الفهرس 
Normal anatomy of coronary arteriesOnly 14 pages are availabe for public view
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Abstract
CAD remains a leading cause of death all over the world. The standard of reference for diagnosis of CAD still is the conventional coronary angiography. The greatest advantage of conventional angiography is the perfect spatial resolution and the option of direct performance of interventions such as balloon dilatation or coronary stent placement. However, only one-third of all conventional coronary angiographic examinations are performed in conjunction with interventional procedure, while the rest are performed only for diagnostic purpose. Conventional invasive coronary angiography is currently the diagnostic standard for clinical evaluation of known or suspected (CAD). The risk of adverse events is small, but serious and potentially life-threatening events may occur, including arrhythmia, stroke, and coronary artery dissection. Furthermore, angiography catheterization induces some discomfort and mandates routine follow-up care. Guidelines recommend that conventional invasive diagnostic angiography be restricted to stringent clinical indications. CT coronary angiography is becoming feasible with the availability of faster mechanical scanners with multi-section imaging capabilities. Potential applications of multi–detector row CT angiography include noninvasive diagnosis of plaques and coronary artery stenosis. Three-dimensional volume- rendered and multiplanar images display arterial anatomy similarly to conventional angiography. (Pannu , et al . 2003) An inherent advantage of MSCT for imaging of the coronary arteries is the cross sectional nature of this technology. It does not display only the vessel lumen and the degree of luminal narrowing in a cast like manner, but also visualize the coronary artery wall & enables detection of lesions within the coronary artery wall that may or may not cause luminal stenosis. Coronary artery bypass graft (CABG) is still a main line in the treatment of the coronary artery disease .However, the endurance of the coronary bypass graft is limited ; after 3 years , 20-30 % of the bypass grafts are occluded . The myocardial infarct rate significantly increases after the bypass surgery. Since the clinical outcome of the patients is closely related to the patency rate of their bypass grafts, it would be important for the patients to have the patency rate of their grafts assessed on time to detect any graft occlusion before the majority of the grafts get occluded. Recently, multislice computed tomography offers an attractive tool for this purpose. Bypass grafts are ideal vessels for evaluation by MSCT because of their greater diameter and their relative spatial fixation. Until recently, CT applications for the assessment of (CAD) almost exclusively directed at the detection and quantification of coronary arterial calcium. In recent years, considerable interest has accordingly been directed at the beneficial use of high – spatial resolution contrast enhanced CT angiography for noninvasive evaluation of the coronary arterial tree. To date, the central rationale of this application has been the noninvasive detection and grading of coronary artery stenosis and follow up after coronary bypass surgery, with the ultimate goal of replacing diagnostic invasive conventional coronary angiography. (Feyter & Krestin,2008) MSCT could be applied in detection of different coronary artery lesions such as coronary calcium scoring, coronary artery stenosis, vessel wall changes, early prediction of acute coronary syndrome, different coronary anomalies, , and follow up after surgical revascularization. It could be used for screening of asymptomatic patient with risk factors and patients with atypical chest pain, and it could become complementary but not alternative to conventional angiography in the assessment of selected patients with stenotic atherosclerotic or non-atherosclerotic coronary disease.