Authors

• Maja Hrabak — University of Zagreb School of Medicine, University Hospital Center Zagreb, Zagreb, Croatia
• Paar — University of Zagreb School of Medicine, University Hospital Center Zagreb, Zagreb, Croatia — ORCID: 0000-0002-0390-8466

Abstract

Cardiac computed tomography (CT) and magnetic resonance imaging (MRI) are infrequently used for assessment of valvular diseases, mainly because of limited temporal and spatial resolution of these techniques compared to echocardiography. However, in specific clinicaI situations they can of value in assessment of patients with aortic stenosis (AS). Using CT and MRI it is possible to depict valve morphology and motion with measurement of valve opening area. Valve calcifications can be detected using CT only, and on non-enhanced scan the amount of calcium can be quantified, with aortic calcium score ≥2065 Agatston units (AU) for men and ≥1274 AU for women being indicative of severe AS. CT examination is a standard pre-TAVR (transcatheter aortic valve replacement) procedure that enables precise measurement of aortic annulus, and evaluation of aortic bulb and aortoiliac morphology. Using MRI it is possible to detect the level of stenosis, and to evaluate myocardial remodeling response with precise measurement of biventricular volumes, ejection fraction and myocardial mass. Moreover using phase-contrast MRI it is possible to estimate maximum flow velocity through the valve with calculation of the maximum gradient. MRI-measured velocities are underestimated compared to echocardiography, and higher measurement error is present for velocities higher than 3,5 m/s. The main advantage of MRI over echocardiography is that it enables valve depiction in any plane. In AS patients using late gadolinium enhancement it is possible to detect replacement mid-wall fibrosis that is associated with worse prognosis after valve replacement, whereas diffuse myocardial fibrosis can be estimated using newer MRI techniques, such as T1-mapping and extracellular volume measurement. MRI scan is safe for patients with prosthetic valves, sternal wires and coronary stents. Using CT and MRI it is also possible to evaluate concomitant ascending aortic aneurysm, but aortic wall calcification can be detected using CT only. (1-3)

Keywords

cardiac computed tomography, cardiac magnetic resonance imaging, aortic stenosis

DOI

Literature

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