The Study Of Quality Control And Clinical Applications Of Multislice Spiral CT Coronary Angiography

[Objective]1. To discuss the quality control of multislice spiral CT coronary angiography (MSCTCA) and a study was undertaken to determine the anatomy and variations of the coronary artery.2. To assess the clinical value of MSCTCA in the diagnosis and therapy of lesions of the coronary artery.[Meterials and Methods]l.Totally 121 patients were examined with MSCTCA[including 28 healthy volunteers, 83 patients of known or suspected coronary heart disease (23/83 patients were simultaneously examined with selective coronary angiography) , 6 patients of implanted stents and 4 patients of coronary artery bypass graft operation], and the used parameters were rotation time: 0.5S, slice thickness:1.25mm, reconstruction interval:0.6mm , Pitch:0.275:1 , FOV:250mm , matrix:512 × 512 , tube voltage:140KV, tube current:180mA. During helical scanning, the ECG tracing was digitally recorded and stored on 3.5 inch floppy disk with retrospectively ECG-gated technology and subsection data gather. The scan delay time was determined on the basis of the result of small dose bolus test(300mgI/ml, 3.5ml/s, 15ml). After the predetermined delay, a bolus of 80 to 140ml iodixanol(300mgI/ml, 2ml/Kg) was injected at the rate of 3-4ml/sec.2. 28 healthy volunteers were detected with retrospectively ECG-gated MSCT during a single breath hold. Tomographic source images were reconstructed at the starting points of 45%, 55%, 65%, 70%,75%, 85% R-R intervals after the previous R wave, followed by volume rendering(VR), multiplanar reformation(MPR),maximum intensity projection( MIP), virtual endoscopy(VE) and curved planar reformat (CPR) for reconstruction of coronary artery. To discuss optimal R-R phases of MSCT, analyzedifferent heart rate for the image quality, and assess clinical value of several reconstructed methods.3. MSCTCA images of 83 patients with known or suspected coronary heart disease were reconstructed at the starting points of 75%R-R intervals, followed by VR, MPR, MIP, VE and CPR for reconstruction of coronary artery. For 6 patients of implanted stents and 4 patients of coronary artery bypass graft operation, stent vessels and bypass graft were reconstructed at the starting points of 75%R-R intervals. Vessel stenosis, its degree as well as the patency of bypass graft and stent were evaluated. To sum up the MSCTCA signs of these diseases, and to evaluate the veracity of MSCTCA in displaying coronary artery stenoses among 23/83 patients simultaneously examined with SCA and MSCTCA, according to golden standard of SCA. [Results]1. MSCT was able to clearly display from the primary to the tertiary, and part of the even quaternary branches of the coronary artery. The left main coronary artery and the left anterior descending artery were all best visualized in 70% R-R phases while the right coronary artery and the left circumflex artery in 75% R-R phases. CT images obtained by volume rendering showed the best quality at 75% R-R phases. It was an inverse relationship between heart rate and MSCTCA image quality.2. The distribution and extent of 16 coronary arterial stenoses revealed by MSCTA were correlated exactly with SCA in 19 coronary arterial stenoces. The sensitivity, specificity, and accuracy were 80%, 95.83%, and 92.39%, respectively. The negative and positive prediction value were 84.21% and 94.52%, respectively. Among 83 patients of known or suspected coronary heart disease, there were 75/83 cases of coarse vessel, 71/83 cases of plaques (with 135 lesions, 36 non-calcified plaques, 31 mixed plaques, 68 calcified plaques) ,and the coronary calcium scores form 32 to 1532.3. 4 patients of coronary artery bypass graft operation(with 70 bypass grafts) and 6 coronary stents were well showed. There were 3/7 branchs of coarse bypass grafts.4. MSCTCA was able to detect other lesions: 1 patients of myocardial birdging.[Conclusions]1. MSCTCA is developing rapidly as a noninvasive, simple, and reliable method for assessing coronary artery intuitionisticly, tridimensionally and dynamicly. It can demonstrate the main coronary artery and its from primary to the tertiary, and even part of the quaternary branches of the coronary artery. The image quality of MSCTCA is highly dependent on proper parameters, contrast medium administration, optimal reconstruction window, decreasing heart rate and image processing. The key of the method is the scan delay time estimated with the test bolus method.2.The measured coronary artery data of MSCTCA is true data in natural function, being vascular inner diameter, and has a good clinical value.3. There was no significant statistical difference between MSCTCA with SCA. And it can replace invasive SCA in most cases.4. MSCT clearly displayed the coronary artery inner surface, along with the degree of vascular stenosis, the nature and calcification degrees of the plaques by two-dimensional, three-dimensional, and four-dimensional images. MSCTCA has a good clinical value in diagnosing diseases, making therapy project, operation plan, assessing operation risk, and visualizing the bypass graft and implanted stents. MSCTCA will be considered as a noninvasive and simple mainly method for CHD after improving spacial and temporal resolutions, and its foreground of clinical application is becoming more and more wide.In a word, MSCTCA has a good clinical value in the primary identification of coronary heart disease and reexamination after revascularization.