, which has been widely used in clinical practice. Large number of studies have shown that MSCT can diagnose coronary artery stenosis with high sensitivity and specificity. But compared with coronary angiography (CAG), MSCT still has its limitations. In this study, images of MSCT and coronary angiography were analyzed to search for the influence factors of the imaging quality and diagnosing coronary artery stenosis.Methods: Sixty patients (45 males, 15 females; age 36-80 years, average age 63±9 years) who were in hospital definite or suspected coronary artery disease were studied. Sixty patients underwent 64-slice coronary CT examination, criteria for exclusion included tachycardia, acute myocardial infarction, contrast medium allergy, renal insufficiency, asthma and chronic obstructive pulmonary disease. According to heart rate, 43 patients tookβ-blockers (metoprolol) 25-50mg before the 64-slice coronary CT examination to make the heart rate of the patients below 70 beats/min (bpm). Using retrospective ECG gating technique, the images of coronary CT scan were reconstructed every 10% R-R phase of the cardiac cycle in order to identify the best quality of coronary CT images. According to results of coronary MSCT imaging, coronary segments were divided into evaluable and not evaluable. In the evaluable segments, the left main stem, anterior descending branch, circumflex artery, right coronary artery and their lateral branches with a diameter more than≥2mm were screened for significant coronary stenosis (≥50% lumen diameter narrowing). During one week, coronary angiography was performed. For the coronary vessel diameter≥2mm, the American Heart Association (AHA) coronary artery segments classification was used to analyze the coronary vessels in each patient. The coronary artery stenosis grading: (1)Normal or mild stenosis:its degree of lumen diameter reduction<50%; (2)moderate stenosis: the degree of luminal diameter reduction≥50% but<75%; (3)a high degree of stenosis: the degree of luminal diameter reduction≥75%. Images of MSCT and invasive coronary angiography were analyzed. The diagnostic accuracy of coronary MSCT was expressed as sensitivity, specificity, positive and negative predictive value. The influence factor of the imaging quality and diagonsing coronary artery stenosis were analyed.Results:1 Seven hundred and five coronary artrty segments( vessel diameter≥2mm) of 60 patients, in accordance with the MSCT image quality, were divided into evaluable and not evaluable groups. The segments not evaluable were 70 (9.93%). Forty-six of them were caused by coronary motion artifacts (65.71%), seven of them were caused by breathing exerise(10.00%), nine of them were caused by severe calcification(12.86%), eight of them caused by poor perfusion(11.43%).2 In the 705 coronary artery segments, 527 (74.75%) were well observed at 70% images reconstruction window of the cardiac cycle. Left coronary were well observed at 70% image reconstruction window of cardiac cycle and right coronary artery at 70% and 40% image reconstruction cycle window.3 The quality of coronary MSCT images were negatively correlated with the heart rate, the correlated index was -0.76.4 Coronary motion artifacts, heart rate, the application of contrast agent, coronary artery, breathing exercises and poor perfusion have impacted on the quality of coronary MSCT imaging.5 The sensitivity, specificity, positive and negative predictive value of coronary MSCT was 81.77% (157/192), 94.59%(420/444), 87.22%(157/180), 92.31%(420/455).6 The main influence factors of diagnosing coronary artery stenosis were: motion artifacts and calcification of the coronary artery as well as stents caused the metallic artifacts and so on.Conclusion:1 Coronary MSCT is a safe and reliable non-invasive method for the diagnosis of coronary artery stenosis.2 A variety of factors have effect on the image quality of the coronary MSCT. A good preparation and a reasonable scan image reconstruction method can improve the quality of MSCT coronary artery images.3 Although many factors have influence on judgment of coronary stenosis, the MSCT of coronary artery had a high sensitivity, specificity and accuracy in the diagnosis of coronary artery stenosis(≥50%). Coronary MSCT can be used as a screening method for the diagnosis of coronary heart disease.
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