الفهرس 
Review of literature anatomyOnly 14 pages are availabe for public view
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Abstract
The presence of myocardial ischemia is an important risk factor for an adverse clinical outcome. Revascularizations of stenotic coronary lesions that induce ischemia can improve a patient’s functional status.Coronary computed tomography angiography (CCTA) is a noninvasive and accurate diagnostic tool to detect coronary artery disease (CAD) and is increasingly utilized in clinical practice. Diagnostic accuracy of 64-multidetector row CCTA has been validated in several multicenter trials, and the high negative predictive value establishes CCTA as an effective noninvasive alternative to invasive coronary angiography to rule out obstructive coronary artery stenosis. However, the diagnosis of CAD stenosis by CCTA demonstrates an unreliable accuracy to define the lesion-specific ischemia. With a concern that widespread use of CCTA may result in excess referral of patients to invasive coronary angiography and unnecessary revascularization of non-ischemic coronary lesions, several methods were developed and suggested to have the ability to evaluate for both anatomical and functional stenosis.At present, the gold standard assessment of the hemodynamic significance of coronary stenosis is fractional flow reserve (FFR). It is defined as the ratio of maximal blood flow in a stenotic artery to normal maximal flow. It can be easily measured during coronary angiography by calculating the ratio of distal coronary pressure measured with a coronary pressure to aortic pressure measured simultaneously with the guiding catheter. FFR in a normal coronary artery equals 1.0. An FFR value of 0.80 or less identifies ischemia-causing coronary stenosis with an accuracy of more than 90%.