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Background
The leading cause of mortality worldwide is coronary artery disease (CAD). CAD occurs when there is endothelial damage that results in lipid deposition in the wall of the artery along with proliferation of smooth muscle. This can result in plaque formation in the artery, and if the plaque is unstable, it can rupture and cause a thrombotic occlusion of the artery, resulting in myocardial infarction. Early diagnosis is imperative in reducing the mortality of CAD, and the gold standard for diagnosis is currently coronary angiography. The problem with coronary angiography is that it is an invasive procedure that is not without risk. Up to 60% of people who undergo this procedure show no evidence of CAD, meaning that these patients were exposed unnecessarily to the risks involved with invasive coronary angiography. One way to decrease this risk exposure is through much less invasive diagnostic imaging with CT and MRI.

Educational Goals / Teaching Points
The goal of this exhibit is to evaluate the current means of diagnosing coronary artery disease and provide a comparison with usage of CT and MRI. Participants will have a good understanding of the benefits and risks when considering which technique is best for evaluating patients for coronary artery disease.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Both CT and MRI have shown great promise in diagnosing CAD, with CT having 91% sensitivity and 93% specificity, and MRI has 73% sensitivity and 86% specificity. CT imaging is an excellent way to demonstrate the atherosclerotic burden of the coronary arteries while giving a good estimate on how vulnerable these plaques are to rupture and to thrombosis. CT can indicate which patients have a high risk of plaque rupture and thrombosis, so that these patients can be given daily statins to stabilize the plaques. One drawback of this method is that patients are exposed to a small amount of radiation during the imaging but less exposure than that of traditional coronary catheterization. MRI provides a radiation free method of diagnostic imaging although the sensitivity and specificity are not as high as CT. MRI has been shown to be excellent in diagnosing stenosis and aneurysms in large coronary arteries. MRI is also good for ruling out coronary heart disease in patients as the CE-MARC study determined the negative predictive value to be 90.5%. CT and MRI offer a great opportunity for providing quick diagnosis of CAD in a noninvasive manner.

Conclusion
Coronary artery disease is known to be the leading cause of death around the world and many deaths can be prevented with early diagnosis and treatment. The current gold standard for diagnosis is invasive coronary angiography. This exhibit will focus on the benefits and risks regarding the usage of CT and MRI when diagnosing coronary artery disease in patients.