Diagnosis Of Multi-Slice Computed Tomography In Coronary Artery Disease

Coronary heart disease is one of serious disease to human health. In long time, coronary angiography (CAG) is the "gold standard" in the diagnosis of coronary heart disease. But it is invasive, dangerous and expensive, which limits the application in diagnosis of coronary artery disease. Therefore, to find one safe and non-invasive method to quantitative evaluate the extent of coronary artery stenosis is becoming increasingly important. With the rapid development of imaging technology, multi-slice CT (MSCT) provides a safe, reliable, non-invasive way in quantitative evaluation of coronary artery stenosis and interventional treatment; also can be used for follow-up after coronary intervention.1. ObjectiveCompare imaging results of MSCT and CAG in patients confirmed or suspected coronary heart disease. Analyse the the reason of dismatching for the results of MSCT and CAG. Evaluate the sensitivity and accuracy in diagnosis of MSCT in coronary artery disease.2. Material and Methods42 consecutive patientin-hospital ward, who were regarded as coronary heart disease, were studied by MSCT and by CAG. There are 29 males and 13 females, aged 48-72 years old. Train everyone to breath hold and control the heart rate less than 70 beats / min. Use GE company 64-slice light speed VCT in MSCT coronary angiography; AW 4.3 workstations in image processing applications; GE company INOVA 2000 cardiovascular imaging machine in CAG. CT: Scan range is from 2 cm below carina of trachea to 2 cm below facies diaphragmatica cordis. After do a small dose of coronary scanning and pre-positioning, do low level experiment at aortic root level then inject 20ml contrast agent(Ultravist 370) to elbow vein using high-pressure syringe by 3-5 ml/s,and calculate the best time delay. Inject 60-100ml contrast agent to elbow vein for imaging with the same flow rate, require patients to hold breath. Start scanning with the best time delay measured, then observe the coronary angiography. Final data is imported to AW 4.3 workstation. Original data is processed to show the full imaging of main coronary artery segments by volume rending, CT virtual endoscopy, curved multiplanarre formations, maximum intensity projection and multiplanar reconstruction. CAG: Intubate in torsion or femoral artery for coronary angiography, observe and measure coronary artery lesions. Evaluate those segments of coronary artery which are greater than 2 mm in diameter. Using CAG results as gold standard, MSCT shows coronary artery stenosis greater than 50% is considered positive. Use SPSS11.0 software to calculate the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of MCST coronary angiography; use chi-square test to evaluate the two methods.Test standardα= 0.1.3. ResultsThere are 351 more than 2 mm in diameter coronary segments in 42 patients. 318 segments are satisfied by the evaluation of angiography and 33 segments are not. The main reason in those 33 segments is fast heart rate, calcification, fast breathing or arrhythmia, which performance vascular artifacts or edge blurring in the imaging. In the 318 segments which are satisfied by the evaluation of angiography, MSCT shows 64 segments more than 50% stenosis and CAG shows 60 segments.54 segments more than 50% stenosis are both showed by MSCT and CAG; and 248 segments are showed negative. In the 33 segments which are not satisfied by the evaluation of angiography, CAG shows 7 segments more than 50% stenosis. MSCT shows in more than 50% stenosis: sensitivity is 90.0% (54/60) and specificity is 96.1% (248/258);the positive predictive value is 84.4% (54/64) and negative predictive value is 97.6% (248/254); the accuracy is 95.0% (302/318). Use match chi-square test to estimate the two methods in show coronary artery stenosis. X2=0.563< X20.1(1),P>0.1, so the two methods in detecting coronary artery disease, there was no significant difference. There are 6 soft plaques which are provided by the CT values less than 50 HU, resulting in 20-35% stenosis, and those coronary angiography are negative.4. Conclusion1. MSCT coronary angiography can clearly display main coronary artery and its branches. However, due to heart rate, rhythm, calcification and so on, there is a certain percentage of the coronary artery segments which can not be displayed.2. When image quality is satisfied MSCT evaluates coronary artery stenosis with high accuracy. For MSCT shows normal coronary patients may be excluded from the diagnosis of coronary heart disease; when MSCT shows mild and moderate coronary artery stenosis, patients can avoid doing CAG; for MSCT shows severe coronary artery stenosis, further treatment should be done.3. According to CT values of coronary atherosclerosis, we can determine the type of plaque. It is helpful to evaluate whether the plaque is stabile and whether the pathogenetic condition is serious.