MRI provides full field-of-view assessment of the ascending aorta, aortic arch, and descending aorta. With use of spin-echo techniques, static views of the cardiac structures and great vessels are assessed in a multi-slice format. Spin-echo MRI has a reported high sensitivity for detecting false lumens and intramural flaps associated with dissection, identifying areas of intraluminal thrombosis, and assessing potential rupture of dissecting aortic aneurysms into visceral spaces or pericardium. Contrast enhancement using special imaging sequences provides evaluation of the site of aortic tear into the intima and potential flow within the false lumen of the aortic dissection free of iodinated contrast administration.
Aortic insufficiency may also be assessed as one of the associated markers of aortic dissection, and the reported sensitivity and specificity of MRI for detecting aortic dissection were 98% for both type A and B dissection. In a comparison of transthoracic and transesophageal echocardiography, CT, and MRI for the diagnosis of aortic dissection, the primary limitations of MRI involved its inability to image significantly unstable patients, and its limited availability in emergency situations at all centers. Therefore, CT or transesophageal echocardiography may be indicated for evaluating aortic dissection, depending on the availability and expertise within specific hospitals.
Is it possible to assess intracardiac masses, both intramural and intracavitary, by MRI?
Tissue characterizations resulting from MRI-induced physical properties allow the assessment of intracardiac masses, with the greatest sensitivity in the atria and great vessels. There is somewhat less sensitivity, although greater specificity, for detecting intramural cardiac masses, due to the similar image intensity between tumors and myocardial tissues. MRI provides assessment of pericardial and pleural spaces and localization of masses extending into or arising from these structures. MRI and echocardiography are probably the two most sensitive techniques for determining the extent of intracardiac masses.