الفهرس 
Anatomy of Coronary ArteriesOnly 14 pages are availabe for public view
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Abstract
U
nstable angina is defined as a new onset of chest pain with exertion (effort angina) within the past 2 months. It is caused by temporarily inadequate oxygen delivery to a portion of the heart muscle (myocardial ischemia) due to either increased oxygen demand (as during exercise) or decreased oxygen supply (as during coronary artery spasm).
MDCT plays an important role in the assessment of acute thoracic disease involving the great vessels such as pulmonary embolism and aortic dissection, as well as non-cardiac causes of acute chest pain.
CT based evaluation for significant coronary artery stenosis has been shown to decrease the number of unnecessary hospital admissions, without reducing the rates of appropriate admissions, by ruling out the absence of acute coronary syndrome.
Multislice CT is a promising non-invasive technique for the detection of CAD. The MSCT scanners are equipped with multiple and thinner detector rows, and has a faster tube rotation speed creating two major advantages: high spatial resolution and short acquisition time that enable high-quality examinations. It is only with this immense increase in the data acquisition volume per unit time, that CT assessment of the coronary arteries has become possible.
Challenges in evaluating the coronary arteries at CT are the small size and tortuous courses of the vessels and their continuous movements being intimately related to the cardiac chambers.
Controlled heart rate and good breath holding help to reduce cardiac and respiratory motion artifacts respectively.
Retrospective ECG gating and proper choice of the reconstruction window significantly improves the examination quality.
To date, the central rationale of CT angiography has been the noninvasive detection and grading of coronary artery stenosis, assessment of coronary artery anomalies and follow up after coronary bypass surgery.
Contraindications to CTCA include irregular heartbeats (arrhythmias), contra-indications to iodinated contrast material including allergy, renal insufficiency and hyperthyroidism, contra-indications to radiation exposure, pregnancy, respiratory impairment, and marked heart failure.