الفهرس 
Anatomical Considerations of the Coronaries and Great Thoracic VesselsOnly 14 pages are availabe for public view
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Abstract
Chest pain is one of the most common and important presenting symptoms in the daily clinical visits and emergency medicine.
It is important to know the different causes of acute chest pain which include: Thoracic (heart, lung, aorta, oesophagus and chest wall), abdominal and psychiatric origins. Differentiating the life threatening causes of acute chest pain, such as acute coronary syndrome, acute aortic syndrome, pulmonary embolism, tension pneumothorax, rupture oesophagus and pericardial tamponade, from other potentially non threatening causes of acute chest pain is also crucial.
In addition to improved technology, the increasing placement of CT scanners in or near the ED suite is another factor that has heightened the attractiveness of using multidetector CT to evaluate acute chest pain.
The main approaches to evaluate chest pain in the ED by using multidetector CT are a comprehensive (Triple Rule-Out) protocol and a dedicated coronary CT angiography protocol.
The Triple Rule-Out CT examination can be a powerful tool for evaluation and triage of patients with a low to moderate risk of ACS in whom diagnostic catheterization is not indicated. However, unlike most CT studies that can be performed by a technologist using a simple protocol, TRO CT studies require more individualized attention. Careful consideration regarding patient selection, patient preparation, and injection and scanning techniques will result in high-quality TRO CT studies to evaluate the aorta, coronary circulation, pulmonary arteries, and adjacent intrathoracic conditions. When compared with conventional management of acute chest pain in the ED, appropriate application of TRO CT can reduce (a) time for patient triage, (b) number of required diagnostic tests, © ED costs, and (d) radiation exposure to the patient.
On the other hand, we should know the practical limitation of Triple Rule Out CT protocol such as (a) Beta-blockers which are required for coronary CTA may not be safe in patients with pulmonary embolism (b) lack of experienced technologists, and physician supervision © Obesity and calcifications limit interpretation (d) Rapid heart rate, arrhythmias, renal dysfunction and contrast allergies.
In conclusion, an optimized TRO protocol provides excellent image quality for aortic, coronary and pulmonary arterial evaluation while minimizing contrast agent dose and radiation exposure. Attention to the details of patient selection and preparation, contrast agent administration, and timing of the scan is the key to high-quality TRO studies.